Resumo em Inglês:

ABSTRACT Nanoparticles have been widely used in recent years, to increase plant tolerance under stress conditions. In this study, TiO2 nanoparticles (NPs) (100 ppm) were applied to tomato plants exposed to drought, and the changes were investigated by physiological, biochemical and proteomic methods. It was determined that TiO2 NPs treatment increased the relative water content and decreased the proline and malondialdehyde content under drought conditions. As a result of proteomic analysis, it was revealed that the expression of a total of 132 proteins changed as a result of the comparison of the treatment groups (drought vs. control, control-100 vs. control, and drought-100 vs. drought). One of the most striking results of the study was the increase of the amounts of photosynthesis-related proteins and plasmamembrane intrinsic protein in both drought and control groups with TiO2 NP-treatmtent. The up-regulation of plasmamembrane intrinsic protein is very important for preserving the water potential under drought conditions. Taken together, it was observed that the water potential of the plant was preserved, lipid peroxidation decreased under drought conditions with the application of TiO2 nanoparticles, and the expression of proteins related to photosynthesis, energy and antioxidant system increased. This study provided clues to the molecular mechanism of the results of many studies available in the literature about nanoparticle treatment under stress condition and showed that TiO2 nanoparticles have a great potential to be used to increase the stress tolerance of tomato plants under drought conditions.

Resumo em Inglês:

ABSTRACT The objectives of this work were to use Sesuvium verrucosum to produce stable and mature compost and vermicompost and to evaluate their influence on the growth and production parameters of the Solanum lycopersicum L. crop. For the preparation of vermicompost, the earthworm Eisenia fetida (Savigny) was used. The proposed treatments were: T1 (negative control) [no organic fertilizer + urea], T2 (positive control) [bovine manure (100%) + urea], T3 (compost) [bovine manure (100%) + urea], T4 (compost) [S. verrucosum (25%) + bovine manure (75%) + urea], T5 (compost) [S. verrucosum (50%) + bovine manure (50%) + urea], T6 (compost) [S. verrucosum (75%) + bovine manure (25%) + urea], T7 (vermicompost) [bovine manure (100%) + urea], and T8 (vermicompost) [S. verrucosum (25%) + bovine manure (75%) + urea]. The results showed that all the treatments were stable, mature and rich in nutrients after 140 days. In general, treatments made from S. verrucosum showed a high pH (7.97–8.45) and electrical conductivity (3.83–8.85 dS m-1). Nonetheless, excluding T7, the treatments made from a proportion of 25% halophyte and 75% bovine manure (T8 and T4) achieved the highest morphological parameters in the different variables that were evaluated, as well as the highest yields compared to controls T1 and T2, followed by T3, T5 and T6, respectively. Therefore, it was concluded that S. verrucosum can serve as a stable and mature organic amendment, rich in nutrients, and that can be used to improve the growth and development of the S. lycopersicum crop.

Resumo em Inglês:

ABSTRACT The production of chili is seriously threatened by bacterial wilt incited by Ralstonia solanacearum in Pakistan. As the information about the distribution and prevalence of the disease and the pathogen is scarce, the present study was performed to ascertain the prevalence, occurrence and distribution of R. solanacearum in different regions of chili cultivation. The results showed differences in the incidence and prevalence of bacterial wilt all over the country. Overall, an incidence of 10% and prevalence of 76% of the disease was observed in the country. The highest incidence of bacterial wilt was observed in the province of Sindh whereas it was the lowest in Baluchistan. The prevalence of the disease followed the similar trend in the provinces. As regards agroecological zones, the highest incidence was recorded in Indus delta followed by sandy deserts whereas it was the lowest in western dry mountains. Almost the same tendency was observed regarding prevalence in the eight agroecological zones. In case of districts, the disease incidence was the maximum in Badin while it was the minimum in the district of Loralai. On the other hand, the disease prevalence was the maximum (100%) in the districts of Badin, Mirpurkhas, and Thatta and the minimum (60%) in the districts of Barkhan, Karak, and Loralai. Of the total 114 isolates of R. solanacearum, 81% were confirmed as Biovar 3 whereas the rest 19% isolates were identified as Biovar 4. The findings will help the farmers to design disease management programs accordingly to avert yield losses.

Resumo em Inglês:

ABSTRACT The decoupling factor (Ω) reflects the leading mechanisms responsible for canopy transpiration and allows to know the relevance of the control of stomatal or canopy conductance on transpiration (T). The Ω is strongly dependent on water availability and can be a good approach to describe how plants minimize excessive water loss by increasing the dominance of biotic factors that controls evapotranspiration under water deficit conditions. We provided an overview of how the Ω concept can be broadly used and applied for studying the sensitivity of evapotranspiration and water conservation potential of canopies under water deficit conditions. A decoupling condition indicates that, under water deficit, the increase of canopy resistance will not have control over the transpiration. Therefore, a structural context of the canopy in which predominantly uncoupled regions will have a lower capacity to reduce evapotranspiration and avoid water losses. Furthermore, because of the water deficit, stomatal closure restricts photosynthesis more than transpiration, and water use efficiency can be lower in decoupled canopies compared to more coupled ones. Yet, we summarized the characteristics that depict structural context predisposing coupled or decoupled conditions that can indicate the capacity of canopy/crop to reduce excessive water losses and maintain a high assimilation/transpiration relation under water deficit.e farmers to design disease management programs accordingly to avert yield losses.

Resumo em Inglês:

ABSTRACT The aim of this study was to select pear cultivars with production stability for the environmental conditions in the tropics. The design was in randomized blocks with 11 cultivars of pear, four replications and plots consisting of four plants. Between 2015 and 2019, the phenological were evaluated based on the beginning, full bloom, end and duration of flowering and harvest. The number and average fruit mass, yield per plant and estimated yield were also quantified. In the last year of evaluation, the quality of the fruits was quantified through the length and average diameter of the fruits, total titratable acidity, total soluble solids content and total soluble solids / total titratable acidity ratio. The data were submitted to the Scott–Knott grouping test and to quantify the divergence between cultivars was used the genetic distance. After detecting significant interaction between genotypes × environments, phenotypic stability of pear cultivars were analyzed by GGE Biplot methods for the estimated yield variable. The ‘Tenra’, ‘Triunfo’ and ‘Seleta’ cultivars are the most suitable for cultivation in regions with subtropical altitude climate. They are genetically similar, more adapted and stable, and have full or partial synchronized flowering for satisfactory productivity.

Resumo em Inglês:

ABSTRACT Integrated nutrient management (INM) is an environment friendly and ecologically adoptable approach of plant nutrition to sustain crop productivity and maintain soil fertility of fragile agricultural ecosystems. A three-year field experiment on saffron was conducted involving 12 fertilization regimes: control; urea (UN) = 100 kg·ha-1; poultry manure (PM) = 100 kg·ha-1; farmyard manure (FYM) = 100 kg·ha-1; PM50 + FYM50; UN75 + PM25; UN50 + PM50; UN25 + PM75; UN75 + FYM25; UN50 + FYM50; UN25 + FYM75; and UN50 + PM25+ FYM25. Results showed that PM alone and combined with 50% UN (UN50 + PM50) were effective compared to the controls in increasing the number of flowers (58%), flower dry weight (59%), stigma length (70%), dry weight of stigma (40%), number of daughter corms plant-1 (35%), and corm diameter (71%) of saffron over years. In addition, the same treatment combination increased corm weight (96%), corm yield (96%), and stigma yield (35%) over controls across the years. This treatment combination was followed by UN50 + PM25 + FYM25, while UN50 alone did not perform at par to the rest of the fertilization regimes. These results showed that UN50 + PM50 might be developed as potent strategy for boosting the growth and yield (stigma and daughter corms yield) of saffron in temperate climatic conditions.

Resumo em Inglês:

ABSTRACT Isoflavonoid composition of freshly harvested soy sprouts of six cultivars grown in Colombia was analyzed. Evaluations on the effect of storage time at 12 °C and exogenous application of the elicitor 2,6-dichloro isonicotinic acid (INA) were carried out to establish their influence in the ability of soy sprouts for synthesizing isoflavonoids. In addition, elicited and non-elicited sprouts of soy cultivar Soy SK-7 was assessed for total phenolic content and antioxidant activity according to the growth stage (VE, VC, and V1) and tissues (cotyledon-epicotyl and hypocotyl-root). Isoflavonoid content and antioxidant capacity were dependent on the cultivar, growth stage, tissue, and storage time at 12 °C. Growth stages VE and V1 and the hypocotyl-root exhibited the highest total phenolic content and antioxidant activity. In general, 6”-O-malonylgenistin, daidzin and genistin were the major constituents in the cultivars. Soy SK-7 and Panorama 358 displayed the highest amounts of 6”-O-malonylgenistin (155.9 µg/g) and daidzin (83.5 µg/g), respectively. Results showed that the isoflavonoids and phenolic contents and antioxidant activity were significantly increased by application of INA. This information can be useful to produce soybean sprouts with increased amounts of bioactive compounds and improved response to abiotic and biotic stresses.

Resumo em Inglês:

ABSTRACT Ryegrass and turnip are weeds that cause high yield losses when infesting barley, thus requiring adequate management. In this context, the aim of this study was to evaluate the selectivity of different herbicide treatments and weed control in the barley crop, cultivar BRS Cauê. Two field experiments were conducted in randomized blocks, with four replications. The treatments used were: pendimethalin (800 g·ha-1), sulfentrazone + diuron (175 + 350 g·ha-1), and imazaquim (150 g·ha-1 of a. e.) applied pre-emergence; and iodosulfuron (3.5 g·ha-1), pyroxsulam (18 g·ha-1), metsulfuron-methyl (3.96 g·ha-1), 2,4-D (670 g·ha-1 of a. e.), clodinafop-propargyl (48 g·ha-1), bentazon + imazamox (600 + 28 g·ha-1), saflufenacil (49 g·ha-1), bentazon (720 g·ha-1), carfentrazone-ethyl (120 g·ha-1), and imazamox (42 g·ha-1) applied post-emergence, with two controls (one weeded and the other infested). The use of the herbicide imazaquim caused high levels of phytotoxicity in barley. Gas exchange was less responsive to herbicide applications in relation to barley phytotoxicity and productivity. Clodinafop-propargil showed the best control of ryegrass, while the herbicides iodosulfuron, pyroxsulam, metsulfurom-methyl, 2,4-D, bentazon + imazamox, saflufenacil, bentazon, carfentrazone-ethyl, and imazaquim showed high efficiency in the control of turnip species. Imazaquim caused reduction of up to 74.7% in barley grain yield. On the other hand, iodosulufuron and piroxsulam allowed the highest grain yields of the barley cultivar, BRS Cauê, by promoting partial control of ryegrass and total control of turnip species, followed by clodinafop-propargyl and metsulfuron-methyl, which controlled ryegrass and turnip, respectively, allowing an increase in yield grain in relation to the infested control.

Resumo em Inglês:

ABSTRACT Identifying Coffea arabica cultivars that are more efficient in the use of nitrogen is an important strategy and a necessity in the context of environmental and economic impacts attributed to excessive nitrogen fertilization. Although Coffea arabica breeding data have a multi-trait structure, they are often analyzed under a single trait structure. Thus, the objectives of this study were to use a Bayesian multitrait model, to estimate heritability in the broad sense, and to select arabica coffee cultivars with better genetic potential (desirable agronomic traits) in nitrogen-restricted cultivation. The experiment was carried out in a greenhouse with 20 arabica coffee cultivars grown in a nutrient solution with low-nitrogen content (1.5 mM). The experimental design used was in randomized blocks with three replications. Six agromorphological traits of the arabica coffee breeding program and five nutritional efficiency indices were used. The Markov Chain Monte Carlo algorithm was used to estimate genetic parameters and genetic values. The agromorphological traits were considered highly heritable, with a credibility interval (95% probability): H2 = 0.9538 – 5.89E-01. The Bayesian multitrait model presents an adequate strategy for the genetic improvement of arabica coffee grown in low-nitrogen concentrations. Coffee arabica cultivars Icatu Precoce 3282, Icatu Vermelho IAC 4045, Acaiá Cerrado MG 1474, Tupi IAC 1669-33, Catucaí 785/15, Caturra Vermelho and Obatã IAC 1669/20 demonstrated greater potential for cultivation in low-nitrogen concentration.

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ABSTRACT Hydroponic is a technique of growing plants in a soilless medium by using a sponge, rock wool, hydroton, coconut coir, and perlite as an alternative for crop production systems. Recently, biochar has been reported to be a potential substrate for hydroponic cultivation techniques due to its physicochemical properties which can help increase vegetable production. A greenhouse study was conducted to investigate the effect of biochar as hydroponic substrate on the growth, colour and nutritional content of red lettuce (Lactuca sativa L.). This study utilized the nutrient film technique (NFT) hydroponic system and was conducted using a randomized complete block design with five treatments, including T1 (hydroton only), T2 (perlite only), T3 (palm kernel biochar), T4 (palm kernel biochar + hydroton), and T5 (palm kernel biochar + perlite). Data analysis revealed the treatment, which consists of both palm kernel biochar and hydroton (T4) resulted in a significant increase in plant growth and yielded the highest plant height (19.86 cm), leaf width (14.16 cm), plant fresh weight (68.19 g), and dry weight (8.29 g). The leaves nutrient content (N, P, K, Mg, Ca) of red lettuce grown in palm kernel biochar and hydroton (T4) substrates suggested the presence of optimal growth conditions for ensuring optimum yield with high quality. The application of palm kernel biochar and hydroton (T4) as substrate also showed a higher lightness value (L* = 66.67). Besides, the methanolic leaf extracts from the red lettuce grown in palm kernel biochar and hydroton (T4) showed the highest bioactive metabolite content. In addition, the application of palm kernel biochar (T3) as a hydroponic substrate decreased the algal density in the nutrient solution. In conclusion, the combination of palm kernel biochar and hydroton as a substrate was observed to be the best in enhancing the growth performance, colour, and nutritional content of red lettuce (Lactuca sativa L.), and it is therefore recommended to be used as the growth substrate in the NFT system.

Resumo em Inglês:

ABSTRACT Coffee seedlings are commonly produced on substrate composed of a mixture of soil and cattle manure, supplemented with chemical fertilizers. Alternatives to reduce production costs and produce seedlings of greater quality and health include the use of commercial organic substrates, which require less handling. The use of beneficial microorganisms such as arbuscular mycorrhizal fungi (AMF) can be considered a good alternative for production of more vigorous coffee seedlings. The main goal of this study was to evaluate the effect of the inoculation of AMF isolates on coffee seedlings development in a commercial organic substrate (based on coconut fiber) and conventional substrate (mixture composed of soil and cattle manure compost). Ten AMF were tested: Rhizophagus irregularis, Glomus macrocarpum, Claroideoglomus etunicatum, Rhizophagus clarus, Glomus spp., Gigaspora margarita, Acaulospora morrowiae, Acaulospora scrobiculata, Acaulospora spp., and Dentiscutata heterogamma. Plant growth, shoot P content, mycorrhizal colonization, extraradical mycelium length, phosphatase activity, and photosynthetic pigments were evaluated. The effects of mycorrhization depended on both the inoculated fungal species and the substrate for seedling cultivation. Inoculation of G. margarita, Acaulospora spp., and Glomus spp. in the conventional substrate conferred the best growth plant responses, increasing shoot biomass by 160 to 320%. In the commercial substrate, the most efficient AMF were R. clarus, Glomus spp, A. morrowiae and A. scrobiculata, with up to 149% of shoot biomass increase. The commercial organic substrate and the inoculation of some of the AMF isolates were highly beneficial to coffee seedlings development and can replace the use of the conventional substrate. These results open new opportunities for the use of AMF as an inoculant to improve coffee seedling production in commercial organic substrates.

Resumo em Inglês:

ABSTRACT The aim of the present study was to investigate the effect of the grape cultivar combined with rootstocks on yield and fruit traits of grapevine in the São Francisco Valley, in the Northeast of Brazil. The experiment was carried out over eight growing seasons (2014 to 2018) in Petrolina, Pernambuco, Brazil. The treatments were represented by five seedless table grape cultivars (A Dona, Arizul, Marroo Seedless, BRS Clara, and BRS Maria Bonita) and six rootstocks (IAC 313, IAC 766, IAC 572, SO4, Harmony, and Paulsen 1103) in a randomized block experimental design with three replicates. Principal component analysis showed that 59.2% of the variation found in the data was related to principal component (PC) 1 (42.76%) associated with the number of bunches and berry weight, length, and diameter variables; and PC 2 (16.4%) correlated with yield per vine. The yield per vine showed a significant positive correlation with number of bunches, bunch length, soluble solids content, and titratable acidity, and showed a negative correlation with berry length. A Dona and Marroo Seedless grapes had the highest yield, regardless of the rootstocks they were grafted onto, whereas BRS Clara had high values for soluble solids content and titratable acidity and a balanced SS/TA ratio. In contrast, BRS Maria Bonita had the lowest yielding grape cultivar, although it had the greatest bunch weight and berry length. The rootstocks affected the agronomic performance of the table grape cultivars in most variables, depending on the effect of different grape cultivars × rootstock combinations.

Resumo em Inglês:

ABSTRACT The Mexican bean weevil Zabrotes subfasciatus (Boheman) (Coleoptera, Chrysomelidae, Bruchinae) has become one of the main pests of common bean (Phaseolus vulgaris L.) (Fabaceae) worldwide. The association of resistant bean varieties with botanical insecticides has a great potential for controlling the pest, but it has been little studied so far. Therefore, the present study aimed at selecting a botanical insecticide and evaluating its combined effect with an arcelin-bearing common bean resistant genotype against Z. subfasciatus. We evaluated three botanical insecticides, the rotenone-based Roteline® and the neem-based NeemSeto® and NeemPro®, on the development of the insect. NeemPro® was the most effective, presenting ovicidal effect and prolonging egg-to-adult period, being selected for the following bioassay. Then we evaluated the effect of NeemPro® combined with the resistant common bean genotype IAC 818 (RAZ-59) on some biological parameters of the pest. The most severe effects on Z. subfasciatus were caused by the resistant genotype. However, significant effects in some parameters of the pest were also verified for the botanical insecticide and for its combination with this resistance type/trait in the conditions of the experiment.

Resumo em Inglês:

ABSTRACT Cut flowers are known for their beauty and variety of colors and shapes. However, they quickly lose their commercial value after harvest due to the intensity of physiological processes that result in senescence. This work aimed to evaluate the effects of bioregulators on the postharvest longevity of lisianthus flowers (Eustoma grandiflorum cv. Flare Deep Rose) by applying a pulsing solution for 24 hours. The treatments consisted of 70 µM of 6-benzylaminopurine (BAP); 5 µM of gibberellic acid (GA3); 10 µM of abscisic acid (ABA); and deionized water as control. Turgidity, floral development, total and reducing sugar contents, respiration rate, colorimetry, anthocyanin contents, phenolic compound contents, and phenylalanine ammonia-lyase (PAL) enzyme activity were evaluated. BAP resulted in higher PAL enzyme activity and greater accumulation of anthocyanins when compared to the other treatments. The treatment GA3 resulted in the highest increase in respiration rate during storage, causing a larger number of inflorescences with wilting and senescence symptoms, reducing postharvest quality. The treatment ABA resulted in greater turgidity and floral opening, delayed senescence, and maintained respiration rate due to the greater total sugar contents on the fourth and 12th days. The application of ABA contributes to the maintenance of inflorescence quality for lisianthus at postharvest, but it reduces anthocyanin contents, providing petals with lighter colors.

Resumo em Inglês:

ABSTRACT Black node disease is one of the most limiting biotic stresses affecting bean production in the Andean countries. The objective of the study was to evaluate the degree of resistance to Boeremia noackiana against genotypes of Phaseolus vulgaris, Phaseolus polyanthus, and their interspecific crosses using two disease evaluation methods (pathogenicity test in the greenhouse and in vitro) to contribute the generation knowledge towards the use of durable resistance. Black node disease severity was assessed using a descriptive scale and the leaf detached method under greenhouse and in-vitro conditions. The results of the study confirmed the isolate Ascochyta ASC 001 pathogenicity, allowing the different genotypes to be discriminated. A contrasting resistance response was confirmed for the two methodologies used to estimate severity. Accession G35575 (P. polyanthus) was the most resistant whereas NCB 226 (P. vulgaris) was the most susceptible. Regional cultivars Simijaca and Cabrera, together with Cargamanto Blanco and Bacata, showed fluctuations in their reaction to the disease from intermediate to susceptible. Resistance was confirmed in the interspecific crosses of the ASC series, which can be an alternative in breeding programs for durable resistance in common beans. The percent leaf area affected was identified as a variable that can be easily assessed, and the processing and analysis of digital images in vitro avoided the use of destructive sampling. This technique is a fast, useful, and economical tool for this type of studies, as it provides the possibility of accelerating the selection of genotypes with resistance.

Resumo em Inglês:

ABSTRACT The immediate need for the increase in wheat production to meet the future world demand, associated with the occurrence of drastic climatic events, such as drought, makes it necessary to develop drought-resilient genotypes. The aims of this work were to evaluate the use of drought-tolerance indices for the selection of wheat genotypes, to compare the genetic gains in grain yield using different selection strategies by means of a multi-trait index, and to select superior drought-tolerant wheat genotypes. The total of 31 tropical wheat lines was evaluated in two experiments. Five agronomic traits were accessed. The grain yield data from the stress and nonstress experiments were used to obtain five drought-tolerance indices. The data were subjected to mixed model analysis, and four selection scenarios were designed. There was a significant effect of genotype for all traits. The inclusion of drought-tolerance indices in the selection index provided superior genetic gains in drought condition. Seven lines were selected due the high frequency of favorable alleles for drought-tolerance and other important agronomic traits. Drought-tolerance indices are appropriate for characterizing the response of wheat genotypes to drought-stress. The inclusion of drought-tolerance indices along with agronomic traits in multi-trait selection strategies provides for superior gains in grain yield compared to the non-inclusion of the indices.

Resumo em Inglês:

ABSTRACT For proper disease management, accurate diagnosis of the pathogen is essential. Therefore, in the present study Ralstonia solanacearum causing bacterial wilt of chili was characterized to determine the distribution of biovars of the bacterium in the eight agroecological zones with varying climatic conditions and edaphic factors. Among all the 114 isolates of R. solanacearum, 77% showed mucoid growth while 23% isolates gave non-mucoid growth. Similarly, the isolates with mucoid growth were found positive for hypersensitivity response (HR), while those with non-mucoid growth showed negative HR. All the isolates grew well at 37 °C, while none of the isolates produced its colony at 41 °C. All the 114 isolates of R. solanacearum showed positive responses for all the biochemical tests used for confirmation of the bacterium. Out of 114 R. solanacearum isolates, 81% were identified as Biovar III while the remaining 19% were recognized as Biovar IV. Biovar III constituted 37 and 70% in the provinces of Punjab and Sindh, respectively, while Biovar IV formed 19 and 30%. On the other hand, in Khyber Pakhtunkhwa and Balochistan, only Biovar III was recorded. Similarly, Biovar III was observed from all the eight agroecological zones of the four provinces of the country and found to be predominant. On the other hand, Biovar IV was recorded from four agroecological zones located in the provinces of Punjab and Sindh. All the isolates yielded a 750-bp band that corresponded to R. solanacearum. It is concluded that Biovar III is widely prevalent in the country warranting stringent control measures.

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ABSTRACT Apple cultivars in Korea have been experiencing poor fruit sets due to early spring low temperatures and global warming. Therefore, the present study aimed to investigate the effects of temperature on fruit setting and to select apple cultivars tolerant to extreme temperatures based on the temperature response of their pollen. The effect of temperature on pollen germination percentage (PGP) and on pollen tube length (PTL) was determined under laboratory conditions using the pollen of ten apple cultivars. The two parameters were evaluated using a pollen germination medium, at temperatures ranging from 5 to 45 °C, at 5 °C intervals. The temperature variations considerably affected pollen germination and tube growth in all the examined cultivars. The maximum pollen germination percentage ranged from 61.5 (“Green Ball”) to 99.9% (“Shinano Gold”) with a mean of 85.2%, whereas the maximum pollen tube length ranged from 716.5 (“Tsugaru”) to 989.8 µm (“Arisoo”) with mean of 855.1 µm. There were differences in the cardinal temperatures (Tmin, Topt, and Tmax) of PGP and PTL between cultivars. Mean cardinal temperatures Tmin, Topt, and Tmax computed using the modified bilinear model were 4, 27.7, and 44.9 °C and 6.3, 28.6, and 43.7 °C for PGP and PTL, respectively. Our preliminary results may be used to select low-temperature and global warming-friendly apple cultivars for farmers and can also be exploited to develop temperature-tolerant apple cultivars during flowering.

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ABSTRACT Soil compaction negatively impacts soil physical functions, affecting root growth and crop yield. This study aimed to evaluate different soybean cultivars’ agronomic and physiological performance as a function of compaction in Rhodic Ferralsol under no-tillage (NT) with a clay loam texture in the Brazilian Cerrado biome. The experiment was implemented in Rio Verde, Goias state, central Brazil. The experimental design was a randomized block with a 3x2 factorial scheme with six replications. The first factor corresponded to three soybean cultivars from different maturity groups (MG) identified as super-early (MG = 6.2); early (MG = 6.8), and medium (MG = 7.9). The second factor was the cultivation in compacted and uncompacted soil. The experiment evaluated the soil physical properties: bulk density, total porosity, water content at matric potential -6 kPa, aeration capacity and water and air holding capacity in 0.0-0.1 and 0.1-0.2 m layers, agronomic and physiological traits (gas exchange). Soil compaction negatively affected the agronomic traits of soybean cultivars, with better performance of the medium cycle cultivar. Net photosynthesis, stomatal conductance, and transpiration rates were reduced up to 50% under compaction and were not influenced by cultivars. Our findings suggest that soil compaction negatively affected the performance of soybean cultivars with lower maturity groups reflecting in lower plant height, shoot and root dry mass, number of pods and grain yield. The choice of soybean cultivars with a longer cycle can be an alternative to minimize the adverse effects of soil compaction.

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ABSTRACT Brazilian semi-arid tropical is responsible for the production and export of fine table grapes, but the demand for phosphate fertilizers and other agricultural inputs increases the cost of production and threatens local water bodies by leaching of phosphorus (P). The objectives of this study were to quantify the organic and inorganic fractions of P and to determine chemical and microbiological attributes related to its mineralization in soils cultivated with vines in São Francisco Valley. It was hypothesized that P fractions and microbial activity would increase in areas fertilized with phosphate. Soil samples from vines were collected in cultivated areas and in fallow systems. P fractionation, macro-elements analysis, microbial biomass phosphorus (Pmic), and phosphatase enzyme activity were determined and correlated with each other and with the total proportion of synthesized glomalin. In both treatments, the inorganic P fractions exceeded the organic ones, and the total phosphorus available in those soils was associated with the most recalcitrant fractions, reducing risks of leaching of this element and contamination of water bodies. Pmic was higher in the winery areas due to the presence of phosphate fertilizers and organic matter, hence the activity of alkaline phosphatase enzymes and the production of total glomalin increased respectively in three and four evaluated areas, indicating that P-mineralized bacteria and arbuscular mycorrhizal fungi have been positively affected by the current agricultural system.

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ABSTRACT Vines are highly responsive to agricultural management techniques, such as training systems. Three training systems, i.e., conventional, high, and double training, for the ‘Niagara Rosada’ vine were studied considering aspects related to the yield, physicochemical, and antioxidant characteristics of the grapes. The experiment was carried out during two seasons (2017 and 2018), and the vines grafted on IAC 572 Jales. The training systems did not influence the fruit production per vine and yield of the ‘Niagara Rosada’ table grape, but some improvements were observed, such as a greater number of berries per bunch in vines managed in the conventional training systems and a higher fresh mass of berries when cultivated in the high and double training systems. Grapes from the double training system had higher soluble solids contents, an important sensorial characteristic in table grapes. The high training system, in turn, provided ‘Niagara Rosada’ table grapes with a greater content of bioactive compounds (e.g., phenolic compounds, flavonoids, and anthocyanins) and antioxidant activity.

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ABSTRACT Investigating the physiological potential of seeds and genetic divergence between families is essential to identify promising materials for the generation of improved populations. This study was undertaken to examine the germination potential and estimate genetic divergence between Passiflora full-sib families (FSFs) based on physical and physiological seed traits. The experiment was consisted of 86 FSFs from the first cycle of recurrent selection for resistance to the cowpea aphid-borne mosaic virus. Seeds were evaluated for 19 physical and physiological traits. Dissimilarity estimates were obtained by generalized Mahalanobis distance, and the method unweighted pair group method with arithmetic mean was employed for cluster formation. The FSFs showed high germination potential and seed vigor, with mean of 92.4%, 5.68 e 5.81 cm for germination, germination speed index (GSI) and shoot length of seedlings, respectively. Cluster analysis resulted in four groups formed, being Group I composed by 68 FSF more the control Passiflora edulis. The trait 1,000-seed weight (TSW) was the trait that most contributed to explaining the dissimilarity between families, with 31.9%. The trait GSI (physiological), TSW (physical), as well as traits provided by the GroundEye® system (CIELab-b, hue, and circumference of seeds), were efficient in determining genetic divergence detected between the families of passion fruit. These traits can be taken as a basis in the selection of genotypes with higher physiological seed quality.

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ABSTRACT Nasturtium (Tropaeolum majus) is an ornamental and medicinal plant that has edible flowers. Drought and salt stress decrease flower production and quality, including affecting sugar metabolism and ethylene production. Ethylene can accelerate the nasturtium senescence process, decreasing its postharvest quality. The use of polyamines, mainly spermine, may be a strategy for reducing the harmful effects of these stresses on the metabolism of sugars and phenolic compounds and for decreasing the production of ethylene, which accelerates senescence, in nasturtium flowers. Therefore, the objective here was to evaluate the role of spermine application on sugar and phenolic compounds and on ethylene production in nasturtium flowers grown under drought and salt stress. Two experiments were performed in isolation and at the same time in order to achieve this. Spermine down-regulated ethylene production and up-regulated the content of sugars and phenolic compounds on nasturtium flowers grown under drought and saline stress. Sugars and phenolic compounds down-regulated ethylene production in nasturtium flowers. Spermine can be used to mitigate the harmful effects of drought and salt stress on nasturtium flowers by increasing sugar and phenolic compounds and decreasing ethylene production.

Resumo em Inglês:

ABSTRACT In view of the current situation of black soil degradation, straw return as an important conservation tillage measure has been extensively promoted. Based on 15N tracing technology, this paper carried out experiments of different straw returning modes, including CK (conventional fertilizing tillage with straw-free returning), straw mulching (i.e., M), straw mixed with topsoil (i.e., T), and straw deep incorporation (i.e., D), to explore the influence of straw returning on the distribution and stability, and the carbon and nitrogen content of water-stable aggregates in black soil, and to analyze the distribution and stability of aggregates on the carbon and nitrogen content of aggregates. The results showed that the macroaggregate content, mean weight diameter (MWD) and geometric mean diameter (GMD) of the returned soil layers were 16.53-84.65%, 16.73-128.73% and 23.47-97.14% higher than those in CK, respectively. The contents of organic carbon, total nitrogen and 15N accumulation of aggregates in the straw-returning soil layer were 6.38-23.55%, 8.65-31.19% and 13.52-150.19% higher than those in CK, respectively. Pearson correlation analysis and redundancy analysis showed that the content of macroaggregates and stability of aggregates were positively correlated with the carbon and nitrogen contents. In conclusion, straw return significantly improved soil structure characteristics and carbon and nitrogen content. The results of this study provided a theoretical basis and technical guidance for farmland soil improvement in black soil areas, and selected an appropriate straw returning mode according to local soil conditions to maximize the effect of straw returning.

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ABSTRACT The aim of this study was to test the hypothesis that lemongrass and thyme essential oils (EOs) reduce Botrytis cinerea development and control gray mold in ‘Italia’ grapes. The fungitoxicity evaluation was performed by EOs direct contact with the pathogen, in culture medium, and by exposure to the EOs volatile phase. Individualized rachis berries were inoculated by subcuticular injection of a conidia suspension and after 4 hours sprayed with the EOs of lemongrass and thyme (100 to 1,000 mg·L-1), or oils blend (500 mg·L-1 thyme + 100 mg·L-1 lemongrass), and then stored at 25 °C / 75% relative humidity. To verify the possibility that the EOs protect the fruit against B. cinerea, the berries were sprayed with 400 mg·L-1 of each EOs or with the blend (200 mg·L-1 thyme + 200 mg·L-1 lemongrass), and after 24 hours inoculated with B. cinerea. On clusters, thyme (800 mg·L-1) and the blend (500 mg·L-1 thyme + 100 mg·L-1 lemongrass) were sprayed 4 hours after inoculation and then stored at 25 and 1 °C. The disease incidence and severity were analyzed, as well as the fruit quality attributes. EOs had antimicrobial effect, in-vitro, incorporated into the culture medium or by volatilization against B. cinerea. On detached berries, the thyme and oil blend reduced the gray mold severity when inoculated 4 hours before spraying. In clusters, thyme at 800 mg·L-1 significantly reduced the gray mold development only in fruits kept at 1 °C, without impairing the clusters quality, which could be an alternative for the disease management in postharvest.

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ABSTRACT Synthetic insecticides used in the management of the mealybug Diaspis echinocacti (Bouché, 1833) (Hemiptera: Diaspididae) can contaminate co-products from this plant. The use of Agave extracts and/or mineral oil is a sustainable alternative to reduce the residual effect of these chemicals in the palm production chain. The objective here was to determine the effectiveness of Agave genotype extracts applied alone or mixed with mineral oil against the cactus scale mealybug D. echinocacti. Two experiments were carried out to achieve this goal. The first one aimed to select the most promising Agave genotype extract concentration (CL80) to kill 80% of the first instar mobile nymphs of D. echinocacti (Experiment 1), and the second to determine the effectiveness of the selected extract against nymphs, pupae, and adults of different ages of this mealybug in laboratory and greenhouse (Experiment 2). The extract of the genotype Agave fourcroydes cv. Cabinho with lethal concentration (LC80) of 10.9 mL/10 mL is the most efficient in causing mortality of D. echinocacti. The lethal concentration of the A. fourcroydes cv. Cabinho killed 80% of the first instar motile nymphs and more than 74% of the nymphs, pupae, and adults of different ages of D. echinocacti in the laboratory and greenhouse followed by Agave sisalana cv. Tatuí 3. Furthermore, the mortality of this scale mealybug was higher with applications of mineral oil (Assist), alone or mixed with sisal extracts.

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ABSTRACT Off-season corn is the main form of corn crop in Brazil. During the maturation stage of the plants, the availability of heat is reduced, and frosts may occur. The aim of this study was to determine the effect of row spacing reduction and population increase in corn cultivars on agronomic parameters and leaf burn caused by moderate frost to minimize the effects of abiotic stresses on grain yield. We used a randomized block experimental design in a 3 × 4 × 2 factorial scheme: row spacing of 40, 80, and 120 cm; populations of 25,000, 43,750, 62,500, and 81,250 plants·ha-1; and Fort cultivars (semi-erect leaves, and early cycle) and DKB 950 (erect leaves and super-early cycle). Three field trials were conducted in the state of São Paulo, Brazil, from mid-March. The spacing reduction provided antagonistic effects on yield with different response from hybrids in the most of locations. Population density increased plant height, stalk lodging and grain yield; populations ≥ 68,000 plants per hectare provided the best yields. Specific determinations were made in the area where moderate frost occurred; higher leaf area index and less Brix in the stem at 40 cm spacing were obtained, but without any increase in plant dry mass and grain yield. The hybrid with erect leaves was more adapted to the reduced spacing and exhibited less leaf damage by frost. The effect of frost was greater at reduced row spacings; therefore, this factor should be considered when selecting the population arrangement of off-season corn in areas with frequent frost.

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ABSTRACT Corn, Zea mays (L.), is one of the most expressive crops in Brazil, due to its wide-ranging uses as animal feeding, biofuel production or used for human consumption. However, there is a huge gap between the actual yield and the natural yield potential of the crop, due to insects’ attack. Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) is a key corn pest in seed producing regions, due to its attack on corn ears. Plant resistance is a valuable tool for Integrated Pest Management systems and may maintain insect populations at a level that is below an economic or damage threshold. This study aimed to evaluate the biological performance of L. zonatus in different corn genotypes, under laboratory conditions, searching for possible characterization of antibiosis/antixenosis. To achieve this goal, ten nymphs (1st instar) were transferred to polyvinylchloride (PVC) ring containing a corn ear (R6) of each genotype. Each ring corresponded to one replicate, for a total of five replicates per genotype in a completely randomized design. The parameters assessed included the duration of each instar, nymphal period, nymphal survival (%), percentage of mortality of each nymphal stage, adult longevity, and adult weight. The results demonstrate that XB 8018 Bt, 30F53, IAC Airan, XB 8030 and 30F53 YHR genotypes reduced the mean survival and caused high mortality of L. zonatus nymphs at the second instar (above 75.00%) indicating the occurrence of antibiosis/antixenosis. The higher mortality rates were observed at the second nymphal instar.

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ABSTRACT Plant-growth-promoting bacteria of the genus Azospirillum and Herbaspirillum can improve crop yields of maize in tropical environments. The main mechanism proposed for its promotion is related to the auxins produced by these species. The aim of this study was to compare the maize growth response of inoculation using two species, Azospirillum baldaniorum Sp245 (Ab-Sp245) and Herbaspirillum seropedicae ZAE94 (Hs-ZAE94) during the initial growth under controlled conditions. A pot experiment was conducted with five harvests measuring bacterial counts, root morphology, biomass, and nitrogen content, and soluble metabolites for 38 days. Depending on the harvest period, a differential growth response between the two strains test was compared to the control. Plants use the bacterium applied to improve nitrogen acquisition and transform it into higher biomass and nitrogen accumulation, especially for Ab-Sp245. On the other side, Hs-ZAE94 altered the soluble metabolites resulting in higher NO3-, NH4+, and N-amino and lower soluble fractions compared to Ab-Sp245 and the control. The observed plant-bacteria interaction is closely fine-tuned and regulated by the strain used and differences in growth promotion effects cannot solely attributed to the root morphology.

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ABSTRACT Fusarium is the main disease of black pepper (Piper nigrum L.) in Brazil, and grafting using resistant rootstocks can be a sustainable management strategy. Several wild Piper species have been considered resistant to infection. However, further studies on the grafting process are needed to generate a safe technical recommendation for farmers. This research was carried out with the objective of evaluating the initial compatibility of grafting through the interaction between two techniques (top cleft and side cleft) and six rootstocks. The P. nigrum ‘Bragantina’ was grafted onto four wild Piper species (Piper aduncum Link, Piper tuberculatum Jacq., Piper marginatum Jacq., and Piper hispidum Kunth) and two black pepper cultivars (‘Kottanadan Broto Branco’ and ‘Bragantina’-homograft). P. tuberculatum and P. marginatum were incompatible with P. nigrum ‘Bragantina’ in the two grafting techniques. There was total suppression of leaf development with incompatible rootstocks inside cleft grafting. The wild rootstocks had twice as many shoots at the base of the seedling than the cultivars in the top cleft grafting. Side cleft grafting was able to suppress by half the shoots at the base of the rootstock, while the aerial part was maintained. Top cleft grafting provided greater survival, shooting, and leaf emission, which was more evident when using P. aduncum species as rootstock, reaching practically twice the shooting (59.3%) in comparison with the side grafting (30.6%). Therefore, the top method and the use of P. aduncum as rootstock for the production of grafted black pepper seedlings is recommended.

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ABSTRACT The intercropping of corn with forage grasses increases soil cover and may improve soil structural quality. The objective of the study was to evaluate the soil structural properties and the development of second-crop corn intercropping with forage grasses under no-tillage system. The experiment was carried out in an area of Sítio Santo Antônio, located in the municipality of Borrazópolis, Paraná state, Brazil, on a Red Latosol with a very clayey texture. The experiment consisted of five treatments: corn + Urochloa brizantha cv. Marandu (T1), corn + Urochloa brizantha cv. Piatã (T2), corn + Urochloa brizantha cv. Xaraés (T3), corn + Urochloa ruziziensis (T4), and non-intercropping corn (T5). In the corn crop, the following characteristics were evaluated: plant height, first ear in insertion height, stem diameter, corn yield, dry mass of corn straw mulch, dry mass of grasses shoots and dry mass of grasses root. Dry mass of the aerial part and roots of the grasses were evaluated. In the 0–0.10 and 0.10–0.20-m soil depth, soil physical properties were also determined: tensile strength and friability, stability of aggregates, bulk density and total porosity, and degree of compactness. The treatments of corn in intercropping with grasses showed positive results regarding the stability of aggregates, reduction of bulk density and increase of total porosity in the 0–0.10-m soil depth. The intercropping of corn + U. ruziziensis showed the lowest values of degree of compactness and higher production of dry mass of the aerial part.

Resumo em Inglês:

ABSTRACT One of the most effective and cost-efficient methods to manage plant parasitic nematodes is to use resistant cultivars. However, little information on the resistance of commercial okra cultivars grown in the country was available. Therefore, nine okra cultivars were evaluated for their comparative resistance against Meloidogyne incognita, the most damaging root-knot nematode. None of the tested okra cultivars showed high level of resistance. However, three cultivars viz. Pusa Swami, PB Selection and Green Star appeared as moderately resistant. Sabz Pari, Neelum and Tulsi were found moderately susceptible to the nematode. Two cultivars i.e. Ikra-1 and Ikra-2 were susceptible and Arka Anamika was highly susceptible. The okra cultivars differed significantly in their growth parameters depending on their response to M. incognita. Moderately resistant cultivars sustained little damage as compared to moderately susceptible or susceptible cultivars while the highly susceptible cultivar suffered the maximum damage by the nematode. Significant differences in the numbers of galls, eggmasses and reproductive factors of M. incognita on the nine okra cultivars were also observed. The highest numbers were found on Arka Anamika, followed by Ikra-1 and Ikra-2. The lowest numbers were found on the moderately resistant cultivars, followed by the moderately susceptible ones. High and positive correlations between the number of galls and eggmasses and the decreases in growth metrics were found using linear and non-linear regression analysis.

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ABSTRACT It is necessary to diversify the scion/rootstock combinations for Persian lime cultivation, notably under tropical rainfed conditions. Therefore, in this work we evaluated the performance of a new cultivar, BRS EECB IAC Ponta Firme, up to six years after planting on 26 citrus rootstocks under Aw climate in northern São Paulo state, Brazil. Thirty single-tree randomized replications of each rootstock were evaluated without irrigation at 1,000 trees·ha-1. Lemon-type, followed by mandarin rootstocks induced the largest tree size and higher mean yield, probably related to the higher drought tolerance. The true dwarfing rootstocks of Flying Dragon trifoliate orange and Lindcove citrandarin were highly drought-intolerant, but, in addition to Swingle citrumelo and four other citrandarins, they did not present huanglongbing-symptomatic trees during the evaluation period under strict control of the insect vector. Overall, BRS EECB IAC Ponta Firme fruit quality was minimally influenced by the rootstock cultivar and fulfilled the requirements for both domestic and export fresh fruit markets. Due to superior production efficiency associated with high yield in relation to the canopy size, the Goutoucheng sour orange, BRS Ary, BRS Bravo and BRS Matta hybrids were selected as potential rootstocks of rainfed BRS EECB IAC Ponta Firme lime under Aw climate (tropical savannah) conditions.

Resumo em Inglês:

ABSTRACT Anthracnose caused by Colletotrichum horii is one of the most important diseases in the persimmon tree. This study aimed to determine the influence of environmental variables on conidia germination, mycelial growth, and infection in persimmon fruit and shoots/twigs. The germination was quantified at 10, 15, 20, 25, and 30°C, with 6, 12, and 24 hours of wetness period. The effects of the same temperatures were also evaluated for mycelial growth, sporulation, and infection on ‘Fuyu’ fruit. The infection on shoots/twigs were quantified at 5, 10, 15, 22, 25, 27, and 35°C. The conidia germinated at all temperatures and wetness combinations, except at 10°C, with 6 hours of wetness. At 24 hours of wetness, the optimal temperature for conidia germination was 21.3°C. The optimal temperature for mycelial growth ranged between 21.7 to 24.3°C. The optimal temperature for lesion growth on fruit was 25.7°C; at 25°C, the incubation period was of two days, and the latent period lasted 12 days. On shoots/twigs, the temperature of 35°C anticipated in two days the onset of symptoms and 5-10°C delayed in eight-10 days the onset of symptoms in relation to temperature of 25°C. In nonlignified shoots, C. horii can cause symptoms from 15 to 35°C. In lignified twigs, C. horii was able to cause symptoms from 5 to 35°C. Because of the incidence and disease progression in most of climatic situations, our results reinforce the importance of monitoring and constantly removing diseased shoots, twigs, and fruits from the orchard to reduce the spread of the pathogen.

Resumo em Inglês:

ABSTRACT In this study, the aim of this study was to identify the source of resistance using KASP markers developed for Rpp1 – Rpp5 and screening for resistance in field trials in F2 populations. Ten F2 soybean (Glycine max (L.) Merrill) populations derived from crosses between rust-susceptible (55I57RSF IPRO, 63I64RSF IPRO) and rust-resistant sources (PI 200492, PI 594538A, PI 587880A, PI 594723, PI 230970, PI 506764, PI 459025A and PI 200487) were evaluated. All F2 plants were individually evaluated in field conditions for ASR phenotypic reactions and classified according to sporulation level. KASP markers were developed according to assays associated with Rpp genes available at SoyBase. Based on a slight difference in map position and different phenotypic disease reactions of PI 200492, we suggest that PI 594723 carries a resistance gene Rpp1-b. The Rpp1-b gene from PI 594723 was mapped on Chr 18 in a 12.4 cM region. The PIs carrying Rpp1-b (PI 594723, PI 587880A, and 594538A) showed strong resistance to ASR compared to the lines carrying Rpp1 (PI 200492). A total of 26 KASP markers were significantly associated (P < 0.01) with ASR resistance. Among those, M1, M5, and M6 (Rpp1), M13 and M14 (Rpp2), M16, M17 and M20 (Rpp3), M25 and M26 (Rpp4), and M27 and M28 (Rpp5) have the potential to be used in marker-assisted selection strategies.

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ABSTRACT Toxic levels of aluminum (Al) in the soil can reduce the growth of different grain crops. To understand the effects of Al in soybean (Glycine max L.) seedlings Al accumulation and its effect on anatomy, morphology, and metabolism in roots of two soybean genotypes were evaluated: Suprema and A7002. For this, soybean plants were grown in nutrient Clark solution, pH 4.0, without Al (control) and with 100 µM of Al for 72 hours. Both genotypes accumulated Al in the roots, however, Suprema showed a higher Al accumulation than A7002. The latter genotype showed Al accumulated only in the cell walls of the epidermis and root cap, which did not affect root growth. On the other hand, in Suprema, Al accumulated in the cells of the root cap, epidermis, and the nucleus of the ground meristem cells, which resulted in inhibited root growth and structural damage in the root epidermis cells. Al modulated the primary metabolism with increases in the levels of glucose, fructose, sucrose, and malate in the roots of the genotype A7002 and reduced the starch levels in the Suprema genotype. The findings of this study suggest the A7002 genotype seems to be more resistant to Al than Suprema, mainly by the use of two important mechanisms: an increase in malate content and Al immobilization in the external cells of the root.

Resumo em Inglês:

ABSTRACT The cultivation of Coffea arabica L. in a low-altitude region is a sustainable alternative for diversifying the income of farmers. On account of the variability of available cultivars, the use of indirect selection through initial vegetative development may be an auxiliary tool for identifying the most suitable genotypes for this environment. This study aimed to identify the dwarf Arabica coffee cultivars with better initial development in a low-altitude region and the morphological traits with greater relevance for the early selection of cultivars with high yield potential. The experiment was installed in the northeast of São Paulo, Brazil. The experimental design used was randomized blocks with four replications. The treatments consisted of 17 dwarf Arabica coffee cultivars. There is variability among dwarf Arabica coffee cultivars for initial vegetative development. The growth and increase in the number of nodes of the plagiotropic branch can be used in early selection to identify cultivars with greater yield potential. The cultivars IAC Obatã 4739, Obatã IAC 1669-20, and Tupi IAC 1669-33 present higher initial vegetative performance in low-altitude environments. The results obtained are useful to breeders and producers for choosing the cultivars best adapted to cultivation in this environment.

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ABSTRACT The frequency of extreme weather events has increased in almost all regions of the world. In this context, it is vital to understand how the location, scale, and shape of their frequency distributions are changing over time. This study used the flexibility of neural networks to model changes in the probability of daily extremes of maximum (Tmax) and minimum (Tmin) air temperature data in Campinas, Brazil — one of South America’s longest meteorological records spanning from 1890 to 2022. Based on the Extremal Types Theorem, we employed a conditional density network to model the parameters of the generalized extreme value distribution (GEV-CDN) as functions of time. Our findings indicate that a GEV-based model, where the location and scale parameters vary over time, best described the variations in the Tmin series. However, a GEV-based model with only the location parameter varying over time best described the variations in the Tmax series. From an agrometeorological perspective, these results suggest that the probability of Tmax values leading to crop failures is rapidly increasing. The findings indicate a decrease in the probability of agronomic frost events in Campinas over the past 133 years, but the rate of this decrease has slowed in recent years. This result, combined with the negative value of the GEV’s shape parameter, suggests that it is unlikely that Campinas may become an agronomic-frost-free region. To facilitate visualization of the changes in the probability of Tmax and Tmin values from 1890 to 2022, we have developed an internet application available at https://climatology-iac.shinyapps.io/Shinny/.

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ABSTRACT Amazonian soils have been suffering severe changes resulting from human activities in the region, causing significant changes in soil attributes that can contribute to greater susceptibility to erosion processes. Therefore, the present work aimed to estimate the erodibility in natural and anthropic environments in the southern region of the Amazon. Eight areas in the region were selected, including areas of native forest, savannah, cerradão, pasture and reforestation, delimiting 32 sampling points per area, with collections at a depth of 0.00-0.20 m, totaling 256 samples. Next, texture analysis and quantification of soil organic carbon were performed, and then erodibility was estimated by indirect prediction methods, Tukey’s test, Pearson’s correlation and factorial analysis of principal components. According to the results obtained, it was observed that the evaluated areas of native forest 1 and 2, cerradão and pasture present high susceptibility to erosion in relation to the cerrado, reforestation with genipap, teak and mixed areas. Therefore, it was noted that the high level of erodibility is associated with a greater predominance of sand fraction, K factor, Ki Kr and low clay content, as well as with the management employed in the areas.

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ABSTRACT Phureja Group potato is endemic and important for northern Andean countries such as Colombia, Ecuador and Venezuela, where it is grown over a wide range of elevation. The objective of the study was to compare the biomass accumulation of five potato cultivars in three contrasting environments in elevation from a latent response variable of vector nature, analogous to “heat efficiency index”. Destructive samplings were carried to obtain biomass. A biomass accumulation model was proposed using a latent response variable that integrates total biomass per plant with thermal time, analogous to the “heat use efficiency index”. The proposed latent response variable allowed measuring the efficiency in biomass accumulation and making comparisons between elevations and cultivars, with a nonparametric longitudinal variance analysis. The middle location was where the highest efficiency in accumulation of total biomass was observed. The accumulation of total biomass was slow at the higher elevation location during the vegetative stage, but it increased considerably after the initiation of the growth of tubers. The study showed a clear genotype-environment interaction, suggesting that biomass accumulation changes with elevation according to the cultivar. The methodology used in this study has the potential to be used in the longitudinal comparison of cultivars and environments, even when variations in elevation or temperature alter the length of growing cycles.

Resumo em Inglês:

ABSTRACT Ammonia volatilisation causes major nitrogen losses from the soil and applied urea which results in low urea-N usage efficiency. Incubation experiment and pot experiment were conducted to assess the effect of enriched rice straw biochar on ammonia volatilisation, soil pH, exchangeable ammonium, available nitrate, and rice plant growth in comparison to the urea without additives under waterlogged conditions. During the incubation study, urea was amended with different rates of enriched rice straw biochar (5, 10, 15, and 20 t ·ha-1). Urea amended with biochar at 5 to 10 t·ha-1 had successfully minimized ammonia loss compared to urea without biochar. Besides, application rate of 5 to 10 t·ha-1 of biochar also preserved more ammonium ions (65.37% and 66.54%, respectively), while at the same time, the retention of nitrate ions was 50.9% and 45.3% over urea without biochar. Similarly, 5 to 10 t·ha-1 of enriched rice straw biochar increased soil N level and improved rice plant growth significantly in pot experiment. Precisely, incorporation of enriched rice straw biochar at rate of 5 and 10 t·ha-1 offers wide variety benefits to soil amendments and rice plant nutrient uptake. Hence, the findings suggest that urea amended with enriched rice straw biochar altered the nutrients level in soil by improving rice plant growth.

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ABSTRACT Elephant grass stands out among lignocellulosic biomass plants utilized for second-generation biofuel production due to several advantageous characteristics compared to other raw materials. Its short production cycle and ability to thrive in adverse soil and climate conditions contribute to its appeal. Additionally, breeders seek genotypes with high productivity potential and adaptability to various favorable cultivation environments. This study aimed to estimate genetic parameters, predict genetic values using mixed models (REML/BLUP), and evaluate stability and adaptability for energy biomass production in elephant grass genotypes. The experiment was conducted in Campos dos Goytacazes, RJ, Brazil, utilizing a two-replicate experimental block design that included 40 elephant grass genotypes. Four harvest assessments were performed between 2016 and 2019. Genetic parameter estimation and selection of superior genotypes based on genetic value using the REML/BLUP procedure were performed using Selegen software. Stability and adaptability analyses were obtained through the harmonic mean of genotypic values (HMGV), enabling the identification of stable and highly productive genotypes. Genotypes 17, 18, 32, 16, 36, 6, 15, 31, and 34 exhibited outstanding performance in terms of HMGV, indicating enhanced stability, adaptability, and simultaneous productivity, thus ensuring robustness in cultivation. These selected genotypes hold potential for future breeding programs aimed at improving elephant grass yield for biomass production.

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ABSTRACT Phosphites can be considered an additional strategy to be included in disease management programs. Therefore, this study aims to evaluate the application of potassium phosphite (KPhi) in common bean seeds, in the reduction of intensity of root rot (Rhizoctonia solani) and in the compatibility with Rhizobium tropici, a nitrogen-fixing bacterium. The emergence speed index (ESI) and the percentage of total emergence were evaluated in seeds inoculated with R. solani and treated with KPhi. The number of nodules per root system, dry nodule mass, quantified the compatibility Phi x R. tropici, dry mass, nitrogen content, and nitrogen accumulation in the shoots. KPhi promoted a higher ESI and increase in plant stand compared to the control treatment. The number of nodules formed and the nitrogen content and accumulation in the KPhi treatments were similar to control (seeds inoculated with R. tropici). Thus, the treatment of seeds with KPhi provides control of R. solani and is compatible with R. tropici.