Abstract in English:ABSTRACT Hybrid rice seeds from sterile lines have displayed a new type of heavy chalkiness in the subtropical zone of China in recent years, which was named top-gray chalkiness, resulting in a lower quality of hybrid rice seeds in large-scale production. In this study, the morphological characteristics of the chalky hybrid rice seeds were investigated, the microscopic structures of their chalky parts observed, the α-amylase activit and relative nutrient content analyzed, and the germination indexe and microorganism populations of the chalky hybrid seeds determined. The results revealed that top-gray chalkiness in hybrid rice seeds originated from the top site of the grain, and that the chalky part was probably infected by bacteri and fungi to form a gray colo and which further resulted in a lower germination rat and germination potential. This observed chalkiness in rice seeds differed from the previously reported rice chalkiness categories both in the occurrence positio and color. Besides, the amylopectin content declined in the chalky par and the protein content in the chalky part increased as compared to the normal seeds. This research could provide technical support for the hybrid rice breeding enterprises during the breeding of hybrid rice seeds in large-scale production.
Abstract in English:ABSTRACT This study investigated the effect of different phosphites on the control of coffee leaf rust (CLR) caused by Hemileia vastatrix, considered the major disease affecting coffee yield worldwide. Three-month-old coffee plants were sprayed with two doses each of the phosphite solutions (standar., and double), as follows: K (40% P2O5; 1.., and 3 mL∙L-1), K (30% P2O5; ., and 6 mL∙L-1), Cu (2.., and 5 mL∙L-1), Mn+Zn (., and 6 mL∙L-1., and Na (., and 6 mL∙L-1) 24 h before being inoculated with H. vastatrix. Leaves were not washed or washed with deionized water after the foliar phosphites spray. Plants sprayed with water served as the control treatment. Inoculation was performed on the abaxial side of the first pair of expanded leaves using a camel hairbrush with a suspension of urediniospores (1 mg per leaf). All phosphites applied at the standard doses (from 1.5 to 3 mL∙L-1) reduced the total number of pustules (TNP) per leaf by 28-69% regardless of washing treatment. The biggest reductions were observed for Cu phosphite, which decreased the TNP per leaf by 6., and 69% withou., and with leaf washing, respectively. A similar trend was observed when the double doses of phosphites (from 3 to 6 mL∙L-1) were used, though Na phosphite without leaf washin., and Mn/Zn phosphite withou., and with leaf washing were not efficient to reduce the TNP per leaf. Without leaf washing, only C., and Na phosphites decreased CLR severity at the standard doses (53-61%), whereas all phosphites, except the Mn/Zn phosphite, reduced CLR severity at the double dose. The CLR severity was decreased using K 30%, K 40., and Cu phosphites when applied at the standard doses with leaf washing (41-59%). With double doses, only C., and Na phosphites decreased CLR severity by 55% for both treatments. In conclusion, the efficiency of the phosphites for CLR control varied according to the accompanying cation, dos., and washing conditions. The Cu phosphite resulted in the best CLR control regardless of the dose use., and the washing conditions.
Abstract in English:ABSTRACT Climate and soil databases can be used for delineating homogenous environmental zones over large areas of agricultural land to support agricultural research planning and spatial extrapolation of the results of field experiments. In other countries, such framework has proven useful to improve the efficiency and impact of investments in agricultural research. Furthermore, this approach can also contribute to identify key locations with the greatest potential for spatial extrapolation in terms of crop production area with similar climate and soils. In this paper, soil and weather databases covering the main agricultural land in Brazil were developed, and crop-specific technology extrapolation domains (TEDs) were identified for maize, soybean, and sugarcane crops. These databases were useful and viable option for the generation of homogeneous zones maps for different crops and regions. Given the spatial scale of the database applied, it was possible to represent a large area in few TEDs, without losing information regarding climate and soil variability, facilitating the spatial extrapolation of technologies throughout Brazil. Few TEDs are needed to represent a large part of the area of sugarcane (32 TEDs to cover 51% of the area), maize (21 TEDs for 51% of the area), and soybean (17 TEDs for 50% of the total area). Such information may help several areas of the agricultural sector, such as supporting new research that works on areas with large scales, or areas not explored yet.
Abstract in English:ABSTRACT Interspecific competitions are important mechanisms in structuring ecological communities, including agroecosystems, in which different species may share the same food resource. In melons, two major pests coexist in time and space, Liriomyza sativae Blanchard (Diptera: Agromyzidae) and Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). The former feeds on the leaf mesophyll, while the latter on the phloem sap. Therefore, the same niche exploitation can trigger interactive processes between both populations. The present research aimed to determine if there are positive or negative interactions between whiteflies and leafminers under field conditions. The experiment was conducted in four commercial melon fields in northeast Brazil in two planting seasons. Thirty random plants were weekly selected for detection of whitefly nymphs and leafminer larvae throughout the entire crop cycle. The data was organized and analyzed considering the species abundance of L. sativae (larvae) and B. tabaci (nymphs and adults) in the same plant. Thus, the coabundance of species was investigated by using regressions with Poisson errors. The results suggest different fractions of negative, positive and neutral (not significant relationships) coabundance between the two species. Among 34 significant interactions, 56% were negative, suggesting that more than half of significant interactions are due to interspecific competition with negative coabundance.
Abstract in English:ABSTRACT Apple orchards require the presence of a different genotype to pollinate the fruit producing cultivar. This is due to the process of gametophytic self-incompatibility present in most species and cultivars of the genus Malus. The fruit producing cultivar and the pollinizer must be genetically compatible to ensure fruit set and symmetrical and adequate fruit formation. The aim of this work was to evaluate five potential pollinizers for the new apple cultivar SCS426 Venice by genotyping the self-incompatibility locus (S-locus) and by controlled pollination in the field. The S-locus was screened using molecular markers and the fertilization capacity was evaluated by monitoring the fruit set after artificial pollination. Three genotypes were identified as semi-compatible (selection 135/140, cultivar SCS433 Felix 3 and SCS425 Luiza) and two as fully compatible (‘SCS431 Felix 1’ and ‘SCS434 Felix 4’) with ‘SCS426 Venice’. Regardless of the level of compatibility, all genotypes tested are efficient for the fertilization of ‘SCS426 Venice’ flowers and can be used as pollinizers in commercial orchards of this cultivar.
Abstract in English:ABSTRACT The objective was to evaluate the effect of winter cover crops on the agronomic performance of maize during five crop seasons in a clayey Inceptisol with reduced mineral nitrogen (N) inputs. The treatments were seven single cover crops: white oats (Avena sativa L.), black oats (Avena strigose Schreb.), ryegrass (Lolium multiflorum L.), canola (Brassica napus L.), vetch (Vicia sativa L.), fodder radish (Raphanus sativus L. and red clover (Trifolium pratense L.); a mix (black oats + vetch and a fallow. During summer, in succession to the cover crops, maize was grown under no-tillage. The attributes were evaluated in two stages of maize development: flowering (morphological components and physiological maturation (yield components). Differences in morphologica and yield variables were observed in all crop seasons, with emphasis on grain yield, number of grains per row (NGR and ear length (EL). The use of vetch showed greater contribution to the development of maize in relation to the other cover crops used, promoting an increase in stem diameter (SD), E and NGR in all crop season and directly reflecting in higher grain yield. On the other hand, when maize was grown under cover crops commonly used in southern Brazil, such as ryegras and white oats, the yield was similar to fallow. The results showed that vetch promoted higher maize yields, probably by N mineralization and reinforce the hypothesis that cover crops in the off-season can aggregate benefits to crops in succession, especially in terms of nutrition.
Abstract in English:ABSTRACT The quality and phenolic compound composition might be affected by production system due to microclimate around the bunches and sunlight interception provided by vegetative canopy architecture and environmental conditions. The aim of this study was to characterize the quality and antioxidant potential of ‘BRS Cora’ grapes with different trellis systems and rootstocks in rainy seasons under tropical conditions. Three trellis systems and two rootstocks were studied in production cycles during the first halves of 2017 and 2018, using a randomized-block experimental design. Interactions between the trellis systems,rootstocks and cycles differentially affect the fruit quality. The association between vertical shoot positioning or an overhead trellis with ‘IAC 766’ induced higher polyphenol compound contents. In turn, the trellis systems overhead trellis and lyre provided greater stability for the berry weight, soluble solids, total soluble sugar contents, yellow flavonoids, total extractable polyphenol compounds or antioxidant activity in both production cycles. The results of this study inferred that the grape quality and phenolic compound composition were not only affected by some specific climatic factors but also by the trellis system, rootstock, and the interaction between the three factors.
Abstract in English:ABSTRACT Banana (Musa spp.) is a crop with outstanding economic and social expression throughout the world. The objective of this study was to investigate the effect of different mulches types in growth production and postharvest of banana ‘BRS Platina’ not irrigated. The experiment was conducted in the farm of the Federal University of Lavras (UFLA). Micropropagated banana plants of the cultivar BRS were planted in the field with a spacing of 2.5 × 3.0 m (1333 plants ·ha-1), without irrigation. About 20 days after planting, different mulches were installed: black polyethylene films, double-sided polyethylene films (white and black), organic mulch (from the own crop) and control (bare soil). The experimental was set up in a randomized block design with four treatments, six blocks and six plants per treatment, totaling 144 plants. Among the six plants used in each treatment, two constituted the border, therefore four plants were evaluated. The analysis performed in the first and second crop were: growth analysis, postharvest quality, production and productivity. Both organic and inorganic (plastic film) mulch provide greater growth and yield of banana ‘BRS Platina’ not irrigated, in two years of production and can be used in the cultivation of this crop.
Abstract in English:ABSTRACT Actinobacteria of the genus Streptomyces are part of the soil microbiota from rice-growing areas and along with other microorganisms, such as Trichoderma spp., combine to act as natural enemies against the destructive soil-borne pathogen Rhizoctonia solani, causal agent of rice sheath blight disease. In this study, seven actinobacteria of the genus Streptomyces and three fungi of the genera Trichoderma and Purpureocillium were isolated from soils cultivated with rice using the serial dilution method. Streptomyces spp. M2A2 was selected for its ability to significantly reduce the in vitro growth of R. solani by 52% after 96 h by antibiosis in dual culture, while in the control treatment the mycelial growth was 100%. Furthermore, biocontrol efficacy of treated plants of the susceptible cultivar Fedearroz 68 with actinobacteria was confirmed and the onset of symptoms were delayed up to 14 days, compared to the control treatment. Rice plants treated with Streptomyces spp. M2A2 showed lesions of R. solani reaching 0.7% of the plant height, the effectiveness of this treatment was similar to the difenoconazole treatment, whereas in the control treatment, the lesions covered 34% of the plant height. When compared to the antagonist fungus Trichoderma spp. M2H1, Streptomyces spp. M2A2 presented a better performance of biological control. The results clearly demonstrated that Streptomyces spp. M2A2 isolate from soils of rice growing areas has biocontrol efficiency against R. solani and therefore can be a promising biocontrol agent.
Abstract in English:ABSTRACT The aim of this study was to evaluate the effect of controlled atmosphere storage on quality of native and cultivated yerba mate produced in Arvorezinha (RS) and São Mateus do Sul (PR) after 0, 3, 6 and 12 months of storage under ambient conditions, low oxygen (1.0 kPa) and high carbon dioxide (3.0 kPa) partial pressures. Total chlorophyll concentration reduced over the storage period regardless of the atmosphere condition, form of cultivation and production region. Total carotenoids, regardless of the form and place of cultivation, decreased until three months of storage under 1.0 kPa O2. Although, the O2 reduction to 1.0 kPa maintains greener color and higher chlorophyll concentration after 12 months of storage. High carbon dioxide partial pressures (3.0 kPa) in the storage chamber increases the polyphenol concentration until six months of storage. The raw material originated from São Mateus do Sul (PR) has higher chlorophyll concentration and greener color, resulting in greater storage potential.
Abstract in English:ABSTRACT The water deficit is one of the main limiting factors to the yield of sweet oranges. The present study aimed to determine alternative rootstocks to ‘Rangpur’ lime for ‘Pera’ sweet oranges grown on tropical hardsetting soils with greater potential tolerance to water deficit. Six citrus scion/rootstock combinations were grown during eight years in an orchard established in Sergipe, Brazil. The tree height, number of fruits per plant, cumulated fruit yield, leaf proline content and survival rate of trees were evaluated between 6th and 8th year after planting. Greater rate of tree loss occurred among the sweet orange onto ‘Orlando’ tangelo, which also induced the lowest cumulative fruit yield. After prolonged water deficit, moderate to high proline content was found in trees grafted on Sunki of Florida mandarin × C13 citrange – 012° (TSKFL × CTC13-012), ‘Orlando’ tangelo, ‘Indio’ and ‘Riverside’ citrandarin. Conversely, after a short water deficit during the wet season, trees on ‘San Diego’ citrandarin and Rangpur lime clone of Centro Nacional de Pesquisa Mandioca e Fruticultura – CNPMF 03 ‘Rangpur’ lime showed higher proline content. Trees onto TSKFL × CTC13-012 and ‘Indio’ also induced the greatest accumulated fruit yield at the 8th year after planting. It is assumed that ‘San Diego’ and CNPMF 03 ‘Rangpur’ induce response more quickly to water deficit, whereas TSKFL × CTC13-012 and ‘Indio’ are less susceptible to prolonged deficit. Therefore, trees on ‘San Diego’ and Indio citrandarin, CNPMF-03 ‘Rangpur’ lime, TSKFL × CTC13-012 hybrid present greater potential to tolerate water deficit and produce more fruits on the hardsetting soils of the coastal tablelands of the Brazilian Northeast.
Abstract in English:ABSTRACT The use of irrigation can improve the productivity and nutritional quality of the forage cactus in environments with a water deficit, resulting in profit to the producer. The productive performance, bromatological composition and economic benefits of using irrigation were investigated in this study with forage cactus clones regulated deficit irrigation (RDI). The study was conducted in an experimental design of randomised blocks, in a factorial scheme with subdivided plots. The plots consisted of water regimes based on the crop evapotranspiration (ETc) (rainfed, 40, 80 and 120% ETc). The cactus clones [‘Miúda’ (MIU), ‘Orelha de Elefante Mexicana’ (OEM) and ‘IPA Sertânia’ (IPA)] comprised the subplots. The total number of cladodes per plant, the fresh and dry matter yields and the bromatological composition were evaluated. Economic viability was assessed using the net revenue and benefit to cost ratio (BCR). The irrigation depths did not increase the yield of the clones. The OEM clone showed 276 and 343% greater fresh and dry matter production, respectively, when compared to the IPA clone; however, when compared with the MIU clone, it was 63%, both on a fresh and dry matter production. The water regimes had no effect on the nutritional quality of the cactus. Only IPA showed no profit during the first cycle (BCR < 1). It can be concluded that planting one irrigated hectare with the OEM and MIU clones offer economic returns starting from the first production cycle (18 months).
Abstract in English:ABSTRACT The search for alternative rootstocks to the ‘Rangpur’ lime tree is a challenge to the sustainability of citrus in the Tabuleiros Costeiros (Coastal Tablelands) of Northeastern Brazil. New varieties should meet high drought tolerance with water deficit, cohesive soils, resistance to citrus diseases and inducing high production of fruit. In this work, the performance of ‘Pera’ sweet orange was evaluated on ‘Tropical Sunki’ mandarin and 27 hybrid citrus rootstocks in Umbaúba, Sergipe. A local selection of the ‘Rangpur’ lime was the control. Planting was in 2013 at tree spacing of 6.0 × 3.0 m, without irrigation. Tree size, fruit yield and quality, tree survival rate and graft-compatibility were assessed until 2019. Experimental design was completely randomized blocks with 29 treatments, three replicates and four plants in the plot. Two selection indices were applied to the data to assist in decision making. The ‘Tropical Sunki’ mandarin induced similar cumulative fruit yield in relation to the ‘Rangpur’ lime, suggesting a good drought tolerance of the former rootstock. The TSKC × (LCR × TR) - 073 induced slightly lower productivity, compensated by higher productive efficiency and higher concentration of soluble solids, whereas LCR × TR - 001 and HTR - 166 were highly efficient dwarfing rootstocks. The multiplicative and the rank sum indices showed high correlation, both classifying ‘Tropical Sunki’ mandarin, ‘Santa Cruz Rangpur’ lime, LVK × LCR - 010 and - 038, HTR - 127, in addition to the three aforementioned hybrids, as superior to the local selection of ‘Rangpur’ lime.
Abstract in English:ABSTRACT To identify the optimum intercropping system of sorghum and clover in terms of quantity and quality of forage yield, a two-year experiment was conducted in a semi-arid region of Iran, during the 2016 and 2017 growing seasons. Treatments consisted of eight cropping systems: S75C25 (75% sorghum + 25% clover), S50C50 and S25C75, as replacement series; S100C50, S50C100, and S100C100 as additive series; and sole cultures of sorghum and clover. The highest and lowest dry matter (DM) yield (29.17 and 10.71 Mg·ha-1) were found in the S100C100 and clover monoculture systems, respectively. Although the highest content of crude protein (CP) and digestible dry matter (DDM) were recorded from clover monoculture, the maximum yield of CP and DDM were obtained from the S100C100. Increasing the proportion of clover in intercropping decreased the acid detergent fiber and neutral detergent fiber, increased the relative feed value, net energy for lactation and dry matter intake. Increasing the proportion of sorghum in intercropping improved the yield of DM, CP and DDM. The land equivalent ratio for DM yield was higher than one in all intercropping treatments but were significantly higher in the additive intercropping systems. Overall, it could be concluded that sorghum and clover additive intercropping systems increased forage yield and quality, however if simultaneous increase of the quantity and quality of forage is the interest of this study then the S100C100 system had a significant advantage over other treatments and can be a suitable alternative for sorghum and clover monoculture systems in semi-arid regions.
Abstract in English:ABSTRACT Genetic variability is essential for gains in breeding programs. The cyclic process of progeny recombination is a strategy to raise the chances of selecting better genotype combinations. The objective of this study was to identify superior progenies between common bean genes groups in first recurrent selection cycle for root system traits. Parents of the Andean and Middle American gene groups were hybridized in a complete diallel scheme. Thereafter, the parents and F1 and F2 populations were planted in the field. To establish the base population of recurrent selection (C0), seven segregating populations (F2) with superior performance for root system were selected and intercrossed, resulting in recombinant progenies (C1). To estimate the selection gain, the parents and C0 and C1 genotypes were compared with regard to the following variables: total root length (TRL, cm), projected root area (PRA, cm2), root volume (VOL, cm3) and number of root tips (RT). The difference between genotype combinations indicates the presence of genetic variability and effectiveness of recurrent selection. The mean genetic progress for root system-related traits was 12.9% (TRL), 12.6% (PRA), 12% (VOL) and 11.5% (RT) in the first recombination cycle. The mean phenotypic performance of seven of the C1 progenies exceeded that of their parents for all root system traits. These progenies are promising as base populations of the next selection cycle.
Abstract in English:ABSTRACT The genetic improvement of sour passion fruit has the main objective of obtaining genotypes with high fruit yield and quality. The determination of the ideal early selection is extremely relevant to reduce costs and time in the selection of promising genotypes for use in genetic improvement programs. In this context, this work aimed to determine the ideal selection phase through estimates of genetic parameters, phenotypic, genotypic correlations and analysis of repeatability. A total of 14 yellow passion fruit hybrids in Lençóis (Bahia State, Brazil) were evaluated in a randomized block design with five replications and nine agronomic traits from three harvests with five fruits evaluated per repetition. Genetic parameters, repeatability coefficient and phenotypic and genotypic correlations were estimated for each evaluation cycle. For most parameters, the traits changed according to the evaluation cycle. Most of the genetic parameters showed favorable genetic conditions for the selection in the first harvest. The correlations between the traits fruit weight, peel and seedless pulp weight, fruit length and diameter were more stable in the different harvests. Through the repeatability analysis based on the principal components of covariance and correlation, it was possible to estimate a sample of 13 fruits per hybrid for prediction with accuracy of 90% for the physical traits of sour passion fruit.
Abstract in English:ABSTRACT Soybean is the main crop grown in Brazil and is important to quantify the capacity of increase in yield by crop production intensification and management. This study aims to quantify yield gap and agricultural efficiency (AE) for soybean in Central Cerrado biome, Brazil. Yield gap by management (YGMG) and water deficit (YGWD) and AE and climate efficiency (CE) were calculated based on potential (PoY), attainable (AtY) and actual (AcY) yields. Potential yields and AtY were simulated for the main sowing date, ranging from Oct 11 to Nov 01, using the agroecological zone crop model, from 1980/81 to 2016/17 growing seasons. The sites were Rio Verde (GO), Cristalina (GO), Barreiras (BA) and Peixe (TO). Actual yield was obtained from official statistics for each site. Agricultural efficiency rate for this period and its relationship with CE were analyzed. The YGMG were 4,345, 3,446, 4,531 and 2,649 kg·ha–1 for Rio Verde, Cristalina, Peixe and Barreiras, respectively. Barreiras had a higher YGWD when compared with other sites, reaching a mean of 6,526 kg·ha–1. However, Barreiras had a higher AE (51%), indicating that crop management applied in this region can explore the environmental conditions more than other sites. Agricultural efficiency showed an increasing rate from 0.70 to 1.21% per year, while the relation between AE and CE fitted an exponential negative function, by which higher water volume available reduced AE. Thus, it is possible to double soybean yield through improvements in management based on AtY (7,409 kg·ha–1) and AcY (3,260 kg·ha–1) in Central Cerrado biome, Brazil.
Abstract in English:ABSTRACT The objective of this study was to determine the effects of dip wash treatments with 2% citric acid (CA), 0.2% benzoic acid (BA), 0.2% sorbic acid (SA) and acidic electrolyzed water (AEW) followed by 2 kJ·m–2 ultraviolet (UV) irradiation on the postharvest decay and quality of strawberry fruit cultivar ‘Malvina’, as compared to control, and UV alone treated samples. Weight loss, firmness, soluble solids content, titratable acidity, total phenolics content, total anthocyanins content, antioxidant activity and decay incidence of control and treated strawberry fruits were investigated during cold storage at 8 °C for 21 days. The result showed that UV-treated fruits had a lower weight loss, higher titratable acidity, phenolic and anthocyanin content and were firmer than the untreated fruits. Dip wash in AEW before UVC treatment reduced weight loss and increased firmness of strawberry fruits but did not significantly affect total phenolic content, total anthocyanins content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity and fruit decay. Dip wash treatment with organic acids followed by UVC irradiation was significantly more effective than UV treatment alone in reducing fruit decay and weight loss and in maintaining at higher levels titratable acidity, total anthocyanins content, total phenolic content and antioxidant activity of strawberries during refrigerated storage. The present findings demonstrate that dip wash treatment with 0.2% SA, 0.2% BA or 2% CA followed by UV treatment can be an effective method for maintaining the phytochemical content and delaying the decay of strawberry fruit during cold storage.
Abstract in English:ABSTRACT In viticulture, training systems and rootstocks are crucial factors in the growth and development of plants, thus affecting the production and quality of grapes. Therefore, the present study aimed to determine the best combination of rootstock and training system for ‘Sauvignon Blanc’, in Jundiaí, state of São Paulo, Brazil. To assess the data, a randomized block design in a 2 × 2 factorial scheme was used, that is, two rootstocks (‘IAC 766 Campinas’ and ‘106-8 Mgt’) and two training systems (low and high espaliers), with four replications. The characteristics assessed were production, physicochemical analysis and concentration of bioactive compounds. With regard to the physicochemical composition of the grape must, the results indicated that the tested combinations are within the standard requirements for the winemaking industry; outcomes may change according to the rootstock used, i.e., an increase in production or an increase in the nutritional quality of the fruits. Nevertheless, ‘106-8 Mgt’ rootstock showed great yield in both training systems, that is, an increase of up to 80%. Finally, ‘Sauvignon Blanc’ must be grafted on to ‘IAC 766 Campinas’ rootstock through a low espalier system to achieve a high content of phenolic compounds and flavonoids, and high antioxidant activity.
Abstract in English:ABSTRACT Biochar is a material produced by the pyrolysis of agro-industrial waste, which has become one of the most promising management tools to improve soil quality. The aim was to determine the effects of incorporating biochar from different coffee wastes in sandy soil, cropped with maize, on soil chemical and microbial attributes. The experiment followed a factorial design 2 × 3 + 1 with two types of biochar, including coffee ground (CG) or coffee husk (CH) in 3 doses (4, 8, and 16 t·ha-1) and a control fertilized solely with bovine manure (3 t·ha-1). The variables analyzed were soil organic carbon, chemical attributes, microbial biomass (C, N and P), soil basal respiration and microbial gene abundance (16S rRNA, 18S rRNA and nifH gene). Most chemical attributes were strongly increased by CH application, while CG at 8 t·ha-1 increased the soil C:N ratio (3.5 times), P (2.1 times) and K+ (7.9 times) and at 4 t·ha-1 increased the C content, microbial biomass C and N (3, 2.1 and 1.6 times, respectively). The application of CG biochar at 16 t·ha-1 showed trend to increase the abundance of bacteria, fungi and diazotrophic genes (11, 10 and 2%, respectively). Contribution of both coffee biochar types, but mainly CH, was more effective than the soil that received organic manure alone. Biochar from coffee wastes is a promising tool to improve sandy soil quality.
Abstract in English:ABSTRACT Metal contamination problems have become common everywhere with several known cases of metal toxicity in the agriculture sector. Metals including copper (Cu) are important to plant metabolism in trace amounts; however, excessive amounts can cause toxicity to the plants. The biochars have potential to absorb these trace elements in soil. A study was conducted to determine the characteristics and potential of different plant-based biochars to control Cu uptake and influence on the growth of maize (Zea mays L.). Five biochars from different agricultural waste materials, such as rice husk (RH1 and RH2), empty fruit bunches (EFB1 and EFB2) and oil palm kernel (OPK), were selected in the study. Each biochar was applied at 20 t·ha-1 on Cu contaminated soil, and maize was grown for 56 days in pots with 10 kg of acidic soil. The rice husk biochar (RH1) with a substantial number of heterogenic functional groups (alcohols and phenols, carboxylic acids and derivatives, amines, saline, alkynes) on its surface and more porous structure was able to retain more nutrients. It also give the best results in terms of reducing the Cu concentrations (1.61 mg-kg-1) in plants and plant uptake (10.15 µg·pot-1). Other than that, the highest plant growth parameters were also perceived in rice husk biochar applications. Hence, RH1 biochar had the most promising results in terms of controlling the plants Cu uptake and improved maize plant growth.
Abstract in English:ABSTRACT There is little information on how different spatial arrangements affect modern maize hybrids under irrigation in the maize second growing season in Brazil. The objectives of this study were to evaluate the performance of maize genotypes with different canopy architecture as a function of different spatial arrangements in the Southeast Brazil. Two maize hybrids with semi-erect (DKB 390) and erect (DKB 230) leaves were cultivated during the second season and evaluated for different plant densities (4, 7 and 10 × 104 plants?ha?1) and row spacings (0.25, 0.50 and 1.00 m), under irrigation in a tropical environment. The increase in plant density increased plant height and ear insertion height, but reduced stalk diameter. The absorbed photosynthetically active radiation and the leaf area index also increased in higher plant densities, with a reduction of the SPAD index. The increase in plant density enhanced grain yield, however, there was no difference of yield between different row spacings. The hybrid DKB 230 (upright leaves) showed greater yield potential compared to DKB 390 (semi-upright leaves). The critical leaf area index was 5.2 and 4.3 for the hybrids DKB 230 and DKB 390, respectively. The estimated plant density that provides the maximum yield are 9.7 × 104 and 8.8 × 104 plants?ha?1 for the hybrids DKB 230 and DKB 390, respectively.
Abstract in English:ABSTRACT Asian soybean rust (ASR), triggered by Phakopsora pachyrhizi, can cause great yield losses on soybean and nickel (Ni) has potential to control this disease. This study evaluated the effect of using soybean seeds with different Ni contents on ASR control by performing two experiments. In experiment 1, seeds with different Ni contents were obtained by spraying plants three times with solutions containing either 60 or 100 gNi·ha-1. Plants sprayed with water served as the control treatment. In experiment 2, plants originated from seeds obtained in experiment 1 (T1 = 0.9 µgNi·seed-1, T2 = 1.2 µgNi·seed-1, and T3 = 1.6 µgNi·seed-1) were inoculated with P. pachyrhizi at the V4 growth stage. The ASR severity was evaluated 16 days after inoculation (DAI) and the chlorophyll (Chl) a fluorescence parameters at 8 and 16 DAI. The ASR severity decreased by 64 and 47% for treatments T2 and T3, respectively, in comparison to T1 treatment. The photosynthetic apparatus was negatively affected by ASR. The efficiency of the use of light by photosystem II decreased while the energy dissipated by nonregulated form increased in the infected leaflets. There was no significant difference for Chl a fluorescence parameters for T1, T2, and T3 treatments applied to inoculated plants probably due to the biotrophic lifestyle of P. pachyrhizi associated with lower ASR severity. In conclusion, the potential of using seeds with higher Ni content as a tool for ASR integrated management control is highlighted in this study.
Abstract in English:ABSTRACT Chromium contamination in soils affects plant growth and this metal can accumulate in plants tissues. In addition, Cr can affect soil microbial biomass and activity. On the other hand, plant growth-promoting rhizobacteria (PGPR) can protect plants against metals and, at the same time, promote plant growth and could alleviate adverse effects on microbial biomass. This study evaluated five PGPR on maize growth, Cr accumulation and soil microbial biomass in a Cr-contaminated soil. Five PGPR (LCC04, LCC41, LCC69, LCC81 and IPA403), isolated from soil under permanent application of composted tannery sludge and contaminated with Cr, were inoculated in maize plants grown in soils with (+Cr) and without (–Cr) Cr. In Cr-contaminated soil, LCC41 promoted the highest growth of maize, while LCC04 contributed with the highest N accumulation. The shoots of maize accumulated less Cr with LCC81, while LCC41 contributed to the highest Cr accumulation in roots. The translocation of Cr was highest with IPA403, while LCC81 contributed to reduce Cr translocation. In conclusion, LCC41 and LCC81 could be effective as PGPR inoculants to promote plant growth and reduce Cr accumulation in maize, respectively, in Cr contaminated soil.
Abstract in English:ABSTRACT The demand for the increased productivity of sugarcane crops has required changes in its production chain, such as the use of pre-sprouted seedlings (PSS) of sugarcane into the chain. In this system, the inoculation of beneficial microorganisms, such as plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF), can improve seedling development. The objective was to evaluate the beneficial effect of PGPB and AMF inoculation on sugarcane PSS production system. Experiments were carried out in greenhouse using a commercial substrate with different levels of fertilization to evaluate the plant biomass and nutritional status. The bacteria strains are able to produce indole acetic acid and to amplify the nifH gene. The coinoculation of strains IAC-BeCa-095 with AMF (Glomus macrocarpum and Glomus etunicatum) improved the plant shoot biomass (25%) on the fertilized substrate. The strains IAC-BeCa-088 (Burkholderia caribensis), IAC-RBca5 (Pseudomonas sp.) and IAC-RBca10 (Bacillus sp.) without AMF and fertilization improved the shoot biomass by up to 35%. Coinoculation with strain IAC-BeCa-095 (Kosakonia radicincitans) and AMF improved the shoot and root biomass by up to 27 and 75%, respectively, in the conventionally fertilized substrate, demonstrating a synergistic effect of these microorganism consortia. The use of beneficial microorganisms may be a viable practice in the production of PSS sugarcane. Moreover, this study is the first to demonstrate the synergistic effect of endophytic bacteria (K. radicincitans) or rhizobacteria (Bacillus sp.) with AMF and Pseudomonas sp. or B. caribensis, without AMF inoculum on the production of sugarcane PSS to improve plant growth and plant nutrition.
Abstract in English:ABSTRACT Acrocomia aculeata (Jacq.) Lodd. ex. Mart. (Arecaceae) is a neotropical oil palm of widespread occurrence in the American continent and with great economic potential for the energy and food sectors. Genetic breeding studies for the species are very recent, with a need for basic knowledge from the genetic diversity in agronomic traits. Thus, the aim of this work was to estimate genetic variance, heritability, and genetic gain as well as to propose strategies of selection. Two-year evaluations of eight agromorphological characteristics were carried out in two experimental fields composed of 50 open-pollinated progenies. The results revealed moderate heritability for progeny average to thorn density in the abaxial side ( = 0.402 in Pindorama) and relative chlorophyll index ( = 0.458 in Presidente Prudente). The selective accuracy was 0.634 and 0.677 for the same traits, respectively. In the combined analysis, the higher values of heritability were obtained to thorn density on the abaxial region of leaves and relative chlorophyll index (0.616 and 0.666, respectively). Moderate to high magnitude values of genetic gain was reached for traits with greatest agronomic interest, as plant height Gs (%) = 19.64, number of leaves Gs (%) = 26.43, stipe diameter at breast height Gs (%) = 12.51, and relative chlorophyll index Gs (%) = 38.12. In conclusion, the results indicate considerable genetic variability for the evaluated traits and suggest that their most effective use for the purpose of genetic gains would be based on the combined selection between and within progenies.
Abstract in English:ABSTRACT Cell suspension culture has been used as a model to study metabolic changes to several stresses. To have detailed information of nitrogen (N) limitation on sugarcane metabolism, a controlled study of the primary metabolites and representative compounds of secondary metabolism was developed using suspension cells growing under three different N regimes: normal condition (40 mmol·L–1 NO-3), slightly deficient (12 mmol·L–1 NO-3) and completely deficient (0 mmol·L–1 NO-3). Sugarcane cells were harvested after 3 and 7 days of treatment. A range of changes in the levels of amino acids, organic acids, sugars and phenolic compounds were observed upon the growth conditions applied. Nitrogen limitation remarkably affected the amino acids and carbohydrates biosynthesis, which, associated with the changes observed on phenolic compounds contents, indicates the upregulation of carbon sink compensation mechanisms in these sugarcane cells exposed to N starvation. As expected, the results showed that N limitation might cause an extensive metabolic reprogramming of both carbon and N metabolism in sugarcane cells, and these changes are related to the intensity of the starvation. Nitrogen is essential for plant growth and development, and its limitation sharply reduces crop yield. Thus, these results open new perspectives for in planta studies concerning carbon and N metabolisms balance in this crop.
Abstract in English:ABSTRACT This study aimed to estimate the production of seeds per umbel and to assess both the effect of gibberellic acid (GA3) and umbel order on seed germination in Amazon chicory species. The experiment was conducted in two steps. Firstly, traits related to seed production were evaluated. Afterward, a germination test was carried out, and the following parameters were assessed: germination speed index (GSI), average germination time (AGT), germination percentage (%G), percentage of abnormal seedlings (%AS), and percentage of non-germinated seeds (%NGS). Remarkably, there was strong interaction between the analysed factors. The highest production of seeds per plant was observed in the treatment containing the blend of seeds from different umbels (1.41 g·plant-1), in which the number of umbels by order and the total number of seeds per plant were the major traits related to the improved yield. The application of GA3 at 200 mg·dm-3 increased %G in second-order seeds. Regardless of GA3 application, seeds from secondary umbels showed shorter AGT by up to two days, while no difference in GSI was observed. Collectively, these results offer novel and timely information on the seed germination behavior in Amazon chicory, revealing practical advice of utmost importance for local producers.
Abstract in English:ABSTRACT The iron concentration (FeC) and zinc concentration (ZnC) in common bean grain are quantitative traits, and appropriate breeding techniques are required to achieve genetic gain. The aim of this study was to obtain a recurrent selection population of black bean to increase the FeC and ZnC in the grain and to select the superior progenies for formation of the next cycle and obtain lines. The base population was formed by crosses among ten parents. A total of 351 progenies were obtained, and, after two generations of selection, the 27 best progenies were evaluated in two field trials for FeC, ZnC, 100 seed weight and yield. Analyses of variance were carried out and genetic parameters were estimated. The heritability estimates ranged from 59 to 94% for the four traits. The estimates of expected gain from direct selection for each trait (3 to 21%) and simultaneous selection (1 to 4%) indicate success from selection. The eight progenies, selected based on simultaneous selection, have superior mean values, including to those of ‘BRS Supremo’ (10% for FeC, 8% for ZnC, 5% for 100 seed weight and 3.8% for yield), the Brazilian black bean cultivar with the highest FeC and ZnC. The recurrent selection population shows high genetic variability and potential for obtaining lines superior to the cultivars currently on the market, allying high agronomic performance and high FeC and ZnC in the grain. Furthermore, this population shows potential for generating a new recurrent selection cycle, from recombination of the eight superior progenies.
Abstract in English:ABSTRACT Most Brazilian soils have restrictions on agricultural use related to acidity and nutrient availability. This study aims to evaluate a zinc (Zn) and lead (Pb) mining by-product (Zincal™), regarding its capacity to correct soil acidity, and to serve as a source of Zn. For evaluation of its efficacy, a comparison with dolomite + Zn sulfate was conducted. The experiment was set up in two soils, a Quartzarenic Neosol and a Red Latosol, and conducted under controlled conditions in the laboratory. Treatments consisted in the application of two doses, aiming at 75 and 95% base saturation of both liming materials, as well as in a control treatment without acidity correction. The effect of said treatments on pH, base saturation, Al3+, H+Al, Ca2+, Mg2+, Zn, Mn and Pb contents were evaluated over 120 days. Similar responses were obtained from both liming materials, regarding their capacity to increase the pH of the soil, reduce Al3+ and potential acidity (H+Al), and increase base saturation. Differences observed in these attributes were dose-related. In regard to Ca and Mg, the content released in soil correlates with the content present in the liming materials. Zincal™ released more Mg and less Ca than dolomite, hence proving to be efficient in releasing Zinc.
Abstract in English:ABSTRACT Super sweet corn breeding must develop hybrids that fully meet the expectations of the market. In this sense, the determination of keytraits for the selection of sweetcorn genotypes is a fundamental condition for breeding success. The objective of this work was to identify key traits for the selection of promising and contrasting genotypes of super sweet corn. The experiments were carried out in Guarapuava (PR), in two sowing dates. Seventeen traits related to the yield and quality of the ear were evaluated. To perform the multivariate analysis, data were subjected to diagnosis of multicolinearity, analysis of canonical variables, genetic divergence, hierarchical clusters, factor analysis, and canonical correspondence analysis. Grain yield, yield of dehusked ears, and number of commercial ears were considered related key traits in the identification of promising super sweet corn genotypes. Hybrid D3-20 × D5-41 presented higher averages than the others, considering the yield related keytraits.
Abstract in English:ABSTRACT Deficiencies of boron and zinc occur in coffee plantations despite the many fertilizer sources offered by the industry for the agriculture. Sparingly soluble fertilizers (SSF) have been used in several countries for many years. However, their effectiveness when applied to leaves is highly contested, and information about their use efficiency is still lacking. Experiments were set up to characterize the SSF of B and Zn according to particle size of fertilizers, and the spreading and retention of the particles in the leaf, comparing SSF (calcium borate, Zn oxide, and Zn borate) with soluble sources (boric acid and Zn sulfate) in four doses (mg.L-1): Experiment I (B 0, 130, 260, and 520), Experiment II (Zn 0, 200, 600, and 1,800), and experiment III (B 0, 43, 129, and 387, and Zn 0, 200, 600, and 1,800), to supply B and Zn for coffee plants. Microparticles of the SSF were found adhered to coffee leaves, and the Zn oxide was the one with the smallest particle size. SSFs were effective at increasing the Zn and B leaf concentrations in coffee. Dry matter of coffee increased 15% with applications of 270 mg.L-1 of B as calcium borate and 384 mg.L-1 of B as boric acid. Foliar application of Zn oxide at the dose of 1,800 mg.L-1 of Zn increased the leaf areas of the plants. High doses of Zn sulfate caused toxicity to coffee plants due to high saline concentrations. The microparticles found retained on the surface of the coffee leaves increased leaf concentration of B and Zn, which explained variations in the dry matter measurements and show the potential of the SSF for the development of fertilizers to improve the availability of micronutrients to coffee.
Abstract in English:ABSTRACT Nutrient loss from the weathering process is a major challenge for tropical agriculture. Biochar with nutrient retention capacity has been proposed as an amendment to retain plant-available nutrients. Meanwhile, information on diazotrophic population responses to biochar application in the humid tropics is still poorly explored. A field study was carried out over three cropping cycles of maize in a typic paleudults of Peninsular Malaysia. During the first cropping cycle, the soil was amended with palm kernel shell biochar (PK), rice husk biochar (RH), palm kernel biochar with fertilizer (FPK), rice husk biochar with fertilizer (FRH), fertilizer (F), and control soil (C). Soil samples were taken at each harvesting stage and analyzed for pH, cation exchange capacity (CEC), total N, ammonium (NH4+–N), nitrate (NO3––N), microbial biomass N, and urease activity. Total and active diazotrophs were quantified from soil DNA and RNA, respectively, employing quantitative polymerase chain reaction (qPCR) amplification of the nifH gene. Palm kernel shell and rice husk biochars maintained a significant NH4+–N and NO3––N, respectively, during the second cropping cycle. Both biochars promote the total and active diazotrophic population. A detrimental impact on the nifH transcript was detected from fertilization even when biochar was co-amended. Two possible land management options for tropical soil were proposed from the overall data. First, the application of fertilizer with biochar can reduce N loss against weathering. Second, the application of biochar alone may improve biological N2 fixation in tropical soils.
Abstract in English:ABSTRACT Most studies on genomic selection in plant breeding compare different statistical methods of univariate approach. However, multi-trait methodologies should be considered since they allow the simultaneous selection of superior genotypes in several economic traits. Here, the aims were to compare the selection accuracy and efficiency of the multivariate partial least square (MPLS) method compared with random regression best linear unbiased predictor (rrBLUP), Bayesian Lasso (Blasso) and univariate partial least square (UPLS) and to develop genomic selection indexes efficient for superior genotypes identification in plant breeding. Ten F2 populations with 800 individuals were simulated, considering four traits with different heritabilities. Genomic selection analyses using rrBLUP, Blasso, UPLS, and MPLS were conducted. Four genomic selection indexes were elaborated by the sum of the marker effects obtained for each trait, weighted by the respective residual variance. Multi-trait indexes were developed based on the assumptions of each methodology mentioned (rrBLUP, Blasso, UPLS, and MPLS), and were denominated I-rrBLUP, I-Blasso, I-UPLS, and I-MPLS. Processing time, selective accuracy, selection gains, and selection coincidence were used to compare the methods and the selection indexes proposed. The MPLS method had similar results compared to UPLS method for the low heritability traits and was less efficient than the rrBLUP and Blasso. The genome selection indexes provided the highest total genetic gains. The I-rrBLUP and I-MPLS indexes stood out for high efficiency in selecting superior genotypes in the shortest processing time. Results suggest that the genomic selection indexes proposed in this study may be promising for plant breeding programs.
Abstract in English:ABSTRACT Guava is of great economic importance in Brazil. The development of new cultivars by obtaining inbreeding lines has been a promising option. The objective of this work was to evaluate the S2 families of Psidium guajava using seed attributes. Different characters of physiological quality of guava seeds were studied, in addition to performing digital phenotyping of characteristics of geometry, texture and colors of the seeds. The variables were analyzed simultaneously using the Ward-Modified Location Model (MLM) method and carried out individual analyses of variance for estimating genetic parameters of the population. The formation of more than one group of divergent genotypes was observed, the geometry characteristics were more impacting for the discrimination of the genotypes, a high phenotypic correlation was observed with the germination variables and dry matter weight. High heritabilities were verified for the variables related to seed quality, indicating success in selecting vigorous genotypes. The Ward-MLM method is a useful tool to detect genetic diversity among genotypes of inbred guava. Thus, the most divergent genotypes with high germination potential can be recommended for future crosses or self-fertilized to obtain new lines in the guava breeding program.
Abstract in English:ABSTRACT The excess of nitrogen (N) causes the overgrowth of sweet potato foliage, increasing the self-shading and reducing the root yield. Therefore, a combined N and paclobutrazol (PBZ) application can reduce the vegetative overgrowth and benefit the sweet potato yield. The purpose of this study was to evaluate the plant growth, yield, uptake and removal of N by sweet potato plants fertilized with N and treated with PBZ during two planting seasons. The treatments consisted of four N rates (0, 50, 100 and 200 kg·ha–1), three forms of PBZ application (PBZ-10: PBZ applied at 10 days after side-dressing N fertilization [DASNF]; PBZ-25: PBZ applied at 25 DASNF, and PBZ-10 + 25: PBZ applied at 10 plus 25 DASNF), and a control (without PBZ application). Paclobutrazol application temporarily reduced the length of the main branches of sweet potato planted in the rainy season, but it did not reduce the shoot biomass of plants in both planting seasons. A single application of PBZ at 10 DASNF increased the yield of fresh storage roots in the two planting seasons, but, during the rainy season, the increases were greater when two applications were carried out. The application of 50 kg·ha–1 N in the rainy season was sufficient to reach the maximum yield of fresh storage roots, but, in the dry season, the N fertilization increased the N uptake without benefiting the root yield.
Abstract in English:ABSTRACT Producing high-quality seeds for agroecological agriculture is needed because the plants will be exposed to a diversity of environments and management practices. Sowing times and population densities can influence the quality of seeds produced by landraces. Further, seeds for agroecological cultivation must not be contaminated by transgenes. In this context, it is necessary to know the agronomic performance of landraces outside of the recommended growing period to avoid gene flow with transgenic cultivars. Thus, the objective of this work was to determine the germination rate, vigor and sanitary quality of seeds of maize genotypes cultivated in an agroecological system at different sowing times and densities. A split-split-plot design was used in the 2016/2017 and 2017/2018 growing seasons. The physiological quality evaluation was based on germination and vigor tests, and the sanitary quality was obtained by visually examining the seeds. The results showed a significant simple effect of genotype, sowing time and density, as well as double and triple interactions among factors for all evaluated traits. The most suitable time for sowing the corn landraces evaluated in an agroecological system in western Santa Catarina is September, when the seeds exhibited the highest percentage of germination and vigor and there was a lower incidence of pathogens. At this time, a density of 55,000 plants·ha–1 had the best result for germination. Late sowing was tested to avoid gene flow from transgenic varieties that usually are sown in September, but the results indicated penalties, such as a decrease in seed yield and quality.
Abstract in English:ABSTRACT In spite of the chemical, physical, and biological benefits that Crotalaria spectabilis can provide to the soil, it is little used as a green manure crop by farmers. Inoculation with strains of legume-nodulating nitrogen-fixing bacteria that are efficient and competitive may be a strategy to enhance accumulation of N in C. spectabilis and stimulate adoption of this green manure crop. The aims of this study were i) to evaluate the symbiotic and agronomic efficiency of new strains of Bradyrhizobium on C. spectabilis in an oxisol (red latosol) compared to that of noninoculated controls (without and with mineral N) and with the approved strain BR2811, seeking to corroborate possible recommendation as inoculants for this species; and ii) to determine, the contribution of these treatments to N accumulation in the plant of C. spectabilis in four periods of cutting for determining possible and ideal periods for its incorporation in the soil. Experiments were carried out in pots and field. Inoculation with the new strains UFLA05-03, UFLA05-09, and UFLA05-14 and with BR2811 on C. spectabilis is effective since it increases the production of N-enriched plant biomass when compared to the control without N mineral. However, UFLA05-03 stands out among these strains because it behaves similarly to the control with mineral N both in relation to shoot N accumulation and dry matter just after 150 days in the field.
Abstract in English:ABSTRACT Nickel (Ni) was the latest element to have its nutritional essentiality recognized for plants (Brown et al. 1987). It is a component of various enzymes, including glyoxalases (family I), hydrogenases, superoxide dismutase and urease (Chen et al. 2009). Inadequate Ni supply promotes changes in the plant metabolism, including processes related to nitrogen metabolism, such as amino acids, urea and ureides metabolisms (Rodríguez-Jiménez et al. 2016; Bai et al. 2006). Legumes that are dependent on N2 fixation (e.g., soybean) have their process impaired by Ni deficiency, because this element is an essential catalytic cofactor of [NiFe]-hydrogenase, an enzyme found in some symbiotic bacteria that recycles the H2 produced by a side reaction of nitrogenase in root nodules formed by the plant-bacteria association (Cammack 1995; Bagyinka 2014). Moreover, Ni has shown the potential to control soybean diseases, such as powdery mildew (Barcelos et al. 2018) and Asian soybean rust (Einhardt et al. 2020a; 2020b).
Abstract in English:ABSTRACT Heat stress can impact crop development and yield and amino acids play diverse essential roles in plants. This work aimed to study the long-term effects of foliar spray with L-arginine in antioxidant machinery, physiology, nutrition, productivity and fruit quality of tomato plants subjected to transient heat stresses. Six concentrations of L-arginine were sprayed on the plants: 0 (control), 0.10, 0.25, 0.50, 1.0 and 2.0 g·L–1. The content of hydrogen peroxide (H2O2), a reactive oxygen species, decreased concurrently to the increasing arginine concentration. The ascorbate peroxide (APX) activity had an inverse behavior to that observed for H2O2 content (r = –0.79), not only indicating that arginine is able to modulate APX, but also suggesting that this enzyme plays an important role on the mitigation of H2O2 generation under heat stress. Ascorbate peroxide and catalase (CAT) activities had a positive correlation (r = 0.82), showing that these enzymes may work in tandem. The influence of arginine on photosynthesis activity and gas exchange was generally weak and depended mainly on the plant developmental stage. Yield was increased by 19.8 and 23.1% in plants that received 1.0 and 0.5 g·L–1 of arginine, respectively, when compared to control plants. In conclusion, the use of exogenous L-arginine can protect tomato plants against oxidative imbalance under transient heat within protected environments.