Resumo em Inglês:

ABSTRACT Chill hours availability influence break dormancy, sprouting and production of temperate fruits trees in different regions. However, there are few reports on the subject for fig tree. This study aimed to evaluate the effects of the accumulated chilling hours on the physiology and dormancy release of fig cultivars. Stem cuttings of five fig cultivars were collected at the end of winter over two crop cycles and exposed to 0, 40, 80, 120 and 160 accumulated chilling hours (CH) in a cold chamber (8±0.5 ºC). Physiology of fig buds was then evaluated with regards to antioxidant enzymes activity, carbohydrate and nitrogen contents. The exposure of fig stem cuttings with two buds to different accumulated CH presented physiological changes for antioxidant enzymes activity, carbohydrates and nitrogen contents and confirming that the cultivars responded differently to the climatic conditions of each crop cycle. Results detected that the lowest accumulated CH in field in 2018 (2.7 CH) enabled a greater effect of the artificial CH when compared to 2017 (19.5 CH). Each fig cultivar had a critical accumulation point. The cultivars Roxo de Valinhos and Pingo de Mel require less CH to break dormancy, while Troyano requires more CH to finish this vegetative rest period.

Resumo em Inglês:

ABSTRACT This study aimed to analyze rice straw alternative managements to maximize the rice-soybean succession yield and to quantify their impacts on soil properties. The experiment was set up in a completely randomized design with six replicates. Nine rice straw managements were evaluated: straw burning (M1), straw harvesting (M2), straw incorporation with disc harrow and two passes (M3) or three passes (M4) of leveling disc harrow, straw incorporation with knife-roller and soybean no-tillage (M5), straw incorporation with knife-roller and two passes (M6) or three passes (M7) of leveling disc harrow, straw incorporation with two passes of knife-roller and two passes (M8) or three passes (M9) of leveling disc harrow. Straw incorporation by knife-roller provided the lowest soil organic matter (SOM) contents due to slow mineralization of fresh straw incorporated shallow into the soil, although SOM increased in the surface layer related to the initial content. Rice-soybean succession yield was more affected by the physical than by the soil chemical properties. The straw incorporation with one pass of knife-roller and two passes of leveling disc harrow (M6) can replace the straw burning, without affecting the rice-soybean succession yield and soil physical quality, with a reduction in machinery operations, allowing early soil tillage.

Resumo em Inglês:

ABSTRACT We aimed to verify the morphophysiological changes in jaboticaba tree (Plinia peruviana (Poir.) Govaerts) saplings under shade gradient to improve knowledge on the appropriate light environmental conditions for the saplings production and field homogeneous or intercropping cultivation of this species. The saplings were grown under full sun and artificial shade levels (30%, 50%, and 80%). Growth, photosynthetic pigments, gas exchanges, chlorophyll fluorescence, and leaf anatomy characters were evaluated. Our results showed that jaboticaba tree saplings growth was improved under full sun and 30% of shade. Under 50% and 80% shade the saplings demonstrate phenotypic plasticity, such as larger and thinner leaves. Chlorophyll fluorescence, chlorophyll content, and quantum yield of photosystem II were higher under higher shade level, but the CO2 assimilation rate was not different between light conditions. These changes are typically found in shade-tolerant plants and is related to perform photosynthesis more efficiently in highly variable light conditions. Despite that, we recommend that cultivation be carried out under full sun or up to 30% shade to maximize jaboticaba tree saplings growth in nurseries and orchards.

Resumo em Inglês:

ABSTRACT Soybean tolerance to defoliation may be affected by population density, as the plant population interferes with the crop leaf area index . This study aimed to evaluate the effect of defoliation at the beginning of pod formation on the agronomic performance of soybean at different plant densities. The experiment was conducted under field conditions in Campos Novos, SC, Brazil, during 2016/2017 and 2017/2018 growing season. The experimental design was a randomized block in a split-plot arrangement. The main plot consisted of three densities (100,000, 300,000, and 500,000 plants ha−1), whereas the subplots consisted of the cultivar NA 5909 RG submitted to five defoliation levels (0, 16.6, 33.3, 50, and 66.6%). Grain yield ranged from 4,219 to 5,356 kg ha−1 in the 2016/2017 growing season and 3,732 to 5,186 kg ha−1 in the 2017/2018 growing season. Plant density did not interfere with the grain yield response to defoliation performed at the beginning of pod formation. The 16.6% defoliation increase grain yield by 7.5 and 5.6% relative to the control in 2016/2017 and 2017/2018 growing seasons, respectively. The soybean tolerate defoliation of up to 33.3% at R3 with no significant decrease in grain yield, regardless of the plant density.

Resumo em Inglês:

ABSTRACT The aim of this study was to assess yield components and grain yield of soybean cultivars in response to sowing densities. For this, two soybean cultivars and five sowing densities were tested, in a two-factor scheme. The following yield components were measured by the end of the cycle: plant height; insertion height of the first pod; number of nodes per plant; number of pods with one, two, three and four grains; number of pods per plant; number of grains per plant; weight of a thousand grains; humidity and grain yield. Sowing densities did not cause significant variations of grain yield (bags ha-1) for any cultivar, however, higher populational densities promoted a reduction in the number of pods with two and three grains, as well as a reduction in the total number of pods and grains per plant for both cultivars. Cultivar NS 5700 IPRO was the most productive, with a higher number of pods with two and three grains and number of pods and grains per plant.

Resumo em Inglês:

ABSTRACT Growth analysis (GA) is used to quantify plant development based on morphophysiological changes. GA is a practical tool to evaluate nursery techniques to make them more efficient. The objective of this essay was to quantity measure morphophysiological growth variables of Eucalyptus grandis x Eucalyptus urophylla and Hymenaea courbaril (jatoba) container seedlings to characterize growth stages. The essay was conducted in a shade house located in the western state of Paraná. GA analyses were performed at 10-day intervals on seedlings of both species. When evaluating Hymenaea courbaril seedlings results indicated ​​increased values of height, diameter, root and shoot dry biomass up to 130 days after emergence (DAE). Seedling growth stage-based GA were 70, 100 and 130 DAE for the Eucalyptus hybrid and 50, 80, and 110 DAE for jatoba which presented accelerated, intermediate and reduced seedling growth.

Resumo em Inglês:

ABSTRACT The photosynthetic metabolism is a key point to improve soybean yield. In this work, we demonstrated that radiation use by soybean plants can be improved, aiming to improve the grain yield in the lower canopy. The objective of this study was to observe whether the increase in solar radiation input in the canopy of soybean plants improves their yield performance. Three experiments were carried out during the 2017/2018 season. For each experiment, treatments consisted in the opening of one or two side rows of cultivation at the R2 and R5 stage of soybean plants (NA5909RR) until maturity, plus a control. Increase on solar radiation provided by the oppening of rows enhanced the yield potential in the nodes of the lower canopy, mainly when two rows were opened. The main benefits of increasing the radiation available throughout the canopy of soybean plants are observed in the number of pods and thousand-grain weight, demonstrating the importance of increasing the availability of assimilates in lower leaves. Interestingly, the benefits of the increase in solar interceptation were observed regardless of the yield potential of the area, which varied between 4.9 and 6.7 ton ha-1.

Resumo em Inglês:

ABSTRACT The aim of the work was to analyze the influence of variables such as shading, temperature and humidity in the production and rooting of mini-cuttings of Sequoia sempervirens (D. Dom) Endl. in a clonal mini-garden. The experiment was conducted at the Forest Nursery at the University of Santa Catarina State - CAV/UDESC, Lages - SC. The minicuttings were obtained by vegetative rescue of a single clone (A228). The original S. sempervirens individuals studied are located in the National Forest of São Francisco de Paula -RS (FLONA). Sprouts were collected 90 days after the application of girdling rescue techniques. Subsequently, mini-stumps were obtained, which were submitted to three different treatments: T1 - Mini-stumps without shading protection, T2 - Mini-stumps with single layer of shading and T3 - Mini-stumps with double layer of shading. There was no significant difference for humidity and temperature in relation to the production of mini-cuttings by the mini-stumps, while for shading the treatments T2 and T3 showed greater efficiency. It is possible that the shading treatments on S. sempervirens mini-stumps allows the vegetative tissue to be more juvenile, obtaining excellent results in cutting.

Resumo em Inglês:

ABSTRACT Phytophthora infestans is the most important disease in potato crops. Its control is based on the use of chemical products that have developed pathogen resistance and high economic and environmental impacts. To reduce these effects, the use of plant varieties or cultivars resistant to this pathogen has been proposed. The aim of this study was to evaluate the heritability of resistance to this pathogen in a population of elite Solanum phureja genotypes. In this study, 1,355 clones with three replicates from 20 families were included in the evaluation. Heritability was assessed in the broad and narrow senses. Results of the relative area under the disease progress curve varied between 0.08 and 0.64, indicating that the population contains genes that code for resistance. Heritability in both directions (narrow 0.022 and broad 0.255) showed significant differences, indicating an influence of dominance genetic effects and environmental effects. Thus, to use these genotypes in potato breeding programs, hybridization methods should be used instead of selection methods.

Resumo em Inglês:

ABSTRACT Maize is importance in the semiarid region due to its forage potential. However, the large number of hybrids on the market hampers the selection of the hybrid by the producer. Given the above, the objective of this paper is to identify genotypes with productive potential for forage and grain production according to the characteristics of the semiarid region of Brazil. Twenty genotypes with different genotypic classes were evaluated in two years (2018 and 2019) in the municipality of Gracho Cardoso, state of Sergipe. The experiments were carried out in a randomized complete block design (RCBD), with two replicates. Genotype characteristics, grain yield, and forage mass were evaluated and the results were estimated using mixed models and GT Biplots. The genotypic classes consisting of topcrosses and intervarietal hybrids showed high average grain yield and the three classes produced equally on average for forage mass. It was observed that the HI, HTC, and V genotypic classes were the most responsive for grain yield, forage mass, and dry matter content, respectively. Therefore, it is concluded that the genetically broad-based hybrids (HTC and HI) were the most promising for the semiarid of region of Sergipe, while interspecific hybrids were the most productive and stable.

Resumo em Inglês:

ABSTRACT The distribution modeling in diameter classes is an important indicator of the potential use of a forest community, as well as the projection of future forest production. The objective of this study was to evaluate the diametric structure and to select probabilistic density functions for three woody species in forested arboreal Caatinga vegetation in Bahia, Brazil. The study was carried out in the Contendas do Sincorá National Forest in the state of Bahia, Brazil. A total of 16 plots of 20 x 20 m were installed and all individuals with diameter at breast height equal to or greater than 5.0 cm were measured. The three species with the highest population density (Commiphora leptophloeos, Manihot catinga and Patagonula bahiensis) were selected for analysis and modeling of the diametric structure. Four probabilistic density models were adjusted. The Akaike information criterion was used to select the best model. The results found indicated that the three species presented a decreasing type curve. The Log-Normal function best described the diametric distribution and it can be indicated to describe the diametric distribution and assist in making decisions about the management and conservation of these species. It is concluded that the Normal function was less adequate to represent the distribution of the studied species.

Resumo em Inglês:

ABSTRACT Baru tree (Dipteryx alata Vogel.) is a been an alternative to establish an Integration Crop-Livestock-Forestry Systems (ICLFS), combining native species preservation with sustainable food production. However, the management procedure of herbicides for weed control is one of the major limiting factors to include tree components within ICLFS. Thus, the study evaluated the tolerance of D. alata submitted to different concentrations of glyphosate on the plants, to make the introduction of this forest species in ICLFS. The treatments comprised different doses glyphosate: 0.0 (control); 960; 1920; 2880 and 3840 g a.e ha-1. Shoot height, stem diameter, shoot dry weight, root dry weight and total dry weight, as well as Dickson Quality Index and phytotoxicity were assessed. The phytotoxicity in plants varies according to the applied doses of glyphosate, with progressive yellowing in the leaves up to well-developed necrosis and leaf senescence in the highest doses. All doses tested reduced the biometric and qualitative attributes of D. alata seedlings, demonstrating that no treatment was selective, although the plants are tolerant at dose 960 g a.e ha-1 tested. Increases in doses of glyphosate do not cause the death of seedlings D. alata that shows a great potential to compose ICLFS.

Resumo em Inglês:

ABSTRACT The identification of pod- and seed-related traits of soybean genotypes and their interaction with water uptake can be applied in breeding programs with a view to establishing cultivars developed for the production and maintenance of high-quality seeds. The objective was to evaluate the water uptake of pods and seeds of soybean cultivars with different lignin contents after different soaking periods. The experimental was arranged in a completely randomized, 7×10 factorial design, with four replications. The factors consisted of seven soybean cultivars and 10 soaking periods (1, 2, 3, 4, 5, 6, 7, 8, 24, 48 hours). The pods and seeds were grown in a greenhouse and harvested at the phenological growth stage R8 (at full maturation, when 95% of the pods had mature color). The following traits were evaluated: lignin content in pod and seed coat, moisture content, and rate of water uptake of pods and seeds. Soybean cultivars with pods with high lignin contents have a lower rate of water uptake. The lignin contents of the seed coats, within the chosen limits, did not affect the seed water uptake.

Resumo em Inglês:

ABSTRACT Fungal virulence is multifaceted and dependent on multiple factors including the pH of the spore suspension. In this study, we accessed effects of six pH values of Beauveria bassiana, and Metarhizium anisopliae medium for the growth, sporulation, and mortality on sugarcane stalk borer Diatraea saccharalis. The culture of fungi was performed onplates containing the PDA (Potato Dextrose Agar) medium. Virulence was tested in D. saccharalis larvae distributed in four replicates of 15 larvae. To evaluate the performance of the isolates, they were grown at different pH values in an artificial chitin medium to confirm the degradation capacity of the fungi at each pH. No significant difference was observed for the sporulation at pH ranged from 4 to 9 for both fungi. In the mortality assay, larval mortality was higher at pH 7 and 8 for both fungi, reaching 87% for B. bassiana and 81% for M. anisopliae.

Resumo em Inglês:

ABSTRACT Studies related to climate change and agricultural value chains have in common the growing concern on conserving water resources. Thus, the concept of the water footprint stands out, which measures the amount of water (in volume) necessary to produce a unit (in mass) of a given product. Among Brazilian agricultural activities, coffee farming emerges as one of the most important, even though the crop is sensitive to potential climatic changes, especially to the increase in temperature and periods of drought. An alternative to mitigate the effects of climate change is shade management, which is common in agroforestry systems. Therefore, the objective of this study was to evaluate the influence of shade management on the water footprint of coffee activity in the region of “Matas de Minas”. The water footprint was calculated for the field and product processing phase. Despite reducing the evapotranspiration of the coffee plant, shade management provided an increase in the water footprint, since it decreased the crop yield. The water footprint data obtained are expressive, with a calculated value of 13,862 m3 t-1 for full sun management and 16,895 m3 t-1 for shade management, in which both are the most recommended for the agricultural sector.