Bioavailability of Nutrients in Seeds from Tropical and Subtropical Soybean Varieties

The selection of varieties or species of plants with higher nutrient uptake efficiency and nutrient concentration for biofortification of food crops is a key tool to reduce malnutrition. Soybean (Glycine max L. Merr) is one of the most important food crops, because it is consumed directly or indirectly, in the form of seeds, processed (milk and/or derivatives), or used as a protein component of animal feed worldwide. In order to select plants with higher nutrients concentration in seeds, 24 soybean varieties for tropical and subtropical conditions and different general features were assessed. There was great variability in photosynthesis rate, chlorophyll content, seed yield (SY), and concentration and uptake of nutrients by seeds between the varieties. Not genetically modified (NGM) crops showed higher nitrogen (N), cooper (Cu), and manganese (Mn) concentration and higher N, potassium (K), Cu, iron (Fe), Mn, and zinc (Zn) uptake, while for genetically modified (GM) crops only calcium (Ca) concentrations were higher. Varieties BRS 284 and BMX Magna RR showed the highest nutrients concentrations in the group with the highest nutrient efficiency. The genetic variability observed among the varieties regarding uptake and translocation of nutrients into seeds allows selecting more promising materials to be used in the biofortification of nutrients in soybean seeds.     

Interaction of Glyphosate with Zinc for the Yield,Photosynthesis, Soil Fertility and Nutritional Status of Soybean

Application of glyphosate herbicide in genetically modified (GM) soybean [Glycine max (L.) Merrill] in soils with low zinc (Zn) concentration may interfere in the uptake of this and other nutrients, with negative impact on productivity. Thus, an experiment was conducted in greenhouse conditions on Ustoxix Quatzipsamment soil to investigate the effects of the interaction of glyphosate with Zn for the yield, photosynthesis, soil fertility and nutritional status of soybean. The treatments consisted of two soybean varieties [BRS 133 (conventional—NGM) and its essentially derived transgenic line BRS 245RR (GM) with and without glyphosate application] and five Zn rates (0, 5, 10, 20 and 40 mg kg^?1, source zinc sulfate (ZnSO₄)), with four replicates. Except for the copper (Cu) and iron (Fe) concentrations, the introduction of the herbicide-resistant gene is the predominant factor reducing nutrient uptake, photosynthetic (A) rate, stomatal conductance (Gs), leaf chlorophyll and ureide concentrations. The administration of Zn rates lowered the leaf phosphorus (P) concentration, and there was significant increase in Zn concentration in the soil and in the plant. Except for the 20 mg kg^?1 of Zn rate, the use of the herbicide did not affect the shoot dry weight (SDW) and seed yield, and on average, the maximum seed yield was obtained with Zn concentrations of 26.4 and 18.7 mg kg^?1 extracted by Mehlich 1 and diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA), respectively.     

Climatic favourability zones for Eucalyptus rust in Brazil

Brazilian forest‐based industries are supported by more than 5.5 million hectares of Eucalyptus growing under different climatic conditions with different degrees of favourability for rust Puccinia psidii, including both traditional and expanding areas, where such disease is of major concern for the industry, foresters and scientists. The main objective of this study was to define favourable climatic zones for Eucalyptus rust in Brazil with the following aims: (i) to develop a spatial method for estimating the mean night‐time temperature (T_ng); (ii) to assess and validate a Eucalyptus rust model; and (iii) to map Eucalyptus rust favourability zones in Brazil based on the proposed model. A straightforward method, based only on latitude, day of the year, maximum and minimum air temperatures, was developed to estimate T_ng, which is a key variable for a proper application of Ruiz rust model. Based on 37 field experiments with natural rust occurrence, it was observed that climatic conditions are determining factors for disease severity. Significant correlations between disease severity observed in the field and climatic conditions were found: a negative correlation with temperature (r = .50, p < .01) and a positive correlation with relative humidity (r = .89, p < .0001). A significant correlation (r = .81, p < .0001) between the normalized infection index, produced from Ruiz model, and the average rust score was also observed. Once the model was validated under field conditions, it was applied using historical average data of air temperature and leaf wetness duration to obtain monthly Eucalyptus rust favourability maps for the whole country. These final maps show that favourable climatic zones for Eucalyptus rust are extremely dynamic, with high temporal and spatial variability in Brazil and that climatic conditions should be considered for expansion of Eucalyptus to new areas, in breeding programmes, and for defining the most suitable seasons for forest establishment in each climate of the country. These results provide forestry managers with practical tools to reduce uncertainty about the expected severity of Eucalyptus rust in Brazil.     

Effect of Nitrogen and Potassium Fertilization on Banana Plants Cultivated in the Humid Tropical Amazon

Banana (Musa spp.) is widely cultivated in tropical regions because of their economic importance for the local market as the source of food for the regional population. In the Amazon region, the banana crop was cultivated in the river basin before the 90th decade of the last century, but after the black sigatoka (Mycosphaerella fijiensis) and the increases of the bacteria wilt (Raostonia solanarum), the crops migrated to upper land soils with low natural fertility where there was no influence of floods for natural fertilization from the regional rivers. Nitrogen (N) and potassium (K) have been the foremost nutrient required by the banana trees and the aim of this study was to evaluate during two growing periods, the influence of the N and dipotassium oxide (K₂O) fertilization in yield and nutritional status of banana. The experimental design was a completely randomized blocks in a factorial 3 × 4 scheme with three replicates. The treatments were three N rates (0, 267, and 533 kg ha^?1) and four K₂O rates (200, 800, 1,600, and 2,400 kg ha^?1). The field plots had seven plants where the useful area had only five plants spaced 3 m × 2 m. The foliar N and sulfur (S) content were significantly influenced by the N rates, while foliar K, magnesium (Mg), and copper (Cu) were significant under the K₂O rates. The N, K₂O, and N × K₂O interaction interfered the foliar zinc (Zn) content. In both crop cycles, the bunch biomass and banana yield were not influenced by the N and K₂O rates.     

Magnesium-manganese interaction in soybean cultivars with different nutritional requirements

Manganese (Mn) deficiency in soybean has occurred mainly in soils with surface dolomite lime application, which increases pH and the magnesium (Mg) concentration in the surface layer. The objective of this study was to investigate the influence of Mg on the Mn uptake in four soybean cultivars with different nutritional requirements. The experiment was conducted under greenhouse conditions in a completely randomized design, in 4 × 2 × 4 factorial scheme [four soybean cultivars, two Mg rates (0.1 and 1.0 mmol L^?1) and four Mn rates (0.0, 1.0, 2.0, and 5.0 µmol L^?1)], with four replicates. The cultivars used in the experiment were: IAC 17 and FT Estrela (for soils fertility or high nutritional demand) and IAC 15–1 and DM Nobre (for soils partially corrected or medium nutritional demand). The root dry weight (RDW), shoot dry weight (SDW), SDW/RDW ratio, chlorophyll content, seed yield and foliar concentrations of nitrogen (N), phosphorus (P), potassium (K), Mg, calcium (Ca), iron (Fe), Mn, and zinc (Zn) were determined. The application of the highest Mg rate increased seed yield. This was also observed with a Mn rate up to 3.0 μmol L^?1. There was an interaction of Mg and Mn in the plant, and it was found that the IAC 17 cultivar was the most sensitive to Mn, while FT Estrela had the lowest performance. N, P, K, and Zn concentrations were significantly influenced by Mn rates. The Mg and Mn rates had a significant effect on Mg foliar concentrations. The rate of 1.0 mmol L^?1 of Mg provided the lowest levels of nutrients to the plant and increased SDW and seed yield, regardless of the nutritional requirement of each cultivar.     

Osmoregulators in <Emphasis Type="Italic">Hymenaea courbaril</Emphasis> and <Emphasis Type="Italic">Hymenaea stigonocarpa</Emphasis> under water stress and rehydration

The objective of this work was to evaluate the effect of different water deficiency and rehydration levels on the concentrations of osmoregulators in two plant species (Hymenaea courbaril and H. Stigonocarpa) in the Amazon. We adopted a 2 × 5 × 5 factorial system, referring to 2 species (H. courbaril and H. stigonocarpa) and 5 stages of hydration and rehydration. The five hydration and rehydration stages were established in: (1) Control treatment E0; (2) Plants with 13 days of stress after incubation—E13; (3) Plants with 26 days of stress E26; (4) The plants that were established after 26 days after incubation and rehydrated for two days (RD2); (5) rehydrated for two days (RD4). The plants that were established after 26 days after incubation and rehydrated for four days. The experiment totaled fifty young plants with five replicates. Biochemical measurements were performed at the beginning of the experiment (E0) at 13 (E13) and 26 (E26) days after the water stress, in which the plants were rehydrated, repeating the analyses after two (RD2) and four (RD4) days. Both species increased the sucrose concentration by 18%, with a decrease of 52% in starch content. The RD4 time presented the highest mean starch concentration (0.19 mmol g^?1 of the residue for H. courbaril and 0.27 mmol g^?1 of residue for H. stigonocarpa). Increased proline concentrations were recorded for controls until RD2 for both species. For glycine betaine, the highest increases in treatments E26 and RD2 were observed for the H. courbaril species. Our rehydration period was not sufficient for total recovery of pre-stress concentrations of all studied solutes.     

Influence of multiple- and single-species infestations on herbivore-induced cotton volatiles and <Emphasis Type="Italic">Anthonomus grandis</Emphasis> behaviour

Plants interact with multiple organisms throughout their life cycle. As a result, they are commonly attacked by multiple species of herbivores, leading to the induction of plant defence systems. Herbivore-induced plant volatiles (HIPVs) play an important role in the interaction between community members and can be used to manipulate insect pest behaviour, being a valuable tool in integrated pest management strategy. In this study, the interaction of two chewing insects, the boll weevil, Anthonomus grandis, and the fall armyworm, Spodoptera frugiperda, and of one piercing-sucking insect, the Neotropical brown stinkbug, Euschistus heros, was evaluated for the induction of volatile compounds in cotton under single- and multiple-species attacks. As a control, the emissions of undamaged plants were also measured. In addition, the effect of HIPVs on boll weevil behaviour was also assessed. Qualitatively, single- and multiple-species herbivory induced a similar volatile blend. There was, however, a difference in the amount and proportion of compounds emitted. Plants infested with E. heros emitted a blend of volatiles more similar to that of the undamaged control compared to the other herbivore-induced treatments. The plant volatiles emitted due to simultaneous multiple-species herbivory were induced faster than volatiles emitted by sequential herbivory events, indicating different induction mechanisms depending on the attack configuration. In addition, cotton volatiles induced by an individual attack of A. grandis were attractive to conspecifics, as were the volatiles induced by multiple-species herbivory in both simultaneous and sequential attacks. The use of cotton HIPVs, both under multiple- and single-species attack, can be used for the development of alternative methods for semiochemical-based weevil management, e.g., enrichment of aggregation pheromone traps with plant volatiles.     

Dris calculation methods for evaluating the nutritional status of oil palm in the Eastern Amazon

This study aimed to evaluate six Diagnosis and Recommendation Integrated System (DRIS) calculation methods, including two ways to choose the nutrient ratio [F (Letzsch) or R (Nick) values] combined with three functions (Beaufils, Jones, or Elwali and Gascho), and to generate nutritional diagnoses for oil palm. A total of 144 foliar samples in 33 plots in the Eastern Amazon, Brazil, were used. Except for potassium (K) in all calculation methods, the DRIS indices showed no correlation with soil nutrients. Regardless of the formula, the nutritional balance index correlated with the productivity (significant r values) and similar diagnostics were obtained. These diagnoses were reliable according to the chi-square test (χ2), and most observed frequencies presented χ2 calculated less than χ2 tabulated. The average frequencies of samples with nutrient deficiency were 51%, 42%, 37%, 35%, 32%, 30%, 30%, 25%, 20%, 12%, and 12% for samples with nitrogen (N), boron (B), manganese (Mn), sulfur (S), K, copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), phosphorus (P), and magnesium (Mg), respectively. All tested DRIS methods may be used, and their diagnoses indicate the most common nutritional deficiencies in oil palm.