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What is the relation between seed quality and food security? Here we built a summary diagram that links the development stages of the seeds with their potential of providing grain yield. This idea was tested using cowpea as a model crop, grown in a tropical environment. Initially, seed quality attributes such as water content, dry weight, germination, vigor, and longevity were characterized during seed development. With this, we were able to elucidate at which point the late maturation phase and the acquisition of seed with superior physiological quality starts. From these data, the proposed summary diagram highlighted the seed quality as a technological basis for generating a more productive plant community. It also showed that only seeds with a high-quality profile have a better chance to establishment in an increasingly challenging agricultural environment. Overall, we bring the concept that cowpea seeds with superior quality besides being the essential input for tropical agriculture is also a strategy that can contribute food security. [ABSTRACT FROM AUTHOR]

Foliar fertilization has been used as a supplemental strategy to plant nutrition especially in crops with high yield potential. Applying nutrients in small doses stimulates photosynthesis and increases yield performance. The aim of this study was to evaluate the efficiency of foliar application of molybdenum (Mo) to soybean and maize. The treatments consisted of the presence (+Mo) and absence (-Mo) of supplementation. Plant nutritional status, nitrate reductase (NR) activity, gas exchange parameters, photosynthetic enzyme activity (Rubisco in soybean and maize and PEPcase in maize), total soluble sugar concentration, leaf protein content, shoot dry matter, shoot nitrogen accumulated, number of grains per plant, mass of 100 grains, and grain yield were evaluated. For soybean and maize, application of Mo increased leaf NR activity, nitrogen and protein content, Rubisco activity, net photosynthesis, and grain yield. These results indicate that foliar fertilization with Mo can efficiently enhance nitrogen metabolism and the plant's response to carbon fixation, resulting in improved crop yields. [ABSTRACT FROM AUTHOR]

Stimulant fertilization isthe supplementary application of low doses of foliar fertilizers to otherwise well‐fertilized crops, and literature suggests that it may increase grain yield. However, the physiological mechanisms behind this potential yield increase are not well understood. This study investigated the effect of supplementary foliar nitrogen (N) in soybean [Glycine max (L.) Merr.] and maize (Zea mays) nutrition, photosynthetic parameters, antioxidant metabolism, agronomic parameters, and grain yield. We tested the presence or absence of low rates of late season (R3 and V10 of soybean and maize, respectively) foliar N fertilization in a main season soybean followed by an off‐season maize. While there were no effects of N application on leaf nutrient concentration, the net photosynthetic rate, stomatal conductance, water use efficiency, and carboxylation efficiency increased due to foliar N fertilization in both crops. The improvement in photosynthesis occurred due to a concomitant increase in Rubisco activity and in the concentration of sugar in the leaves prior to grain filling. Foliar N fertilization also improved antioxidant metabolism, suggesting that fertilized plants were less affected by environmental stresses during their cycle. The improvement in the metabolic activity due to foliar N did not affect grains per plant but increased a hundred grain mass and grain yield of both soybean and maize. Our results suggest that foliar N applied as stimulant fertilizer is a promising strategy to increase yield of maize and soybean crops. Core Ideas: Foliar N fertilization stimulates the carbon metabolism of soybean and maize crops.Photosynthetically active crops reduce cell damages by increasing antioxidant metabolism.Foliar N improves the grain filling to increase grain yield. [ABSTRACT FROM AUTHOR]

Thermomagnesium (TM) or magnesium (Mg) silicate (MgSiO3) is a byproduct of the nickel (Ni) industry. As a fertilizer, TM elevates the pH of acidic soils as well as provides Mg and silicon (Si) to plants. This novel practice can be a pivotal sustainable strategy to enhance soybean [Glycine max (L.) Merrill] development, particularly in tropical environments. Therefore, the present study aimed to evaluate the effects of TM application on the chemical properties of soil; Mg and Si contents in soil and plants; contents of reducing sugars, sucrose, and starch in leaves; and yield of soybean. The experiment was performed under controlled conditions in a greenhouse during the 2016–2017 cropping season. Two soil types (clayey and sandy) and five TM rates (0, 55, 273, 709, and 2,018 mg kg−1 of TM, and 0, 293, 410, 645, and 1,260 mg kg−1 of TM, respectively) with four replicates were used. In both soil types, pH as well as Mg and Si contents increased with increasing TM rates. Similarly, leaf contents of Mg, Si, reducing sugars, and sucrose as well as yield of soybean increased with increasing TM rates. Conversely, leaf starch content decreased with increasing TM rates. Therefore, TM positively affects whole-plant carbohydrate partitioning, thereby improving soybean development, grain filling, and yield. [ABSTRACT FROM AUTHOR]

• Deep root growth was improved by increasing soil fertility with lime. • Photosynthesis and water use efficiency are enhanced in high fertile soils. • Long-term liming increased soybean grain yield proportionally to the lime rate. Soil acidity is one of the major drivers of yield-limited crop productivity, particularly when combined with dry spells during crop development. Liming is a widely used strategy for alleviating the negative effects of soil acidity, ensuring greater crop root development to assist the plant in periods of low water availability, promoting full photosynthetic activity and, consequently, increasing crop yield. Here, we investigated the long-term effects of surface liming on soil chemical properties as well as soybean root growth, nutrition, photosynthetic parameters and grain yield during three growing seasons (2016–2019) in a region prone to dry spells. The long-term liming experiment was established in 2002. We evaluated the long-term effects of four surface lime rates: control, soil not treated with lime; ½ RLR, soil treated with half the recommended lime rate; 1 RLR, soil treated with the full recommended lime rate; and 2 RLR, soil treated with twice the recommended lime rate. The last lime application occurred in 2016. Our results revealed that increasing lime rates applied to soil surface up to 2 RLR increased soil fertility and root growth, besides to enhance the root distribution along soil profile. These changes contributed to boost soybean leaf photosynthetic pigments and gas exchange, leading to better growth, nutrition and grain yields, despite periods of dry spells. Our results suggested that in tropical agricultural systems with intensive cultivation throughout the agricultural year, higher lime rates can be applied without nutritional imbalances in the soil and plants. Our study provided important clues on how long-term liming changes soil fertility and triggers the cascading effects in improving root growth and distribution, as well as soybean photosynthetic metabolism and yield. [ABSTRACT FROM AUTHOR]

(1) Background: The aim of this study was to explore whether supplementary magnesium (Mg) foliar fertilization to soybean and maize crops established in a soil without Mg limitation can improve the gas exchange and Rubisco activity, as well as improve antioxidant metabolism, converting higher plant metabolism into grain yield. (2) Methods: Here, we tested foliar Mg supplementation in soybean followed by maize. Nutritional status of plants, photosynthesis, PEPcase and Rubisco activity, sugar concentration on leaves, oxidative stress, antioxidant metabolism, and finally the crops grain yields were determined. (3) Results: Our results demonstrated that foliar Mg supplementation increased the net photosynthetic rate and stomatal conductance, and reduced the sub-stomatal CO2 concentration and leaf transpiration by measuring in light-saturated conditions. The improvement in photosynthesis (gas exchange and Rubisco activity) lead to an increase in the concentration of sugar in the leaves before grain filling. In addition, we also confirmed that foliar Mg fertilization can improve anti-oxidant metabolism, thereby reducing the environmental stress that plants face during their crop cycle in tropical field conditions. (4) Conclusions: Our research brings the new glimpse of foliar Mg fertilization as a strategy to increase the metabolism of crops, resulting in increased grain yields. This type of biological strategy could be encouraged for wide utilization in cropping systems. [ABSTRACT FROM AUTHOR]

• Bacterial consortium improved the soybean gas exchange. • Bacterial consortium alleviates oxidative damage by improving antioxidant metabolism. • Dry spells causes less damage to the soybean yield treated with bacterial consortium. Short dry spells are an important grain yield constraint in tropical regions. Plant growth-promoting bacteria (PGPB) and their metabolites can mitigate the impact of drought stress by promoting changes in plant metabolism, physiology, and biochemistry. However, the effects of PGPB on soybean Glycine max (L.) Merril] under drought stress in tropical regions have not been established. The experiments were carried out under tropical field conditions with short dry spells. Therefore, in this study we used a three-factorial trial to evaluate the effects of bacterial consortium consisting of N 2 -fixing Bradyrhizobium japonicum (strain SEMIA 5079) and Bradyrhizobium diazoefficiens (strain SEMIA 5080), the biocontrol agent Bacillus subtilis (strain QST 713), and the plant growth-promoting Azospirillum brasilense (strains Ab-V5 and Ab-V6) with or without application of microbial secondary metabolites (MSM, rhizobial metabolites enriched in lipo-chitooligosaccharides (LCOs)) during two growing seasons. Photosynthetic pigments, gas exchange parameters, antioxidant enzyme activity and proline concentrations in leaves, nodulation, plant growth development and grain yield were evaluated. The bacterial consortium comprising Bradyrhizobium spp., A. brasilense strains and MSM application increased the contents of chlorophyll a (14.5 %), chlorophyll b (30.8 %), total chlorophyll (17.2 %), and total carotenoids (27.3 %) compared with Bradyrhizobium spp. treatment alone. This consortium also increased the net photosynthetic rate (17.7 %), stomatal conductance (56.5 %), internal CO 2 concentration in the substomatal chamber (8.3 %), and transpiration (44 %) compared with plants that received the standard inoculation (Bradyrhizobium spp. only), while reducing the leaf contents of hydrogen peroxide (−18.8 %) and proline (−29.4 %), lipid peroxidation (−15.9 %), and the activities of superoxide dismutase (−18.2 %), catalase (−21.2 %), and ascorbate peroxidase (−19.1 %). Taken together, the results indicate that a beneficial bacterial consortium comprising Bradyrhizobium spp. and A. brasilense strains combined with MSM application can alleviate oxidative damage during dry spells. Furthermore, this consortium improved soybean nodulation, plant growth development, and grain yield by up to 12.2 %. [ABSTRACT FROM AUTHOR]