Non-Structural Carbohydrate Metabolism, Growth, and Productivity of Maize by Increasing Plant Density

Increasing plant density seems to improve the productivity of maize crops, and the understanding of how the metabolism of non-structural carbohydrates is affected in plants under high crop density is critical. Thus, with the objective of further clarifying this issue, maize plants were subjected to densities from 30,000 to 90,000 plants ha−1, and the plant growth, soluble sugars and starch contents, invertase and sucrose synthase activities, and plant production were evaluated. We found that the stalk is more sensitive to the increasing plant density than leaves and kernels. The dry weight of the stalk and leaves per single plant decreased more drastically from low to intermediate plant densities, while grain production was reduced linearly in all plant density ranges, leading to higher values of harvest index in intermediate plant densities. The sucrose concentration did not change in leaves, stalk, or kernels of plants subjected to increasing plant densities at the R4 stage. Also, the specific activity of soluble invertase, bound invertase, and sucrose synthase did not change in leaf, stalk, or kernels of plants subjected to increased plant density. The productivity was increased with the increase in plant density, using narrow row (0.45 m) spacing

Non-Structural Carbohydrate Metabolism, Growth, and Productivity of Maize by Increasing Plant Density

Increasing plant density seems to improve the productivity of maize crops, and the understanding of how the metabolism of non-structural carbohydrates is affected in plants under high crop density is critical. Thus, with the objective of further clarifying this issue, maize plants were subjected to densities from 30,000 to 90,000 plants ha−1, and the plant growth, soluble sugars and starch contents, invertase and sucrose synthase activities, and plant production were evaluated. We found that the stalk is more sensitive to the increasing plant density than leaves and kernels. The dry weight of the stalk and leaves per single plant decreased more drastically from low to intermediate plant densities, while grain production was reduced linearly in all plant density ranges, leading to higher values of harvest index in intermediate plant densities. The sucrose concentration did not change in leaves, stalk, or kernels of plants subjected to increasing plant densities at the R4 stage. Also, the specific activity of soluble invertase, bound invertase, and sucrose synthase did not change in leaf, stalk, or kernels of plants subjected to increased plant density. The productivity was increased with the increase in plant density, using narrow row (0.45 m) spacing

Proline and trehalose in maize seeds germinating under low osmotic potentials

ABSTRACT Although it is relatively well known that adult plants tend to accumulate proline and trehalose in their tissues as a physiological mechanism in response to drought, there is scarce information about the development of this physiological response in seeds. Thus, the objective of this research was to verify if maize seeds are able to develop mechanism of osmoprotection, when are germinating under low osmotic potential, and the possibility to use the levels of trehalose and proline in a defined seed part, aiming to differentiate genotypes regarding drought tolerance. The experiment was performed as a factorial arrangement of 2 x 5 (2 hybrids x 5 osmotic potential) within a completely randomized design, with four replicates. It was found that the proline content in the embryo axis of maize seeds germinating under water limitation is directly proportional to the intensity of this stress. Distinct hybrids show different proline levels accumulated in the embryo axis, when seeds are germinating under the same conditions of water limitation. The trehalose content tends to decrease in the embryo axis and in the endosperm of maize seeds germinating under increasing water limitation, but the reduction is not directly proportional to osmotic potential

Nutrient allocation among stem, leaf and inflorescence of jatropha plants

ABSTRACTInformation on the partitioning of nutrients among various organs in jatropha plants, as a complementary tool for the recommendation of fertilization, is still not available. This study aimed to evaluate the contents of macro and micronutrients in stems, leaves and inflorescences of jatropha branches at the beginning of flowering. At the beginning of flowering, adult jatropha plants were sampled and divided into five compartments: inflorescences, leaves from vegetative branches, leaves from flowering branches, stems from vegetative branches and stems from flowering branches. Jatropha inflorescences are a drain of nutrients. Leaves are important sources of nutrients demanded by the inflorescences at the beginning of flowering. The higher allocation of nutrients in the inflorescences suggests the need for preventive/corrective fertilizations, which must be performed at least 30 days before flowering, providing plants with nutrients in adequate amounts for a good yield.</p

Nutritional status of jatropha under cattle manure and natural phosphate in rainfed conditions

ABSTRACTThere is little information on the technical recommendation of fertilization for jatropha in the semi-arid region. This study aimed to evaluate the nutritional status of jatropha plants fertilized with cattle manure and natural phosphate under rainfed conditions. The experiment was set in a randomized block design, with three replicates, arranged in a 4 x 4 factorial scheme, corresponding to 4 doses of cattle manure (0, 4, 8 and 12 t ha-1) and 4 doses of natural phosphate (0, 250, 500 and 750 kg ha-1). The application of 8 t ha-1 of cattle manure, in isolation or associated with 500 kg ha-1 of natural phosphate, promotes adequate conditions to obtain jatropha plants with sufficient levels (g kg-1) of N (29.8), P (5.1), K (33.8), Ca (17.1), Mg (14.0) and S (2.6) and micronutrients (Cu = 8.0 and Mn = 94.4 mg kg-1) in its leaf tissue

Addition of silicon to boron foliar spray in cotton plants modulates the antioxidative system attenuating boron deficiency and toxicity

Abstract Background Boron (B) nutritional disorders, either deficiency or toxicity, may lead to an increase in reactive oxygen species production, causing damage to cells. Oxidative damage in leaves can be attenuated by supplying silicon (Si). The aim of this study was to assess the effect of increasing foliar B accumulation on cotton plants to determine whether adding Si to the spray solution promotes gains to correct deficiency and toxicity of this micronutrient by decreasing oxidative stress via synthetizing proline and glycine-betaine, thereby raising dry matter production. Results B deficiency or toxicity increased H2O2 and MDA leaf concentration in cotton plants. H2O2 and MDA leaf concentration declined, with quadratic adjustment, as a function of increased leaf B accumulation. Proline and glycine-betaine leaf concentration increased under B-deficiency and B-toxicity. In addition, production of these nonenzymatic antioxidant compounds was greater in plants under toxicity, in relation to deficient plants. Adding Si to the B spray solution reduced H2O2 and MDA concentration in the plants under nutrient deficiency or toxicity. Si reduced H2O2, primarily in B-deficient plants. Si also increased proline and glycine-betaine concentration, mainly in plants under B toxicity. Dry matter production of B-deficient cotton plants increased up to an application of 1.2 g L− 1 of B. The critical B level in the spray solution for deficiency and toxicity was observed at a concentration of 0.5 and 1.9 g L− 1 of B, respectively, in the presence of Si, and 0.4 and 1.9 g L− 1 of B without it. In addition, the presence of Si in the B solution raised dry matter production in all B concentrations evaluated in this study. Conclusion Our findings demonstrated that adding Si to a B solution is important in the foliar spraying of cotton plants because it increases proline and glycine-betaine production and reduces H2O2 and MDA concentration, in addition to mitigating the oxidative stress in cotton plants under B deficiency or toxicity