Aplicação foliar de silício na atenuação de danos de deficiência hídrica em cultivares de feijão-caupi

Abstract

Water is one of the main limiting factors for the growth and development of crops, which can compromise the yield of plants, especially in cowpea, justifying the use of irrigation. However, when cultivated in the semi-arid region, characterized by water limitation, attention should be paid to the efficient use of water, which can be obtained by using more tolerant genotypes to water restriction. Stress due to water deficit in the plant can be mitigated through the application of endogenous elicitors such as silicon. The beneficial effects of Si can be divided into two groups: physical and physiological. The physical benefits are related to the accumulation of Si in the cell wall of plants, forming a physical barrier to the reduction of water loss and physiological are related to potentiate the activities of enzymes such as peroxidases and increase production of molecules such as proline. The research was carried out, in the year 2017, in the city of Campina Grande - PB: with a randomized complete block design using the 4x2x3 factorial scheme with 5 replications. The evaluated factors were constituted by four cowpea genotypes, two irrigation slides (50 and 100% of the reference evapotranspiration - ETo) and three silicon doses (0, 100 and 200 mg L-1) via leaf application, in the form of potassium silicate. Plant physiological evaluations (leaf water potential in the morning), growth (plant height, absolute growth rate, shoot growth and leaf area), biochemical (proline content and antioxidant enzymes) were performed. The objective of this study was to evaluate silicon as a stress attenuator due to water deficiency in cowpea cultivars. Therefore, silicon provided attenuation of water deficit with increased growth and development of cowpea cultivars. The antioxidant enzymes superoxide dismutase (SOD) and ascorbate peroxidase (APX) were potentiated with foliar application of silicon, increasing tolerance of the cultivars to the water deficit. The cultivars BRS Guariba and BRS Aracé expressed an increase in the content of proline, under water deficit and supplemented with Si, which promoted greater osmoprotection of the plants.