Hidrogel como alternativa para o desenvolvimento de leguminosas no semiárido

Abstract

The present study was developed to evaluate to the initial development of three species of leguminous plant with application of hydrogel, through hydric stress. This was to verify which leguminous plants would be more suitable for use as green manure in the recovery of degraded areas in the semiarid region. The experiment was carried out in a greenhouse at the Agricultural Science Center oh the Federal University of Ceará, located ate the Pici Campus, Fortaleza-CE. A soil (Planossolo Háplico) originated in the region of Pentecoste-CE was used. The experimental design was completely randomized, in factorial 3x2, being 3 species and 2 treatments with and without the use of the hydrogel. Three different species of beans were used: Vigna unguiculata, Vigna radiata and Canavalia ensiformis. The hydrogel used was the potassium polyacrylate polyacrilamide co-polymer. Meansurements were performed concerning plant height and stem diameter on the 10th and the 30th day. At the end of the experiment meansurements were concerning dry mass of the aerial part and the roots, number and mass of nodule, root/shoot ration and evaluation of nitrogen and carbon contends in the soil and both in the plant roots and aerial parts. The species C. ensiformis was superior in height and stem diameter at the 10th day and also presented higher dry mass of the aerial part, dry mass of the root, great accumulation of nitrogen in the aerial part, accumulation of carbon both in the aerial part and in the roots. At the 30th day, this species did not differ significantly from Vigna unguiculata in the variables stem diameter and nitrogen accumulation in the roots, it presented higher mean values than those obtained by Vigna radiata. The use of hydrogel in all the three beans improved the attributes: stem diameter at 30th day, root dry mass, root/shoot ratio, nodule mass, root nitrogen accumulation, carbon accumulation both in the root and the shoot. These values confirmed the hydrogel capacity to enable plant development under water deficit. The soil carbon content of the hydrogel treatment was lower than the control, suggesting a significant influence on the microbiota and soil organic matter decomposition. Both species Canavalia ensiformis and Vigna unguiculata were more suitable for use as recuperators of degraded soils because they presented, respectively, as higher biomass production and a higher mass of nodules, the latter a more efficient biological nitrogen fixation.