EFEITO DO NITRATO DE CÁLCIO NA REDUÇÃO DO ESTRESSE SALINO NO MELOEIRO

Abstract

This work aimed to evaluate the effect of the use of calcium nitrate on the reduction of stress in the melon plants exposed to excess salt in the irrigation water. The experiment was carried out at the Centro de Ciências e Tecnologia Agroalimentar (CCTA/UFCG), Pombal-PB, from 09/19/2009 to 11/20/2009, using the hybrid melon 'Hales Best Jumbo'. The treatments consisted of the use of two levels of salinity of the irrigation water (0.3 and 5.0 dS m-1) versus rates of N in the form of calcium nitrate (5.5; 6.25; 7.0; 8.5 g N per plant). The experimental design was in randomized blocks, in factorial scheme 2x4, with four repetitions. The highest rates of photosynthesis, stomatic conductivity, transpiration, leaf area, total dry mass and the fruit yield per plant were observed in melon plants irrigated with water of low salinity (0.3 dS m-1) compared to the ones with the saline water (5.0 dS m-1), and for the rates of N between 6.10 and 8.5g of N per plant for both levels of salinity. The suply of N in the form of calcium nitrate was effective on reducing the stress in melon plant the caused by the salinity of the irrigation water up to the rates of 6.20g of N per plant. In absolute terms we can affirm that the best performance of the melon plant was achieved with the dose of 6.25g of N per plant when irrigated with water of low salinity.