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

Abstract

This paper aimed to evaluated the effect of the use of potassium nitrate on the reduction of stress on 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 19/09/2009 to 20/10/2009, using the hybrid melon 'Hales Best Jumbo'. The treatments consisted of two levels of of salinity of the irrigation water (0.3 and 5.0 dS m-1) and rates of N in the form of potassium nitrate (5.5; 6.25; 7.0 and 8.5g per plant). The experimental design was randomized blocks, on the factorial scheme 2x4, with four replications. The highest rates of photosynthesis, stomatic conductivity, transpiration, leaf area, total dry mass and the fruit yield per plant were observed on melon plants irrigated with low salinity water (0.3 dS m-1) compared to the ones with the high saline water (5.0 dS m-1), and on rates of N between 6.10 and 7.8g of N per plant for both levels of salinity. The supply of N in the form of potassium nitrate was effective on reducing the melon plant the stressing effect caused by the salinity of the irrigation water up to the rate of 6.85g of N per plant. On absolute terms we can affirm that the best performance of the melon plant was achieved with the rate of 7.0g of N per plan when irrigated with normal water and 6.25 of N per plant when irrigated with saline water.