Efeito do nitrato de potássio na redução do estresse salino no meloeiro.

Abstract

The irrigation has been pointed out as the main alternative for socioeconomical development of semi-arid regions. However, when improperly done it facilitates the soir salinisation and the degradation of hydric and edophic means. Thus, the aim of this work was to evaluate the effect of the use of potassium nitrate on the reduction of stress on the melon plant 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 1 9/09/2009 to 20/1 0/2009, using the hybrid melon 'Hales Best Jumbo'. The treatments were done by means of the use of two leveis of salinity of the irrigation water (0.3 and 5.0 dS m'l) versus rates of N in the form of potassium nitrate (5.51 6.251 7.0 and 8.5g per plant). The experimental design was randomized blocks, on the factorial scheme 2x4, with four repetitions. The highest rates of photosynthesis, stomatic conductivity, transpiration, leaf área, total dry mass and the fruit yield per plant were observed on melon plants irrigated with normal water (0.3 dS m'l) compared to the ones with the saline water (5.0 dS m 1), and on rates of N between 6.10 and 7.8g of N per plant for both leveis of salinity. The furnishing 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.