Viabilidade do uso de água salina no cultivo de genótipos de abacaxizeiro.

Abstract

This research evaluates the effect of different salinities o f irrigation water on the rates of growth, development, physiology, production and quality of the fruit of pineapple genotypes (Ananas comosus comosus (L.) Merril) "Pérola", Smooth Cayenne and "Roxo". The experiment was established in a randomized block design in a split plot scheme, with three replicates, being tested in the main plots five salinity levels and in the split plots the genotypes. The work was carried out between 2001 and 2002 at the Pineapple Research Station, in Sapé, PB, Brazil, which belongs to Empresa Estadual de Pesquisa Agropecuária da Paraíba - Emepa. The irrigation waters were prepared by the addition of NaCl in enough amount for the attainment of the salinity levels corresponding to the electrical conductivities (ECw) o f 0.28, 0.78, 1.28, 1.78 and 2.28 dS m"'. A drip irrigation system with a lateral line o f drippers per row spaced at 15 cm was used, with irrigation at every other day with water depths of 5 mm. The evaluations were done in four phases: in the initial growth at 6 months, in the floral induction at 12 months, in the fruit development at 15 months and in the maturation of the fruit and in its harvest at 18 months. The salinity of the irrigation water, in the interval of ECw 0.28-2.28 dS m"1 affected the pineapple genotypes in different ways, as well as, the developing stages o f the plant. The "Pérola" cultivar presented better results related to stalk length, leaf area index, leaf area ratio, relative water content, fruit length, crown length and total soluble solids, whereas the Smooth Cayenne cultivar was more tolerant to cultivation with saline water, having better performance related to fruit weight, fruit phytomass, fruit diameter, crown weight, crown / fruit relation, acidity, harvest index, number of leaves, leaf phytomass, stem phytomass and total phytomass. The "Roxo" hybrid did not present good performance in the cultivation with saline water. The genotypes presented similar results in relation to the stomatic conductance, having the Smooth Cayenne bigger photosystem quantic efficiency (PSII) than the others. In the partition of the assimilated, the leaves constituted the main destination of the photosynthates, followed by the fruit, stem, younglings and crown. In relation to the effect of the saline water on the cultivated soil, it was observed that the parameters pH, ECes, SARes and ESP, did not reach levels which could compromise growth and development of the plants.