Crescimento e pigmentos fotossintéticos de genótipos de feijão caupi submetidos à irrigação com água salina.

Abstract

The cowpea, also known as bean-string beans or macassar, constitutes the main subsistence crop in the North and Northeast of Brazil, especially in the Interior Northeast. In Northeastern Brazil waters used in irrigation have, in most cases, the concentration of salts in the range of electrical conductivity from 0.1 to 3.0 dS m"1, can its use in agriculture, allied to intense evaporation and lack of adequate soil drainage, causing salinity problems. Given the above objective to identify cowpea tolerant and sensitive to salinity of irrigation water based on biomass production and photosynthetic pigments in northeastern Brazil. The experiment was conducted in a greenhouse in a greenhouse at the Federal University of Campina Grande (UFCG). Seeds of 10 different genotypes of cowpea, assigned by Embrapa Meio Norte, located in the city of Teresina, PI, sown in polyethylene pots with capacity for 20L of soil. The treatments consisted of the combination of two factors: salinity of irrigation water, with four levels and ten different genotypes. The statistical design was a completely randomized design with three replications, being studied factors arranged in a 10 x 4 factorial. 40 proposed treatments were arranged in 120 portions, ie vessels 120 spaced 0.5 m 0.5 m between plants and between lines. At 65 days after sowing were determined the total leaf area, dry weight variables: dry weight of shoot, dry weight, root dry weight and total dry weight of seeds; physiological parameters: SP AD index, chlorophyll a , b, and total carotenoids, chlorophyll a relationship: chlorophyll b and total chlorophyll ratio: carotenoids. The variables were analyzed statistically by F test at 5% probability. For statistical analysis we used the computer program ESAL-SISVAR. The salinity of the irrigation water decreased the production of fitomassas and leaf area, and increased the content of chlorophyll, with genotypes 1 (MNC01-649F-2-1), 2 (MNC03-736F-2), 5 (BRS-Marataoa ) and 6 (MNC02- 676F-3) and the most tolerant genotypes 3 (PINGO GOLD-1-2), 4 (BRS-Gurgueia), 7 (MNC02-683F-1), 8 (MNC03-5-737F -4), 9 (MNC03-737F-5-9), 10 (BRS-Tumucumaque) were the most sensitive to salt stress.