Germinação e desenvolvimento inicial de porta-enxertos e enxertos de mangueira sob condições de salinidade.

Abstract

The present study was conducted under greenhouse conditions at the Department Agricultural Engineering of the Federal University of Campina Grande (UFCG) in Campina Grande, during the period of January to June 2001, with the objective of studying the effects of the salinity of irrigation water in different varieties of mango (Mcmgifem indica L.) in the germination phase and initial growth and development of the rootstocks. The treatments consisted of six levels of electrical conductivity of irrigation water- ECw (0.7; 1.7; 2.7; 3.7; 4.7; 5.7 dS m"1) tested in two varieties (Espada and Manguito) recommended as rootstocks. As graft was the commercial varieties Tommy Atkins and Keitt were utilized being of good productivity and acceptance in the market of fruits "in natura.".The susbtrate used was triturated coconut shell and carbonized rice straw. A completely randomized experimental design was adapted in 6x2 scheme factorial, with four repetitions and 13 plants per repetition, totaling 624 plants. The irrigation waters were prepared with NaCl. In the root-stocks the parametes appraised, after 30, 40, 60 and 90 days after sowing (DAS) were: days for germination, percentage of emerged plants, index of emergency speed, growth indexes (number of leaves, plant height, diameter of the stem, leaf area, green weight of the aerial parts, roots and total), and physiological indexes (absolute growth rate relative growth, liquid assimilation ratio, of leaf area, root to aerial parts relation and water content in the aerial parts of the plant). The variables, number of leaves, diameter of the stem and height of the plants 30 days after grafting (DAE) were aslo appraised. The salinity of the irrigation water affected the percentage of germination significantly, index of emergency speed and provoced increment in terms of days to germinate. The increase of the salinity of the irrigation water induced significant reduction in the vegetative growth (number of leaves, plant height, diameter of the stem, leaf area, green and dry weight of the aerial parts, roots and total ), in the two rootstocks. The rootstock Espada was found to be tolerant to the salinity, in terms of germination percentagem, plant height and diameter of the stem. The increase of ECw influenced significantly the percentage of the grafts emergence, number of leaves, plant height and diameter of the stem, where larger survival rate of the grafts was observed for the Espada. There was a negative interference of salinity in absorption of the macronutrientes except for phosphoros and sulfur. The rootstock Espada absorbed more amounts of sodium, phosphorus and sulfur and the absorption of calcium and magnesium and were reduzed. All the micronutrientes had absorption inhibited by the accumulation of sodium in the leaves, Fe and Zn being the least in the leaves of the variety Espada where as the sodium was superior. The variables electrical conductivity of the drained water (ECdw), leaching fraction (LF), concentration factor and daily mean consumption (DMC), were also influenced with the incremento of electrical conductivity of the irrigation water resulting in increase of ECdw and of LF, while concentration factor (CF) had an inverse relationship with LF. The water consumption by plant was reduced with the elevation of ECw in the two rootstocks in a similar way.