Desenvolvimento inicial de mudas de Anadenanthera colubrina sob diferentes níveis de sombreamento e salinidade da água de irrigação

Abstract

The Caatinga biome presents a wide variety of important plant species for the Northeast Region. However, this vegetation is one of the least known in the country and is among the most threatened Brazilian ecosystems, due to the intense exploitation of its resources associated with the lack of information that allows its dissemination. The Brazilian Semiarid is a region that presents unfavorable hydrogeological conditions for the development of most plant species. The native species of this biome are constantly subjected to abiotic stresses, including thermal, water and saline stress. Given the above, this research aims to evaluate the development of Anadenanthera colubrina (Angico Branco) seedlings under different levels of shading and salinity of the irrigation water. The research was conducted at the Center for Teaching and Research in Urban Agriculture (NEPAU), belonging to the Department of Plant Science at the Federal University of Ceará (UFC). The experimental design used was in randomized blocks in a split-plot scheme with four replications, totaling 80 experimental units. The plots were formed by four environments with different levels of light intensity: 0% (full sun), 30%, 50% and 70% of retention of solar radiation flux and the subplots formed by five increasing levels of salinity of the irrigation water : 0.4, 1.6, 2.8, 4.0 and 5.2 dS.m-1. The following variables were evaluated: soil salinity, plant height, stem diameter, number of leaves, gas exchange, biomass production and Dickson quality index. Soil salinity increased when irrigation with waters with high electrical conductivity was performed, and the concentration of salts was accentuated in environments with lower levels of shading. It was observed that the combination of salinity and solar radiation factors affected the initial development of Angico seedlings. Biometric parameters, biomass production, gas exchange and Dickson quality index were compromised by the increase in the electrical conductivity of the irrigation water, this stress being accentuated when the seedlings were under full sun conditions. However, the use of artificial shading favored the development of seedlings even when irrigated with higher salinity water.