Adaptabilidade e potencial fitorremediador de espécies vegetais em solo salino

Abstract

Salt degraded area reclamation is an important strategy for the optimal use of natural resources and agricultural productivity. In this sense, salt removal by tolerant crops is a viable alternative, emerging as an efficient and low cost technology. Plant species such as Atriplex nummularia have recognized efficiency in salt affected soils reclamation and is disseminated throughout the world, however, it has not spread knowledge in Brazilian semiarid region. The study of more accepted species, as their adaptability and ability to reclaim saline soils, can increases products supply and reduces consumer pressure on native vegetation. So, this study was carried to investigate use possibility of plant species: sabiá (Mimosa caesalpiniifolia Benth), leucena (Leucaena leucocephala (Lam) de Wit.), neem (Azadirachta indica A. Juss) and oldman saltbush (Atriplex nummularia L.) for reforestation of salt degraded areas, in single and intercropped manure, evaluating plants growth in field, their physiological behavior and soil properties under cultivation. For this, the design utilized was in four randomized block in field, with four individualized treatments with four selected species, three intercropped treatments with the other three species and atriplex two by two, and a control treatment (no crop), totaling eight treatments, in 32 experimental plots. The soil salinity did not influence plant growth of saltbush, neem and leucena, however, it reduce the levels of K+, Ca2+ and Mg2+ for all plants. Plant species responded differently for, physiological, biochemical and water relations variables. However, crop treatments promoted improvements in soil chemical and physical quality. Soil salinity (EC) and exchangeable sodium percentage (ESP) were significantly reduced compared to control treatment. Average PST (%) and EC (dS m-1) were 45.88 and 4.63 (control), 9.69 and 0.96 (Atr), 17.39 and 1.64 (Atr x Leuc), 19.63 and 2.00 (Atr x Nim), 22.60 and 2.25 (Atr x Sab), 23.27 and 2.73 (Leuc), 27.72 and 3.02 (Nim), and 25.10 and 4.48 (Sab), respectively. The phytoremediation treatments reduced the levels of Na+ e Cl- in soil. Physical attributes improvement was found by evolution in porosity and macroporosity increasing and soil density reducing. In addition, treatments effect was evidenced by hydraulic conductivity increase, until three times higher than control, in crop treatments there was a decrease of 23.68 g kg-1 in water dispersed clay, whereas in the control treatment was observed an opposite behavior, with increase of 18.33 g kg-1 in clay dispersion during experiment. So, the species Atriplex nummularia, Azadirachta indica, Leucaena leucocephala and Mimosa caesalpiniifolia can be recommended as phytoremediation crops in salt affected soils in Brazilian semiarid.