Aplicação exógena de peróxido de hidrogênio na mitigação do estresse salino em gravioleira.

Abstract

The Northeast region of Brazil has been highlighted without a national scenario with fruit production, mainly tropical fruits, but as concentrations of salts present in the water in these areas affect the growth and development of plants; in this way, it becomes a necessity to search for alternatives for use; waters in irrigation; Among alternatives, the use of hydrogen peroxide can optimize soil and / or saline water management in irrigated agriculture. In this context, the objective of the present study was to evaluate the emergence, growth, physiology and quality of saplings irrigated with saline waters and the exogenous application of hydrogen peroxide. The study was conducted in plastic bags under greenhouse conditions, using a Neolithic Regolithic Eutrophic with a sandy loam texture from the municipality of Campina Grande, PB, during the period from May to October 2017. The treatments were distributed in the design of randomized blocks, in a 5 x 5 factorial arrangement, with five levels of electrical conduction of irrigation water - CEa (0.7, 1.4, 2.1, 2.8 and 3.5 dS m-1) and five concentrations of hydrogen peroxide - H 2 O 2 (0, 25, 50, 75 and 100 μM), with four replicates, a plot consisting of three plants. Hydrogen peroxide concentrations were applied by imbibing the seed for a period of 24 hours. Later as applications as different concentrations of H2O2 were carried out via foliar spray through the adaxial and abaxial foliage. With increasing saline stress, there was a decrease in all growth variables, with a leaf area being the most impaired variable. An application of hydrogen peroxide attenuated the deleterious effects of irrigation water salinity on an emergence, stem diameter and leaf area. The exogenous application of hydrogen peroxide at concentrations of 25 and 50 μM attenuated the deleterious effects of water salinity on stomatal conductance, CO2 assimilation rate and chlorophyll a content, with a concentration of 25 μM being the most efficient. Irrigation with water from 0.7 dS m-1 negatively affected the quality of soursop seedlings. Concentrations of 31 and 100 μM H2O2 promoted higher values of relative leaf area and leaf and stem dry matter, respectively. The use of saline water with electrical conductivity of 1.22 dS m-1 can be used for irrigation of soursop seedlings, as it promotes an acceptable average reduction of up to 10% in growth.