Ecofisiologia de quiabeiro sob soluções nutritivas salinas e ácido salicílico em cultivo hidropônico.

Abstract

One of the limiting factors for agricultural production in the semi-arid region of Northeast Brazil is the high concentrations of salts present in the water used for irrigation. To reduce the effects of salinity on plants, it is essential to use strategies to mitigate the deleterious damage caused by saline stress, with emphasis on the foliar application of salicylic acid. In this sense, the objective of this work was to evaluate the effects of foliar application of salicylic acid as an attenuator of saline stress in the physiology, growth, production and postharvest of fruits of

okra cv Canindé in a hydroponic system. The work was carried out in a greenhouse, in Pombal- PB, using the hydroponic cultivation system of the Nutrient Laminar Flow Technique - NFT.

The treatments consisted of four levels of electrical conductivity of the nutrient solution - ECsn (3.0; 5.0; 7.0 and 9.0 dS m-1) and four concentrations of salicylic acid - SA (0; 1.2; 2.4 and 3.6 mM) distributed in a completely randomized design in a split-plot scheme, with ECsn levels considered as plots and AS concentrations as subplots, with four replications and two plants per plot. The increase in the saline levels of the nutrient solution from 3.0 dS m-1 inhibited the synthesis of photosynthetic pigments, the foliar gas exchange, the maximum and variable fluorescence and the electron transport rate of okra cv Canindé in hydroponic cultivation, at 63 days after transplantation. The electrical conductivity of the nutrient solution above 3.0 dS m-1 accompanied growth, root volume, number and fresh mass of fruit per plant, average fruit length and average fruit weight of okra cv Canindé in cultivation hydroponic. The exogenous application of 1.8 and 2.4 mM of salicylic acid associated with saline nutrient solution, respectively 4.0 and 9.0 dS m-1, alleviated saline stress in chlorophyll a and b contents and fruit production respectively in the culture of okra cv Canindé in NFT hydroponic system. The concentrations of 2.1 and 2.4 mM of salicylic acid associated with saline nutrient solution of 9.0 dS m-1 increased the levels of soluble solids and titratable acidity, respectively, in fruits of okra cv Canindé.