Morphophysiology of “Crioulo” Cashew Rootstock Seedlings under Saline Water Irrigation and Potassium Silicate Doses

Abstract

Aims: This work aimed to evaluate the effects of saline water and potassium silicate on the physiological and morphological changes of “Crioulo” cashew rootstock seedlings. Study Design: The experimental design was the randomized block, corresponding to five levels of irrigation water electrical conductivity – ECw and five doses of potassium silicate, with four replicates and two plants per plot Place and Duration of Study: The study was carried out in a greenhouse at the Center of Sciences and Agri-Food Technology of the Federal University of Campina Grande, Campus of Pombal – PB, Brazil, between August and November of 2017. Methodology: The five levels of irrigation water electrical conductivity – ECw (0.3; 1.0; 1.7; 2.4 and 3.1 dS m-1) were prepared by the addition of NaCl, CaCl2 and MgCl2, maintaining an equivalent proportion of 7:2:1, respectively, in the water from the local supply system (0.3 dS m-1); the five doses of potassium silicate (0, 250, 500, 750 and 1000 mg L-1) were applied on the leaves, using the  commercial product Quimifol Silício, composed of 10% silicon (Si) and 10% potassium (K), completely soluble in water. The plant material was the “Crioulo” cashew genotype, adapted to semi-arid conditions, obtained from a commercial plantation area located in the municipality of Severiano Melo – RN, Brazil, and widely used in the production of rootstocks in seedling production nurseries of the region. Results: Irrigation with 1.7 dS m-1 water causes acceptable reduction of 10% in the morphophysiology of “Crioulo” cashew rootstocks seedlings; the estimated potassium silicate dose of 524,78 mg L-1 led to improvements in the physiology, morphology and quality of the cashew rootstocks seedlings. Conclusion: The "Crioulo" cashew rootstocks seedlings present moderate resistance to the salinity of the irrigation water; irrespective of salinity of irrigation water, fertilization with potassium silicate improves the morphophysiological characteristics.