Growth and content of organic solutes in cauliflower grown with brackish water in a hydroponic system

Abstract

The compatible organic osmolytes carbohydrates, amino acids, protein, and proline have a fundamental role in the acclimatization of plants under conditions of abiotic stress. Therefore, the objective of this study was to evaluate the content of carbohydrates, amino acids, protein, and proline in the cauliflower leaves and inflorescence at different developmental stages, under salt-stress in hydroponic conditions. Cauliflower plants were cultivated in a hydroponic system using the Nutrient Film Technique - NFT. The experimental design was in randomized blocks with six levels of electrical conductivity of the nutrient solution - ECsol (1.7, 5.3, 7.4, 9.6, 11.2, and 12.9 dS m^-1) and five replications. The results obtained showed that the salt stress affects contents of organic solutes in the leaves at 30 days after transplanting (DAT) and, mainly at 60 DAT and in the inflorescence. Salinity reduced the levels of soluble carbohydrates with increase in water salinity at 60 DAT in the leaves. As for the contents of free amino acids, soluble proteins and proline in plants, a reduction was observed up to a certain level of water salinity, increasing at the highest levels, mainly free proline in the leaves. In the inflorescence the amino acid and proline contents increased with the increase in salinity, but the carbohydrate and amino acid contents were higher in comparison to the leaves. In general, organic solutes did not contribute to the osmotic adjustment, but at higher levels of ECsol 9,6; 11,2 and 12,9 dS m^-1, may have contributed to mitigate the effects of salts on the cauliflower plants.