Organic fertilization and osmoregulators as strategies to mitigate salt stress in watermelon

Abstract

Irrigation has been considered as an alternative to the socioeconomic development of semi arid regions. However, when used improperly can favor the salinisation and degradation of water and soil resources. Therefore, we aimed to evaluate management techniques, such as the effect of organic fertilizer, nitric and exogenous application of proline in reducing the negative effects of the crop irrigated with saline water watermelon. The experiment was conducted under field condition in the municipality of São João do Rio do Peixe – Paraiba, using the hybrid watermelon 'Quetsali'. The experimental design was a randomized block design in a factorial 2 x 2 x 2 design with four replications. The treatments consisted of two doses of cattle manure (0 and 20 t ha ^{- 1}), two levels of salinity of irrigation water (0.3 and 4.0 dS m^-1) and doses of proline (5 mmol L^{- 1}) and N in the form of potassium nitrate. The use of water with low electrical conductivity (0.3 dS m^-1) was more effective in improving the physiology, growth and yield on watermelon in relation to water with high salt concentration (4.0 dS m^-1). Proline was more efficient than KNO₃ in the osmoregulation of watermelon process by providing higher performance in photosynthesis, intercellular CO₂ concentration, leaf number and production. The manure provided physiological, morphological changes and production in watermelon plants subjected to irrigation with saline water.