MITIGATION OF ADVERSE EFFECT OF DROUGHT ON TOMATO THROUGH EXOGENOUS APPLICATION OF POTASSIUM AND CHITOSAN

Abstract

The present investigation was conducted to evaluate the effect of exogenous application of potassium and chitosan on the improvement of drought tolerance in tomato at Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh during the period from November, 2023 to March, 2024. The experiment was performed in Completely Randomized Design (CRD) with three replications and two factors. The factors included three growing conditions (well water, water deficit stress, foliar application of 1% K (2.23% K2SO4) and foliar application of chitosan @ 50 ppm under water deficit stress) and three tomato genotypes (Rajkumar, Bipul plus and BGL-757). Interaction effect of growing conditions and tomato genotypes significantly influenced the different phenological, morphological, physiological and biochemical traits as well as yield components and yield of tomato. Drought tolerant genotype showed less membrane injury and more proline content under water stress condition as compared to well water condition. Maximum relative water content, water retention capacity, chlorophyll content and SPAD value of leaf and canopy temperature depression were observed under well water condition. Better values in morphological traits, yield components and fruit yield and biochemical traits of tomato were also measured under well water condition. Non irrigated water stress significantly reduced the studied traits except proline content of leaf of tomato where drought tolerant genotype performed better than the susceptible one. Foliar application of chitosan and potassium ameliorated that reduction in different degrees and improved these traits under water stress condition. Based on drought tolerance index Rajkumar showed the highest and BGL-757 showed the lowest tolerance for the selected traits. The results concluded that foliar application of chitosan and potassium under water deficit stress can mitigate the harmful effects of drought and significantly improve the majority of the studied traits of tomato. Based on overall responses of tomato genotypes to water deficit stress Rajkumar may be considered as comparatively drought tolerant and BGL-757 as drought susceptible.