Enhancing Chickpea (Cicer arietinum L.) Tolerance to Salinity through Plant Growth Regulators

Abstract

During the period of 2020-21, a research study was carried out at the Plant Protective Culture Unit within the semi-controlled environmental settings of the Bangladesh Agricultural Research Institute. The aim of the study was to mitigate the negative impacts of salinity stress on chickpea by applying various concentrations of salicylic acid (SA) and gibberellic acid (GA3). Plants were subjected to four different levels of salinity stress, including a control group, mild stress, moderate stress, and severe stress. This was achieved by irrigating them with four varying concentrations of saline water (5, 7.5, 10 and 12.5 dSm-1) starting from the 14th day after sowing (DAS) and continuing until maturity at 100 DAS. On the other hand, the control plants received regular irrigation with tap water. Two concentrations of salicylic acid (SA) specifically 200 ppm and 400 ppm, along with gibberellic acid (GA3) at 10 ppm and 20 ppm, were administered as a foliar spray once a week, commencing at 20 days after sowing (DAS) and continuing until the flowering stage. Data related to chlorophyll levels in the leaves and water-related traits, including relative water content (RWC) and water retention capacity (WRC) were collected seven days after the foliar spray of these plant growth regulators at the flowering stage. Additionally, measurements of total dry weight, yield, and various yield-contributing factors were taken at the point of maturity. The results indicated that chickpea suffered adverse consequences due to salinity stress which included a reduction in chlorophyll content, a decrease in relative water content, a decline in water retention capacity, a decrease in total dry weight and a lower overall yield. However, the foliar application of different doses of salicylic acid (SA) and gibberellic acid (GA3) under varying levels of salinity stress had beneficial effects in alleviating the impact of salinity stress. Interestingly, it was observed that lower concentrations of SA at 200 ppm and GA3 at 10 ppm were more effective in mitigating the adverse effects of salinity stress and improving salinity tolerance in chickpea, especially under mild salinity stress conditions (5 dSm-1) as evidenced by the positive influence on the parameters mentioned above.