Effect of salt stress on different tiller positions in rice and the regulatory effect of prohexadione calcium

Soil salinization has resulted in a significant decrease in crop yields, particularly affecting the production of crops like rice (<i>Oryza sativa</i> L.). Prohexadione calcium (Pro-Ca) can enhance crop resilience against failure by managing plant height. However, its impact on various tiller positions during the tillering phase of rice under salt stress remains unknown. This study explores the distinct effects of salt stress on the physiological traits of the main stem and different tiller segments of rice plants, along with the role of Pro-Ca in mitigating salt stress. The findings revealed that under salt stress conditions, the number of tillers and leaves on the main stem decreased significantly in rice. Moreover, the levels of malondialdehyde (MDA) and H₂O₂ in the leaves and stems of each tiller position notably increased. The percentage of tillers experiencing reduction or elevation was higher than that of the main stem compared to the respective control. Application of Pro-Ca through foliar spraying under NaCl stress effectively alleviated the impact of salt stress on the tiller growth of rice during the tillering phase. It also boosted the activities of antioxidant enzymes like superoxide dismutase (SOD) and peroxidase (POD) in the leaves and stems of the tillers. Furthermore, it successfully mitigated the damage inflicted by salt stress on the cell membrane of rice tillers during the tillering phase. The regulatory effect of calcium on cyclic acid was particularly pronounced in alleviating the impact on the tillers under salt stress conditions.