Effects of strigolactone on photosynthetic and physiological characteristics in salt-stressed rice seedlings

Saline stress has been identified as the primary factor inhibiting rice seedling growth, which represents a complex abiotic stress process. Most plant hormones have been shown to alleviate the plant damage caused by salt stress. The effects of synthetic strigolactone (GR24) on Jinongda 667 rice seedlings treated with 200mM NaCl were studied. Photosynthesis and its related physiological characteristics were analyzed in salt-stressed rice seedlings treated with GR24. NaCL stress inhibited the growth of the rice, including plant height and root length, by approximately 14% and 40%, respectively. Compared to the control check group (CK), the adverse effects of salt stress on the growth status, leaf photosynthesis, and physiological/biochemical indices in the rice seedlings were alleviated in the GR24 treatment group. With increases in the GR24 concentration, the plant height and root length of the seedlings increased. The plant height in the groups treated with 1/2 Hoagland's complete nutrient solution + 200mM NaCl +1 mu M GR24 (T4) and 1/2 Hoagland's complete nutrient solution + 200mM NaCl +5 mu M GR24 (T5) were significantly different than the 1/2 Hoagland's complete nutrient solution + 200mM NaCl group (T1) (P<0.05), and there were significant differences between the T5 and T1 groups in root length (P<0.05).The chlorophyll content in the rice seedling leaves was significantly different between the T1 group and all other groups (P<0.05). The net photosynthetic rate of the T1 group was not significantly different from the T2 group (P>0.05). The transpiration rate, stomatal conductance, and intercellular CO2 concentrations showed the same trends as the net photosynthetic rate. The MAD, POD, and SOD activities were significantly increased by 68%, 60%, 14%, respectively, compared to the CK group (P<0.01). When the GR24 concentration was 1 mu M, the rice seedlings were resistant to the adverse effects of high salt stress. Therefore, the addition of proper concentrations of GR24 could improve the rice yield in saline-alkali land.