Abstract
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 200 mM 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 + 200 mM NaCl +1 μM GR24 (T4) and 1/2 Hoagland’s complete nutrient solution + 200 mM NaCl +5 μM GR24 (T5) were significantly different than the 1/2 Hoagland’s complete nutrient solution + 200 mM 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 μM, 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.
Highlights
Saline stress has been identified as the primary factor inhibiting rice seedling growth, which represents a complex abiotic stress process
Experiments with the control check (CK) and 1/2 Hoagland’s complete nutrient solution + 200 mM NaCl treatment (T1) groups showed that 200 mM NaCl significantly suppressed the growth of rice seedlings (P < 0.05), including the plant height, root length, stem leaf weight, and root weight
The 1/2 Hoagland’s complete nutrient solution + 200 mM NaCl + 1 μM GR24 (T4) and 1/2 Hoagland’s complete nutrient solution + 200 mM NaCl + 5 μM GR24 (T5) groups had significantly different plant heights compared to the T1 group (P < 0.05), but there were no significant differences between the 1/2 Hoagland’s complete nutrient solution + 200 mM NaCl + 0.1 μM GR24 (T2), the 1/2 Hoagland’s complete nutrient solution + 200 mM NaCl + 0.2 μM GR24 (T3), and the T1 groups
Summary
Saline stress has been identified as the primary factor inhibiting rice seedling growth, which represents a complex abiotic stress process. 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. Et al (2009) found that DWARF27, an iron-containing protein, was involved in the MAX/RMS/D pathway, in which D27 acts as a new member participating in the biosynthesis of strigolactones[9] It shows that phytohormones are involved in the physiological and biochemical reactions of abiotic stress, which play important roles in reducing damage caused by stressful environments[10,11]. The effects of exogenous GR24 on photosynthesis, as well as its related physiological and biochemical reactions, in salt-stressed rice seedlings were studied. The relationship between exogenously added GR24 and the growth status of rice seedlings under salt stress and the related parameters of photosynthesis and enzymatic activity in rice seedling cells were investigated to confirm the optimal amount of GR24 for reducing damage to rice seedlings under salt stress and provide a theoretical foundation for the expansion of rice planting areas
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