Effects of Silicon Formulations on Cold Tolerance of Rice Seedlings.

To investigate the effects of silicon formulations on the cold tolerance of rice seedlings, Song Japonica 16 (not cold tolerant) and Dongnong 427 (cold tolerant) rice varieties were used as test materials and four different types of silicon formulations, Si-50-G, Si-60-G, Si-T-G, and Si-E-G, were applied as foliar sprays at the seedling stage, and a control group CK (equal amount of distilled water) was set up. One week after the first silicon spray, two types of rice were subjected to low-temperature stress treatments at day/night temperatures of 12 °C/10 °C for 2, 4, 6, and 8 days. The effects of different silicon formulations on the chlorophyll, proline (Pro) and soluble sugar contents as well as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities of rice seedlings under low-temperature stress were compared to find out the effects of silicon formulations on the cold tolerance of rice seedlings. The results showed that silicon formulations could significantly increase the chlorophyll content of rice seedling leaves, with Si-50-G being the most effective, with a significant increment of 40.17% compared to the CK at 2 days of low temperature. Four silicon formulations significantly increased the proline content and soluble sugar content of rice leaves at low temperature for 4-8 days. For Song Japonica 16, the most significant increment in leaf POD activity was observed in Si-E-G treatment at 2, 4 and 8 days of temperature stress, with 73.58%, 20.95% and 217.24% increases compared to the CK, respectively. For 4 and 6 days of temperature stress, the most significant increase in CAT activity was observed in Si-E-G treatment, with 25.70% and 75.78% increases compared to the CK, respectively. For Dongnong 427, the Si-60-G treatment showed the highest increase in leaf SOD activity for 4 and 8 days of temperature stress, with significant increases of 58.15% and 82.76% compared to the CK, respectively, and the Si-E-G treatment showed the highest increase in leaf POD activity for 2 and 8 days of temperature stress, with significant increases of 97.75% and 245.10% compared to the CK, respectively. It showed that the spraying of silicon formulations could significantly enhance the cold tolerance of rice. This study provided a scientific basis for the rational use of silicon formulations to enhance cold tolerance in rice and had important theoretical and practical significance for ensuring sustainable high and stable rice yields in Heilongjiang Province, as well as for the development of silicon fertilizers. [ABSTRACT FROM AUTHOR]