Study on Irrigation Depth to Alleviate High Temperature and Heat Damage of Super Early Rice during Grain-filling Period

Abstract

【Objective】The purpose of this paper is to reveal the mitigation effect of different irrigation depths on high temperature and heat damage during grain-filling period of super early rice, and to determine the suitable irrigation depth. 【Method】With ‘Lingliangyou 268’ as test materia, field experiment was conducted with conventional irrigation (irrigation depth of 2.5 cm) as CK and irrigation depth of 5 cm, 7.5 cm, 10 cm under natural high temperature heat injury. The population temperature of rice, physiological indices of flag leaves, rice yield and its components indices were measured to study the effect of different irrigation depths on alleviating high temperature and heat injury of super early rice during grain-filling period. 【Result】The results showed that the average temperature of super early rice population decreased by 0.6~1.9 ℃ with increase irrigation depths. After 22 days, the SPAD attenuation rate of flag leaves of super early rice decreased by 8.89%~25.87% compared with the control. MDA content of flag leaves decreased 1.89~2.51 nmol/g (wet weight). The activities of catalase (CAT) was increased, and the content of osmoregulation substance was increased. With the continuous development of high temperature and heat damage and the growing of rice, the activities of CAT decreased, while the activities of POD and SOD increased, however, increasing irrigation depth had little effect on the activities of POD and SOD in flag leaves.Rice seed setting rate increased by 2.88%~5.06%, 1 000 grain weight increased by 0.53~0.93 g, and rice yield increased by 2.9%~7.9%. 【Conclusion】The irrigation depth of 7.5~10 cm can effectively alleviate the high temperature and heat damage of “lingliangyou 268” during grain-filling period.

Keywords

• super early rice
• grain-filling period
• high temperature heat injury
• irrigation depth
• alleviating effect