Effects of flooding duration in different growth stages on growth and yield component of rice

Abstract: Flooding is one of main disasters affecting agricultural production in China. Its influence on rice is rarely studied in Guizhong District in Guangxi. In this study, we investigated the effect of different flooding duration in different growth on growth and yield component of rice. The experiment was carried out in Nalu Cun of Laibing City, Guangxi, China (109(52( E, 24(4(N). The soil was sandy loam. Sixiang No.1 and Baixiang No.139 both as early and late rice were planted in pots in 2015 and 2016. Flooding of early rice started in different growth stages of tillering, booting and flowering. At each growth stage, flooding lasted for 0 (control), 2, 4, 6, 8 and 10 days, respectively. Because the precipitation during the booting and flowering stages of late rice was small the flooding of late rice was designed at 3 different date in tillering stage. At flooding, the water surface remained 2-3 cm higher than plant height. Flooding duration of late rice was same as that of early rice. During the experiment, the tiller number before and after flooding, the heading stage time and its duration, grain number per panicle, seed setting rate, 1000-grain weight and yield per pot after harvest were determined, and the relationships between yield and yield components were analyzed by path analysis. The results showed that the seedling death rate was less than 7.5% when the flooding duration at the tillering stage was below 2 days, not significantly different from control. As the flooding duration increased to 4-10 days, the death rate increased. When the flooding lasted for more than 6 days the death rate of early rice could reach more than 80% and even all the plants died. The death rate of Sixiang 1 reached 50% after flooding 6 days while it was still smaller than 50% for Baixiang 139 after flooding less than 10 days. The death rate was below 40% for the treatment of flooding at flowering stage. The initial heading stage time of flooding 8 d was postponed than that of control when flooding at different growth stages, and heading duration duration was also prolonged. The yield was not significantly decreased when the flooding at the tillering stage lasted for less than 4 days, but flooding for 6 days could result in the reduction of yield by 80% and flooding for 8-10 days could result in the death of plants. The yield reduction rate of flooding for 2 d at the booting and flowering stages was higher than 50%. The path analysis of yield component showed that the yield was mainly affected byeffective panicle number, seed setting rate and 1000-grain weight for the flooding at the tillering stage, by seed setting rate, number of grain per panicle and 1000-grain weight for the flooding at the booting stage, and by effective panicle number and seed setting rate for the flooding at the flowering stage, respectively. The study provides important information for formulating flooding disaster warning system and management methods of dual-rice in Xinan region.