Changes and relationship of climate and late-rice yield in chenzhou city of south hunan province of CHINA

Abstract

The changes and relationship of climate parameters and late-rice yield per unit area during the growth periods of late-rice from 2010 to 2019 were quantitatively analyzed in order to provide scientific guidance for countermeasures against climate change and sustainable production of late-rice. The climate parameters include cumulative daily sunshine hours (S), mean daily temperature (T), cumulative daily precipitation (P), mean daily relative humidity (H), daily highest and lowest temperatures (T_h and T_l), days of high temperatures (D_{T ≥ 30℃} and D_{Th ≥ 35℃}) and low temperature (D_{Tl < 15℃}). Results showed that: (i) Late-rice yield was significantly increased quadratically from 5621.33 kg hm² in 2010 to 6333.65 kg hm² in 2019 with a mean of 5959.2 kg hm².  (ii ) According to the suitable climate conditions for growth of late-rice, T and P were low but H was suitable in the whole field growth period of late-rice, T was suitable in the transplanting-tillering stage, but was low in the booting-heading and milk ripening-mature stage. D_{T ≥ 30℃}, D_{Th  ≥ 35℃} and   D_{Tl < 15℃} was meanly 7.7, 7.5 and 6.4 d, respectively, which showed possible occurrence of the damages to late-rice due to high and low temperatures. iii) Only T, T_h and T_l in the booting-heading stage showed significant positive correlation with year, and the optimal regression models were in quadratic and exponential types. The climate parameters of S, T and T_h in the boot-heading stage were significantly positively correlated with late-rice yield, and the optimal regression models were all in quadratic types. Daily highest temperature (T_h) affected late-rice yield most (61.04%), followed by T (36.50%), and S affected least (2.46%). Considering the current conflict in the field planting periods between tobacco and late-rice, late rice varieties needs to be bred with short growth period and high tolerance to both high and low temperatures.

Bangladesh J. Bot. 52(2): 639-647, 2023 (June) Special