Abstract:

To understand the yield response of japonica rice of northeast China to low temperature in different time periods of booting stage, and to establish the model and index of the influence of temperature and accumulated temperature on japonica rice yield, we utilized the law of air temperature decreasing with altitude and conducted a natural low-temperature rice pot experiment on the north slope of Changbai Mountains. In the experiment, we selected seven altitudes (low temperature strength), three durations of low temperature (2, 3 and 5 d), three periods of low temperature influence at booting stage (early, middle and late period), and used one proper temperature as control. The experimental data were used to establish a regression equation. The results showed that the response of rice yield change to low temperature at booting stage was significantly sensitive, while the influencing mode was in accordance with logarithmic or linear function. The lower the temperature and the longer the low temperature duration time, the greater the temperature influence coefficient and the lower the rice yield per unit area. The relationship of rice yield with daily mean temperature was closer than that with daily minimum temperature. The influence of low temperature at different booting periods on rice yield was different. The influence of short-term low temperature in 2 days in early panicle differentiation period was slightly greater than that in middle and late period. The influence of low temperature lasting for 3 days in early and middle panicle differentiation period (before and after meiosis of pollen mother cell) was more significant. The influence of low temperature lasting for 5 days in each of the 3 periods could be particularly significant, and all could result in a severe yield reduction. In summary, the rate of rice yield reduction will be increased by 2.0, 3.2 and 4.5 percentage points respectively with every 1℃ decrease of the average temperature lasting for 2, 3 and 5 d during the key period of the booting stage. The rate of rice yield reduction will be increased by 9.1, 8.3 and 7.7 percentage points when the cold accumulated temperature is increased by every 10℃∙d at the early, middle and late panicle differentiation period. When the cold accumulated temperature in the key booting stage is more than 6, 12 and 18℃∙d, the light, moderate and severe rice chilling injury will occur, respectively.

Key words: japonica rice of northeast China, booting stage, rate of yield reduction, low temperature, mountain experiment