Abstract:

There have been a lot of studies on the influencing factors of rice growth duration and its predicting models in plain and hilly regions with a low altitude, but few studies involving the relationship between rice growth duration (or the effective temperature accumulation it needed) and altitude in mountain areas. In order to study the variation of rice growth duration with altitude and its temperature accumulation effect, a group of field experiments at 8 sites with different altitudes from 540 to 1 800 m in Panxi region, Sichuan province were conducted, in which, 3 sowing dates and 5 cultivars including hybrid indica rice, indica rice, and japonica rice were selected. The experimental results were as follows. The rice growth duration in days was not only different with the cultivars used, but also strongly influenced by therm-photo environment. The duration in days from sowing date to full heading period and the effective temperature accumulation it needed had largely instability at the sites selected. They were mainly and certainly related with altitude and latitude of the sites. A series of lineal regression equations of growth duration in days from sowing to full heading and the total growth duration (y) responding to latitude (x1) and altitude (x2) of the sites were founded. However, the relationship between the effective temperature accumulation needed (y) and the latitude (x1) and altitude (x2) obeyed a quadratic function. With the altitude ascending, the duration in days from sowing date to full heading period prolonged, while the effective temperature accumulation it needed increased firstly and decreased secondly. effective temperature accumulation was the highest in the middle altitude region which was about 1 200 m to 1 300 m.

Key words:

Rice, Growth duration, Altitude, Effective temperature accumulation, Panxi region