Effects of climatic variation and warming on rice development across South China

Rice Oryza sativa L. development - and also its response to climatic change - is mainly determined by temperature and photoperiod. An experiment was conducted to study the influence of meteorological factors on growth and development of hybrid rice in South China, in which seeds were sown at different sites at different dates in the spring. The 29 experimental sites were spread over a large area, with latitudes from 21°39′ to 34° 16′ N and altitudes from 1 to 1862 m above sea level. It was found that the length of the growth period at low latitudes (21 to 25°N) was mainly determined by temperature and showed a single-peaked curve with an optimum temperature at about 25.7°C. The temperature response of development is almost linear at high latitudes (25 to 35°N), but the dependence is not as close and significant as that at low latitude, due to longer daylength and its higher variation. A phenological-simulation model with a biological basis was used to simulate the developmental stages of rice in South China. It described both thermal sensitivity and photo-periodism using nonlinear equations. The model was validated by data of sowing-date experiments carried out at different geographical sites, and then was applied to evaluate changes in the length of the rice-growth period in response to climate warming during the period from 1951 to 2006. Because there was significant warming, and the length of the growth period was sensitive to this change over the Yunnan-Guizhou Plateau, the length of the growth period was narrowed by 6 to 14 d (comparing 1990 to 2006 with 1951 to 1989), whereas it was shortened by 1 to 2 d in most low plain areas in South China. The probability of serious temperature related crop failure will increase if planting of a late-maturity variety is adopted in high altitude areas. © Inter-Research 2008