Climate warming accelerates crop development and shortens growth duration. Adoption of new cultivars and change in planting date may either retard or amplify the acceleration. However, the extent to which cultivar and planting date shifts regulated the acceleration remains uncertain. Using an up-to-date data series at 82 agro-meteorological stations in China where rice phenology was observed from 1981 to 2012, we quantified the contributions of climate warming, cultivar and planting date shifts to rice growth duration on the basis of degree-days calculation.
Results/Conclusions
Results from a linear regression of growth duration length (GDL) vs. time showed that the GDL between emergence and maturity was significantly prolonged for single rice in 37% of the data series, but no trends were statistically detected in 56% of the data series. For early rice, prolonged and shortened GDL was observed in 27% and 17% of the data series, respectively. In contrast, 63% of the late rice data series exhibited a significant shortening of GDL, and the remaining 37% did not show significant trends. On average, the GDL was prolonged by 2.1 d/10yr for the single rice and 0.4 d/10yr for the early rice. The prolonged GDL in reproductive phase was more pronounced than that in vegetative phase. GDL of the late rice was significantly shortened by 4.3 d/10yr, with 4.0 d/10yr in vegetative phase. Over the last three decades, climate warming contributed negatively to GDL change with the fraction of -34% for the single rice, -32% for the early rice, and -5% for the late rice. Cultivar shift in single and early rice prolonged GDL with the positive contribution of 58% and 54%, respectively, but shortened GDL of the late rice with a contribution of -61%. Nevertheless, planting date in two-thirds of the late rice stations was significantly advanced, which positively contributed 34% to the GDL change. In conclusion, adoption of new cultivars has offset the negative effect of climate warming on growth duration for single and early rice, but amplified the negative effect for late rice since the early 1980s. Introduction of cultivars with long GDL in late rice area may improve the utilization of light and temperature, and thus contribute to grain yield.