Rice reproductive growth duration increased despite of negative impacts of climate warming across China during 1981–2009

• Up-to-date national rice phenology observation data at hundreds of stations were used.
• Spatial–temporal changes in rice phenology across China from 1981 to 2009 were analyzed.
• Change of accumulated thermal development unit was used to explain cultivar shift.
• Reproductive growth duration increased despite of negative impact of temperature increase.
• Long and short duration cultivars were adopted for single-rice and late-rice, respectively.

Changes in rice phenology during 1981–2009 were investigated using observed phenological data from hundreds of agro-meteorological stations across China. Spatiotemporal changes of rice phenology across China, as well as the relations to temperature, day length and cultivars shifts were analyzed and presented. We found that major rice phenological dates generally advanced while rice growing period changed diversely for different rice cultivation systems in different agro-ecological zones. Length of vegetative growth period (VGP) increased at 59 (67.0%) stations for single-rice, however, decreased at 36 (54.5%) and 35 (51.5%) stations for early-rice, and late-rice, respectively. Length of reproductive growth period (RGP) increased at 71 (70.3%) and 49 (55.7%) stations for single-rice and early-rice, respectively, however, decreased at 46 (54.8%) stations for late-rice. The changes were ascribed to the combined effects of changes in temperature, photoperiod and cultivar thermal characteristics. Increase in temperature had negative impacts on the lengths of VGP and RGP. Day length slightly counterbalanced the roles of temperature in affecting the duration of VGP. Furthermore, we found that during 1981–2009 cultivars with longer growth duration of VGP were adopted for single-rice, but cultivars with shorter growth duration of VGP were adopted for early-rice and late-rice. Cultivars with longer growth durations of RGP were adopted for single-rice and early-rice, as well as late-rice at the middle and lower reaches of Yangtze River. However, in the southwestern China and southern China, cultivars with shorter or almost same growth duration of RGP were adopted for late rice.