Spatiotemporal changes of rice phenology in China during 1981-2010

Investigating how climate affects multiple consecutive crop growth stages is helpful to provide guidance for adopting appropriate agronomic practices. Based on the observed data from 51 agro-meteorological stations across China during 1981-2010, we qualified the spatio-temporal variability of eight consecutive phenological stages of rice [sowing (SD), emergence (ED), transplanting (TPD), tillering (TD), booting (BD), heading (HD), milk ripe (MRD), and maturity date (MD)] and the durations of three growth phases [vegetative growth phase (VGP), reproductive growth phase (RGP), and whole growth phase (WGP)]. We also explored the correlation and sensitivity of each of the growth phases to three climatic factors [i.e., mean temperature (T-mean), precipitation (PRE), and sunshine hours (SSH)]. We found that SD, ED, and TPD of single rice advanced by 0.22, 0.15, and 1.15 days 10a(-1), while TD, BD, HD, MRD, and MD delayed by 0.26, 1.14, 0.66, 2.47, and 1.50 days 10a(-1), respectively. For early rice, the dates of all the phenological stages advanced to different extents, except MRD. For late rice, SD, ED, BD, and MRD delayed, while dates of the other phenological stages advanced. The durations of VGP, RGP, and WGP prolonged for both single rice and early rice, but these shortened for late rice. Overall, the durations of three growth phases were negatively correlated with T-mean, but positively correlated with PRE and SSH during corresponding growth phase across rice cultivation region. Sensitivity analysis indicated that increases in temperature tended to reduce duration of single-rice and double-rice VGP. Increases in PRE tended to increase duration of late-rice RGP, and increases in SSH tended to increase duration of single-rice RGP. The results indicated that climate change during the past three decades had a negative impact on rice growth and development. However, the observed phenological changes indicated that agronomic practice with long seasonal cultivar has mitigated these adverse effects.