Phenology is a reliable biological indicator for reflecting climate change. Global climate change might advance or delay crop phenology, and studies of crop phenology changes have significant value of reference for guiding regional agriculture production. Recently, a research discloses the spatiotemporal differentiation of changes in wheat phenology and attribution analysis in China.

This research entitled "Spatiotemporal differentiation of changes in wheat phenology in China under climate change from 1981 to 2010" has been published in No.48(7), 888-898, 2018 in Science China- Earth Sciences (Chinese Version) and No.61(8), 1088-1097. 2018 in Science China- Earth Sciences (English Version), Climatic Change (DOI: 10.1007/s10584-018-2264-5) and Agricultural and Forest Meteorology, 2018(248):518-526, recently. The lead author of these articals is Dr.GE Quansheng, a professor in Institute of Geographic Sciences and Natural Resources Research. Researchers show the spatiotemporal differentiation of changes in wheat phenology and attribution analysis among wheat-planting regions based on historical records of wheat phenology covering a period of 1981-2010 collected from 48 agro-meteorological stations in China.

As a major grain crop, studies about wheat phenology change under climate change have attracted wide concern home and abroad. However, many previous studies only focus on some limited key phenological stages (mainly date of anthesis or maturity) due to the restrictions of observation data or the simulation ability of crop models. Changes of multiple consecutive phenological stages during crop growing seasons nationwide are still unclear. In addition, crop phenology is co-determined by climate change and crop management, attributing changes in crop phenology to climate change is difficult, because there have been concurrent changes in crop management. lots of existing studies only take climate change into account, while other important climatic factors such as crop management measures are neglected. This could increase uncertainty in their results because crop management measures affect crop growth simultaneously.

Based on the latest wheat-planting regional schema, this study reveals the different changes in wheat phenology among regions over the past three decades in China. Researchers found that climate during wheat growing season has become warmer and drier in the past. Under the background of climate change, on a national scale, dates of sowing, emergence, trefoil and milk ripe have advanced while dates of tillering, jointing, booting, heading, anthesis and maturity have been delayed. However, phenology changes vary across regions. They also discovered that as average temperature during growing season increased, growing season lengths of spring wheat shortened while that of winter wheat lengthened. In all wheat-planting regions, the GSL increased with the increasing of total precipitation and sunshine duration during the growing season. In particular, the sensitivity of GSL to sunshine duration for spring wheat was stronger than for winter wheat.

The relative contributions of climate change and crop management on changes in wheat phenology were different. Average relative contribution of crop management to changes in dates of sowing and emergence, and length of VGP for spring wheat and changes in dates of sowing, emergence, anthesis and maturity, and length of WGP for winter wheat was greater than that of climate change. Among the three contributors climate change, average temperature contributed the greatest part to changes in dates of sowing, emergence and anthesis, and length of WGP for spring wheat and also dominated changes in dates of sowing, anthesis and maturity, and length of RGP and WGP for winter wheat; and cumulative sunshine hours was the greatest contributor to changes in length of VGP for both spring wheat and winter wheat while impacts of cumulative precipitation on wheat phenology seemed very slight.

This research indicates climate change over the past three decades alleviated the irrigation pressure in the winter-spring wheat production area to some extent but strengthened the irrigation pressure in the spring wheat production area, the northern winter wheat production area and the southern winter wheat production area. Therefore, the adoption of water-saving agricultural practices is a sensible production strategy for these regions and adopting cultivars that are resistant to drought and high temperatures will facilitate agricultural production in these regions and enhance adaptation to climate change. In addition, the researchers discovered that crop management that wheat producer used in the past helped reduce lengths of VGP and WGP while increase lengths of RGP. Therefore, the shorter duration wheat varieties with a higher yield or better yield stability in changing climate might have been planted, which could be a viable strategy adapting for climate change. Regional differences in phenological change are considerable and should be considered an important factor in agricultural production and management.

"To the best of our knowledge," wrote the four researchers, "this work provides a better understanding of the spatiotemporal differentiation of changes in wheat phenology in China, which has great scientific value and data vale. Relative research results can provide theoretical reference for guiding agriculture production.

This research was funded by the National Natural Science Foundation of China, Strategic Priority Research Program of the Chinese Academy of Sciences, National Key Research and Development Program of China,Youth Innovation Promotion Association, CAS, Key Research Program of Frontier Sciences, CAS and Program for "Kezhen" Excellent Talents in IGSNRR, CAS. (SCIENCE CHINA PRESS)

See the articles:

Liu Y J, Chen Q M, Ge Q S, Dai J H. Spatiotemporal differentiation of changes in wheat phenology in China under climate change from 1981 to 2010. Science China Earth Sciences, 2018, 61(8), 1088-1097, DOI:10.1007/s11430-017-9149-0.

Yujie Liu, Qiaomin Chen, Quansheng Ge, Junhu Dai，Yue Dou. "Effects of climate change and agronomic practice on changes in wheat phenology", Climatic Change, DOI: 10.1007/s10584-018-2264-5.