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Wheat is one of the most common and productive crops in the world, and the growth and production of wheat are sensitive to climate change. Climate change affects wheat phenology by influencing sowing/maturity dates and the duration of growing stages, and ultimately affects the grain yield. Reliable prediction of changes in wheat yield is significant for maintaining global food security. However, studies addressing the potential impact of crop phenology changes on grain yield are rarely reported, which is a big challenge. Using the CERES-Wheat model and first-order differential equation models, we quantified the impact of future climate change on wheat phenology and grain yield for two periods (P1: 2011-2040; P2: 2041-2070) under three representative concentration pathways (RCP2.6, RCP4.5, RCP8.5) in China's twomain wheat-growing areas (Northwest SpringWheat-Growing Area(NWSWA) and Huang-Huai-Hai Winter Wheat-Growing Area (HHWWA)); the baseline period was 1981-2010. Accumulated thermal time during thewhole growing period (WGP) tends to significantly increase in NWSWA and HHWWA under all RCPs and periods. This rising accumulated thermal time will reduce the time to anthesis and maturity and shorten the vegetative growing period (VGP), reproductive growing period (RGP), and theWGP. In P2, spring wheat grain yield is projected to diminish by a regional average of 2.67% for RCP2.6, 4.07% for RCP4.5, and 5.66% for RCP8.5, which is dominated by the lower accumulated solar radiation during the VGP in NWSWA. Additionally, for the winter wheat grain yield in HHWWA in P2, its grain yield reduction is projected to decline by 4.8% (RCP2.6), 7.9% (RCP4.5), and 9.8% (RCP8.5), which is caused by increasing accumulated thermal time in the VGP. These results suggest that breeding high-temperature-tolerant varieties with high calorie requirements is an adaptive strategy to mitigate the negative impact of climate change on wheat yield in the study areas. [ABSTRACT FROM AUTHOR]

The land surface characteristic influences climatic environments by controlling the land surface energy and water fluxes. Although large progresses have been made in coupling detailed crop models into land surface models, there is much room left for improved estimates of surface fluxes in double cropping system, such as the winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) system under intensive influences of climate change and human activities in the North China Plain (NCP). Here, we modeled the growth and surface fluxes in winter wheat–summer maize double cropping system in the NCP through modified SiBcrop model. The parameters related with the crop growth in winter wheat and maize sub-models were emphasized to better simulate the seasonal dynamics of phenology phase, leaf area index (LAI), and latent (LH) and sensible (SH) heat fluxes. Observational data for phenology, LAI, and energy fluxes were compiled from Yucheng and Guantao stations, to calibrate and validate the SiBcrop model. The results showed that the adjusted SiBcrop captured better the seasonal dynamics of phenology, LAI, LH, and SH, relative to the original code. The largest biases in model results were in SH when horizontal advection prevails and in LH when there is summer maize senescence. Sensitivity analysis illustrated that growth duration, emergence date, LH, SH, and Bowen ratio were quite sensitive to sowing date of wheat, and growth duration and emergence and harvest dates to sowing of maize. The calibrated SiBcrop also simulated the LH and SH well at Guantao station. The adjusted SiBcrop is capable of assessing the responses of surface biophysical processes to the changes of human management and climate change in the double cropping system in the NCP. [ABSTRACT FROM AUTHOR]

As one of the most populous countries, China has policies protecting the amount of land available for crop production, but it does not consider the quality of land. Thus, an important issue is the impact on crop production by land use change under such policies and by notable climate variability during the past decades. Using a productivity attenuation method, we estimated the climatic productivity of winter wheat (WWCP) in the North China Plain, based on land use classification data and daily weather data from 1980 to 2010. Impacts of historic climate variability and land use change on WWCP were quantified. Results indicate: (1) on average, WWCP for newly-increased dry land was lower than that for the lost land, which may result in reduced land quality associated with conversion. (2) In recent years, the increasing area of dry land provided sufficient wheat yield to compensate for the loss resulted from reduction of WWCP. (3) Both historic climate variability and land use change decreased WWCP, but the effects of the latter (within -1%) were less than those of the former (about -3%). Given the scarce land resource and rapidly growing food demand, the approach through expanding the area of cultivated land to maintain grain yield is not a long-term guarantee of food security. Thus, cultivated land conservation policy should shift from protecting land quantity into preserving land productivity. In addition, agriculture policies should further emphasize the critical role of adaptation strategies in coping with climate change. Obtaining higher yield production will depend upon adopting adaptation measures which could effectively mitigate effects of dramatic climate change or even take advantage of possible climate conditions. [ABSTRACT FROM AUTHOR]