Analyzing The Effects Of Climate Factors On The Winter Wheat Productivity In Hebei Province Using Yield Gap Method

Hebei plain is one of the most important winter wheat production base with itsadequate solar radiation resources, seasonally fluctuating temperature andprecipitation, fertile deep soil which is suitable for winter wheat production. However,Hebei region belongs to continental monsoon climate zone, where with its seriousshortage of rainfall, intense spatial and temporal climate variation that is not suitablefor winter wheat. Furthermore winter wheat growth season is very long that extendsfrom autumn to mid-summer, and it exhausts much more water than what climateprecipitation can provide. So winter wheat yield in this area suffers a rapid fluctuationyear from year.This study introduced the concept of the ‘Yield Gap’(the difference between thedifferent levels of potential productivity and actual yield of winter wheat yield) toreflect on restricted degree of yield to the potential productivity. Firstly, the study tookLuancheng County, Heibei Province as the representative sample. The different levelsof potential productivities were simulated by Crop Growth Dynamic model (CGD)using daily weather data. The key meteorological factors influencing the yield gapswere found through correlation and stepwise regression analysis in order to examinethe varying regulation of climate effects on winter wheat yield. Secondly, Differentlevels of potential productivities and yield gaps were simulated and analyzed usingCGD for fourteen selected representative sample counties in Hebei main wheatproducing region. Classification analysis of regional distribution of the yield gap wascarried out by the Hierarchical Cluster Analysis. The variation regulation and thecorresponding climatic impacts of yield gap were discussed.The main conclusions are as follows:1. A deep analysis to the single station of Luancheng suggested that, in the earlystages of wheat growth, light and temperature factors more significantly increasedboth light-temperature potential productivity and climate potential productivity;However, after heading, wheat accelerated its reproductive growth and demanded more light and air-temperature, which made the actual yield improvedmore in this stage. Precipitation played an important role in almost all the stage ofwinter wheat growth, showing a tendency that more precipitation decreased the yieldgap. Whereas in the very late mature stage (about ten days before harvest), moreprecipitation did not benefit to actual yield of winter wheat.2. Fourteen Counties were selected to represent the winter wheat productionsituation in Hebei Province. The analysis suggested that, in1980-2010, thephotosynthetic potential productivity of winter wheat was getting lower significantly.There was no any significant increasing or decreasing trend for productivities bycombined radiation and temperature, and precipitation. But the actual yield showedsignificant increasing trend. Regionally, the classification result for the14representative counties indicated that the14counties were classified into four groupsusing potential productivity, actual yield and yield gaps. The first group was located atthe south central region of Hebei Province, including Feixiang, Gucheng, Nangong,Dingzhou, Ningjin, Luancheng, Shenze, Yongnian, where both different levels ofproduction potential and actual yield of wheat were very high. The second group wasthe central region of Hebei Province(Zhuozhou, Hejian included). It had highphotosynthetic potential productivity, whereas the other potential productivity andactual yield was quite low. The third group was located in the northeastarea(Zunhua,Sanhe), in which the main characteristic was that photosyntheticpotential productivity and actual yield were both at high level, whereas the potentialproductivities of radiation and temperature, and precipitation was lower. The lastgroup, consisted of only Haixing County, located in the east area, had lowest potentialproductivity and actual yield. The cluster analysis could provide the theoretical basisfor the reasonable planning of winter wheat production and management decision.