Comprehensive and quantitative analysis of growth characteristics of winter wheat in China based on growing degree days

Abstract The characteristics of the growth of winter wheat are the basis for determining a reasonable amount of irrigation water, regulating wheat growth, improving environmental conditions and increasing yield. Plant height, leaf area index (LAI), dry-matter accumulation (DMA) and harvest index (HI) are commonly used as indices of the growth of winter wheat, and growing degree days (GDD) is an important meteorological factor affecting these indices. The characteristics of plant height, LAI and dry-matter accumulation of winter wheat in 50 regions of China were analyzed based on qualitative analyses and quantitative calculations. Normalized logistic models were used to analyze the growth indices based on GDD, and we discuss the relationships between maximum LAI, HI and irrigation amount. The rate of increase in the height of winter wheat increased with GDD and was low in the early stages, high in the intermediate stages and low in the late stages. Plant height was highest when GDD increased to about 1200 °C. LAI first increased and then decreased, and the trends of change of LAI were similar among the regions. LAI was highest when GDD increased to about 1200 °C. LAI was near its maximum when plant height was near its maximum, but dry-matter accumulation still increased with GDD. The rate of dry-matter accumulation was highest when GDD was about 1200 °C. Plant height and LAI were near their maxima, but nutrients were mainly supplied to the booting and filling stages, which maintained the accumulation of dry matter. A quadratic polynomial function could describe the relationship between HI and maximum LAI. The optimal HI was 0.45 when maximum LAI was 6.5. The relationship between the maximum LAI and irrigation amount was also described by a quadratic polynomial function. Maximum LAI was 6.45 when irrigation amount throughout the growth period was 466.4 mm, when HI was approximately optimal. The growth of winter wheat in China could be simulated by GDD and a normalized logistic model, and maximum LAI and irrigation amount for the optimal HI could be obtained. This study provides a theoretical basis and an available method for predicting the yield of winter wheat and improving other models of crop growth.