Grain yields of different wheat cultivars and their relations to dry matter and NPK requirements in dryland

Objectives Loess Plateau is the main dryland wheat production area in China, where the grain yield is usually lower than other areas. Therefore, it is of great significance to understand the relationship of grain yield of different wheat cultivars to dry matter and N, P, K requirements for introducing and breeding new cultivars with high yield and high nutrient efficiency, reasonable fertilizer application, and promoting local wheat production.

Methods In 2014 and 2015, 123 winter wheat cultivars from local and other main winter wheat production areas in our country were planted in a typical rainfed dryland on the Loess Plateau, and plant samples were collected at the harvest period to investigate the relationships between wheat grain yield and the requirements of dry matter, nitrogen (N), phosphorus (P) and potassium (K) for yield formation.

Results The obtained results showed that the grain yield was significantly and positively correlated with above-ground biomass, harvest index, the uptakes and harvest indexes of N, P and K, but negatively correlated with the requirements of dry matter, N and P of different cultivars. Results of the two-year averages showed that when the wheat grain yield was increased from 5474 kg/hm² to 7891 kg/hm², the above-ground biomass was increased from 12194 kg/hm² to 17032 kg/hm², harvest index was increased from 38% to 54%, and uptakes of N, P and K from 159 kg/hm² to 231 kg/hm², 21.3 kg/hm² to 29.5 kg/hm², and 79.1 kg/hm² to 136.9 kg/hm², respectively. At the same time, the harvest indexes of N, P and K increased from 62% to 83%, 75% to 90%, and 20% to 37%, respectively, while the dry matter requirement decreased from 2611 kg/Mg to 1873 kg/Mg, and the requirements of N and P from 35.1 kg/Mg to 23.7 kg/Mg and 4.5 kg/Mg to 3.2 kg/Mg. Requirement of K also decreased from 19.9 kg/Mg to 11.9 kg/Mg with the increase of grain yield, but no significant correlation was found between grain yield and K requirement.

Conclusions In dryland, the high yield cultivars usually have higher above-ground biomass, harvest index, nutrient uptake, and nutrient harvest index, and lower dry matter and nutrient requirement. For increasing grain yield in practical wheat production in dryalnd, new cultivars should be introduced or bred to increase the biomass and improve the relation of grain yield to biomass, nutrient uptake and harvest index, and fertilizer management should be based on the nutrient requirement of high yield cultivars, the local soil nutrient supply capacity and climatic characteristics to ensure the crop with sufficient nutrient uptakes and efficient transport to grain, and then to fully exploit the cultivar’s yielding potential.