Response of nitrogen and dry matter accumulation in middle and high yield wheat cultivars to water and nitrogen supply

Objectives For a good wheat production with a high yield, water and nitrogen (N) fertilizer are two critical elements. Here, we studied the response of middle and high yield wheat cultivars to water and N supply rates, with yield as the target.

Methods Field experiments with a randomized complete block design, two factors and three levels were carried out from 2016 to 2018, with Taikemai 33 (middle yield cultivar) and Jimai 22 (high yield cultivar). The three irrigation rates were 300, 450, and 600 m³/hm², and the three N application rates were 135, 180, and 225 kg/hm². The dry matter (DM) and N accumulation before and after the flowering stage were analyzed, and the quantity of N accumulated in grain was calculated. The relationship among yield, yield components and the N and DM accumulation were examined.

Results Water, N application rate and their interaction (P < 0.05) influenced panicle number, grain number per panicle, 1000-grain weight, grain yield, and partial N productivity of the two wheat cultivars. The response of the middle yield wheat to water was W₂ > W₃ > W₁ and N₂ > N₃ > N₁ for N application rate. The response of the high yield wheat cultivar to water was W₃ > W₂ > W₁ and N₂ > N₃ > N₁ for N application rate. Wheat yield was positively correlated with the transfer of post-anthesis DM accumulation in grain but negatively correlated with it before anthesis. Our result indicated that DM accumulation and its transfer to the grain before anthesis was important for yield formation. The wheat yield had a positive linear correlation with the transfer of N accumulated before anthesis and was negatively correlated with that after anthesis. Thus, N accumulation before anthesis was more critical than after anthesis for grain N accumulation. There were positive correlations among pre-anthesis N accumulation, total N accumulation, pre-anthesis N transfer, post-anthesis N transfer, the contribution of pre-anthesis N transfer to grain, and N harvest index (P < 0.05). There was a positive correlation among spike number, grain number per spike, and grain yield (P < 0.05).

Conclusions The transfer of DM accumulated after anthesis and N accumulated before anthe‘sis has a significant effect on yield formation and N accumulation in grain, respectively. Suitable water and N supply influences the contribution of DM and N transfer before and after anthesis. The high and middle yield wheat cultivars have a similar response to N 180 kg/hm². However, the high yield cultivar prefers higher irrigation water rate (600 m³/hm²), while the middle yield type prefers lower irrigation water rate (450 m³/hm²).