Nitrogen Translocation in Winter Wheat Varies with Cultivars and Nitrogen Fertilization

Abstract

【Background】 Excessive application of nitrogen fertilizer is often used by farmers in China as an insurance to guarantee winter wheat yield despite its detrimental impact on the environments such as leaching to groundwater and development of eutrophication. Breeding new varieties with improved nitrogen use efficiency is an alternative to sustain wheat production without compromising the environment. 【Objective】 The objective of this paper is to experimentally compare the difference in nitrogen uptake and translocation between different varieties of winter wheat in response to nitrogen fertilization in the loess plateau of China. 【Method】 The experiment was conducted from 09/2018 to 07/2019 at Taigu experimental station of Shanxi Agricultural University. We compared six cultivars: Liangxing 99, Hanmai 13, Shannong 22, Liangxing 77, Yannong 999 and Shannong 29. Added to each cultivar was two nitrogen fertilizations: 150 kg/hm2 and 270 kg/hm2. In each treatment, we analyzed the relationship between wheat yield and N use efficiency (NUE) as well as N translocation. 【Result】 The varieties Shannong-29, Hanmai-13 and Yannnong-999 were more N-use efficient. Compared with other three varieties, they saw a significant increase in N accumulation in grains and pre-anthesis N translocation and post-anthesis N accumulation; their grain yield and NUE thus increased by 17.85%~22.35% and 9.20%~12.31%, respectively, due to the increased N uptake from the 20~200 cm soil. Fertilization also affected N translocation and accumulation. For the three N-efficient varieties, increasing N application from 150 kg/hm2 to 270 kg/hm2 significantly reduced N accumulation in stem, sheath, leaves and the grains, but boosted pre-anthesis N translocation in stem, sheath and leaves, and post-anthesis N accumulation in the grains. These combined to increase average grain yield and NUE by 11.98% and 4.89%, respectively. For the varieties with low N use efficiency, increasing N application also boosted N accumulation in their grains though not as significant as in other varieties. For the same variety, its yield, NUE and N content in the grains were all positively correlated with pre-anthesis N translocation, especially for the varieties with high NUE. 【Conclusion】 Wheat varieties with high NUE gave high yield because they are more efficient to translocate N from organs to the grains. Pre-anthesis N translocation in stem, sheath and leaves can be used as a proxy for NUE. In terms of fertilization, increasing N fertilizer application from 150 kg/hm2 to 270 kg/hm2 can promote yield and NUE, especially the varieties with high NUE.

Keywords

• nitrogen use efficiency
• winter wheat
• variety
• soil nitrate
• nitrogen uptake and utilization
• yield