Response of dry matter and nitrogen accumulation of wheats with different gluten contents to topdressing rate of nitrogen fertilizer

Objectives The response of dry matter and nitrogen accumulation of wheats having various gluten contents to nitrogen topdressing was studied.

Methods The experiment was carried out in Beijing Experimental Base, Institute of Crop Sciences at the Chinese Academy of Agricultural Sciences between 2016 and 2017. The tested cultivars were high gluten wheats Gaoyou 2018 and Shiluan 02-1, medium gluten cultivars Zhongmai 8 and Zhongmai 175, and low gluten cultivars Yangmai 22 and Yangmai 15. The three topdressing N rates were 75 kg/hm², 105 kg/hm² and 135 kg/hm² at jointing stage, on the basis of basal application of N 105 kg/hm² and P 135 kg/hm². The dry matter and N accumulation before and after anthesis, and the translocation and contribution rate of stored N were investigated. The yield and yield components were also determined.

Results With the increase in topdressing N rate, the dry matter accumulation of different gluten wheats at flowering stage was increased, but its proportion varied in the vegetative parts. The leaf dry matter in high gluten wheat increased and that in ear decreased; the stem dry matter in medium and low gluten wheats increased, while those in leaves decreased. At maturing stage, increased topdressing N rate significantly increased the dry matter proportion in glume and rachis. The accumulation of N in vegetative organs and grains, whereas the transfer of N from vegetative organs to grains of all types of wheat were increased at maturity. The pre-anthesis N transport rate and contribution rate of vegetative organs of medium gluten wheat were decreased significantly, while the contribution rate of pre-anthesis nitrogen in vegetative organs of high and low gluten wheats were increased gradually. The amount of nitrogen transport after anthesis in medium gluten wheat was increased significantly, while the contribution rate of nitrogen after anthesis of low gluten wheat was decreased significantly. The spike number per spike of low gluten wheat, grain number of high gluten wheat and 1000-grain weight of high and medium gluten wheats were significantly increased by increasing rate of N topdressing. Although the yield of wheat with different gluten types were increased, the difference was not significant.

Conclusions Under the experimental conditions, N 105 kg/hm² topdressing improved dry matter accumulation and distribution, nitrogen accumulation and transportation of high gluten wheat, which attributed to higher grain number per spike and 1000-grain weight, and stabilize yield. N 135 kg/hm² topdressing significantly improved dry matter and N accumulation and transportation, and yield in moderate gluten wheat. The application of N 135 kg/hm² in low gluten wheat promoted dry matter accumulation, nitrogen accumulation and translocation before flowering, increased the contribution rate to grain nitrogen, and increased yield by increasing the number of spikes.