Effect of nitrogen topdressing rate on yield and quality of mediumand strong gluten wheat cultivars

Objectives The experiment explored the effect of nitrogen topdressing rates on the yield and quality of strong- and medium-gluten wheat varieties, to provide references for high quality and high yield of medium- and strong-gluten wheat production.

Methods In Beijing experimental base of Institute of Crop Sciences, Chinese Academy of Agricultural Sciences during 2016–2017, a two-factor randomized block design was adopted for this experiment. The factor A was wheat cultivar, and the tested 4 cultivars were Gaoyou2018 (strong gluten), Shiluan02-1 (strong gluten), Zhongmai8 (medium gluten) and Zhongmai175 (medium gluten). The factor B was topdressing N rates of 75, 105 and 135 kg/hm² at jointing stage. During the maturity period, the number of panicles per unit area, grain number per spike, the 1000-grain-weight, the yield of biomass and the grain yield were investigated. The content of crude protein, protein components, wet gluten content, the sedimentation value and dough rheological properties were determined.

Results On the basis of basal applying N 105 kg/hm², the grain yield, panicles per hectare, grain number per spike, 1000-grain-weight, protein yield and biomass yield of the tested cultivars were increased with the increase of nitrogen topdressing rate from 75 kg/hm² to 135 kg/hm², with an average increase of 6.1%, 2.6%, 8.5%, 4.6%, 10.3%, and 15.3%, respectively. With the increase of nitrogen topdressing rate, the total protein and protein component contents were increased, and the glutenin content was increased the highest. Compared with N₇₅, the glutenin contents of N₁₀₅ and N₁₃₅ treatments were increased by 13.2% and 14.6%, respectively. Increasing rate of nitrogen topdressing led to increased sedimentation value, wet gluten content, water absorption, dough development time and stability time of the two gluten types of wheat cultivar. The above processing quality indicators for the high gluten wheat cultivars were increased by 4.3%, 2.2%, 1.6%, 13.8%, and 22.0%, respectively, and for the medium gluten cultivars were by 13.8%, 7.4%, 0.8%, 9.5%, 10.2%. The dough weakening showed decrease trend following the increasing of topdressing nitrogen rates, and the high and medium gluten cultivars were averagely decreased by 9.65% and 12.0%, respectively.

Conclusions Increasing the topdressing rate of nitrogen fertilizer at jointing stage could increase the yield and procession quality of both the medium- and strong-gluten wheat cultivar. Comprehensive considering the fertilizer input, wheat yield and quality index, topdressing nitrogen rate of N 105 kg/hm² is recommended for medium-gluten wheat cultivar, and 135 kg/hm² for strong-gluten cultivars under the experimental conditions.