Response of yield and quality of winter wheat materials from different ecological regions to nitrogen topdressing rate

Objectives Field experiments were carried out to investigate the effects of different nitrogen application rates at jointing stage on N accumulation, yield and processing quality of winter wheat materials from Tibet Plateau and the northern winter wheat ecological regions, to provide theoretical basis and technical reference for the rational management of nitrogen fertilizer in different ecological regions.

Methods A field experiment adopting two-factor randomized block design was carried out. Factor A was winter wheat materials which consisted of Zangdong 25 and HeieHvede from Tibet Plateau ecological zone; as well as 08RH66B and 09RH32B from the northern winter wheat ecological zone. Factor B was N rate of topdressing: 75 kg/hm² and 135 kg/hm² at the jointing stage. The grain number per spike, bulk density, thousand-grain weight and yield were measured, and the crude protein content, sedimentation value, gluten content and dough rheological properties were measured by grain milling. The total stem number of the wheat population was determined at the wintering, regreening and jointing stages, and the plant N content was determined at the flowering and mature stages.

Results There were significant or extremely significant differences in N content, yield, protein content and processing quality among the four materials. The two materials from the Tibet Plateau ecological zone were significantly taller than the materials from the northern winter wheat ecological zone, but their thousand-grain weight and yield were significantly lower than the latter. The N content, yield, sedimentation value, water absorption, dough formation time, stable time, and flour quality index of Zangdong 25 from Tibetan Plateau and 08RH66B from the northern winter wheat ecological zone were respectively higher than those of HeieHvede and 09RH32B from the same ecological area. The rate of N topdressing significantly or extremely significantly enhanced the N accumulation, yield, protein content and processing quality of dough of all the tested materials.

Conclusions The growth and development traits of winter wheat materials from different ecological zones are different, nitrogen demand varies significantly among winter wheat materials for adaptability and quality performance. The effect of nitrogen topdressing at jointing stage is positive in increasing the yield and procession quality of wheat, although the optimum topdressing amount of nitrogen still need studied for specific wheat cultivar.