Effects Of Nitrogen Fertilization,Sowing Date And Rate,Straw Returning On Formation Of Grain Yield And Quality And The Physiological Mechanisms In Wheat

According to analysis on conditions and technique requirement of wheat production in the rice-wheat double cropping system in the Yangtze River-Huai River Plain,a series of field experiments were carried out to clarify the effects of sowing date and rate,nitrogen fertilization,straw returning,on grain yield and quality and the underlining physiological mechanisms in wheat.1 Effects of nitrogen fertilizer on grain yield and quality in wheatIn a field trial,winter wheat(Triticum aestivum L.)cultivar Xumai 31 was grown to study the effects of nitrogen application rates and basal-top-dressing ratios on grain yield and quality in wheat.The final grain yield improved with increasing nitrogen rate and reached the highest at nitrogen rate of 225 kg ha-1,and then decreased at nitrogen rate of 300 kg ha-1.The yield variation due to nitrogen rate was related to the changes in the number of kernels per spike and the spike number.The contents of total protein,albumin,gliadin and glutinin were increased with higher nitrogen rate.Final yield was the highest with the basal-top-dressing ratio of 5:5 at nitrogen rate of 225 kg ha-1 in this experiment.According to the fitting equation for relation between N application rate and grain yield/protein content,the recommended nitrogen fertilization to pursue higher yield with 8266.9 kg/ha was nitrogen rate of 289.07 kg ha-1 with a basal-top-dressing ratio of 5:5 in the present study.2 Effects of straw returning and nitrogen fertilization on grain yield and quality in wheatWinter wheat(Triticum aestivum L.)cultivar Xumai 31 was grown in a field trial to study the effects of straw returning and nitrogen fertilizer on growth and population performance,carbohydrate and nitrogen(N)metabolism,grain yield,starch and protein quality in wheat.Grain yield was increased due to increased spikes per hectare in the straw returning treatments.Straw mulching increased total contents of protein and wet and dry gluten.Nitrogen reduced content of starch,while increased contents of protein and gluten in grain,and flour viscosity of peak,trough,breakdown and final viscosity under straw returning.In general,the spike number and kernel number per spike increased with enhancing nitrogen application rate,which led to higher grain yield under straw returning with the highest yield(7576.7 kg·ha-1)at nitrogen rate of 260.47 kg·ha-1,accroding to the fitting equation for relation between N application rate and grain yield under straw returning.3 Effects of sowing date and rate on grain yield and quality in wheatWinter wheat(Triticum aestivum L.)cultivar Xumai 31 was grown n a field trial to study the effects of sowing date and sowing rate on growth and population performance,carbohydrate and nitrogen metabolism,grain yield,starch and protein quality in wheat.Pre-winter development of wheat was improved by early sowing date.After the regeneration period,the difference in growth and development decreased under different treatments.It was founded that effect of different sowing dates and sowing rates on the spike number per ha,grain number per spike and yield was significant different.The highest grain yield was observed in treatment of mid sowing rate with appropriate sowing date.At late sowing conditions,better grain yield was observed with higher sowing rate.Sowing date and sowing rate significantly affect falling number and wet-gluten content in flour.Falling number and wet gluten content increased with late sowing and reached the highest value at the appropriate sowing date,and then decreased with further delayed sowing.Depending on the 3D mesh plot of grain yield under different sowing dates and rates,the appropriate sowing date is early Octber with a sowing rate of 17.5 plants per acre.