Effects Of Night Warming In Winter And Spring Seasons On Grain Quality Of Different Types Of Wheat And Its Physiological Mechanism

Warming is the main impact of global climate change and global warming shows diurnal warming asymmetry.Warming mainly occurred in winter and spring seasons,and the increment of temperature amplitude at night is greater than during the day.Warming will be significantly affected the quality,yield of wheat through changing its plant morphology,growth and physiological characteristics because wheat is the type of overwintering.Understanding the impact of night warming in winter and spring seasons on winter wheat grain quality formation and nitrogen metabolism has important significance for elucidating the regulation mechanism of asymmetric warming on high yield with high quality of wheat.In this study,two winter wheat cultivars,Yangmai 13 and Yannong 19,were tested.Field experiments were conducted setting the double factors of warming(WT means winter warming treatment;ST means spring warming treatment;WST means winter and spring warming treatment)and ratio of basal to topdressing nitrogen(3:7;5:5)to investigate the effects of night warming in winter and spring seasons on grain quality formation of wheat.The physiological mechanism of the effect of increasing temperature in winter and spring seasons and postponing N application on protein formation was explained by nitrogen metabolism.The purpose of this study was to provide a reference for guaranteeing high yield of wheat with high quality.The main results are as follows:1.Night warming in winter and spring seasons could improve wheat grain quality.Night warming in winter and spring seasons significantly increased 1000-grains weight,starch and protein accumulation.Compared to CK,WST and WT significantly increased content of protein,protein components,GMP,HMW-GS and LMW-GS,wet gluten and SDS-Sedimentation value while ST was only slightly different from CK.However,the warming treatments decreased starch content,amylopectin content and slightly increased amylose content,amylose/amylopectin ratio and pasting properties.2.Postponing N application under night warming in winter and spring seasons could enhance grain protein quality.Compared to CK(5:5),postponing N application(3:7)increased 1000-grain weight,protein content,protein and starch accumulation.Postponing N application increased gliadin and glutenin content,HMW-GS and LMW-GS content,GMP content,wet gluten and SDS-Sedimentation value and decreased starch content,amylopectin content and pasting properties.These indicated that postponing N application has positive effect on wheat grain quality.However,there was no significant difference in the volume percentage and starch granule diameter of type A,B and C starch granule between warming treaments and control.Postponing N application under night warming in winter and spring seasons decreased starch granule diameter and volume percentage of type A and C,but increased volume percentage of type B.Postponing N application under night warming in winter and spring seasons could improve wheat grain quality.3.Night warming in winter and spring seasons and postponing N application could enhanced quality of superior and inferior grains and the amplification of quality in inferior grains was greater.Night warming in winter and spring seasons and postponing N application increased 1000-grain weight,protein content and accumulation,starch accumulation,protein components content and GMP content of superior and inferior grains.The effect of night warming on qualities of inferior grains was higher than those in superior grains.1000-grain weight,protein content and accumulation,starch accumulation,Gliadin and Glutenin content and GMP content of superior grains was higher than in inferior grains,but Albumin and Globulin content of superior grains was lower than inferior grains.In an overall view,Night warming in winter and spring seasons and postponing N application could enhanced protein content and accumulation of superior and inferior grains and improve its quality.The amplification of quality in inferior grains was greater.4.Night warming both in winter and spring seasons and postponing N application could increase grain protein formation through promoting nitrogen uptake and assimilation as well as facilitating its allocation to grain.Night warming and postponing N application increased grain-filling rate and content of total protein,protein components and GMP.Night warming in winter and spring seasons and postponing N application increased the flag leaf area and nitrogen content at anthesis,activity of nitrate reductase and glutamine synthetase in flag leaves from-10 to 21DAA and activity of glutamic-pyruvic transaminase in grains within 21 days after anthesis.These results indicated that night warming and postponing N application enhanced the growth of source organ and strengthen the capacity of nitrogen assimilation.Night warming and postponing N application remarkably increased the pre-and post-anthesis nitrogen accumulation,stored nitrogen translocation and the grain nitrogen distribution,which could promote the synthesis of protein.In addition,the effects of winter night warming treatments on protein formation were higher than those of spring night warming.Night warming both in winter and spring seasons and postponing N application increased grain protein content through promoting nitrogen uptake and assimilation as well as facilitating its allocation to grain.In conclusion,night warming both in winter and spring seasons is good for obtain high quality of wheat.Night warming both in winter and spring seasons could improve wheat quality by promoting capacity of nitrogen uptake,facilitating its allocation to grain and grain protein formation.Postponing N application increased the positive effect on quality of night warming both in winter and spring seasons.Night warming in winter and spring seasons and postponing N application increased protein content and accumulation and the increaments of quality in inferior grains was greater.