Coevolution Relationship Between Phenotypic Traits And Yield Formation Of Winter Wheat In Different Climatic Regions

According to the theory of crop evolution ecology,the increasing of crop yield is a group selection process that weakens the competition among plants and promotes the efficient utilization of resources.According to the law of constant final production,it is difficult for wheat population with single niche and high density to increase the yield by maximizing individual biomass.The main way to increase crop yield is to increase the distribution of dry matter to reproductive organs and reduce the input to competitive organs.The distribution pattern of dry matter to competitive organs is affected by different environmental resources,which leads to different adaptation strategies.In this study,in order to understand the coevolution relationship between phenotypic traits and yield formation of winter wheat in three different climatic regions,we selected three winter wheat regions:Northwest region（Dingxi,Gansu）,Huanghuai region（Luoyang,Henan）and the lower reaches of Yangtze River（Nantong,Jiangsu）for retrospective comparative study.In this study,we selected 20 wheat varieties from three different climatic regions in recent 20 years（among them,17 varieties were local varieties,and 3 varieties were compared in all three places）,and conducted field experiments under six densities.The above ground plant type and dry matter distribution characteristics were determined at flowering stage and maturity stage,1)we took the highest yield of each variety in different density as the main variable to analyze the difference of yield formation characteristics of winter wheat in different climatic regions;2)we analyzed the evolution trend of aboveground phenotypic traits in the process of production increase.The main results are as follows:（1）The yield of different wheat varieties in the same climate region was significantly different.The coefficient of variation of wheat yield in Dingxi（10.67%）was the largest,followed by Luoyang（7.61%）,and Nantong（6.95%）was the lowest.The mean yield of wheat varieties under different densities in different climate regions was significantly different.Luoyang obtained the highest average yield(8.37 t ha^-1),followed by Nantong(7.65 t ha^-1),and Dingxi was the lowest(5.68 t ha^-1).（2）The abundance of environmental resources will affect the yield of wheat varieties.Among the wheat yield traits in Dingxi,the number of grains per spike and 1000-grain weight contributed the largest to 15.3%and 12.1%,respectively.Among the wheat yield traits in Luoyang and Nantong,the number of spikes per unit area and the number of grains per spike had the highest contribution rate to 20.9%and 21.5%,18.4%and 13.7%,respectively.The contribution rate of aboveground biomass to yield was generally higher than the harvest index.（3）The abundance of environmental resources will affect the plant type structures and dry matter distribution pattern of wheat.In the process of increasing the yield of wheat varieties in three locations,the plant height decreased,the spike length increased and the flag leaf area and specific leaf area increased.The correlation degree between Agronomic Traits and yield was different in different climatic regions:Among the agronomic traits of Dingxi wheat,stem dry weight and leaf dry weight are the most correlated with yield,spike height and flag leaf height are the most correlated with yield in Luoyang wheat,and specific leaf area and flag leaf area are the most correlated with yield in Nantong wheat.In the process of increasing yield,the dry matter distribution patterns are different in different climatic regions:the input of stem and leaf of are increased in Dingxi;the input of leaf are increased in Luoyang;the input of stem are increased in Nantong.（4）The abundance of environmental resources will affect the competition response.In Dingxi,the plant height,stem weight ratio,flag leaf area,and leaf weight ratio of wheat varieties increased with the increase of planting density.In other words,plants respond to competition by increasing plant height and leaf area.In Luoyang,the flag leaf area and leaf weight ratio of wheat varieties decreased with the increase of planting density,the plant height and stem weight ratio of wheat varieties increased with the increase of planting density.In other words,plants respond to competition by increasing leaf area.In Nantong,the plant height and stem weight ratio increased with the increase of planting density,but the flag leaf area and leaf weight ratio had an opposite trend.That was,plants respond to competition by increasing plant height.The results of this study showed that under different environmental resources,the ways to increase yield and the evolutionary trend of phenotype were different.In Dingxi,the number of grains per spike and 1000-grain weight was the critical factor affecting yield,reducing the height of flag leaf and the biomass allocation of plants to competitive organs can further improve wheat yield.In Luoyang,the number of spikes per unit area and the number of grains per spike had an important impact on yield,and reducing the dry matter input of stem is beneficial to the increase of yield.In Nantong,the number of spikes per unit area and the number of grains per spike were the key factors affecting yield,and reducing the dry matter input of leaf area is beneficial to the increase of yield.When dealing with the competition of light resources caused by the increase of planting density,wheats in three regions have shown different strategies.In Dingxi,wheat varieties showed an increase in plant height and leaf area;in Luoyang,wheat varieties showed an increase in leaf area,and in Nantong wheat varieties showed an increase in plant height.