The Relationship Between Competitive Ability And Productive Performance Of Spring Wheat Cultivars Under Different Combinations Of Irrigation Water And Nitrogen Fertilizer

Improving yields of per unit area is the main objective of crop breeding.Based on the objective,breeders usually select the individuals which has properties like greater biomass, more breeding generations and best individual performance,as the goal of breeding. However,crop production is a population process rather than individual performance.The colony consitituted by individual performing best individually will perform worse when grow together,primarily due to strong competition and biological stress among individuals. Reflecting on the problem,Donald put forward 'ideotype' concept,The core content is that high-yielding crop should be composed of groups of weak competitors,aiming at improving communal performance.Many researchers proposed that we should reduce growth redundancy caused by increasing crop competitive ability in modern crop breeding for the purpose of improving communal yield.However,whether curtailing redundant competitive can gain higher yield? Is the relationship between competitive ability and seed yield correlated negatively? Furthermore,The competitive ability of crop always changing in different circumstances,their competitive ability and competition results will be different under different conditions.To determine the relationship between competitive ability and grain yields of two spring wheat cultivars dingxi-24 and heshangtou that under different water-fertility levels,de Wit replacement series experiments were conducted in 2007 and 2008,cultivars were grown in pairwise mixtures and were compared with monoculture.There was no significant relationship between competitive ability and productive performance of two spring wheat cultivars dingxi-24 and heshangtou in 2007.The yield of dingxi-24 was lower than assembled treatment of heshangtou in the group W₀N₀,W₀N₁ and W₀N₂ when grown in monoculture,On the contrary,the yield of dingxi-24 was higher than that of heshangtou in the treatment group W₁N₁,W₂N₀ and W₂N₂.When compared the competitive ability between dingxi-24 and heshangtou in mixture,there was no definite relationship for different treatments in 2008,there was a positive correlation between the competitive ability and the productive performance of dingxi-24 and heshangtou.The yield of dingxi-24 was higher than that of heshangtou grown in monoculture.Meanwhile,the competitive ability of dingxi-24 was stronger than that of heshangtou.As a result,we concluded that there are no definite relationship between competitive ability and productive performance of two spring wheat cultivars,their competitive ability also changed with the altered external nutrients. Considering the relationship between competitive ability and productive performance,The results in 2008 showed that both the harvest index and the aboveground biomass of dingxi-24 was higher than that of heshangtou,morever,the seed yield was higher than heshangtou,which was deviated with Donald's ideotype.However,the ultimate goal in modern crop breeding is to improve the economic output rather than to optimize the competitive ability.So we should focuse on the improvement of both harvest index and aboveground biomass enhancement,rather competitive ability itself in the modern crop breeding systems.