| The crop genotypes and the environment interaction?G×E interaction?is inevitable in dryland agricultural production.Most smallholder farmers expect their crops with a higher yield,as well as higher yield stability.However,there is no consistent conclusion on the relationship between yield potential and yield stability until now;which slows the breeding progress for dryland crops.The eastern region of Gansu,as the main growing region for dryland winter wheat,has a greater variation in annual precipitation,as well as spatial distribution.In experiment 1,we investigate the relationship between yield potential and yield stability of dryland wheat,via analyzing wheat genotypes evaluation experiment in the past 20 years?1999-2009?.In experiment 2,we try to explain the yield potential and yield stability of dryland winter wheat via reproductive allometry.The main findings are as follows:1.In the past 20 years,there were four replacement of control cultivars in the wheat genotypes evaluation experiment in the eastern region of Gansu,namely Lantian4?1999-2002?,Xifeng20?2002-2006?,Xifeng27?2006-2013?and Longyu4?2013-2019?.The yield increased as an annual rate of 2.2%(71.3 kg hm-2 per year),and with greater annual variation[variation coefficient?CV?:20.2%].2.The yield potential is determined by maximum yield in different environments,while yield stability is estimated by CV of grain yield.During 1999 to 2006?Control cultivars:Lantian4 and Xifeng20?,the average yield potential for all genotypes is 5081Kg hm-2 with limited interannual variation?CV:4.2%?;while average yield potential has been improved to 5744 Kg hm-2 with greater interannual variation?CV:22.7%?.3.The datum of the winter wheat genotypes evaluation experiment indicated there were no?13 of 20 years,P>0.05?or positive?7 of 20 years,P<0.05?correlation between yield potential and yield stability,in the past 20 years.Especially in the recent six years?2013-2019?,Longyu4 as a control cultivar,the significantly positive correlation?P<0.05?between yield potential and yield stability was found in five of six years.Thus,there is a risk of decreasing yield stability while the yield potential improved.4.The maximum grain yield with 4971 Kg hm-2 was found in Lantian575,and minimum in Jingxuan1 with 3704 Kg hm-2,16.6%higher and 13.1%lower than that of Longyu4(4263 Kg hm-2),respectively,in a multi-site field experiment with 13 dryland wheat genotypes from 2017 to 2019.While comparing the yield performance across the environments,the high-yielding and worse-yielding were Ningxian and Lingtai in2017-2018 growing season,as severe lodging for all wheat genotypes in Lingtai.The analysis of variance?ANOVA?showed significant G×E interaction on dryland wheat grain yield?P<0.001?.5.The significant positive correlation?R2=0.45,P<0.05?between yield potential and CV of grain yield of 13 wheat genotypes was found in a multi-site field experiment from 2017 to 2019.This finding indicates that there is a tradeoff between yield potential and yield stability of dryland wheat genotypes.6.The allometric relationship between reproductive?R,estimated by grain yield?and vegetative?V?biomass showed that R-V allometric exponent?slope of log R-log V?>1,in13 dryland wheat genotypes;the maximum is 1.27?Lingmai479?and the minximun is1.11?Longyu0869?.7.The correlation analysis showed that R-V allometric exponent were significantly correlated to yield potential?R2=0.31,P<0.05?and CV of grain yield?R2=0.62,P<0.01?,respectively,in 13 wheat genotypes.Thus,both the yield potential and yield stability are affected by variation in the R-V allometric relationship.In summary,there is a trade-off relationship between yield potential and yield stability of dryland winter wheat;which can be explained by reproductive allometry.We speculate that such trade-off is a biological constraint,and could not be eliminated by crop breeding.We propose the future crop breeding should emphasize both the yield potential and yield stability,rather than only yield potential. |
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