| With the increase of world population and the decrease of cultivated land,the breeding of high-yield wheat varieties has always been a hot topic.However,only when more photosynthate is distributed to harvest organs can high yield be achieved.Therefore,in order to screen wheat with high yield and low consumption,230 Chinese wheat micro core germplasms were used as experimental materials,which were divided into field experiment and indoor hydroponic experiment to investigate and analyze their morphological and physiological characteristics.The field experiment was carried out in Yanjin County experimental base of Xinxiang City,Henan Province from 2018 to 2019 to study the differences of agronomic traits,root morphology,leaf physiology and yield of different genotypes of wheat,and the correlation analysis,principal component analysis and wheat material clustering analysis were carried out.The indoor experiment was carried out in the artificial climate laboratory in 2019.Bainong 207 was used as the control and hydroponics was carried out in batches to study the differences of root respiration rate,morphological characters and biomass of aboveground and root of different genotypes of wheat at seedling stage,and cluster analysis was carried out according to the results of principal component analysis.The main results are as follows:Statistical analysis showed that the coefficient of variation of above ground agronomic traits,root phenotype and root respiration of indoor wheat micro core germplasm seedlings were more than 10%,indicating that there were abundant genetic variations in the tested genotypes,and the selection range of germplasm resources had great improvement potential.The correlation analysis showed that there was information overlap among different traits.Therefore,the principal component analysis was used to reduce the dimension and comprehensively evaluate the tested genotypes.230 genotypes were divided into class IV,and class I included 212 genotypes.The relative values of respiration,shoot dry weight and root dry weight of these genotypes were small.The second type includes 8 genotypes.The relative value of respiration is larger,the relative value of shoot dry weight is smaller,and the relative value of root dry weight is smaller.The third group included two genotypes,which had higher relative value of respiration,higher relative value of shoot dry weight and lower relative value of root dry weight.The fourth group included 8 genotypes,which had lower relative value of respiration,lower relative value of shoot dry weight and higher relative value of root dry weight.Cluster analysis statistical method was used to comprehensively evaluate the characters of wheat materials tested in field experiments,and 230 wheat genotypes were classified into VI classes:Class I varieties contain 61 genotypes,77 genotypes of class II,52 genotypes of class III,26 genotypes of class IV,11 genotypes of class VI,3 genotypes of class V,and 11 genotypes of class VI.The type I and type II genotypes of wheat have lower shoot dry weight,plant height,tiller number,root length and root dry weight,larger nitrogen balance index and average root diameter,and relatively higher yield.They have some characteristics of energy saving and high yield wheat.According to the statistical analysis results of various indexes in the field experiment,there were abundant genetic variations in maturity,agronomic traits above ground,root phenotype,leaf physiology,yield components and other traits of the tested wheat,and there was great potential for improvement in the selection range of germplasm resources.Principal component analysis showed that root length,root surface area,root volume,panicle weight,NBI,chlorophyll content,grain number per panicle and aboveground dry weight had larger characteristic roots.Correlation analysis showed that root length,root surface area,root volume and average root diameter were significantly correlated with root dry weight;1000 grain weight and grain number per panicle were significantly correlated with yield;NBI was positively correlated with chlorophyll content;There was a significant positive correlation between plant height and aboveground dry weight;Flag leaf fresh weight and flag leaf surface area were significantly positively correlated with aboveground dry weight.Therefore,cluster analysis was carried out on the basis of root dry weight,shoot dry weight,yield per mu and flag leaf chlorophyll content.The results of cluster analysis showed that 230 genotypes could be divided into group III.Among them,there were 217 genotypes in class I,which had low root dry weight,low shoot dry weight,the lowest yield per mu and relatively high chlorophyll content.The second type includes 8 genotypes.The dry weight of root is relatively small,the dry weight of shoot is relatively large,the yield per mu is relatively high,and the chlorophyll content is relatively large;Among them,the third type includes five genotypes,which have heavy root dry weight,heavy shoot dry weight,high yield and relatively small chlorophyll content.The relative value of shoot dry weight was significantly negatively correlated with that of shoot dry weight at maturity stage,significantly positively correlated with that of root dry weight at maturity stage,significantly positively correlated with the relative value of average root diameter at maturity stage,and significantly positively correlated with the relative value of specific root length at maturity stage,The results showed that there was consistency between seedling stage and mature stage,and the root system was more stable than shoot.The relative value of root respiration rate at seedling stage was negatively correlated with the above ground agronomic traits at maturity stage,positively correlated with the average root diameter at maturity stage,negatively correlated with other root parameters,positively correlated with 1000 grain weight,and negatively correlated with the number of grains per spike,It was not conducive to the increase of grain number per spike,but conducive to grain filling and 1000 grain weight.In conclusion,the morphological and physiological characteristics of different wheat genotypes were significantly different.The physiological characteristics of flag leaf and the growth of root system played an important role in yield formation.The lower respiratory consumption of root system makes more photosynthetic products distributed to harvest organs,which is beneficial to grain filling and 1000 grain weight increase.The results provide a new idea for high yield and low consumption wheat breeding under the condition of limited improvement of photosynthetic production potential. |
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