| The 11 cultivars released in different decades by Liaoning,China(38.55-42.32°N)and Ohio,USA(38.45-41.22°N),having the common ancestors(Amsoy and Williams),were used to graft onto the rootstocks of super-high-yield cultivars Liaodou 14 and Zhonghuang 35 by grafting method at cotyledon stage,respectively.The 11 cultivars released in different decades treated with self-grafting and non-grafting were used as the control.Under the condition of pod experiment,the root system physiological activity,leaf photosynthetic physiological index,leaf protective enzyme activity,nutrient content of different organs,agronomic traits and quality were determined.Discussing the effects of morphology,physiology,yield and quality of the cultivars released in different decades,trying to clear the importance of root system improvement on yield formation,so as to reveal the role of root system improvement in soybean breeding.The results of the study are as follows:1.Advantages of super-high-yield soybean root system physiological functionGrafting with super-high-yield cultivars as rootstocks having a significant impact on the weight of root bleeding SAP and root activity of cultivars released in different decades.At R5 and R6 stages,after grafting with super-high-yield cultivars Liaodou 14 or Zhonghuang 35 as rootstocks,compared with self-grafted plants,the weight of root bleeding SAP and root activity increased significantly.Therefore,the roots of super-high-yield cultivars Liaodou 14 and Zhonghuang 35 have higher physiological activity at reproductive stage.2.Effects of super-high-yield soybean cultivars as rootstock on photosynthetic physiology of cultivars released in different decadesThe leaf photosynthetic rate,stomatal conductance,transpiration rate and leaf greenness values showed a single peak curve in the whole growth stages.The photosynthetic rate,stomatal conductance,transpiration rate reached peak value at R2 stage,and the leaf greenness values reached peak value at R4 stage,and then began to decline.At R5 to R6 stages,the daily decrease rates of non-grafted and self-grafted plants for photosynthetic rate,stomatal conductance,transpiration rate and leaf greenness were by 1.43%,3.67%,3.38%and0.82%,respectively,but those of cultivars grafted onto Liaodou 14 and Zhonghuang 35 rootstocks were by 1.11%,3.26%,2.05%and 0.48%,respectively.After grafting onto the rootstocks of super-high-yield cultivars,the daily decrease rates of leaf photosynthetic rate,stomatal conductance,transpiration rate and leaf greenness values at seed filling period have reduced significantly.Indicates that the root system improvement can make higher photosynthetic characteristics of cultivars released in different decades at reproductive stages.3.Effects of super-high-yield soybean cultivars as rootstock on leaf protective enzyme activity of cultivars released in different decadesGrafting with super-high-yield cultivars as rootstocks having a very significant impact on the leaf protective enzyme activity of cultivars released in different decades at seed filling stages.The interaction between cultivars and graft treatments reached significant leveal of SOD activity and POD activity.After grafting with super-high-yield cultivars as rootstocks,compared with self-grafted plants,the SOD activity,POD activity,CAT activity and MDA content of cultivars released in different decades were increased by 19.69%,83.29%,83.29%and 19.69%,respectively.4.Effects of super-high-yield soybean cultivars as rootstock on nutrient absorption and accumulation of cultivars released in different decadesGrafting with super-high-yield cultivars as rootstocks,the N,P and K percentage content of different organs of cultivars released in different decades varied similarly.After grafting with super-high-yield cutivars as rootstocks,compared with self-grafted plants,the N,P and K percentage content and accumulation of stem and seed of cultivars released in different decades both have improved.Among them,the growth of current cultivars is greater than the common parent and middle cutivars.After grafting with super-high-yield cultivars as rootstocks,compared with self-grafted plants,the N,P and K accumulation of per plant of cultivars released in different decades were increased by 12.01%,10.73%and 10.73%,respectively,and harvest index were increased by 0.54%,0.39%and 0.39%,respectively,while use efficiency were reduced by 5.67%,2.65%and 3.82%,respectively.5.Effects of super-high-yield soybean cultivars as rootstock on agronomic traits and quality of cultivars released in different decadesGrafting with super-high-yield cultivars as rootstocks having no significant impact on morphological traits of cultivars released in different decades,while have effects on yield and quality.After grafting with super-high-yield cutivars as rootstocks,compared with self-grafted plants,the seed weight per plant of common parent,Ohio middle,Liaoning middle,Ohio current and Liaoning current cultivars were increased by 4.5%,6.9%,9.4%,6.9%and 9.4%.The increase of seed weight per plant was attributed to the yield of pods per plant,seed per pod,seeds per plant,100-seed weight and seed-stem ratio increased significantly.After grafting with super-high-yield cutivars as rootstocks,compared with self-grafted plants,the protein content was increased by 1.32%,significantly.The increase of current cultivars is greater than middle cutivars and common parents,but fat content was reduced by 0.32%. |
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