| Oligosaccharide,a kind of new physiological active substances,is beneficial to promote crops growth,increase the yield,improve the quality and crop resilience.However,the effects of different oligosaccharides and the oligomix on crop growth and the underlying mechanism are still unclear.This thesis takes tomatoes and lettuce as research objects.In the study,chitosan oligosaccharide（ZH-C）,cello-oligosaccharide（ZH-A）,xylooligosaccharide（ZH-B）and oligomix（ZH-M）which were mixed by these three oligosaccharides（mass ratio 1:1:1）were chose to explore the optimal concentration using in agriculture,the ability and mechanism to the regulation of seedling growth,the resistance to low temperature stress,the improvement of crop yield and quality,combining the simulation of chilling stress in greenhouse and the Field trials.The studies found that:（1）with the concentration of 80 mg·L-1,the single oligosaccharide and compound oligosaccharides immersion and foliar spraying had significant positive effects on seed germination and growth.Especially in xylooligosaccharide treatment（ZH-B）,the biomass of root increased by twice compared with the（CK）.（2）The yield of tomato was significantly increased by oligomix（ZH-M）treatment,with an increase of 33.26%.In contrast,each single oligosaccharide treatment does not significantly increase the yield,but the fruit diameter,single fruit weight and sugar content increased significantly.（3）The results also showed the significantly increase of the lettuce biomass and the improvement of the quality in oligosaccharides treatments.While the oligomix（ZH-M）showed the best effects on lettuce growth.Among them,the fresh weight and leaf area index increased by 52.58%and 57.60%.Root dry weight,total root lengths,total volume and surface area increased by 35.07%,89.10%,49.23%and 40.68%,respectively.The content of soluble sugar,amount of chlorophyll,and Vc rose by 25.20%,21.50%and 12.08%,respectively,while the nitrate content dropped by 27.65%.（4）Different oligosaccharide treatments lead to the difference in hormone levels of tomato auxin（IAA）,methyl jasmonate（JA-ME）and other hormones:ZH-M treatment increased the content of auxin（IAA）by 30.46%above ground,ZH-B treatment increased the content of auxin（IAA）by 36.10%in underground.In addition,except for ZH-A treatment,the content of JA-ME increased by 17%under other oligosaccharide treatments.As a result,ZH-M has the largest biomass above ground,ZH-B has the largest biomass below ground,and ZH-A has the longest main root.（5）Compared with the CK,the content of abscisic acid（ABA）in tomoto in oligosaccharide treatment increased significantly under chilling stress:the content of ABA in ZH-C treatment was significantly increased by 19.49%.Thereby activating the defense system,and induced the soluble sugar increasing,eventually reduced the damage degree of cell membrane.In addition,oligomix also have cold resistance,but not as effective as chitosan oligosaccharides.The results demonstrated oligosaccharides can significantly promote plant growth,quality and chilling resistance ability by regulating phytohormones.In addition,different oligosaccharides showed some differences in plant regulation.Oligomix played comprehensive effects.These may provide further evidences for the development and application of oligosaccharides in modern agriculture. |
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