| Due to the problems of low yield and expensive price,and the public needs cannot be met of high-quality tomato,discussing sorghum companion and water stress at a certain stage of plant growth and development can influence tomato quality according to the demand law of tomato to water and nitrogen nutrition.In this experiment,the varieties"TiePi" and "Provence" were used as the research objects to carry out experiments,and the varieties and measures that can improve the quality of tomato were compared through pot experiments.Therefore,pot experiments were continually used to explore the effects of water stress and sorghum companion on tomato sugar metabolism,plant physiological characteristics and soil microecology.The effects of water stress and sorghum companion on sugar metabolism,plant physiological metabolism and soil Microecology of the demand law of tomato were revealed,which provided practical theoretical guidance and practical basis for large area planting of high-sugar and high-quality tomato.The main conclusions are as follows:(1)Selection of the best tomato cultivation measures.The changes of sugar and acid content of the varieties "TiePi" and "Provence" under different measures were compared.Among them,the sugar content of "TiePi" ranged from 9.53%to 10.97%,and the acid content ranged from 0.42%to 0.63%,Which is higher than that of "Provence".And the sugar and acid contents were 10.84%and 0.59%respectively of water control during the fruit expansion period;the sugar and acid contents were respectively 10.97%and 0.42%by associated sorghum,which were higher than those in the control.(2)The changes of sugar and acid content and sugar metabolizing enzyme activity in fruits of two planting patterns under water stresses were clarified.Under severe stress(W3,35%field water holding capacity),the sugar and acid content of fruit increased significantly,which was the best stress treatment to improve tomato quality.Under conventional planting,the contents of glucose,fructose and soluble sugar increased by 28.40%,39.86%and 28.45%respectively,the malic acid and citric acid content had no change.The activities of sucrose synthase(SS)and sucrose phosphate synthase(SPS)decreased,while the activities of invertase(Inv)increased under water stress.In the associated mode,sugar content increased significantly by 39.91%,51.72%and 22.69%,citric acid and malic acid content increased significantly by 27.74%and 23.33%respectively.With the deepening of stress degree,SS and Inv activities increased gradually,and SPS activities decreased.Among them,the contents of glucose,fructose and citric acid in associated mode were significantly higher than those in conventional cultivation.(3)The changes of plant physiological characteristics under severe stress of the two planting patterns were clarified.Under conventional planting,the activities of proline(Pro)and peroxidase(POD)of W3 increased significantly by 229.88%and 213.54%respectively,while malondialdehyde(MDA),catalase(CAT)and superoxide dismutase(SOD)were no significant changes.Abscisic acid(ABA)and gibberellin(GA3)in roots significantly increased 215.68%and 17.98%respectively,while methyl jasmonate(MeJA)decreased by 24.35%significantly.while ABA,GA3,MeJA and indoleacetic acid(IAA)in shoots all are on the rise.In the associated mode,Pro and POD increased by 649.43%and 217.77%,respectively,while SOD decreased by 38.64%.ABA,GA3 and IAA in roots significantly increased by 290.20%,30.94%and 118.43%respectively,and four hormones in shoots all are on the rise.(4)The changes of soil chemical properties and enzyme activities of the two planting patterns under severe stress were clarified.Under the two planting patterns,the content of NH4+-N in soil increased significantly by 78.91%and 78.65%,respectively.The activity of phosphatase in the associated mode increased significantly by 87.26%.(5)The changes of rhizosphere microbial community characteristics of the two planting patterns under severe stress were clarified.Under the conventional mode,the fungal Sobs,Ace,Chao and Shannon indexes decreased significantly by 43.61%,31.89%,33.46%and 52.69%,respectively,while the Simpson index increased significantly by 810.45%;In the associated mode,the Simpson index of fungi decreased significantly by 59.69%.Compared with conventional fungi Sobs,Ace,Chao and Shannon,the index of associated sorghum increased significantly.Cluster analysis showed that water stress increased the abundance of Actinobacteria and Firmicutes.Actinobacteria has the highest abundance,which is 35.42%and 34.83%,respectively.W3 can increase the abundance of Ascomycota and decrease the abundance of Basidiomycota and Mortierellomycota.Redundancy analysis showed that soil moisture was the main factor affecting the variation of bacterial and fungal community structure,while NH4+-N only had a significant effect on bacteria(6)Correlation analysis showed that there was a significant negative correlation between soluble sugar and SPS and SS,and a significant positive correlation with fructose.Water stress significantly affected the activities of SPS and Inv,which were positively correlated with glucose and fructose.Planting patterns have significant effects on SPS,SS and soluble sugar.POD and CAT were positively correlated with soluble sugar,while SOD was negatively correlated with soluble sugar.Glucose,fructose and soluble sugar were significantly correlated with the contents of plant hormones(ABA,GA3,MeJA and IA A)in each part.In conclusion,severe stress(35%field water holding capacity)and sorghum companion pattern can significantly increase the sugar and acid content in fruits,which is the best cultivation measure to improve the quality of tomato.And the physiological regulation mechanism of plants and the life activities of soil microorganisms under water stress are revealed,which provides theoretical guidance and cultivation techniques for planting high-quality tomatoes. |
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