Effects Of DPC And PP333 On The Effect Of Chemical Control And Fruit Quality Of "Xinxin2" Walnut

Paclobutrazol(PP333)and Mepiquat chloride(DPC),which were commonly used growth retardants in agricultural production,were selected as the experimental reagents in this experiment.The experiment set five concentration gradients of 0mg/L(CK),500mg/L(D1),1000mg/L(D2),2000mg/L(D3)and3000mg/L(D4)of PP333,and five concentration gradients of 0mg/L(CK),200mg/L(S1),300mg/L(S2),400mg/L(S3)and 500mg/L(S4)of DPC to carry on the medicine processing to the walnut.In order to explore the effect of chemical control of PP333 and DPC on the overall development of walnut and provide reference for the input of PP333 and DPC in agricultural production,these two kinds of growth retardants were applied to the leaves of walnut trees.In this experiment,the nutrient branches,fruit branches,leaf anatomical structure,photosynthesis,fluorescence,chlorophyll SPAD value and fruit quality were determined.Variance analysis was used to analyze the differences among different treatments,and the results were as follows:(1)Effects of two kinds of Plant Growth Retardants on the growth of vegetative branches of walnut.Comparing with CK,the application of PP333 to the walnut tree could significantly inhibit the length and lateral growth of the vegetative branches of the walnut;Spraying DPC could obviously inhibit the growth of the vegetative branches of walnut,and the effect on lateral inhibition was not obvious;And the growth was significantly inhibited,and the inhibition effect increased with the increase of concentration in 1-2 weeks after treatment.Meanwhile,late growth of the walnut tree is very small through the investigation of the late growth shows that he inhibition of growth of walnut in the late stage was not a function of the growth inhibitor,but a physiological phenomenon in the walnut itself.(2)Effects of two kinds of Plant Growth Retardants on the growth of the fruiting branches of walnut.The results showed that spraying DPC and PP333 could effectively inhibit the longitudinal growth of the bearing branches of walnut,and the higher the concentration was,the more obvious the inhibition effect was.Comparing with CK,the growth rate of the branch length of D1,D2,D3 and D4 decreased by31%?20%?52%?59% and that of S1,S2,S3 and S4 decreased by 13.86%?47.1%?50.79%?63.49%;Theinhibition effect of high concentration of PP333 on the longitudinal growth of the bearing branches of walnut was better than that of DPC.(3)Comparison of chemical control effects of the two plant growth retardants.The effect of PP333 on the chemical control of walnut was shown in the inhibition of vegetative branches,low concentration(500mg/L),the control effect was not obvious.The effect of DPC on the chemical control of walnut was shown in the inhibition of bearing branches,and the control effect of low concentration of DPC is not as high as that of high concentration PP333.(4)Effects of two kinds of Plant Growth Retardants on SPAD value of leaves In the leaf expansion period,hardcore period,influx time,oil transformation period and mature period,the change trends of SPAD value of leaves of bearing branch and vegetative shoot of walnut are roughly the same.It showed a single peak curve trend chart,and reached the peak in filling stage.Comparing with CK,the SPAD value of the bearing branch leaves of walnut could be improved by spraying different gradient concentrations of DPC and PP333 on walnut tree.(5)Effects of two kinds of Plant Growth Retardants on the photosynthetic fluorescence index of leaves.Spraying suitable concentration of DPC and PP333 on walnut tree could improve the net photosynthetic rate,stomatal conductance,Intercellular carbon dioxide concentration and transpiration rate of the leaves.And the photosynthetic rate showed a single peak curve,and the peak value appeared in the filling stage.Stomatal conductance,intercellular carbon dioxide concentration and transpiration rate trends roughly the same,the lowest value appeared in the period of hard core,and the highest value appeared in oil transformation period,carbon dioxide and transpiration rate change volatility,which may be related to the changes of environment and climate.There were significant changes in q P(photochemical quenching coefficient),NPQ(non photochemical quenching coefficient),FV/FM(the maximal photochemical quantum yield of PS II)and Y [II](the actual photochemical quantum yield),and with the increase of DPC and PP333 concentration,qP showed an upward trend in general,NPQ presented the trend of first increasing and then descending,Y[II] and FV/FM overall also showed an upward trend in general and the change was smaller.(6)Effects of two kinds of Plant Growth Retardants on the structure of plant leaves.The change of stomatal density of CK,S1,S2,S3 and S4 were consistent with the change of the "V" trend,the maximum m value appeared in June,and the minimum value appeared in August;Stomatal density of leaves under DPCtreatment showed a single peak curve,and the maximum value appeared in July.Variance analysis showed that there was no significant difference of stomatal density in CK and the treatments of DPC,the stomatal conductance of the leaves was significantly higher than that of CK in August.Spongy and palisade tissue changed consistently with a single peak curve,the peak value appears in August.Variance analysis showed that there was no significant difference in the thickness of spongy tissue and palisade tissue between CK and DPC treatments.The thickness of the palisade tissue in PP333 treatment of 1000mg/L was significantly higher than that of CK in August.Spraying DPC can reduce the thickness of upper epidermis of leaves,spraying PP333 had no significant effect.Spraying PP333 can increase the thickness of the lower epidermis of the leaf,spraying DPC had no significant effect.(7)Effects of two kinds of Plant Growth Retardants on the quality of walnut.Variance analysis showed that the reducing sugar content of walnut fruit of D1,D3,D4 were significantly higher than S2,D1 was significantly higher than S3;Tannin compounds content of walnut of D2 was significantly lower than S1;The total sugar content of walnut fruit of D2 was significantly lower than S2.Besides,there was no significant difference in the indexes such as cellulose,acid,protein and kernel rate of fruit.