| The deterioration of ecological environment since the beginning of the 21st century has led to more serious ecological and microbial stresses in fruit tree production.With the continuous research and development of new environmental protection biotechnology,microbial protein pesticides are continuously developed and applied.Previous studies have shown that hypersensitivity proteins are a class of proteins secreted by Gram-negative plant pathogenic microorganisms,which can increase the activity of disease-resistant enzymes in plants and the expression of resistance genes,induce plant resistance to pests and diseases,promote plant growth,and enhance fruit quality.In this study,foliar spraying hypersensitivity protein was used to explore the effects of hypersensitivity protein on grape growth and fruiting and tolerances to saline-alkali stress,downy mildew and virus disease.The main findings are as follows1.’Summer black’ grapevines were selected as test material in Dongying saline-alkali land.During grape growing season(April 30th,May 15th,and May 30th),the leaves were sprayed with 0.2%hypersensitive protein.Hypersensitivity protein alleviated the decrease of chlorophyll content and photosynthesis caused by saline-alkali stress.Fv/Fm was increased 5.78%and 6.25%in comparison to the control by spraying hypersensitivity protein in June and July,respectively.Fv’/Fm’ from the determination in June,July,and August was increase 3.3%,7.5%,and 5.7%,respectively.Spraying hypersensitivity protein increased the activity of the reaction center;RC/CSm was increased by more than 9.1%and the activity at the receptor side was increased more than 8.7%compared to the control.The performance index Plabs was more than 17.4%higher than the control.Spraying high-sensitivity protein increased the activities of antioxidant enzymes including SOD,POD,and CAT in leaf.Activity of SOD,POD and CAT was increased more than 13.4%,10.6%and 24.9%,respectively.The application of high-sensitivity protein kept green leaves,decreased Na+content,increased K+content,and thereby decreased Na+/K+under salt stress;the decrement of Na+/K+reached 31.3%.The leaf area,leaf thickness and leaf mass treated by hypersensitive protein were increased by 50%,23.8%and 29.2%,respectively,compared with the control.Internode length,longitudinal stem,and transverse stem were increased by 57.8%,26.1%,and 36.2%,respectively,and the soluble sugar and starch contents in branches were increased by 28%and 15.5%,respectively2.One-year-old ’Ji Gao’ grape seedlings were used to be sprayed with 0.2%hypersensitive protein at the sprouting period,four leaf spreading periods and 30 days after germination.The leaves were inoculated with downy mildew at the second day after the last treatment.The results showed that spraying hypersensitive protein produced inhibitory effect on downy mildew,and the disease index decreased by 20.7.Hypersensitive protein alleviated the decrease of chlorophyll content caused by downy mildew.The Fv/Fm in the leaves sprayed with hypersensitive protein was increased by 11.7%at 9 days after inoculation;simultaneously Fv’/Fm’ was increased by 9.5%,WK was decreased by 13.4%,RC/CSm was increased by 32.6%,and Ψo was increased by 24.9%;resultantly,the comprehensive photo synthetic performance index Plabs was increased 57%.Compared to the control leaves,the activities of SOD,POD and CAT in treated grape leaves increased faster,their peak values were higher,and the activities remained high until 5 days after treatment.Activity of SOD,CAT and POD in the hypersensitive protein-treated █was increased at least 41.5%,30.2%and 39.4%,respectively.The application of hypersensitive protein decreased MDA accumulation and led to more than 37.9%decrement.3.Foliar spraying of 0.2% hypersensitive protein at a week before sprouting and growth period was applied to the‘Sunshine Muscat’ grapevines carrying viruses.Application of hypersensitive protein made vine sprout early 8-10 days.Additionally,hypersensitive protein significantly promoted grapevine growth.Compared to the control,growth increment of shoots was increased by 50.8%,and leaf area,leaf thickness and leaf mass were increased by 31.6%,35.5%and 34.5%,respectively.Soluble sugar and starch content of wintering branches were increased by 22.1%and 21%.Hypersensitivity protein significantly increased grape yield and quality.Single grain weight,fruit diameter and fruit diameter were increased by 7.22%,6.79%,and 3.25%,respectively.The yield per hectare increased by 20.8%.Soluble solids and titratable acid was 3.25%and 4.15%higher than the control.Hypersensitivity protein increased leaf antioxidant enzyme activity of SOD,POD,and CAT.Activity of SOD,POD and CAT was increased by at least 219%,14.9%and 27.3%,respectively.Hypersensitivity protein alleviated the decrease of chlorophyll content caused by viral diseases.The values of Fv/Fm,Fv’/Fm’,RC/CSm and Ψ were increased at least 2.1%,3.8%,8.7%and 5.7%,respectively,and hence the comprehensive photosynthetic performance index Plabs was increased more than 17.9%. |
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