| This study was carried out to screen the effect of various plant bio-stimulants in promoting cucumber growth under soilless culture via root application and select the best bio-stimulants,to find out,best Putrescine(Put),Meta-topolin(MT)and 24-epibrassinolide(EBR)combination on the basis of earlier trial in improving physio-morphological parameters and root activity in cucumber seedlings growth via root application,to study the effect of(5 mM Put+0.02 ppm MT+0.001 ppm EBR)on the basis of earlier trial on antioxidant enzymes under NaCl and to identify the effect of exogenous(5 mM Put+0.02 ppm MT+0.001 ppm EBR)on yield,fruit quality and nitrogen carbohydrate metabolism in cucumber plants under salt stress.1-Effect of various Plant Bio-stimulants on Cucumber Growth in Soilless Culture(Trail 1).In the present study we screened fifteen treatments as follows:T1(water);T2(10 mM Putrescine);T3(250 ppm Seaweed);T4(0.02 ppm Meta-topolin);T5(100 ppm Naphthalene Acetic Acid);T6(400ppm Polyaspartic acid);T7(50 ppm Sodium Nitrophenolate,98%NIT);T8(100 ppm L-tryptophan;T9(1%Fulvic acid);T10(10~7CFU/ml Bacillus subtilis);T11(10~6 CFU/ml Trichoderma);T12(50 ppm L-Alanine);T13(150 ppm Salicylic acid);T14(1mM Silicon)and T15(0.001ppm 24-epibrassinolide).The main results were as follows:a.All bio-stimulants had a highly significant effect on cucumber growth parameters including plant height,stems diameter,leaf numbers,shoot fresh weight,root fresh weight,leaf area and seedlings vigor index compared with control.b.The seedlings treated with 10 mM(Put),0.02 ppm(MT)and 0.001 ppm(EBR)respectively,had significantly increased cucumber seedlings vigor compared with other plant bio-stimulants and with the control.The increase in cucumber seedlings vigor was 55.9%followed by 55.2%and 53.4%obtained from Put,MT and EBR treatments respectively.2-Influence of Plant Growth Regulators Combinations(PGRsc),on Cucumber Growth under Soilless Culture(Trail 2).In this study,we used the best three plant bio-stimulants from trial 1,seedlings were treated with combinations of three plant growth regulator at three different percent of each regulator(0%,50%and 100%),for all of Putrescin,Meta-topolin and 24-Epibrassinolide.Where,Putrescin levels were 0%=0 mM,50%=5 mM,and 100%=10mM/L;Meta-topolin levels were 0%=0 ppm,50%=0.01ppm and 100%=0.02 ppm/L and 24-Epibrassinolide levels were 0%=0 ppm,50%=0.0005 ppm and 100%=0.001 ppm/L,consequently,27(PGRs)combinations were used.Plant growth regulators combinations PGRsc were mixed with substrate first and then seedlings transplanted in the containers on the same day.The main results were as follows:a.Addition of Plant growth regulators combination(5 mM Put+0.02 ppm MT+0.001 ppm EBR)to cucumber seedlings showed a highly significant effect in all cucumber seedlings growth factors i.e.plant height,stem diameter,leaf numbers,shoot fresh weight,shoot dry weight,root fresh weight,root dry weight,leaf area,seedlings vigor(SVI),total chlorophyll content,net photosynthetic rate(Pn),and root activity compared with control.b.The increase in cucumber seedlings vigor index(SVI)was 75.5%,in(5 mM Put+0.02 ppm MT+0.001 ppm EBR)compared with control.c.(5 mM Put+0.02 ppm MT+0.001 ppm EBR)had a highly significant effect on chlorophyll content value compared with control and other combinations,total chlorophyll content increased to be 54.4%in(5 mM Put+0.02 ppm MT+0.001 ppm EBR)compared with control.d.The net photosynthetic rate(pn),and root activity had a highly significant increase in(5 mM Put+0.02 ppm MT+0.001 ppm EBR)compared with all other treatments.3-Effect of Putrescine(Put),Meta-topolin(MT)and 24-epibrassinolide(EBR)Combination on Antioxidant enzymes activities in Cucumber plant under NaCl stress(Trail 3).In this study we used best combination,from(trail 2)and three treatments were used as follows:T1(control),T2(80 mM NaCl)and T3(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl).The main results were as follows:a.Cucumber growth was inhibited obviously under 80 mM NaCl compared with control,and exogenous application of(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),alleviated the effect caused by NaCl stress.The combination of Put,MT and EBR with 80mM NaCl clearly showed a highly significant increase in all plant growth parameters compared with salt stress.The increase by using(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl)was 51%,44.8%and 34.7%in plant height,stem diameter and leaf numbers respectively compared with control.b.The electro leakage of cucumber plants had significantly decreased under(5 mM Put+ 0.02ppm MT+0.001 ppm EBR+80 mM NaCl),the electro leakage value reduced significantly to be 19.7%compared with salt stress alone.The root activity had significantly increased compared with salt stress after application of(5 mM Put+0.02 ppm MT+0.001ppm EBR+80 mM NaCl).Exogenous of(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80mM NaCl),markedly increased soluble protein content in cucumber leaves compared with(80 mM NaCl).c.Exogenous of(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),markedly increased antioxidant enzymes activities SOD,POD and CAT under salinity stress.The increase in SOD,POD and CAT was 19.6%,13.6%and 34.4%respectively in(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl)compared with salt stress treatment.4-Influence of Putrescine(Put),Meta-topolin(MT)and 24-epibrassinolide(EBR)Combination on yield,Fruit Quality and Nitrogen/Carbon metabolism of Cucumber under Salt Stress(Trail 4).In this study we used best result from(trail 2&3),and three treatments were used as follows:T1(control),T2(80 mM NaCl)and T3(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl).The main results were as follows:a.Application of(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),had a highly significant effect on GS and GOGAT activities compared with NaCl alone.The GS increased to be 44.9%in leaves and 24.8%in roots by using(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),compared with salt stress treatment.The GOGAT increased to be 52.5% in leaves and 45.7%in roots by using(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),compared with salt stress treatment.The application of(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),showed the highest GDH activity,GDH had significantly increased to be 17.1%in leaves and 35.5%in roots by using(5 mM Put+0.02ppm MT+0.001 ppm EBR+80 mM NaCl),compared with salt stress treatment.b.The stress of 80 mM NaCl had significantly decreased plant biomass,fruit yield and quality i.e.AsA,protein and soluble sugar contents compared with unstressed plants.(5 mM Put+ 0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),had significantly increased plant biomass as well as early fruit yield and quality compared with salt stress.c.Application of(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),had a highly significant increas on SPS and SS compared with control.The increase of SPS was 43.05% in leaves and 25.2%in roots by using(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl),compared with control.The increase of SS was 20.3%in leaves and 18.5%in roots by using(5 mM Put+0.02 ppm MT+0.001 ppm EBR+80 mM NaCl)compared with control.d.The results showed that(5 mM Put+0.002 ppm MT+0.001 ppm EBR)treatment alleviated the growth inhibition caused by stress by regulating the carbon-nitrogen metabolism in cucumber plants. |
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