| Fittonia verschaffeltii likes high temperature,wet environment and half shade environment,and especially sensitive to temperature,when the temperature is lower than 12℃ in winter,the leaves will fall off.Under 8℃,there is a risk of freezing death,as a result,in winter,it can only be planted in the warm south or in the greenhouse.It not only increases the production cost,but also limits the planting and production range.In this paper,the experimental materials are Fittonia verschaffeltii ’Flame’,Fittonia verschaffeltii ’Summer lotus’ and Fittonia verschaffeltii ’Violet anne’,under low temperature stress,the changes of morphology,physiological indexes of cold resistance and chlorophyll fluorescence parameters,and the effects of SA and ABA solutions with different concentrations on the cold tolerance were also studied,explore the regulation mechanism of exogenous substances on cold tolerance of reticulograss,and determine the best concentration of exogenous substances,the results are as follows:1.At 25℃ and 20℃,the three varieties of F.verschaffeltiis were all in grade I growth state,the leaf and leaf color were normal,and grow normally.After low temperature stress of 15℃,the three varieties of F.verschaffeltiis all had different degrees of freeze injury,’Flame’ and ’Summer lotus’ were in grade III growth state,some leaves wilted and softened,while ’Violet anne’ was in grade II growth state,a few leaves wilted.After low temperature stress of 10℃,the ’Flame’ was in grade Ⅳgrowth state,most of the leaves are wilted,the color of the leaves is dark,and the old leaves wither and fall off,’Summer lotus’ is in grade III-Ⅳ growth state,’Violet anne’ was in the grade II growth state.After 5 ℃ low temperature stress,both ’Summer lotus’ and ’Flame’ netted grass were in grade V state,the whole plant withered and withered,and ’Violet anne’ netted grass was in grade IV growth state.2.Under low temperature stress,the indexes of relative water content,relative chlorophyll content and relative conductivity of leaves of ’Flame’,’Summer lotus’ and ’Violet anne’ had obvious changes.The relative conductivity was increased with the decrease of stress temperature,while the relative water content and relative chlorophyll content were decreased with the decrease of stress temperature.The values of Fo,Fv/Fm and Fv/Fo of the leaves of the three varieties were increased with the decrease of temperature,while the values of Fm,Fv/Fm and Fv/Fo were decreased with the decrease of temperature.According to the changes of the physiological and biochemical indexes of the three varieties,the lower the temperature,the more damage to the plants.3.Using the method of membership function,the author evaluated 7 cold tolerance indexes of reticulated grass,and got that among the three varieties of F.verschaffeltiis,the cold tolerance of ’Violet anne’ was the strongest,the second was ’Summer lotus’,’Flame’ had the weakest cold tolerance.4.SA solution of 0.5 mmol/L,1.0 mmol/L and 1.5mmol/L,and ABA solution of 10 mg/L,20 mg/L and 30 mg/L were used to treat ’Flame’,’Summer lotus’ and ’Violet anne’ under low temperature stress,their electrolyte leakage rate were reduced,and the damage degree of low temperature to plant cell membrane was reduced,and the relative chlorophyll content and water content were increased,so as to improve its cold resistance.It could also reduce the value of Fo and improve the value of Fv/Fm,alleviate the damage of light inhibition to plants.SA solution of 1.0 mmol/L and ABA solution of 10 mg/L were the best concentration to improve the cold tolerance of F.verschaffeltiis. |
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