The Research On The Effect Of Light And Temperature On Hydrocotyle Vulgaris L. And Its Applications In Landscape

Hydrocotyle vulgaris L.commonly known as copper grass.as one of the most popular plants, with the beautiful plant type, green leaf, unique natural style, has great potential for application landscape. To further investigate the Hydrocotyle vulgaris L. in landscape mode applications, we studied the photosynthetic characteristics of Hydrocotyle vulgaris L. at different temperatures and different light stress treatments through experiment.We choose the growing onsistent Hydrocotyle vulgaris L. as experimental material, by measuring the chlorophyll content, chlorophyll fluorescence parameters, the light curve, leaf water content and morphological characteristics change under different temperature and light stress treatment, we analyzed the effects of photosynthetic physiology and growth of Hydrocotyle vulgaris L. under different stress to provide a theoretical basis for the landscape application of Hydrocotyle vulgaris L. Experimental results show that:(1) After4days of high temperature stress, the high temperature of45degrees severely inhibited the growth of the Hydrocotyle vulgaris L. The leaf water content dropped, chlorophyll content increased (excessive water loss caused by the blades), parameter values of Fv/Fm, qP, ETR decreased significantly, the plants showing leaf yellowing, curling petioles droop characteristics; After6days of high temperature stress,the plants in high temperature stress of45℃are all died, in40℃,the leaves turn yellow, Fv/Fm, qP, ETR decreased,light curves changes with no rules; After10days of high temperature stress, high temperature of40"Chave a certain impact on the growth of Hydrocotyle vulgaris L. the specific performance were most leaves turning yellow,the number of the leaves were reduced, Fv/Fm, qP, ETR decreased, net photosynthetic rate were decreased too.(2) The different leval of cold stress had different effects on growth parameters and fluorescence parameters of Hydrocotyle vulgaris L..After low temperature treament for2days, under low temperature stress of-2℃, the plants’ petiolehad a sagging tendency, leaf water content and chlorophyll content changed little, this is due to the plant by freezing, the maximum net photosynthetic rate of only1.551μmol-2s-2; After low temperature treament for4days, under low temperature stress of-2℃, the plant leaves wilted, petiole droopped, qP, ETR decreased,net photosynthetic rate decreased too, the low temperature severely inhibited the grows of Hydrocotyle vulgaris L.; under low temperature stress of0℃,the plants grew normally, petiole had low minority droopped, Fv/Fm, qP, ETR and other values were low; cold stress for8days, under low temperature stress of0℃, plant petiole were all sagging, but there wre still signs of life, Fv/Fm, qP, ETR dropped,10℃(mild degree temperature stress group) and5℃(moderate chilling stress group) were in normal growth,However, leaf water content, chlorophyll content, Fv/Fm, qP, ETR and other parameters decreased, the decrease rule is that the lower the temperature, the greater the decline in value.(3) Hydrocotyle vulgaris L. grow well under strong light stress environment, the measurement results of different treatment period showed a small effect on the external morphology of Hydrocotyle vulgaris L, with increasing light intensity, the chlorophyll content decreased, qP declined, the net photosynthetic rate decreased, but the decline is not, indicated that a long light stress has little effect on plant growth, but will reduce the plant’s energy use efficiency.(4) Low light stress (light intensity is below600μmol-2s-2) would inhibit the growth of Hydrocotyle vulgaris L., showed the maximum net photosynthetic rate were lower, Low light stress for10days, group of60μmol-2s-2weak light stress and group of2μmol-2s-2indoor lighting had a significantly decline on LSP, LCP value, indicated that lack of light cause the light use efficiency fall, plants showed smaller leaves, longer stems; under the conditions of weak light stress (light intensity greater than60μmol-2s-2, less than600μmol-2s-2),the leaf water content of Hydrocotyle vulgaris L. and chlorophyll content increased;Fv/Fm, qP, Fv7Fm’ rose;Fo, ETR declined.(5) Therefore, we came to a conclusion that:15℃-35℃is the optimum temperature suitable for Hydrocotyle vulgaris L. growth, when the temperature is higher than35℃, Hydrocotyle vulgaris L. grow poorly, leaves turn yellow, wither, affect the viewing of plants; When temperatures below5℃,Hydrocotyle vulgaris L. grow equally poorly, leaves turn yellow; when the temperature is below0℃, Hydrocotyle vulgaris L. leaves wilt, stems droops, With the growth of time, but also lead to plant death.300-800μmol-2s-2is the best light intensity for Hydrocotyle vulgaris L. growth, when the light intensity is greater than800μmol-2s-2,it will inhibit the light energy utilization efficiency; when the light intensity is below300μmol-2s-2,the plant leaves become smaller, stems become longer, affect the landscape effects of the plant. Therefore, when the Hydrocotyle vulgaris L. were placed in the room,we can take some artificial light measures. Finally, according to the analysis of experimental results,we discuss the main application form of Hydrocotyle vulgaris L in landscape,there are wetland landscaping, lawn green, ecological floating island and indoor garden green, etc.