The Effects Of Several Chemicals On Leaf Color Changes Of Zelkova Schneideriana

Zelkova schneideriana is tall deciduous tree,one member of Zelkova Ulmaceae with beautiful shape and abundant seasonal leaf colors,which recognized as an excellent ornamental tree.According to it’s leaves color in autumn,three types can be divided:red,yellow,and green.The experiment was aimed at investigating the effects on Z.schneideriana of three types of red,yellow and green with the treatments of spraying different concentrations of salicylic acid,citric acid,sucrose and GA3,to find effective ways to make it’s autumn-leaves more bright and explore the method of artificial regulation in color.Four kinds of non-toxic or low toxicity chemical substances of salicylic acid,citric acid,sucrose and GA3 were selected to the study to explore the discoloration effect on the Z.schneideriana three types of red,yellow and green at spraying different concentrations,through analyzing the color parameter of leaves and the change characteristics of pigment contents of anthocyanin,chlorophyll,carotenoid,seeking the best concentration of the chemical in effectively ameliorating the autumn-leaves color or the color phase.The results showed that,(1)At the period of leaves turn into autumn color,the hue value a*was the highest in the red,reached the maximum in October 25th,showing the best ornamental effect,and comparatively low in the green,the trend is relatively flat.At the later period,the hue value b*in the yellow was significantly greater than the red and green,but it’s color in autumn period have returned to green.The tendency of other value lightness L*,chroma C*as well as hue b*were almost identical.The three kinds of Z.schneideriana all contained Anthocyanin,chlorophyll and carotenoid,but had different content of these pigments.The red,was the highest anthocyanin content,reached 22.1%-44.6%.The green,was the highest total Chlorophyll content,up to 73.0%-80.5%.The yellow,carotenoid content was the highest for 24.7%-35.4%.(2)Regression analysis showed that:the anthocyanin and chlorophyll content are closely related in Z.schneideriana leaves.The anthocyanin content was positive correlation with value a*and negative correlation with L*b*C*,indicating that the increase of the anthocyanin content,the increased red,and decreased lightness,yellowness and chroma.Chlorophyll content and L*a*b*C*were negatively correlated,indicating that the increase of chlorophyll content,the decreased of redness,yellowness,lightness and chroma.Carotenoid content is not into the equation,there is no significant correlation between that carotenoid content and leaf color parameters(P>0.05).The analysis showed that the anthocyanin content increased,chlorophyll content decreased,the leaves turn red,and the anthocyanin content decreased,chlorophyll content increased,leaf will remain green,if the anthocyanin and chlorophyll decreased at the same time,it will make the yellow leaves.The content and percentage of chlorophyll,carotenoid,anthocyanin is the material base and root cause for Z schneideriana has red,yellow,green three different colors(3)Spraying 0.5mmol·L-1 salicylic acid in the red could promote the anthocyanin synthesis,accelerate the degradation of chlorophyll,and deepen the red.Spraying 0.5mmol·L-1 salicylic acid made the yellow extended it’s green period and the color phase delay.Spraying 1.0mmol·L-1 salicylic acid can make the yellow,green leaves turned yellow,the color changing period in advance.(4)Spraying 9.6mmol·L-1 citric acid in the red could accelerate the decomposition of total chlorophyll,significantly promote the anthocyanin synthesis,deepen the red and ahead of schedule.Different concentrations of citric acid treatment could prolong the green period of the yellow Z.schneideriana,maintain green and delay the time.There wasn’t significant effect of citric acid on the green Z.schneideriana.(5)Spraying 600.Ommol L"1 sucrose in the red could accelerate the decomposition of chlorophyll,deepen the red and ahead of schedule.The different concentration of sucrose could prolong the green period of the yellow,to maintain leaf green,and keep the color phase delay.Application of 200.0mmol·L-1 in the green could accelerate the degradation of chlorophyll and carotenoid,make the leaves turn into yellow and advance into the color phase.(6)Spraying O.OOlmmol·L-1 GA3 could slow down the red and yellow Z.schneideriana leaves turn their colors,delay the defoliation period.Spraying 0.01,0.001mmol·L-1 GA3 could turn the red and yellow leaves into yellow,make the color phase in advance.