Studies On Leaf Color Improvements Of Cotinus Coggygria Var.Cinerea Engl.

Cotinus coggygria var.cinerea Engl.is a deciduous shrub or small tree of Anacardiaceae in genus cotinus,which is the main color leaf plant in Beijing Fragrant Hills.The local name for this plant is "Xi Shan Hong Ye",which is well known by the vivid red leaves color in the fall.The C.coggygria var.cinerea from Fragrant Hills in Beijing were taken as the materials.The leaf colors were measured by the spectrophotometric colorimeter and the CIE L*a*b*values(International Commission on Illumination).The UV spectrophotometry was used to measure the contents of anthocyanins and chlorophyll in the leaves.The degrees of discoloration were assessed by the CIE L*a*b*values and the contents of anthocyanins and total chlorophyll(TCH).Using different manure,spraying chemicals,watering with various periods,and stem girdling were applied to improving the leaf color.The main results are presented as follows:1.The trials which used the ’Jin Tu Di’ phosphate fertilizer(JTDN)and the ’Lian Hua’ amino acid fertilizer added with potassium(LH+K)could accelerate the decomposition of chlorophyll and the synthesis of anthocyanins,so that accelerated the leaves coloration significantly.The trials with nitrogen could hinder the leaves coloration,meanwhile the content of TCH keep high level and the relative amount of anthocyanins was decreased.The effects were different in 3-years-old plants and 5-years-old plants when treated with the same fertilizer.The promoting effect of leaves coloration was more significant in 3-years-old plants when treated with phosphate-and potassium-fertilizer.In the trials with JTDN,the hinder effect of leaves coloration was more significant in 5-years-old plants.2.The leaf color changes of 4-year-old C.coggygria var.cinerea Engl,trees with consistent growth vigor were studied by treating them with different concentrations of gibberellins(GA3),salicylic acid,citric acid,and sucrose.The results showed that the application of 1.0×10-2 mmol · L-1 GA3 could put off the leaf-absent period and extend the ornamental period for average of five days compared with the control.The ornamental period was delayed for average of one week by treating the trees with 0.5 mmol · L-1 salicylic acid while the treatment of 1.0 mmol · L-1 salicylic acid advanced the ornamental period by three days.Both the application of 4.8 mmol · L-1 citric acid and 200.0 mmol · L-1 sucrose significantly made the ornamental period in advance by six days and nine days,respectively.Meanwhile they increased the relative content of anthocyanins in leaves and deepened the red color of leaves.3.During the period of leaves coloration,different watering periods and watering sites were applied to C.coggygria var.cinerea.The results showed that watering before the leaves coloration for ten days(September 10-19)and at the end of leaves coloration for ten days(October 20-29)on leaves and roots could decrease the content of TCH in leaves and make the leaves turn red in advance.Watering for consecutive twenty days respectively before the coloration(September 10-29),in the early period of coloration(September 20-October 9)and in the mid period of coloration(September 30-October 19)could also make the content of TCH decreased and advance the ornamental period.Those trials which watered on leaves for 30,40,and 50 days could not help the leaves turn red.In the trials on different watering sites for more than ten days,watering on the root zone could increased the relative content of anthocyanins in leaves more significantly than spraying on leaves and the degree of red color was darker.4.In the girdling trials,comparing with the contrast,stem girdling made the leaves color turn red earlier and the anthocyanin content higher.Meanwhile the content of TCH was significantly lower than contrast and the red color was darker.