Annual Changes In Pigment Content And Anatomical Structure Of Forsythia Koreana 'Sun Gold' Leaves

In the Qinhuangdao region,the leaves of the golden leaf of Forsythia koreana ‘Sun Gold' are generally yellow,but there is a phenomenon of “greening” in the local rainy season and autumn of July and August.In order to clarify the mechanism of leaf color change of Forsythia koreana ‘Sun Gold',in this study,Forsythia koreana ‘Sun Gold' as the research material,Forsythia koreana is the control.During the period of leaf growth,we developed a technology of phenological observation and color chromometer,studied the expression regularity of leaf color;We developed a technology of ultraviolet spectrophotometer measurement,studied the change regularity of the three major pigment content in leaves;We developed a technology of paraffin section and electronic microscopy,studied the leaf anatomical structure's characteristic during the expression of leaf color;We have obtained following conclusion:(1)With the change of seasons,the leaf color shows a yellow-green-yellow-green trend.The leaves are in their initial growth period and are golden yellow.In the rainy season,the leaf color returns to green and the ornamental effect is reduced.After the rainy season,the leaves are golden,and the leaves turn green again after autumn.Mid-May and early September are the best viewing periods for Forsythia koreana ‘Sun Gold'.(2)The changes in the color parameters L*,a* of the golden leaf of Forsythia koreana ‘Sun Gold' can best reflect the annual variation of leaf color.L*,a* values were significantly negatively correlated with chlorophyll a,total chlorophyll,and anthocyanin content.The key role in the leaf color of the Forsythia koreana‘Sun Gold' is a*,which is bigger and the ornamental effect is good;The correlation between chlorophyll a content and a*(-0.9)reached significant level,indicating that chlorophyll a had the greatest influence on the change of leaf color.The relationship between the pigment content and the leaf color parameters was different with the two varieties of Forsythia,The L* and b* values of Forsythia koreana were significant negatively correlated with the content of chlorophyll a,chlorophyll b,total chlorophyll and anthocyanin;In addition,the values of Forsythia koreana's L* and b* had a significant positive correlation with the ratio of carotenoid / total chlorophyll,but the change range of leaves color of Forsythia koreana was only in the green.(3)The analysis results show that the mutant Forsythia koreana ‘Sun Gold' is one of the total chlorophyll and chlorophyll b deficiency type.The ratio of carotenoid / total chlorophyll increased,and the gate / sea was smaller.The main reason for the yellow leaves was the stage of chloroplast development at the plastid stage.(4)The leaves of Forsythia koreana‘Sun Gold' is a shade plant,grow slowly and the leaf area is small under full light;The chlorophyll content is low,after the fall of the three pigment content remained stable;The stoma of the lower epidermis are small,and dense and the palisade tissue cells are closely arranged,showing strong resistance.