光强对野菊生理生化特性的影响

通过分析光强对野菊生长及生理生化特性的影响,揭示适于野菊生长的光照强度,为野菊种植提供参考依据。分别在100%,80%,60%,40%,20%全自然光强水平下种植野菊,生长旺盛期测定野菊相关生长,光合色素含量、光合参数、荧光参数等光合生理及保护酶系统指标,采取透射电镜技术观察叶绿体超微结构。结果表明:野菊叶片在80%以上全自然光强下出现不同程度发黄现象,株高和茎粗在60%全自然光强达到最大值,60%以上全自然光强下野菊分枝数显著增加;光合色素含量和净光合速率均与光强负相关,光合参数与叶绿素荧光参数则随光强下降呈先上升后下降趋势,60%全自然光强下野菊气孔导度、胞间CO2浓度、蒸腾速率、水分利用效率及PSⅡ实际光化学量子产量等生理指标均处于最高水平;60%~80%全自然光强下野菊叶绿体结构无明显异常,全自然光强下基质片层破碎,20%~40%全自然光强下叶绿体数量、淀粉粒数量与体积均明显降低;随光强下降,SOD与CAT活性呈下降趋势,POD活性呈先上升后下降趋势,MDA含量呈上升趋势。综上,野菊在20%~100%全自然光强下均能生长,但在60%全自然光强下生长最佳。

Effects of light intensity on physio-biochemical characteristics of Chrysanthemum indicum

By analyzing the effects of light intensity on the growth, physiological and biochemical characteristics of Chrysanthemum indicum, the light intensity suitable for the growth of Ch. indicum was revealed, which provided a reference for the planting of Ch. indicum. There were five treatment groups of Ch. indicum, which was planted under 100%, 80%, 60%, 40% and 20% all natural light intensity conditions, respectively. In the meantime, these indicators of photosynthetic physiology, such as relative growth, photosynthetic pigment content, photosynthetic parameters, and chlorophyll fluorescence parameters etc. were measured in the peak period of growth of Ch. indicum as well as related indicators of the protective enzyme system, and the ultrastructure of chloroplast was observed with the use of transmission electron microscope technique. In our study, the results showed that the leaves of Ch. indicum occurred yellow phenomenon in different degrees when Ch. indicum was placed at more than 80% of the total natural light intensity condition, the height and stem diameter of plant reached the maximum at 60% of the total natural light intensity. More importantly, the number of branches of Ch. indicum was significantly increased under the total natural light intensity of more than 60%. Both the content of photosynthetic pigment and net photosynthetic rate were negatively correlated with light intensity, while photosynthetic parameters and chlorophyll fluorescence parameters showed a trend of rising first and then decreasing with the decrease of light intensity. The physiological indexes of Ch.indicum including stomatal conductivity, intracellular CO2 concentration, transpiration rate, water use efficiency and actual photochemical quantum yield of PS Ⅱ had been determined, and the results showed that all of them were at the highest level under 60% total natural light intensity condition. The chloroplast structure of Ch. indicum was not obviously abnormal under 60% and 80% total natural light intensity treatments, but the stroma lamella was broken under 100% total natural light intensity, and not only the number of chloroplast, but also the number and volume of starch grains were decreased significantly under 20% and 40% total natural light intensity. With the decrease of light intensity, the enzymes activities of SOD and CAT decreased, the activity of POD increased in the early stage and decreased in the later stage, and the content of MDA showed a decreasing trend. The analysis of results indicated that the Ch. indicum can grow under 20%-100% total natural light intensity, but the best growth condition was under 60% total natural light intensity.