The Physiological And Biochemical Changes Of Tea Fluorescent Green Spot Disease

Tea fluorescent green spot disease was a physiological disease that happened widely in all over the country. The tea plants suffering from this disease were in poor growth. There were many green spots on the lower epidermis of the diseased leaves. It was very strange that these diseased spots can keep green color for a long time, because tea fresh leaves usually turned red or yellow when they were diseased. In order to investigate the causes why the diseased tea trees grew poor and how the spots kept green, the experiment was carried out as follows: Fu Ding Da Bai tea trees were cultivated by different excessive calcium concentrations [CK(30mg/L), T1(75mg/L), T2(150mg/L), T3(300mg/L)] in the solution culture. After three months, when tea trees came to be tea fluorescent green spot disease, the physiological and biochemical changes of diseased tea trees were studied.The main results were as follows:1. The net photosynthetic rate was reduced with the increase of calcium concen- tration. The maximum of T1,T2,T3 was less 13.62%,25.14%,56.11% than CK. The diurnal changes of stomatal conductance were different, we can know that CK and T1 were double apices, but T2 and T3 were not. The maximum of stomatal conductance of T1,T2,T3 was lower 12.93%,28.90%,67.87% than CK. At the same time, the growth of tea plants treated by excessive calcium was not good as CK. The burl interval, the length of treetop and the leaf area were lower than control (CK). The index of leaf shape was increased and the leaves became longer and narrower.2. The Fo of diseased leaves was increased obviously by the excessive calcium. At the initial stages of disease, the Fv/Fm was little reduced, but it was reduced rapidly subsequently. The ETR andΦPSⅡof the tea leaves by the excessive calcium treatments were remarkably lower than CK. Meanwhile, the lower were ETR andΦPSⅡ, the longer was the intimidation. The ETR was decreased sharply earlier but reduced slowly later. The ETR of T1,T2,T3 were 60.07%,24.64%,19.46% as CK.3. It was discovered that the plasma membrane, chloroplast membrane, mito- chondrion membrane, endoplasmic reticulum membrane and vacuole membrane were damaged in different degrees. The chloroplast granum-thylakoid became round. The stroma-thylakoid became incompact and the thylakoid membrane was destroyed variously.4. The activity of SOD,POD was increased earlier but reduced afterward. The maximum of SOD activity presented to 14-Jul, that of T1,T2,T3 was higher 514.6%,532.8%,488.4% than CK. The CAT activity came to the maximum on 14-Jun, and then reduced. Till 14-Oct the CAT activity of the disease leaves was lower than CK.5. The electrolytic leakage in the diseased tea leaves was higher than CK, and it increased with the increase of calcium concentration. The electrolytic leakage of CK,T1,T2,T3 were 26.62%,36.71%,51.47%,60.14% on 14-Oct. We can known that the contents of MDA obviously increased, till 14-Oct that of T1,T2,T3 increased by 153%, 258%, 302%. Based on a comprehensive analysis, the membrane of the diseased leaves were destroyed, the electrolytic leakage and the content of MDA were increased.6. The soluble sugar contents, the soluble protein contents and the free proline contents in the diseased tea leaves increased rapidly. At the initial stages of disease, the diversity was unconspicuous, but the diversity was marked later.7. The activity of Chlase in the diseased leaves was decreased, but the activity of MDCase was increased. The activity of Chlase of T1,T2,T3 was 53.9%,22.2%,,17.1% as CK. The result provided the reasonable explaination for the spots keeping green for a long time.