Early Resistance Screening of China fir to Leaf Blight

• Main Authors: Haung, Miao-Lin, 黃妙霖
• Other Authors: Israel Bau-Jen Jiang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/34708809435645074729

碩士 === 國立中興大學 === 森林學系 === 85 === China fir (Cunninghamia lanceolata) has long been damaged by Leaf Blight of China Fir, a common disease which attacks the species from seedlings in nursery to saplings in the plantation. Plantations at ages 7~8 are particularly suscep- table. The causal agent of disease was isolated and identified as Pestalotia shiraiana P. Hennings. Current study involves seedlings of open-pollinated single-tree families from a local seed orchard in Taiwan. Seedlings were grown in both growth chamb- ers and greenhouse. Before artificial inoculation of the fungus, young seedlings (less than one year)were regularly measured for plant heights. Three weeks after inoculation, these seedlings were investigated for their disease-resistance and growth traits. For growth traits: in the growth-chamber experiment, five families were involved for the study. Analysis of variance results showed that plants in dif- ferent chambers behaved differently in their growth, which suggested a G×E interaction effect. In the greenhouse experiment, where 13 families were used, heritability estimates were high, which implies large between-families varia- tion. Thus early selection was possible. For disease-resistance traits: susceptibility degrees were calcu-lated in both experiments. Results showed that there was a significant between-families variation. However, two symptom traits (healthy/sick, whether the number of infected leaves are more than 10 leaves)showed inconsistent results between the two experiments. Linear logistic model for the growth-chamber experiment did not show significant result. However, the same statistical model applied in the data analyses of greenhouse experiment clearly demonstrated that there were signifi- cant difference in resistance among 15 families. In growth-chamber experiment, we have also measured green- and oven-dried weights of above- and below-ground parts of the plants. It was found that the T/R ratio showed significant difference among seedlings of different classes of susceptibility classes. The larger the T/R ratio, the plants showed more serious signs of damage. In the greenhouse experiment, plant height just prior to inoc- ulation showed positive correlation with individual*s susceptibility degree. These results are valuable information and worthy for further investigation. In general, results demonstrated that early testing of genetic entries of Cunninghamia lanceolata for disease-resistance to Pestalotia shiraiana P. Hennings was possible.