Abstract: Camellia oleifera is an endemic woody oily tree species in China. It is one of economic forest tree species with the largest cultivation area and widest distribution. In May 2011, leaves of 12-year-old C. oleifera were trimmed with different area to simulate leaf loss caused by disease and insect pests, when the height of the trees was 1.5-2.1 m, and the stand density was 1 500 trees per hm². The effect of partial leaf area reduction on the yield and quality of C. oleifera was evaluated. Results showed that the leaf trimming had impact on fruit abscission ratio, average fruit weight, fresh kernel ratio, kernel yield ratio and oil yield ratio of dry kernel. The fruit abscission ratio were 61.2%, 83.8% and 84.1% respectively, when the leaf trimming were 25%, 50% and 75%, which was 1.54, 2.11, and 2.12 times higher than the control. There was no significant difference in fruit abscission ratio between 12.5% leaf trimming and the control. When the leaf trimming was over 25%, fresh kernel ratio was less than 41%, kernel yield ratio less than 14% and oil yield ratio less than 37%, in compared with the control (44.6%, 14.7% and 42.2%, respectively). All the parameters had a decline trend with the trimming. But the shriveled kernel ratio showed a contrary trend, which was increased with increasing the trimmed leaf area. The leaf trimming also had effect on the contents of palmitic acid and oleic acid of the tea oil. Leaf trimming by 75% significantly increased the content of palmitic acid (saturated fatty acid) and decreased the content of oleic acid (unsaturated fatty acid). When the leaf area was trimmed by 50% and 75%, the vigor of C. oleifera trees weakened, sprout was abnormal, new leaves became less, and the average number of fruits was only 2.2 and 0 per tree, respectively which was significantly lower than other treatments. When the leaf area was trimmed by 12.5%, C. oleifera trees had normal growth in the next year and the number of fruits had no difference with the control. The results showed that when defoliation was over 25%, the yield and vigor of the trees in the second year would be affected, and when defoliation above 12.5%, the quality of tea oil would be affected.

Key words: Camellia oleifera, leaf-cutting, fruit abscission ratio, oil yield ratio, fatty acid composition, disease and insect pest