Evaluation Of Seedling Growth And Drought Tolerance In Castanopsis Hystrix

Castanopsis hystrix is a precious, broadleaved tree species native to southern China, which plays an important role in the production of wood products, environmental restoration and greening of towns and cities. With seeds and seedlings of 10 families from Wuping of Fujian Province, seed traits as well as phonological phases, drought stress-based anti-drought traits and 3-year stand performance-based growth traits of seedlings were studies in this species with a view to exploring their adaptability to Zhejiang, resistance to drought and necessity of family-based selection. The results would theoretically lay a foundation for selection and extension of good families, including in greening of towns and cities. The main results are as follows:1. In terms of seed traits in C. hystrix, the average weight of 100 seeds, seed viability, and germination percentage were 270.64 g, 93.56%, and 85.61%, respectively, and differences among families in the weight of 100 seeds and germination percentage were most significant. A ratio of seedlings to seeds was 76.07% on the average for the 10 families but Families 7 and 10 were higher than 90% in the ratio. Differences among these 10 families were most significant in seedling height, ground diameter and the number of branches within three years, which indicated that the great difference in growth existed under natural conditions. Therefore, selection at the family level is necessary.2. One-year-old seedling-based observation of phonological phases showed that there was no significant difference among these 10 families.3. Seedling planting showed that the survival rates of all the 10 families were as high as 100%, and the average conservation rate in the third year was 89.33% with a good growth, which also indicated that C. hystrix may adapt well to the environment of Zhejiang Qiandao Lake area.4. With parameters that reflect good seed and seedling growth traits and a good adaptability to planting sites as an evaluation basis, a scoring method was adopted to screen good families. As results, Family 10 was preliminarily selected as an excellent family for timber forest and Family 6 for ecological public-welfare forest.5. Based on measurement of physiological and biochemical parameters, C. hystrix seedlings from Wuping of Fujian could grow normally under a light drought stress with a soil moisture content ranging from 50% to 75%, but would have heavy antagonistic effects in the soil with a moisture content of 30% and could not grow normally in the soil with a moisture content of 15%. Furthermore, there were significant differences among different families in some of the physiological and biochemical parameters, which indicated that these families might differ from one another in the resistance to drought and have the potential for further selection and breeding. In terms of photosynthetic parameters, these C. hystrix seedlings could maintain the normal, physiological functions of their photosynthetic organs on the whole in the soil with a moisture content of 30%~75%. Furthermore, they could adapt the unfavourable drought environment by promoting root growth to adjust their water use efficiency.Generally, C. hystrix from Wuping of Fujian has a certain ability to resist drought and can be used in plain afforestation. Furthermore, Family 3, 8, and 9 were among good families out of tested families in resistance to drought.