Abstract:

The experimental results of fertilization at eight seed orchards in four provinces from 1983-1992 show that the best result is from the poor soil. The sorts of fertilizer and its prescription should be made up according to the local soil. The soil with a medium fertility or above, should be fertilized mainly with P, K fertilizer, but one with poor fertilizer should be added more N fertilizer. The best time for fertilization is between June to July so as to coordinate with the seed development rhythm and its flower bud differentiation, and another time is Autumn or Spring (April). Therefore it is better to fertilize two times for one growth season. The differences in the amount of fertilizer is based on the ages and sizes of trees. Generally, during the middle period of producing fruit it is 40-70gN, 100-250gP₂O₅, 50-150g K₂O once for one tree. It is also suggested that the chemical fertilizer should combine with the organic fortilizer. The seed production will be increased by 30-100% by using the best prescription of fertilization, and the seed setting rate, weight per 100 kernels, and germination percent also be enhanced.It is found that there are some differences in response to fertilization among different clones. A suitable fertilization can increase the chlorophyll content in needles, the number of female flower bud, and promote vegetative growth slightly.

Key words: Seed orchard of Chinese fir, Fertilization prescription, Time of fetilizing, Effect of fertilization