INFLUENCE OF ENVIRONMENTAL CONDITIONS ON THE POLLEN VITALITIES OF POPLARS

This paper deals with the influence of environmental conditions on the pollen vitalities of 8 clones of P. deltoides, P. nigra and P. trichocarpa during the period of collection and storage. There are significant variations among different species in the moisture content and germination rate of the pollens. During the time when they are in water culture of floral shoots in greenhouse, the high temperature (more than 40℃), which occurs 12 hours before the collection resulted in the decrease in the vitality of pollens. The germination rate was higher when the pollen was collected 1 or 2 days after the split open of the anther than that collected 3 or 4 days later. Low temperature and dryness are necessary for the storage of pollen. The speed of unfreezing and time of absorbing water could influence the vitality of pollens which had been stored under low temperature. It's beneficial for the pollen to have an absorption of water for 2 hours under 4℃ to recover its vitality. The germination rate of P. deltoides would reduce by 40% after 45 days storage under -18℃, while that of P. nigra and P. trichocarpa raised under the same condition. The germination rate of P. trichocarpa was not influenced by 50 days storage under -80℃.