杨树2n花粉形态判别方法的比较

Discrimination Methods in 2n Pollen in Populus

采用醋酸洋红染色法,在研究胡杨和毛白杨不同无性系间花粉粒形态差异的基础上,研究不同形态判别标准条件下2n花粉发生频率调查的准确性。研究结果表明,胡杨花粉粒的平均直径为29.7μm,比毛白杨花粉粒的平均直径32.4μm略小。胡杨或毛白杨无性系对花粉粒直径影响显著。通过调查四分体时期四分体、三分体以及二分体的比例,可估算2n花粉的理论频率。胡杨和毛白杨各无性系2n花粉的理论频率与以2n花粉粒直径大于花粉粒平均直径的1.28倍为标准时统计的2n花粉实际频率差异不显著,而与以2n花粉粒直径大于37.0μm为标准时统计的2n花粉实际频率差异极显著。这说明以37.0μm作为判别胡杨或毛白杨2n花粉形态判别标准会导致较大的误差。而以各无性系花粉粒平均直径的1.28倍作为2n花粉形态判别标准更加科学合理。

Based on the differences of pollen grain shape among clones in Populus euphratica and Populus tomentosa,we studied the accuracy of estimate in percentage of 2n pollen determined under different standards. The average diameter was 32. 4 μm for P. tomentosa,which was slightly larger than that of P. euphratica（ 29. 7 μm）. Clonal effect was significant for diameter of pollen grains. The theoretical percentage of 2n pollen could be estimated based on the rates of tetrad,triad and dyad at tetrad stage. However,the actual percentages of 2n pollen could be achieved according to diameter from two standards of 2n pollen beyond 37. 0 μm and diameter of 2n pollen as 1. 28 times as that of normal pollen in P. euphratica and P. tomentosa,respectively. By χ2test,the estimate of the theoretical percentage of 2n pollen agreed with the actual percentages of 2n pollen that was estimated by the first standard. However,there was significant difference between the estimate of the theoretical percentage of 2n pollen and the actual percentages of 2n pollen that was estimated by the second standard. Therefore,the first standard for discrimination of 2n pollen（ 37. 0 μm） would result in great estimate error. It is more reasonable for taking the another standard in determining the percentage of 2n pollen.