野菊与菊花杂交中花粉活力和柱头可授性及胚胎发育研究

Pollen Viability,Pistil Receptivity and Embryogenesis in the Cross between Dendranthema indicum and D.grandiflorum

应用石蜡制片、活体压片、光学显微镜及扫描电子显微镜观察等方法,研究了四倍体河南云台山野菊(Den-dranthema indicum)与栽培菊花‘钟山金山’(D.grandiflorum‘Zhongshanjinshan’)种间杂交中父本花粉活力、花粉在柱头萌发、花粉管生长及胚胎发育情况等。结果发现,父本云台山野菊的花粉活力在授粉时为12%左右。人工授粉后的不同时间,在柱头上都观察到正常萌发的花粉粒,且花粉管都能进入柱头,其中,在授粉后0.5 h时,平均每柱头有5.9粒花粉萌发;12 h时,为59.9粒;而24和48 h时,则分别降为47.1和35.7粒。此外,在授粉后8、10、12和15 d时,分别在49.1%、40.8%、39.7%和38.5%子房内观察到正常发育的胚胎,最终杂交结实率为44.8%,而母本自然开放结实率为52.3%。研究表明,授粉前其多数母本雌蕊发育良好、授粉后多数花粉能在柱头正常萌发和花粉管正常生长,在受精后大部分胚胎发育正常是野菊与栽培菊种间杂交较高结实率的重要保证,而授粉前父本较低的花粉活力对杂交结实率影响不大。

Pollen viability of male parent, pollen germination and pollen tube growth on the stigmas, and embryogenesis were investigated in the cross between Dendranthema indicum and D. grandiflorurn using technique of paraffin section, temporary mount method, light microscopy, and scanning electron microscopy as well. It was found that pollen viability was approximately 12% just before pollination,and many pollen grains germinated and pollen tubes penetrated stigmas normally during different time after pollinatior~ There was ar） average of 5.9 germinated pollen grains on each stigma at 0.5 h after pollination and the number reached the highest value,59.9 at 12 h after pollination. Then the number was decreased to 47.1 and 35. 7 at 24 and 48 h after pollination, respectively. In addition, normal embryos were observed in 49.1% ,40.8%,39.7% and 38. 5% ovaries at 8,10,12 and 15 d after pollination, respectively. Furthermore,seed set in the cross was 44.8% and the number of the female parent under open pollination conditions was 52.3%. Taken together,these results suggest that a high percentage of normal pistils in the female parent before pollination, normal germination of many pollen grains and normal growth of most pollen tubes after pollination, and normal development of most embryos after fertilization collectively resulted in a relatively high seed set in the interspecific cross,whereas the relatively low pollen viability of male parent had no negative impacts on seed set.