图1水稻花粉粒在培养基上的萌发(T:30C) Fig.1.Germination of pollen cultivated in culture medium A-0min时的花粉粒：B-2nin时花粉已开始萌发：C-4min时花粉管长至花粉粒直径大小：D-6 min时花粉管长至花粉粒直径的2倍以上：E-8min时的花粉管项端已黪大：F-10min时的花粉管顶 端破裂 A.Pollen of 0 min after placed in culture medium:B.Pollen has germinated after 2 min:C.The length of pollen tube has up to the diameter of pollen after 4 min:D.The length of pollen tube has exceeded twice of the diameter of pollen after 6 min:E.The apex of the pollen tube expanded after 8 min: F.The apex of the pollen tube has broken after 10 min. 23 Biology of plant reproduction 23