The effects of plant growth regulating substances on pollen germination and tube gowth in Fengshui pear (Pyrus serotina)

The results of studying the effects of several plant growth regulating substances on pollen germination and tube growth in pear (Pyrus serotina Rhed.) by cultivating pollens in liquid media showed that GA3,TRIA,IAA and 2,4D stimulated pollen germination and tube growth when pollen was cultivated in their lower concentration media.When they were in higher concentrations,they would inhibit pollen germination and tube growth.The most suitable concentrations that stimulated pollen germination and tube growth were 50~300 mg/L,3~100 mg/L,5~25 mg/L and 5~10 mg/L,respectively,for these four kinds of plant growth regulating substances.NAA inhibited pollen germination and tube growth.The inhibitory effect became stronger with its increasing concentration.PP333 and ABA had some inhibitory effect on pollen germination.Although they had some stimulating effect on pollen tube growth when they were in their lower concentrations,in higher concentrations they still inhibited pollen germination.The inhibitory effect also became stronger with the increasing concentration.The best concentrations for pollen germination were 400 mg/L and 60 mg/L for PP333 and ABA respectively.When they were above these concentrations,the stimulating effect also got worse;they even inhibit pollen tube growth.For instance,when PP333 was at 1 000 mg/L,it greatly inhibited pollen tube growth.