Objective  To study the relationship between pollen germination and growth of autotetraploid Benincasa hispida (Thunb.) Cogn. and endogenous hormones, and explore new ideas for understanding the low fertility mechanism of autotetraploid B. hispida.

Method  Taking autotetraploid and diploid B. hispida as materials, germination and growth of self-pollinated pollen in pistil and the contents of endogenous hormones in pollens and pistils were studied.

Result  The germination rate of self-pollinated pollen of autotetraploid B. hispida was low on the stigma. Pollen tube growth was slow. There were some abnormal phenomenons during growth of pollen tubes, such as uneven thickness, nodule formation, swelling at the tip, two pollen tubes in one pollen, distorted and folded pollen tubes. Compared with diploid B. hispida, the pistils and pollens of autotetraploid B. hispida had significantly lower zeatin riboside (ZR) and isopentenyl adenosine (IPA) contents (P<0.01), significantly lower gibberellin A₃ (GA₃) content (P<0.05) in pistils, silightly lower gibberellin A₃ (GA₃) content (P>0.05) in pollens, slightly lower indole-3-acetic acid (IAA) content (P>0.05), significantly higher abscisic acid (ABA) content (P<0.05), and significantly lower ratio of (IAA+GA₃+ZR+IPA) to ABA contents (P<0.01).

Conclusion  The endogenous hormones in the pistils and pollens of autotetraploid B. hispida regulate pollen germination and growth and cause abnormal phenomenons in pollen tubes, which is one of the reasons for the low fertility of autotetraploid B. hispida.