Pollen tubes inhibitors

Recent investigations indicate that the failure to obtain a positive chemotropic response may be an artifact. Failure to observe chemotropism may result from interference by pollen tube growth inhibitors, a factor causing negative chemotropism, by inherent errors in the surface test method, by the existence of genetically controlled incompatibility systems, and by factors of age of tissues and other characteristics of the plants. 

It is now clear that gynoecial tissues contain potent pollen tube growth inhibitors. Although inhibitors had been invoked to explain various experimental results, concreti (widence of their existenise and activdty has... 

---