Experimentally, while some of these parameters can be easily assessed, others require more cumbersome approaches. Thus, observation of pollen tube growth has proven to be an easy task since Linskens and Esser (1957) set up a technique based on squash preparations and fluorescent microscopy. On the other hand, the assessment of pistil receptivity is more complicated. While in some species easy
methods have been set up to evaluate stigmatic receptivity (Gonzalez et al.,1995a) or ovule degeneration (Stosser and Anvari, 1982) more work needs to be done to set up general, easy and reliable methods to evaluate pistil receptivity and degeneration. Those studies will accelerate work on EPP and will contribute to elucidate the causes for erratic fruit set.