Pistillate Flower Abscission - 1990

Evaluation of the pistillate flower abscission (PFA) potential of UC-67-13 and UC-67-11 was continued at two sites. At a high PFA site UC-67-13 PFA was only moderately lower than Serr for the third year. UC-67-11 demonstrated low PFA potential for a seconq year at this site. Higher PFA potential of UC-67-13 than UC-67 -11 was also found at a second site for a second year. No further evaluation of PFA characteristics of these cu1tivars is planned. Preliminary experiments and circumstantial evidence have suggested that excess pollen might cause PFA. Controlled pollinations were carried out with Serr and Chico using two sources of pollen at high and low dosages. Open pollinations and unpo11inated flowers were included. PFA was highest with open pollinations and lowest with unpo1linated flowers for both cu1tivars. With Serr, PFA declined with decreasing pollen load whereas there was no difference with Chico. Pollen source did not affect PFA. Attempts to associated numbers of pollen grains per stigma with normal versus PFA pistils have not been completed. An effect of bagging in reducing PFA may implicate water relations in this phenomenon. OBJECTIVES 1. To evaluate PFA potential in UC-67-l3 and UC-67-11. 2. To determine the role of pollen in PFA.