Effects of Coatings and Pollenicides on Pollen Tube Growth Through the Stigma and Style of ‘McIntosh’ Apple Blossoms

Abstract

Abstract The use of blossom thinners to prevent fertilization was studied in the laboratory over a three year period. Mature ‘McIntosh’ apple tree branches were cut and blossoms allowed to develop under greenhouse conditions where treatments of several coatings, potential pollenicides and hand pollination were applied. Pollen tube growth through the stigma and style was measured microscopically. Generally, there was more pollen tube growth through the styles of the treated flowers in one of the three years. The most effective coatings for restricting pollen tube growth were Safer-Soap at 40 g·L−1 and PEG-1000 at 20 g·L−1 and 10 g·L−1. Anti-Stress at 50 mL·L−1 and Safer-Soap at 20 mL·L−1 were moderately effective, and Masbrane at 20 mL·L−1 and Nutri-Save at 10 g·L−1 were the least effective. The most effective pollenicides were monobasic ammonium phosphate (MAP) at 15 g·L−1, NaCl at 12 g·L−1, and ammonium thiosulphate (ATS) at 17 mL·L−1. Pollen tube penetration to the base of the style was inhibited by ATS...