Studies on pollen fertility, seed set and seed germination in some rose cultivars

Abstract

The investigation was on the pollen fertility status, seed setting behavior of three cultivars after natural selfing, artificial selfing and artificial cross pollination, tracing the pollen tube growth in stylar region, seed viability and seed germination in rose. The percentage of pollen fertility estimated in 48 cultivars by using versatile stain was found to vary widely with cultivars. Among the Hybrid Teas, cv. Chandrama (76.9%) had maximum pollen fertility. cvs. Aquarius (19.31%) and Roi des Rois (20.47%) had minimum pollen fertility among Hybrid Tea and Floribunda group, respectively. Seed setting was observed to vary greatly with season. High temperature (>27 ºC) adversely affected the fruit and seed set. Naturally selfed flowers of cv. Happiness did not set fruit in both the seasons due to lake of pollen grains falling on the stigma whereas artificial selfing improved the fruit set in cvs. Happiness and Paradise. cv. Queen Elizabeth was found to be better seed parent followed by ‘Paradise’ and ‘Happiness’ based on the degree of fruit setting. Fruit set as well as seed set was low in case of selfed flowers when compared to crosses. Although fruit set maximum (100%) in ‘Queen Elizabeth’ when crossed with cvs. Happiness and Paradise seed set was maximum (23.06) in the cross between ‘Paradise’ x ‘Queen Elizabeth’ followed by ‘Paradise’ x ‘Happiness’ (17.20) during July-Nov., 1987. Seed viability test was carried out by using topographical tetrazolium test for the first time in rose. Embryo along with the cotyledon stained more than half was considered as viable. Embryos unstained and hollow inside were considered as non viable seed. As per the test, percentage of seed viability was ‘Paradise’ and ‘Happiness’ in cv. Proud Land (56%) followed by ‘Cyclamen’ (52%) and ‘Queen Elizabeth’ (51.2). open- pollinated seeds of cvs. Cyclamen, Proud Land and Queen Elizabeth were successfully germinated on moist vermiculite at a constant temperature of 4 ºC. Seed germination was observed from 85-134 days in refrigerated condition. Seed germination was maximum (42.6%) in cv. Cyclamen and was poor in case of cvs. Proud Land (13.35) and Queen Elizabeth (10.6%).