Hybridization and development of inbred line in Petunia

Abstract

Petunia is a popular bedding plant and also used in landscaping for its aesthetic value. Petunia is a major contributor in flower seed industry with an increasing demand for F1 hybrids. Cost of developing hybrids is mainly dependent on cost of inbred development and hybridization. Inbreeding depression leading to poor seed set and reduced seed germination are problems encountered by seed industry. In this background the present study was taken up with the objectives to evaluate various selfing techniques to identify the efficient one for production of large quantity of seeds in short duration to facilitate inbred development and also for hybrid production. Among the different methods of selfing (threading, manual pollination, bagging of single bud and bagging of multiple buds), bagging of multiple buds resulted in minimum days to seed set (22 days), cent percent seed set, higher pod weight (0.252g) and number of seeds/g (8000). Seed germination percentage was high in manual pollination (86.44%) followed by bagging of multiple buds (68.44%). Inbred line IIHRP-WT recorded higher pod weight (0.149g), number of seeds/g (7350) and cent percent seed set compared to other inbred lines. In crossing programme, pollination with pollen mix of same line gave the highest pod weight (0.1109g) and number of seeds/g (11400) over the other methods viz., pollination with single anther and pollen mix of same plant. Floral morphology studies revealed variations for flower colour (white, purple, pink, magenta, bicolour of white and pink), anther and pollen colour (white, yellow and purple), number of anthers (5-7), position of stigma in relation to anthers (pin and thrum), receptivity of stigma in relation to anthesis, dehiscence of anthers and pollen viability (40.66-97.77%). All the inbred lines showed their ability to seed set in selfing experiments except in IIHRP-SI wherein self incompatibility was confirmed.