Development of a technique for in vitro unpollinated ovary culture in rice, Oryza sativa L.

A simple and efficient technique for in vitro unpollinated ovary culture in rice which is also applicable for indica genotypes was developed for breeding and genetic studies. Sampling explants at the auricle distance of 7–12 cm between the two uppermost leaves of a tiller, providing a chilling pretreatment and ovaries with 1/3 of the hulls intact gave optimum response to culture. For callus induction with the spontaneous breaking of ovaries, N₆ media supplemented with NAA (2 mg/l) and DMSO (0.6–0.8%) gave a mean PCI value of 3.8% and range of 0.8–12.5% among genotypes. Media combining 2,4,5-T or 2,4-D with NAA in N₆ medium also has reasonably good callus induction. For calli induced inside, 2,4-D (0.2–0.5 mg/l), NAA (2 mg/l) and KT (1 mg/l) contained media were superior. The maximum green plant regeneration (PPR) of 77.3% was found with the medium containing NAA 0.25 mg/l, IAA 0.5 mg/l and KT 2.0 mg/l. Significant genotype, medium and their interaction effects for per cent ovary survival and callus induction were observed. This revised version was published online in August 2006 with corrections to the Cover Date.