Response of lowland rice (Oryza sativa) cultivars to different sowing dates during raniy season

Abstract

An experiment was conducted during kharif 2001-2003 at Central Rice Research, Institute cuttack to find the photoperiod response of 5 rainfcd lowland rice (Oryza sativa L.) cultIvars namely, 'Durga, Sarala, Gayatn, FR 13A and 'T 147] , at different sowing dates. The date of flowering did not vary much when these gen~types sown between 20 May and 20 July. However, the date of flowering altered when sowing was done on second to third week of August. The shifting in date of flowering was due to the prevalenc of a pre-insensensitive~or basic, vegetative phase followed by photoperiod sensitive phase observed in nce. The basic vegetative phase of Durga, Sarala, Gayatri , FR 13~ and T 14.71 were 76, 75,67, 72 and 77 days, respectively. Flowering of rainfed lowland nce occurs wIthIn the crop grOWIng season if sown from May onwards up to the first week of August. It is suggested that sowing can be delayed up to first week of August for rainfed lowland varieties if there is any crop failure due to floodIng In the beginning of the cropping season.