Division of Botany, Indian Agricultural Research Institute, New Delhi
*This work was carried out at Central Rice Research Institute, Cuttack, for the partial fulfilment for Associateship of Indian Agricultural Research Institute, New Delhi, under the guidance of Mr. Sampath, Cytogeneticist, C.R.R.I., Cuttack.
The response to photoperiod of four wild species was studied under three short day treatments viz. 8 hours, 9 hours and 10 hours. Three of these species namely, O. officinalis, O. australiensis and 0. breviligulata flowered significantly earlier than the controls under short day conditions. The degree of sensitivity to short day treatment varied among the species, O. officinalis being the most sensitive, flowering 16 days earlier under 9 hours day length. Within the three short-day treatments there was no significant difference as regards flowering duration. O. perennis did not flower both under natural day length and under the three-short day treatments. Other vegetative characters viz., height, total number of tillers, number of reproductive tillers, panicle length and total number of grains of the three species which flowered were also studied and it was observed that except total number of tillers and number of reproductive tillers, all other characters were significantly affected by short-day treatment. The results are discussed with reference to the duration, geographical distribution and adaptive significance of the species.
