Responses of Sri Lankan traditional rice to photoperiod at early vegetative stage

Rice is a photoperiod sensitive plant for flowering initiation. effect of photoperiod can be important in vegetative growth and yield determination in rice. the objective of the research was to determine the effect of photoperiod on the vegetative responses of sri lankan traditional rice germplasm (sltrg). forty five traditional rice accessions (tra),5 improved rice varieties (ir),sri lankan wild rice (oryza nivara and oryza rufipogan) and oryza japonica accessions 6782 and 6752 were grown in short day (sd),day neutral (dn) and long day (ld) conditions. days to reach the fifth leaf stage (dfl),plant height (ph) and tiller number (tn) at the fifth leaf stage were recorded. twenty three genotypes including 21 tra,oryza japonica 6752 and oryza nivara did not respond to photoperiod having non-significant values for dfl,ph and tn among photoperiods. the dfl was affected in 25 genotypes; among them both dfl and ph were affected in 7 genotypes. dfl was significantly increased during ld in 4 tra while dfl was significantly reduced in all 5 ir and 5 tra. dfl was significantly increased in oryza japonica 6782 and 5 tra under sd. in 4 tra,dfl was reduced under sd. the tn was affected in oryza japonica 6782 only under sd with increased dfl. the dfl was significantly increased under dn in oryza rufipogan,5 tra and 2 ir. both sd and ld photoperiods differently affected the interaction between dfl and ph in tra while only ld affected that of ir. dn had an effect on the interaction between dfl and ph only in wild rice oryza rufipogon. variation of vegetative growth response to photoperiod may depict the wide genetic basis of sltrg. © 2017,pakistan botanical society. all rights reserved.