Effect of Photoperiod on The Vegetative Growth and Yield Response in Sri Lanka Traditional Rice Variety "Kuruluthuda"

Abstract

Photoperiod is a major environmental factor regulating vegetative development in traditional Sri Lankan rice varieties. Yet limited scientific evidence exist on how kuruluthuda rice (Accessions number,3549) response to controlled light duration. the knowledge gap restricts the development accurate guideline for optimizing planting time and improving growth performance. The present study evaluates the influence on different photoperiod level on vegetative growth on kuruluthuda using completely Randomized design (CRD)with six photoperiod treatments (8h,9h,10h,1 1,1 t h,45 min, and natural day length l2h20min). Each treatment has five replicates. The experiment was conducted from 29 July to 2 September 2025.Plant height, leaf length, leaf width and number of tillers were recorded and analysis one -way ANOVA at the 0.05 significance level. And day length showed minimal variation during the experimental period. The findings indicate that, photoperiod had a significant effect on several vegetative growth traits. The longest photoperiod (T6) produces significantly Higer plant height (118+3. 62cm. p:0.011<0.05) and the greater leaf length (74.20+6.46cm.p:0.05<0.05). indicating that extend light exposure enhance elongation growth and leaf expansion. The number of leaves (12.60+0.92cm. p:0.022<0.05) and Number of tiller (I.60+0.24. p:0.021<0.05) were also higtrest under T6. leaf width showed no significant among treatment (p:0.11>0.05). suggesting genetic control of this parameter. Overall, the results show that kuruluthuda rice exhibits a positive vegetative response to longer photoperiod. Providing essential baseline information for optimizing planting schedules and light -management strategies aimed at improving growth and maximizing yield potential. Key Words: Day length, Kuruluthuda Rice, Photoperiod, vegetative growth parameters.