Abstract:
To overcome challenges imposed unforeseen climate change in rice production,
introduction of short duration rice varieties is considered as an effective strategy. In any
breeding program for crops, genetic variability is an essential requirement for developing
superior cultivar. The objective of this study was to estimate the genetic variability, find
out the correlation among the different quantitative traits of F2 generation twelve crosses
to identify promising lines that can be used for developing high-yielding short-duration
varieties, which are better suited for the Low Country Wet Zone (LCWZ) of Sri Lanka. The
experiment was laid as a randomized population method and fifty plants were selected
randomly for data collection in each population at the Rice Research Station, Labuduwa,
Sri Lanka. The data were recorded on eighteen different agro-morphological traits. The
F2 crosses showed a varying response for days to heading, flowering and maturity. The
majority of F2 crosses reaches 50% flowering less than 65 days, of which Ld 253/Bg 252,
Bg 308/Bg 252, At 311/Bg 252, At 309/At 311 and At 311/At 309 F2 crosses reached this
stage within 60 days. Therefore, these crosses pose the ability to complete their crop cycle
relatively within a short duration. When considering the yield performance, At 311/Bg
252 and At 311/At 309 F2 crosses showed higher number of effective tillers (10 and 12),
thousand grain weight (17.38g and 18.9g) and yield per plant (16.82g and 21.8g), Genetic
variability assessment indicated that above mentioned important yield attributing
characteristics also showed a higher phenotypic coefficient variance and genotypic
coefficient variance for all F2 crosses. High heritability coupled with high genetic advance
were also observed for above traits. Correlation analysis revealed that seed per
panicles(0.203*),thousand grain weight(0.331**) and panicle length( 0.129*) had the
significantly positive contribution to grain yield. Overall, results indicated that among the
F2 crosses evaluated At 311/Bg 252 and At 311 / At 309 crosses can be considered as
promising lines to develop short duration high yielding varieties adaptable for LCWZ of
Sri Lanka. However, comprehensive physiological studies need to be conducted to
investigate the adaptability of these crosses to the variable climatic conditions of LCWZ.
