Genetic variability, correlation, path coefficient analysis and test of normality was conducted in an F 8 recombinant inbred aerobic rice population developed by single seed descent method to evaluate its potential as a mapping population. Estimates of genotypic variance, phenotypic variance, genotypic coefficient of variance (GCV), phenotypic coefficient of variance (PCV), heritability in the broad sense (H) and expected genetic advance at 5% selection index (GA) for grain yield and other attributing characters were computed. In all the cases, PCV was higher than GCV indicating the influence of environment on the characters. High heritability coupled with high GA was observed for several plant traits; number of tillers, plant height, total number of spikelets panicle -1 , biomass plant -1 , straw weight, harvest index and grain yield plant -1 and hence offered good scope for selection. Grain yield plant -1 was found to be positively correlated with plant height, number of tillers, panicle length, panicle exsertion, number of panicles plant -1 , single panicle weight, test weight, number of fertile spikelets panicle -1 , straw weight, biomass plant -1 , harvest index and grain breadth both at genotypic and phenotypic levels. Harvest index exerted maximum positive direct effect, followed by biomass plant -1 and straw weight on grain yield plant -1 at phenotypic level. ShapiroWilks ''W test of normality'' indicated that the population was skewed towards female parent IR50 for some traits and for some others towards Moroberekan, the male parent. Most of the characters that showed skewness were platykurtic with a kurtosis value of less than 3.

tomary statistical analyses are found to be inadequate in discerning the effects of different yield components Improvement of grain yield in the rainfed lowland rice (Oryza on yield (Zobel et al., 1989). Hence, studying grain yield sativa L.) ecosystem is important because that ecosystem covers a under varying moisture conditions and employing more considerable area. The objectives of this study were first to find relationship(s) among grain yield and its components, second to assess reliable statistical analyses may lead to better underthe influence of root morphological characters on grain yield, and standing of the influence of various traits on grain yield. finally to find the relationship of molecular marker heterozygosity Ample genetic variability for root morphological with heterosis-performance of yield related characters in rainfed lowtraits and other components (primary traits) of drought land rice. Nine backcrosses involving transgressants for maximum resistance has been documented over the past few deroot length in rice from a doubled haploid mapping population of cades. These studies have been conducted on specific IR64/Azucena along with parents were evaluated simultaneously for primary trait(s) of interest and its (their) contribution grain yield and related characters as well as root traits under conto drought resistance (Ludlow and Muchow, 1990; trasting moisture regimes. Grain yield showed maximum reduction Acevedo and Fereres, 1993; Sadiq et al., 1994; Hemaunder severe moisture stress conditions. Significant negative correlamalini et al., 2000). Even after several well designed tion between drought tolerance index and grain yield was observed in the well-watered conditions only. Multiple linear regression analysis

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