CORRELATION AND GENETIC VARIATION OF TWENTY DIFFERENT GENOTYPES OF LABLAB BEAN, LABLAB PERPUREUS (L.) SWEET

Analysis of variance indicated highly significant differences among the genotypes in most of the characters. Phenotypic variation was greater than that of genotypic and environment variations for all the characters. The greater portion of total phenotypic variation was due to the genotypic variation. Heritability values were higher for number of inflorescence per plant followed by pod weight and number of pods per inflorescence. Maximum genetic advance expressed as percentage of mean was recorded for number of pod per inflorescence. Phenotypic and genotypic correlation coefficients were calculated for six yield contributing traits. Significant and positive genotypic correlation was noted between pod weight at harvest and pod diameter, and yield per plant; and pod weight at harvest, pod length, number of inflorescence per plant showed significant positive genotypic correlation. Yield per plant exhibited significant positive phenotypic correlation with pod length and number of inflorescence per plant. Lablab bean, Lablab purpureus (L.) Sweet is used both as a green vegetable and as pulse crop. In developing countries like Bangladesh, leguminous crops e.g., pulses and beans have an important role to play for protein nourishment. Pulse and bean contain 20-30% protein on a dry matter basis (Ramanajam 1979). The present investigation was carried out to study the variability, heritability, genetic advance expressed as percentage, correlation coefficient among six agronomic characters in 20 different genotypes of bean. The materials comprised 20 genotypes of lablab bean which were collected from different regions of Bangladesh. Those were grown during rabi season of 2000 - 2001 in the experiment field of Rajshahi University with complete randomized block design and three replications. Data on six agronomical traits viz., pod weight at harvest, pod length, pod diameter, number of flowers per inflorescence, number of pods per inflorescence and yield per plant were recorded. The range of phenotypic coefficient of variation (PCV) was from 9.24 (pod diameter) to 166.78 (number of pod per inflorescence). The value for pod length, number of flowers per inflorescence and yield per plant were 145.37, 137.92 and 77.32, respectively. The genotypic coefficient of variation (GCA) ranged from 6.15 (pod diameter) to 151.92 (number of pod per inflorescence). Like phenotypic coefficient of variation, pod length, number of flowers per inflorescence, yield per plant, and pod weight showed high genotypic coefficient of variation (GCA) i.e., 142.96, 132.71, 68.56 and 63.56, respectively. The result show there was a pronounced variation in all phenotypic, genotypic and environmental coefficient of variability for most of the characters. For all characters the difference between phenotypic and genotypic coefficient of variability was found low. These indicate pronounced genetic control on these characters. The number of pod per inflorescence, pod length, number of flowers per inflorescence, and yield per plants showed higher genetic coefficient of variation which offered scope for their improvement as they were less affected by the environment. Majid et al. (1982) reported in black gram that the phenotypic variance was larger than the genotypic variance for all