MSc

A research programme was carried at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during the period 2003-2005 with the object of assessing the genetic variability in yard long bean genotypes for yield and Fusarium wilt resistance. Data for the investigation were collected from two field experiments.
Thirty genotypes of yard long bean were screened and evaluated for yield and related characters in a field experiment in Randomised Block Design with three replications. Analysis of variance revealed significant differences among the genotypes for all the twenty-eight characters studied. Genotypic and phenotypic coefficient of variation was high for dry weight of roots per plant, pod yield per plant, pod clusters per plant, pods per plant and pods per cluster. Fresh weight of shoot per plant, dry weight of shoot per plant, pod cluster per plant, pods per plant, pod yield per plant, pods per cluster, pod weight, pod length, 100 seed weight, fresh weight of roots per plant, dry weight of roots per plant, nodules per plant, fresh weight of nodules per plant, dry weight of nodules per plant and crude protein content had high heritability coupled with genetic advance.

Pod yield per plant showed significant positive correlation with Pods per plant, pod clusters per plant, days to first harvest, pod weight, days to 50 per cent flowering, seeds per pod, pod length, 100-seed weight and total phenols at genotypic level. Path analysis revealed that number of pods per plant and pod weight were the primary yield contributing characters due to their high direct effect on pod yield.
Mahalanobis D2 analysis clustered the 30 genotypes into eight clusters. Cluster I formed the largest cluster with 10 genotypes while Clusters VI, VII and VIII had one genotype each. The genetic distance was maximum between Cluster IV and VI, while the minimum divergence between clusters III and VIII. The intra cluster distance was highest for the Cluster I. Selection index analysis revealed that genotype VS 86 attained the maximum selection index value followed by Thiruvananthapuram local-1 and Vella valli payar and the minimum estimates were recorded for Kayamkulam local, Malappuram local-2 and Kollengode local.
In the field screening program for Fusarium wilt resistance all the 30 yard long bean genotypes were evaluated on the basis of disease intensity percentage. Genotypes showed significant differences in the degree of disease susceptibility. Among the genotypes, two genotypes were moderately resistant, 18 genotypes were moderately susceptible and 10 genotypes were susceptible to Fusarium wilt. The accessions found to be moderately resistant were Thiruvananthapuram local-1 and Thiruvananthapuram local-3. The susceptible accessions were Sarika, Malappuram local-1, Kalliyoor local, Palapoor local-3, Vella valli payar, Palapoor local-2, Palakkad local, Thrissur local, Kasargode local and Lola.
Comparing yield with disease intensity, the genotypes Thiruvananthapuram local-1 and Thiruvananthapuram local-3 recorded high yield with moderately resistant to Fusarium wilt, while VS 86, Malika and Varuvila local-1 showed high yield with moderately susceptibility. So these genotypes can be used as parents for further crop improvement programme for Fusarium wilt resistance.