Salinity is one of the most significant environmental stresses for sustainable crop production in major arable lands of the globe. Thus, we conducted experiments with 27 tomato genotypes to screen for salinity tolerance at seedling stage, which were treated with non-salinized (S1) control (18.2 mM NaCl) and salinized (S2) (200 mM NaCl) irrigation water. In all genotypes, the elevated salinity treatment contributed to a major depression in morphological and physiological characteristics; however, a smaller decrease was found in certain tolerant genotypes. Principal component analyses (PCA) and clustering with percentage reduction in growth parameters and different salt tolerance indices classified the tomato accessions into five key clusters. In particular, the tolerant genotypes were assembled into one cluster. The growth and tolerance indices PCA also showed the order of salt-tolerance of the studied genotypes, where Saniora was the most tolerant genotype and P.Guyu was the most susceptible genotype. To investigate the possible biochemical basis for salt stress tolerance, we further characterized six tomato genotypes with varying levels of salinity tolerance. A higher increase in proline content, and antioxidants activities were observed for the salt-tolerant genotypes in comparison to the susceptible genotypes. Salt-tolerant genotypes identified in this work herald a promising source in the tomato improvement program or for grafting as scions with improved salinity tolerance in tomato.

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Correlation and path analysis was executed in twenty-three tomato genotypes of Bangladesh for thirteen yield contributing characters.

An experiment for diversity analysis with 66 genotypes of lablab bean (Lablab purpureus L.) was conducted at Department of Genetics and Plant Breeding, Bangladesh Agricultural University (BAU) during 2009-2010. Data were collected from all experimental plants on the following characters: days to first flowering, days to 50% flowering, days to first pod setting, no. of pods per plant, wt. of 20 pods (g), pod yield per plant (g), pod length (cm), number of seeds per pod, number of seeds per plant, 100-seed weight (g), and seed yield per plant (g). As per multivariate analysis, the genotypes were grouped into seven clusters. The highest number of genotypes 15 was included in cluster V followed by cluster II, which contained 13 genotypes. Cluster III, I, VI, IV contained 12, 11, 6, and 5 genotypes, respectively. The cluster VII which included 4 genotypes was the smallest among the 7 clusters. It is important to note that the highest amount of genetic divergence within the cluster group was noticed in the cluster VII having only 4 genotypes. The inter-cluster distances (D2) were higher than the intra-cluster distances. The inter-cluster D2 values varied from 2059.094 to 19302.6. The distances between the cluster VII and V; VII and VI; VII and II and VII and I were comparatively high than the other inter-cluster distances. The genotypes of these clusters were thus more diversified for yield and yield contributing characters. The intracluster distance (8502.795) observed in cluster VII revealed maximum diversity among themselves. While the least variation (625.372) was noticed between genotypes of the cluster II signifying the closeness of the genotypes included in this cluster. Data on the contribution of individual characters towards divergence suggested that no. of pods per plant contributed maximum (34.033%) to the genetic divergence followed by pod yield per plant and 100-seed weight. The genotypes of the cluster VII produced highest pods per plant and those of the cluster II produced lowest pod yield per plant. Seed yield per plant was found to be highest in cluster VII and lowest in cluster II. Results of the study suggested that selection for these traits in climbing genotypes might be effective. By strategically using this diversity, the breeder can develop high yielding varieties of lablab bean. Bangladesh J. Agril. Res. 38(1): 105-114, March 2013 DOI: http://dx.doi.org/10.3329/bjar.v38i1.15195

The results of the study carried out during 2009-2010 with lablab bean (Lablab purpureus) are presented in this paper. Data were recorded from all experimental plants on the following characters as number of pods/plant, pod yield/plant (g), number of seeds/pod, number of seeds/plant; seed yield/plant (g), Range, mean, genetic parameter, correlation co-efficient and path coefficient were studied. High heritability coupled with high expected genetic advance in percentage of mean were observed for most of the characters. The coefficients of correlation showed that seed yield/plant was positively and significantly correlated with days to first flowering, days to 50% flowering, days to first pod setting, number of pods/plant, pod yield/plant and seeds/pod, number of seeds/plant, and seed yield. Path coefficient analysis showed that days to first flowering, days to 50% flowering, number of pods/plant, 20 pod weight (g), pod yield/plant, pod length, number of seeds/pod, number of seeds/plant, 100-seed weight influenced seed yield/plant directly in positive direction. Among the characters, number of seeds/plant had high positive correlation with seed yield/plant. Days to first pod setting exhibited negative direct effects on seed yield. From this result, it can be concluded that days to first flowering, days to 50% flowering, number of pods/plant, pod yield/plant, number of seeds/pod, number of seeds/plant, 100-seed weight are the most important yield contributing characters as they influenced pod yield and seed yield directly in positive direction. DOI: http://dx.doi.org/10.3329/bjar.v38i4.19662 Bangladesh J. Agril. Res. 38(4): 705-717, December 2013

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