Search

The genetic basis of salinity tolerance for three parameters Ct, C50 and C0 in P. americanum using the diallel analysis was investigated. Tolerance for Ct, C50, and C0 was due to both additive and dominance genetic effects with indication of over-dominance. For these three parameters, dominance is predominantly towards salt sensitivity, but it appears that in different accessions, there are different gene effects for each character. Recessive genes are evident in the salt tolerant line ICMV-94474 for Ct and C50, and in the other tolerant line 10878 are also evident for C50 and C0 for recessive genes. Salinity data set were found to be adequate totally for C50 and C0, but partially adequate for Ct. It appears in pearl millet that in some accessions recessive genes are responsible for salt tolerance for Ct, C50, and C0, but this trend is not consistent. Different (dominant / recessive) genes control each accession for Ct, C50, and C0. The maximum narrow sense and broad sense of heritability were found for C50 and this suggests that C50 is the best character for selection, rather than absolute root length. C50 is highly correlated with Ct, and C50 is also signifi cantly correlated with C0. These results suggest that the genetic bases of these genes are linked to some degree. These correlations would be of considerable value in breeding for improved salinity tolerance.

Information about genetic diversity and relationships among the breeding materials has a signifi cant impact on crop improvement. Association between parental divergence and progeny performance has not been well documented in cotton. A cotton study was conducted in the department of Plant Breeding and Genetics, University College of Agriculture, Bahauddin Zakaryia University, Multan, (30.2oN, 71.4oE) Pakistan and National Food Research Institute, Tsukuba, Japan. The objective of this study was to estimate genetic diversity among selected cotton genotypes and their reciprocal crosses. Six U.S. and two local (Pakistani) cultivars all belonging to Gossypium hirsutum L were genotyped by polyacrylamide gel electrophoresis and compared with BioRad molecular weight markers. Cluster analysis revealed low genetic diversity among the parents and pooled the crosses with their parents, indicating success of hybridization. The present study, combined PAGE analysis with cluster analysis confi rmed the genetic similarities between parents and their crosses while it also confi rmed the dissimilarities between the parents as showed by the morphological characters.