The present investigation was carried out with an objective to study genetic divergence based on morpho-agronomical traits and isozyme pattern in eight maize inbreds. These inbreds were evaluated in randomized block design with three replication for ten morph-agronomical traits. Horizontal starch gel electrophoresis technique used to study the isozyme polymorphism in different tissues of eight inbreds. Analysis of variance revealed significant differences among the inbreds for all the ten morpho-agronomical traits. Nature and extent of genetic divergence for morpho-agronomical traits was measured using average taxonomic distances as a measure of dissimilarity coefficient. Eight inbreds were clustered into four groups (A, B, C, D) based on dissimilarity coefficient. Cluster B and cluster D showed the highest inter cluster distance (2.2422) and the lowest was observed between clusters B and C (1.0401). Cluster A exhibited the highest intra cluster distance (0.8519). Based on inter cluster distances inbreds present in cluster B and D were found more diverse  consisted of inbred CML 186 and CM 600 respectively. Six isozyme systems were used for characterization and divergence studies based on similarity coefficients. Inbreds were classified into six clusters (A, B, C, D, E and F). The lowest (0.5957) similarity coefficient exist between inbreds CM 600 and CML 176 and the highest (0.8132) existed between inbreds CML 186 and CML 144. Cluster analysis in both cases reflected the moderate level of genetic divergence among the inbred lines but result may not be completely similar, but somewhat distinct and complementary in nature. Isozyme patterns was found to effective in revealing the nature of relationship among the inbred lines Therefore, divergence study using one estimate can’t replace the need to evaluate the relationship on the basis of the other which may be to used as parents in hybridization programme.

Abstract:The present investigation was carried out for studying heterosis and inbreeding depression of twenty eight hybrids (F 1 ʼ s) and their F 2 ʼ s made by crossing of eight maize inbreds in all possible cross combinations excluding reciprocal. Observations were recorded on ten quantitative traits viz., plant height (cm), ear length (cm), ear girth (cm), number of kernel rows per ear, number of kernels per row, 100 kernels weight (g) yield per plant (g), days to 50 % tassel emergence, days to 50% silk emergence and days to 50% maturity. Variable magnitude of heterosis was observed for different cross combinations for all the traits. Based on higher mean performance (94.33 to 118.67 g/plant) and higher heterotic response (11.95 to 30.48%) eleven crosses were selected. Response of inbreeding depression was significant in positive direction for most of the traits. Among these eleven crosses five crosses CM 300 x CML 142, CM 300 x CML 144, CM 300 x CML 150, CM 300 x CML 176 and CML 150 x CML 144 were selected having high heterotic value (12.31 to 30.48%) and lower inbreeding depression (less than 15%) for their utilization in maize improvement programme for the development of superior inbred lines.

No abstract

Isozyme studies of micropropagated and mother plants of banana cvs. Matti, Ney Poovan, Kechulepa, Dwarf Cavendish, Malbhog, Champa, B.B. Battisa and FHIA-1 were done to test their genetic fidelity. The banding patterns as revealed by electrophoretic variations were evaluated with respect to isozymes of acid phosphatase, catalase, esterase and peroxidase as markers. The genetic fidelity of micropropagated plants and the relationship of the different cultivars were determined by dendrogram using numerical taxonomy and multivariate analysis system (NTSYS). A clustered dendrogram was prepared by unweighted pair group method using averages (UPGAMA) method. At 87% similarity, the micropropagated and mother plants were clustered in four groups reflecting their genomic constitution. Cvs. Matti (AA) and Dwarf Cavendish (AAA) with similar 'A' genome were categorized in Cluster I. Cluster II comprised of cvs. Ney Poovan (AB), B.B. Battisa (ABB) and FHIA-1(AAAB) with genomic constitution of both 'A' and 'B' type. Cvs. Champa (AAB) and Malbhog (AAB) with similar genome were grouped in Cluster III. Cluster IV contained the cv. Kechulepa (BB) having only 'B' genome. However, there was no somaclonal variation among the micropropagated plants and they showed 100% genetic similarity. Thus, the isozyme studies could be a reliable marker for testing the genetic fidelity of micropropagated plants and for evaluating the diversity among the banana germplasm.

No abstract