ESTIMATION OF GENETIC DIVERSITY USING SSRs IN MAIZE INBRED LINES IN RELATION TO HETEROSIS AND COMBINING ABILITY
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Date
2013
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PAU Ludhiana
Abstract
The present investigation was conducted to estimate the magnitude of general and specific combining ability of inbred lines and crosses respectively and heterosis for yield and yield component characters of maize. Forty four F1 crosses were made in a line x tester fashion by using twenty two lines and two testers and all crosses with their parents were evaluated. The data was recorded on nine characters. The lines 3(LM13), 26-2009 and 37-2009 were good general combiners for most of the characters studied. The estimates of gca effects revealed that lines 10-2009, 22(LTP-4), 24-2009, 38-2009, 39-2009, 41(CML32), 95-2009 were good general combiners for grain yield/plant. The hybrids 29-2009xLM13, 37-2009xLM13, 97-2009xLM13, 9-2009xLM14, 97-2009xLM14 were found to be good specific combiners for most of the characters. Fourteen hybrids were found to be good specific combiners for grain yield/plant. The hybrids 3(LM11)xLM13, 3(LM11)xLM14, 13-2009xLM14, 22(LTP-4)xLM14, 24-2009xLM13, 24-2009xLM14, 37-2009xLM14, 39-2009xLM13, 41(CML32)xLM14, 45-2009xLM14, 46-2009xLM14, 59-2009xLM14, 95-2009xLM13, 95-2009xLM14 were found to be good cross combinations which showed significant mid parent heterosis for most of the characters. Unweighted pair group method with arithmetical averages (UPGMA) available in numerical taxonomic and multivariate analysis system (NTSYS-pc) 2.02e was used to group the inbred lines in different clusters. Dendrogram constructed grouped the inbred lines in two clusters (C-1, C-2). But the morphological grouping of parents was not in agreement with the heterotic pattern of their crosses. A set of twelve SSR primers dispersed throughout the maize genome was used to assess the genetic diversity at the molecular level. A total of forty alleles were detected and polymorphism information content (PIC) value ranged from 0.26 to 0.81 with an average value of 0.5. SSR primers with di-repeats revealed a maximum mean PIC value of 0.56, followed by tetrarepeats (0.44) and tri-repeats (0.39). It was able to assign inbred lines to three clusters (C-1, C-2 and C-3). In order to predict the hybrid performance, utilizing SSR markers, genetic distances were calculated among the inbred lines. Correlation coefficients calculated between the genetic distances of inbred lines and mid parent heterosis and specific combining ability for various yield and yield component characters of maize were non significant. Thus it seems rather difficult to make a generalized conclusion regarding the prediction of hybrid performance especially for grain yield, based on genetic distance measures.
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