Combining ability and heterotic relationships in yellow quality protein maize varieties

Issue Date

8-2008

Abstract

One type of corn called quality protein maize (QPM) promises high value to the livestock industry because of its high lysine content. Eight yellow QPM synthetic varieties were used to determine and estimate their combining ability, degree of heterosis in variety crosses for yield and other agronomic traits, identify potential heterotic groups of the parental varieties, and determine appropriate breeding strategies. Gardner-Eberhart Analysis III was used to provide estimates for effects of general combining ability (GCA) and specific combining ability (SCA). Heterosis was also calculated based on mid-parent values. Grain yield was used for principal component analysis of genetic similarities of the parental varieties using Biplot01.XLA to identify potential heterotic groups. Results showed highly significant variations detected among entries for all traits. Subdividing the crosses to GCA and SCA effects showed no significant differences due to GCA noted for all traits. Subdividing the crosses to GCA and SCA effects showed no significant differences due to GCA noted for all traits. Relatively high GCA estimates for yield were, however, observed for SYQ9, SYQ8 and SYQ5. Negative GCA estimates for days to anthesis and silking of SYQ6 indicated earliness of the variety. On the other hand, high GCA estimates for plant height were observed for SYQ9, SYQ5 and SYQ11 while the GCA estimate for ear height was relatively high for SYQ7. Among the variety crosses, high percent heterosis was exhibited by SYQ9xSYQ11, SYQ5xSYQ9, SYQ5xSYQ8 and SYQ5xSYQ6. Four heterotic groups were established from the biplot analysis. Composites of varieties from one heterotic group can be formed. Intra-population improvement, therefore, may be conducted on SYQ9, SYQ8 and SYQ5. Reciprocal recurrent selection involving parents of high yielding crosses or cross of composites may also be done to improve the performance of the reciprocal populations or inbred lines extracted from improved cycles to generate better performing hybrids.

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463x

Volume

33

Issue

2

Page

25-36

Document Type

Article

Frequency

tri-quarterly

Physical Description

tables, biplot

Language

English

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