HETEROSIS AND COMBINING ABILITY FOR YIELD, YIELD COMPONENTS AND POST-FLOWERING STALK ROT RESISTANCE IN MAIZE (Zea mays L.)
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Date
2007
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD.
Abstract
The present investigation on “Heterosis and combining ability for yield, yield
components and Post-Flowering Stalk Rot resistance in maize (Zea mays L.)” was under
taken with nine lines (BPPTI-28, BPPTI-36, BPPTI-38, BPPTI-44, CM-211, CM-210, CM-207,
BPPTI-33 and CM-120) and four testers (BPPTI-29 BPPTI-34, BPPTI-35 and BPPTI-43).
During rabi, 2005-06 the nine elite inbred lines were crossed with four testers in Line x
Tester design, at Agricultural Research Station (Maize), Amberpet. Subsequently in kharif,
2006, the 36 F1 crosses along with standard checks (DHM-115 and BIO-9637) and parents
(lines and testers) were subjected to evaluation by raising the crop in disease sick plot
accompanied by toothpick inoculation, at Agricultural Research Station (Maize),
Amberpet, Hyderabad. The data was collected on days to 50 per cent tasseling, days to 50
per cent silking, days to maturity, plant height, ear height, ear girth, ear length, number of
kernel rows per ear, number of kernels per row, 100 kernel weight, PFSR disease score and
grain yield per plant, which was analyzed for estimation of combining ability, heterosis,
nature of gene action, heritability, correlation and path analysis.
The analysis of variance revealed significant differences among the genotypes for
all the traits studied. Further, non-additive gene action was found to be preponderant for
grain yield, yield components and PFSR disease resistance in the present investigation,
favoring a hybrid breeding programme. The hybrids, in general, were tall and high
yielding, compared to the parents. High level of heterosis was noticed for grain yield per
plant followed by number of kernels per row and 100 kernel weight.
The combining ability analysis revealed importance of non-additive gene action in
governing the characters studied. Among the parental lines, BPPTI – 44 and BPPTI - 33
were good general combiners for earliness viz., days to 50 per cent tasseling, days to 50 per
cent silking and days to maturity. The parents BPPTI – 33 and BPPTI - 38 for PFSR disease
resistance, CM - 211 and BPPTI – 33 for grain yield contributed maximum favourable genes.
The parents BPPTI – 33, CM - 211 and BPPTI – 38 were good general combiners for both
yield and PFSR disease resistance.
The hybrids, BPPTI–36 x BPPTI-34 and CM-207 x BPPTI-35 for earliness, CM-120 x
BPPTI-29 and BPPTI–28 x BPPTI-43 for PFSR disease resistance and CM-120 x BPPTI-29,
CM-207 x BPPTI-34, and CM-210 x BPPTI – 34 for grain yield were the good specific
combiners. The hybrids, CM-120 x BPPTI-29, CM-207 x BPPTI-34 and BPPTI–28 x BPPTI-43
were good specific combiners for both yield and PFSR disease resistance. Hence, these
crosses could be advanced further for isolation of transgressive segregants and also to
develop good inbred lines.
Estimates of heterosis, heterobeltiosis and standard heterosis were variable among
crosses in desirable direction and some of them turned out to be best specific crosses. The
cross combinations BPPTI–44 x BPPTI-35 and BPPTI–44 x BPPTI-29 for earliness, BPPTI–33
x BPPTI-34 and BPPTI–28 x BPPTI-43 for PFSR disease resistance, CM-211 x BPPTI-29 and
CM-211 x BPPTI-43 for yield. Further, the best selected crosses viz., CM-211 x BPPTI-29,
CM-211 x BPPTI-43, CM-120 x BPPTI-29 and BPPTI–33 x BPPTI-43 for grain yield and PFSR
disease resistance may be further exploited in multilocation evaluation before releasing
them for commercial cultivation to the farmer. However, these above hybrids by chain
crossing may be composited to make a gene pool. This pool may be advanced for further
generations to derive and isolate lines with pyramidized gene combinations for grain yield.
Studies on heritability, correlations and path analysis emphasized the need for
selection, based on plant type with greater 100 kernel weight, number of kernels per row,
plant height, ear length, number of kernel rows per ear, ear girth and less disease score
since these were found to be the important direct contributors for grain yield.
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Keywords
HETEROSIS, COMBINING, ABILITY, YIELD, COMPONENTS, POST-FLOWERING, STALK, ROT, RESISTANCE, MAIZE