GENETIC ANALYSIS OF MORPHO-PHYSIOLOGICAL TRAITS ASSOCIATED TO DROUGHT TOLERANCE IN MAIZE (ZEA MAYS L.)
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Date
2008
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu
Abstract
Maize (Zea mays L. 2n = 20) is the 3<sup>rd<sup/> important cereal crop of the world, after rice and wheat. Worldwide, drought is the most pervasive limitation to the achievement of yield potential in maize. Significant yield losses in maize from drought are expected to increase with global climate change as temperature rises and rainfall distribution changes in key traditional production areas. Therefore in order to study the genetics of morphophysiological and biochemical traits associated to drought tolerance in maize, forty one genetically diverse inbred lines were evaluated under irrigated and rainfed environments in 2005 to identify twenty two female lines (with different level of drought resistance) and three male testers (drought susceptible). These were crossed in Line x Tester design. The ninety four genotypes (22 lines + 3 testers + 66 F<sub>1</sub>'s + 3 standard Checks), were grown in two environments irrigated (El) and rainfed (E2) during Kharif 2006 and 2007 at two locations i.e. experimental area of Division of Plant Breeding and Genetics, Chatha and Regional Agricultural Research Station Rajouri of Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu. Three sets of F2 Triple Test Crosses were also evaluated at Chatha in irrigated and rainfed environment during Kharif 2007 to identify the presence of non allelic interactions. The observations recorded on the traits viz., days to 50 per cent tasseling, days to 50 per cent silking, anthesis- silking interval (ASI), days to maturity, plant height, ear height, number of leaves per plant, number of barren plants per plot, ears per plant, ear length, ear girth, kernel rows, kernels per row, 100 kernel weight, grain yield per plant, relative water content, proline content and drought susceptibility index were subjected to Line x Tester analysis and Triple test Cross analysis. Analysis of variance revealed that mean squares due to treatments, parents, lines and crosses were highly significant for all the characters at Chatha and Rajouri in both the years and in both environments as well as pooled over environments. Interaction of crosses with environment was also significant for all the characters at Chatha and Rajouri in both years except for ear girth and kernel rows at Chatha in 2007. Line x Tester analysis indicated that both additive and non-additive components were played role in the inheritance of most of the characters. The magnitude of non-additive component was more than additive component for most of the characters studied. Estimation of combining ability effects revealed that the parental lines L2, L3, L7, L19, and L22 were good general combiners for various morphophysiological characters as well yield components. Parental line LI, L2, L3, L19 and L22 were good general combiners for grain yield per plant at Chatha and Rajouri in both the years and in both the environments as well as pooled over environments. SCA effects indicated that four crosses (L1 x T2, L2 x T1, L14 x T3 and L22 x T2) at Chatha and five crosses (L1 x T2, L2 X Tl, L7 X Tl, L8 X T3 and L19 x Tl) at Rajouri were found promising for grain yield and some other quantitative characters associated with drought tolerance under normal as well as rainfed conditions. Non-allelic interactions are found to be present in all the three crosses viz. LM9 x CM135, CM117 X CM135 and M16-5 x CM139 and in both the environments for all the characters except for number of barren plants and ears per plant under irrigated and ASI under rainfed in cross CM117 x CM135 and for ears per plant under rainfed and number of barren plants and ears per plant under pooled analysis in cross Ml6-5 x CM 139. Further partitioning of non-allelic interaction suggests the prevalence of non-additive (j+1) type of non allelic interaction for most of the characters. In the presence of additive, dominance and epistatic components, suitable breeding procedures like reciprocal recurrent selection would be highly useful tool which can utilize all types of gene effects to improve characters related to drought tolerance. In view of the complexity of the drought resistance, it is essential to have better understanding and appreciation of the plant environment interaction by the maize breeders. Selection must be done simultaneously in stress as well as non-stress environments duly giving proper weightage to all the morpho-physiological and yield attributes, as the chances of getting common progeny in stress as well as in non-stress environments are considerably low.
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