Generation Means Analysis for Estimation of Genetic Parameters for Striga hermonthica Resistance in Maize (Zea mays L.)

Peter Okoth Mbogo,Barrack Owuor,Mathews Mito Dida

doi:10.5539/jas.v7n8p143

Abstract

Striga hermonthica is a parasitic weed species that causes considerable yield loss in susceptible maize cultivars in western Kenya. A generation means analysis was conducted to estimate gene effects influencing resistance/tolerance to Striga hermonthica in maize cultivars adapted to western Kenya. A resistant inbred line developed by Maseno University, MSMP1/P2 was crossed to Striga susceptible inbred line 5057. Experimental units comprised of resistant parent P1, susceptible parent P2, their F1 and F2 generations, and BC1P1 and BC1P2 generations. The six generations were evaluated under Striga sick plots at Nyahera during the short rains of 2012 and long rains of 2013. Field evaluation for entries were grown in a randomized complete block design with three replicates. The results showed significant differences among generations for emerged Striga, Striga damage rating and maize growth including Plant and Ear height. Most of the additive, dominance, additive x additive, additive x dominance and dominance x dominance effects were significant indicating the importance of the additive, dominance and epistatic modes of gene actions in controlling emerged Striga, Striga damage rating, plant and ear height. Most components conferring Striga tolerance behaved in a qualitative manner. Dominance effects had higher mean values over additive effects. Significant dominant genetic effects (d) for Striga emergence and Striga damage rating suggested preponderance of non-additive genetic effects in the inheritance of Striga tolerance. The results also reveal the involvement of duplicate epistasis where the dominance estimate and dominance x dominance interaction had opposite signs. The presence of duplicate type of gene interaction confirms the importance of dominance gene effects.

Highlights

Striga hermonthica (Del.) Benth., is a menacing parasitic weed that belongs to the family Scrophulariaceae and constitutes one of the greatest biotic constraints to food crop production, undermining the struggle to attain food security and economic growth in Sub-Saharan Africa (Sauerborn, 1991)
Experimental units comprised of resistant parent P1, susceptible parent P2, their F1 and F2 generations, and BC1P1 and BC1P2 generations
Dominance, additive x additive, additive x dominance and dominance x dominance effects were significant indicating the importance of the additive, dominance and epistatic modes of gene actions in controlling emerged Striga, Striga damage rating, plant and ear height

Summary

Introduction

Striga hermonthica (Del.) Benth., is a menacing parasitic weed that belongs to the family Scrophulariaceae and constitutes one of the greatest biotic constraints to food crop production, undermining the struggle to attain food security and economic growth in Sub-Saharan Africa (Sauerborn, 1991). The most effective way to minimize the yield loss due to Striga infestation is to use resistant crop varieties (Verkleij & Kuijper, 2000; Haussmann & Hess, 2000; Rich & Ejeta, 2008) because these do not require additional inputs such as labor and chemicals. A tolerant genotype on the other hand germinates and supports as many Striga plants as the sensitive genotype but produces more grain yield and shows fewer Striga damage symptoms (Kim, 1994). The resistant genotype is able to support a significantly fewer Striga plants and produces a higher yield than a susceptible genotype (Dogget, 1988; Ejeta et al, 1992; Haussmann et al, 2000; Rodenburg et al, 2006). Reports of genetic resistance to Striga have been documented in rice (Oryza sativa; Bennetzen et al, 2000; Gurney et al, 2006), sorghum

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Results

Conclusion