genetics of resistance to pink stem borer attack in flint maize populations a. butrón, p. soengas,...
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Genetics of Resistance to Pink Stem Borer Attack
in Flint Maize Populations
A. Butrón, P. Soengas, P. Revilla, A. Ordás,
and R.A. Malvar
Misión Biológica de Galicia
Introduction
• Pink stem borer is the main pest in northwestern Spain
Average yield losses = 15%
Ear damage Stem damage
Plant Breeding is one of the meansthat can be used in a pest integrated control system
Introduction
Life cycle of Sesamia nonagrioides Lef.
Larva
EggsPupa
Moth
Introduction
• Previous studies have identified sources of resistance and determined the genetics involved
• Nevertheless, resistance of flint maize populations has not been fully prospected
Objective: to test the variability for resistance to pink stem borer attack among flint maize populations and to determine the genetics involved
Introduction
• Local flint maize varieties supply:– Early vigor– Early flowering– Lower stem lodging– Relative resistance to
drough stress– High quality flours
Material and methods
Diallel among 10 flint maize populations
Population Origin• Gallego North• Gallego/Hembrillla norteño North• Norteño North• Norteño largo North• Basto/Enano levantino East• Fino Center• Tremesino South• Relámpago 8 hileras Argent.• Amarillo precoz de Simone Argent.• Longfellow USA
Material and methods
• Diallel was tested in 1998 and 1999
• Randomized complete block designs
• Ten plants/plot were infested with Sesamia nonagrioides eggs
• Tunnel length to estimate stem damage
• General appearance of the ear to estimate ear damage (1-9)
• Analysis II of Gardner and Eberhart (1966)
Material and methods
Analysis II (Gardner and Eberhart, 1966)
– Yij = µv + 1/2(vi + vj) + hij
»Yij = observed mean of the cross of varieties i and j
»µv = mean of all varieties
»vi and vj = variety effects
»hij = observed heterosis
– hij = (h +hi + hj + sij)
Results
Analysis of variance of the diallel
Source of variation TL GA
Population * *Variety * *Heterosis NS NS
P x Year NS NS
* Significant at the 0.05 probability level.
Results
Variety effects = difference between a paticular variety mean and the mean of
all varietiesPopulation TL GA
Gallego -5.7 -0.95Gallego/Hn -5.6 -0.33Norteño 1.5 -0.50Norteño largo 2.2 -0.50Fino 10.5 0.75Basto/El -23.6 -0.12Tremesino -6.3 0.97Longfellow 0.5 0.15Relámpago 10.0 0.42Simone 16.6 -0.03LSD 16.5 1.12
Conclusions
Additive gene effects were the most important effects
Variability for stem resistance was larger than variability for ear resistance
Basto/Enano levantino could be the base material in a recurrent selection program