Twenty diverse genotypes of sunflower helianthus annus L. were exposed to naturally occurring population of H. armigera under preliminary screening trials. Nine out of twenty comprising three each resistant, moderately resistant and susceptible were selected on the basis of egg count and larval infestation. The layout of the experiment was a RCBD with four replications. These selected genotypes were further sown for further experiments. Data for various physico- morphic plant characters was taken at different stages of the growth of the crop.
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The nine genotypes were subject to laboratory analysis to find out the chemical plant characters as part of host plant resistance. Various physico- morphic and plant chemical characters and their correlation with eggs and larval population of the pest was studied. Data regarding temperature, rainfall and humidity was taken during the growing period of the crop. Correlation of weather factors with population build up of H. armigera was also studied. Data regarding egg and larval population, physic- morphic, chemical plant factors and weather factors was subject to multiple regressions to find out the basis of host plant resistance. One comparatively resistant and relatively susceptible genotypes (G53) and (ORB-100) were subject to experimentation for evaluation to different pest management techniques and data were taken before and after the application of treatments on these genotypes.Yield data on the basis of heads of genotypes was taken to know the impact of these treatments on resistant and susceptible genotypes. Genotype (G53) showing potential on all other genotypes, when different set of treatments were applied as part of sustainable pest management methods. Cost benefit ratio of each treatment was compared There was significant difference among the treatments C:B ratio.Our investigation showed potential for developing H. armigera resistant genotypes that would reduce seed feeding injury, prevent yield loss and increase growers profit.
Author: ZAFAR, KHALID
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