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Keywords: Applied Sciences
Agriculture & related technologies
Issue Date: 2015
Abstract: The studies were conducted on bio-intensive management of Jassid, Amrasca biguttula biguttula (Ishida) on various genotypes of Bt-cotton. Experiments were conducted in farmer’s field and laboratories of the Agricultural Entomology Department, University of Agriculture, Faisalabad from 2009 to 2011. The objectives of these studies were to control the pest by bio-intensive management methods and find an effective, safe and economical method/s for recommendation to the farmers. A Field experiment was carried to determine resistance or susceptibility of twenty genotypes of Bt-cotton against Jassid (nymph + adult) based on per seedling and per leaf population density count during 2009 and 2010 under field conditions. Laboratory experiments were carried out to study Physico-morphological and chemical plant characteristics with the objective to determine their effects on the population of Jassid. The results revealed that during preliminary field trials, the genotype Auriga-213 showed maximum Jassid populations, whereas the genotype IR-824 had zero population per seedling. Auriga-101 and MNH-886 possessed maximum Jassid populations per leaf (susceptible) whereas MG-06 showed minimum (comparatively resistant). During a final screening trial, the genotypes Auriga-101 and MNH-886 proved to be susceptible, AA-703 and MG-06 appeared as comparatively resistant, while BT-121 and CA-12 were intermediate based on both per seedlings and per leaf population density counts of Jassids. The maximum population of Jassid (nymph + adult) per leaf was recorded on August 01, 2009 and August 16, 2010. There was only one peak in both the study years. The HPSIs (Host Plant Susceptibility Indices) on an average basis during both years showed that Auriga-101 and MNH-886 were susceptible, whereas AA-703 and MG-06 showed minimum HPSI and proved comparatively resistant, based per seedling and per population density counts of Jassid per leaf. The results revealed that minimum temperature during 2009 exerted a positive and significant (P < 0.01) correlation with the Jassid population with a r-value of 0.667 while during 2010 maximum temperature had negative and significant correlation (P < 0.01) with the pest density on per leaf basis with a r-value of 0.558. Relative humidity and rainfall during 2010 and on cumulative basis of both the study years 2009 and 2010 resulted in a significant (P < 0.01) and positive correlation with the pest population. Multiple regression models reveal that minimum temperature during 2009 and 2010 and on cumulative basis of both the study years resulted in maximum impact, while maximum temperature during 2010 also exerted a reasonable contribution to the pest population. The results revealed that hair density on the plant’s midrib, vein and lamina had a negative and significant correlation, length of hair on midrib and vein had a non significant correlation while thickness of leaf lamina had a positive and significant correlation with the Jassid population per leaf. Gossypol glands on midrib and vein showed positive and significant correlation, while on lamina they had a negative and significant effect. Total minerals exerted positive and significant effect, whereas reduced sugar, calcium and manganese showed negative and significant correlation with Jassid density. Multiple linear regression models revealed that hair density on midrib and total minerals in the leaves were the most important characters. The minimum Jassid population was recorded to be 0.35 per leaf with maximum mortality of pest i.e. 88.59 % where all control methods were integrated together. The maximum population was recorded to be 2.22/leaf in those plots where Coccinella septumpunctata was released. The application of Spinosad 240 SC applied 18 singly and integrated with other control methods resulted in higher pest mortality. The results pertaining to seed cotton yield in kg/plot showed a significant difference among various control treatments. The maximum yield was recorded in those plots where all the control methods were integrated whereas yield was minimum where C. carnea was released. The maximum cost benefit ratio was calculated where Spinosad 240 SC was sprayed. The integration of all the control methods resulted in low CBR (Cost Benefit Ratio) due to increase in expenditure.
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