Studies on biochemical and morphological parameters of Bt cotton against sucking pests
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Date
2016
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CCSHAU
Abstract
The present study was conducted at Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana (India). The data on the population/incidence of cotton whitefly revealed that whitefly crossed it's economic threshold level on all the 23 genotypes of cotton during kharif 2014 and 2015. The maximum adult population of whitefly was recorded at 34th SMW and 31st SMW during 2014 and 2015, respectively. The maximum mean incidence was recorded in Western Niroga 151 BGII (45.95 adult/leaf) and 49.70 adult/leaf during 2014 and 2015, respectively. Mean leafhopper population, on all the 23 genotypes was ranged from 0.78-3.76 and 1.07-2.78 nymph/leaf during 2014 and 2015, respectively. During 2014, the peaks were observed on 28th, 33rd and 37th SMW, whereas two peaks are recorded during 2015 i.e. 29th and 35th SMW. Genotype H 1226 had 0.78 and 1.07 nymph/leaf during 2014 and 2015, respectively. The thrips population was commenced at 27th SMW and 25th SMW during 2014 and 2015, respectively. The peak incidence of thrips population was recorded on 33rd and 31st during 2014 and 2015, respectively. All the sucking pests’ population was higher in Bt hybrids. Whitefly and leafhopper population are significantly and negatively correlated with the maximum temperature while significant and positive correlation showed with morning relative humidity, whereas evening relative humidity significantly and positively correlated with whitefly, during 2014. During 2015, whitefly, leafhopper and thrips significantly and positively correlated with the minimum temperature, morning and evening relative humidity while maximum temperature was significantly and negatively correlated with whitefly and thrips population. The morphological parameters viz., leaf area, vein intensity and leaf thickness correlated significantly positive with adult population of whitefly at 60 and 90 DAS, respectively and midrib hardness at 45 DAS while significant negative with leaf hardness at 60 and 90 DAS, respectively. Leafhopper was significant positively correlated with midrib thickness at 60 and 90 DAS. However, significant negatively correlation was present between leafhopper and midrib thickness at 45, 60 and 90 DAS. Similarly ventral surface trichome and dorsal surface trichome length was significant negatively correlated with the leafhopper. Thrips was correlated significant positively with midrib thickness and significant negative with ventral surface trichome length at 60 and 90 DAS. Correlation coefficient of the biochemical parameters viz., sugar content and reducing sugar was significant and positive with the whitefly population at 60 and 90 DAS while significant negatively with gossypol content at 45 and 90 DAS and tannin content at 45 DAS. Leafhopper population correlated significantly negative with the gossypol content and tannin content at 30 DAS while significant positively with chlorophyll a, chlorophyll b and total chlorophyll at 30 DAS.
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