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CHARACTERIZATION AND INHERITANCE OF COTTON LEAF PUBESCENCE

N. N. NAWAB¹, I. A. KHAN¹, A.A. KHAN¹ AND M. AMJAD²

Abstract: Upland cotton (Gossypium hirsutum L.) genotypes have varying densities of trichomes on the leaves. Absence of trichomes increases the attractiveness of the cotton plant to some major insect pests, thus increasing the reliance on pesticides. Leaf trichome density was quantified by two methods. Qualitative grading system is based on the visual examination of the relative density of the abaxial trichomes. Quantitative measure system counts the total trichomes in a specific unit area. Number of trichomes defined a total number of trichomes and trichome branches. Analysis of variance revealed significant variation for number of leaf trichomes in all the 6 generations of the 3 crosses. The segregation pattern for trichome counts in F₂ generations indicated the discontinuous variation, which confirmed the qualitative nature for this trait. The leaves tended to become less hairy as they approach towards maturity and moreover, cotton leaf trichome counts decreased from the apex to the bottom of the same plant canopy not only in the parental populations as proposed earlier but also progressed in the similar fashion in different genetic backgrounds, which meant that the transference of the gene for hairiness in different genetic backgrounds may not effect the pattern of hairiness. There existed a strong relationship between leaf pubescence ratings and trichome counts, indicating its sound morphological basis which is a step forward in the direction of research on trichomes.

¹Department of Plant Breeding and Genetics, ²Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Pakistan.