Abstract

                                The genetic basis of lint production in Asiatic cotton is extremely wide and is governed by a number of genes. Occurrence of lintless types in Asiatic cottons has made it possible to identify some of the genes responsible for lint production. So far, eight lintless mutants have been noted and their genetics studied. Hutchinson and Gadkhari (1937) recognised two types of behaviour which resulted in lintlessness. In the most extreme case, the whole hairiness mechanism of the plant is disturbed including production of lint hairs, resulting in glabrous lintless types. This is governed by two recessive genes ha and h, which are, however, complementary to each other for development of hairiness. In the second case, plant body hairs develop normally but the production of lint hairs is controlled. A number of recessive genes like lia, liu, lid. lie and li have been identified to be responsible for the hairy lintless types. Ramiah and Kaiwar (1942) from further studies in the genetics of lintlessness in Asiatic cotton, recognised a third type of behaviour which brings about a general reduction in the growth rate from flowering time onwards and the arrest of lint development happens to be one of the effects of this gene. The gene responsible for this pleotropic effect was found to express dominance. This was located G. arboreum race bengalense and was called the Punjab Hairy Lintless (Afzal and Hutchinson, 1933). The genetical relationship of this dominant mutant gene with other lintless mutants has been studied by Gadkhari (1950) and Krishnamurthy and Ramachandran (1964). During a survey of Coconada Tract, a number of mutants affecting lint quantity and quality were located in the indicum race (Balasubramanian, et al 1946). CST-1 (Coconada Survey Type 1) is a short linted type governed by a recessive gene lish (Balasubramanian and Santhanam, 1952). CST-4 is an immature linted type governed by a recessive gene In (Balasubramanian et al 1950). A sparse linted mutant, 1711, is governed by a recessive gene lisp (Balasubramanian and Santhanam, 1950). A study on the genetical relation- ship of these three mutant types with the Punjab Hairy Lintless type was taken up and the results are presented in this paper.

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