GENOTYPE-ENVIRONMENT INTERACTION STUDIES IN TOMATO (Lycopersicon esculentum MiLL) UNDER IN VITRO CONDITIONS
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Date
2000
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AAU, Anand
Abstract
Tomato (Lycopersicon esculentum Mill) is an important vegetable crop grown all over the world. Different in vitro techniques are widely attempted in this crop as an aid to conventional breeding. Exploitation of advanced in vitro techniques in this crop needs an efficient regeneration of a cell, tissue or organ into complete plant. Additionally, such a system is necessary for the possible improvement of tomato through transformation technique. Hence, present study was undertaken at Plant Tissue Culture Laboratory, Department of Plant Breeding and Genetics B. A. College of Agriculture, Gujarat Agricultural University, Anand Campus, Anand during 1998-2000, with a view to develop such system for few promising genotypes of tomato under advance evaluation at Vegetable Research Project, Anand. The objectives of the study were (1) to identify the best media for in vitro seed germination, (2) to identify the best explant and genotypes for callusing and organogenesis, (3) to study response of different phytohormones to organogenesis, followed by optimization of culture media for maximum regeneration of plantlets, (4) to study response of different phytohormones for shoot tip culture and induction of rooting and (5) to study acclimatization of in vitro raised plantlets. The characters studied were percentage seed germination, days to callus initiation, percentage callusing, fresh as well as dry weight of callus, callus colour, texture and intensity, biomass increase, number of shoots, length of longest shoot, days to root initiation, number of roots, length of longest root and percentage survival. Three explants viz. cotyledon and hypocotyl for callusing and organogenesis and shoot tip for shoot tip culture experiments were used from 15 days old aseptically grown seedling of four genotypes viz., Pusa Ruby, Junagadh Ruby, ATL-11 and ATL-16. MS (1962) and its modifications, LS (1965) and White's (1963) were used as basal media with addition of various levels of different growth regulators viz., lAA, NAA, BA, IB A, Z and Kn. Vitamins free MS (1962) basal medium appeared as best media for germination of all four genotypes with higher percentage germination (84.17%). Among the lAA : BA and NAA : BA combinations, lAA : BA was found superior for callusing and organogenesis. Hypocotyl exhibited significantly superior performance over cotyledon explant for days to callus initiation, percentage callusing, fresh and dry weight of callus, biomass increase and length of shoot whereas, cotyledon was found better for number of shoots. Significant differences among the genotypes and environments for most of the characters using both the explants indicated genotype specific response to various growth media. Significant G x E interactions suggested that genotypes were highly influenced by differences in growth media with respect to callus initiation, number and length of shoots. In general, all genotypes performed better on MS + 0.1 mgl-1 IAA + 0.25 mgl-1 BA and MS +0.2 mgl-1 IAA + 0.5 mgl-1 BA for callusing and organogenesis, respectively.
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PLANT BREEDING AND GENETICS, AGRICULTURE, A STUDY