INDUCED GENETIC VARIABILITY IN QUANTITATIVE CHARACTERS OF COTTON PLANT BY USING MUTAGENS

Abstract

ABSTRACT •' The objective of this study was to test the induced variability in cotton jj traits as a result of using two tools: hybridization and mutagenic agents ii each alone and/or combined with the other tool. 1 Trials were conducted through three seasons (2000-2002) at ii Sakha Experimental Farm. A.R.C, Kafr EI-Sheikh Governorate, using ij Giza 86 and Giza 88 cotton cultivars in addition to their hybrid all treated by two doses (10 and 20 kr) of gamma ray (y) as a physical mutagen and two doses (200 and 250 ppm) of triethanolamine (T.E.A) as a chemical ,I U' mutagen. • IJ The characters studied were presented in five groups: (1) germinability, , survivality and plant fertility in the M1 only, (2) earliness characters: first fruiting node position and days to the first flower, (3) Vegetative growth characters included plant height (em) and number of vegetative branches, (4) Yield and yield components which comprised number of li' fruiting branches/ plant, boll weight (gm), seed index (gm). number of [ open bolls, seed cotton and lint yield/ plant (gm) and lint%, (5) fiber i properties including fiber length (mm), fiber fineness (micronaire reading) !1 and fiber strength (pressley mdex). " In the M2 induced variability was tested using some genetic !J constants: phenotypic variation_ (Vp). coefficient of phenotypic variability (P.C.V), genotypic variation (V9 , coefficient of genotypic variability II (G.C.V) and broad sense heritability (h2). Moreover, morphological mutants and high yielding mutant plants were selected in addition to the highest yielding controls and planted in the third season as the M3 plants to verify the stability of these mutations.

The results obtained could be summarized as follows: 1-ln the M,-generation both mutagens (y-ray and T.E.A) depressed most <> plant attributes tested in this study than the control. The depressive g I effect increased as the dose increased. _ 0

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2- Concerning fiber characters, for f1oer length (mm) y-ray treatments and the lower dose of T.E.A had stimulus effect on thi_s trait, while the

.J high dose of T.E.A depressed it. With respect to lint fineness expressed "" as micronaire reading, both mutagens increased the micronaire reading (lower fineness) than control. Fiber strength expressed as Pressley index, both mutagens gave higher Pressley index than the control. • 3- Genotypes exhibited significant differences for all studied traits and genotype x treatments interaction was significant for most tr its, as the different responses of genotypes to the mutagenic treatments