PJB-2012-296
ESTIMATION OF COMBINING ABILITY IN F2 POPULATION OF UPLAND COTTON UNDER DROUGHT AND NON-DROUGHT REGIMES
MUHAMMAD HUSSAIN SOOMRO1*, GHULAM SARWAR MARKHAND1 AND AMEER AHMED MIRBAHAR1,2
Abstract
A six-by-six complete Gossypium hirsutum L., diallel cross was evaluated for general and specific combining abilities in F2 generation during 2006 under drought and non drought conditions at Shah Abdul Latif University Farm, Khairpur. The characters considered were plant height, leaf area, leaf fresh weight, leaf dry weight, number of leaves per plant, number of sympodial branches per plant, number of bolls per plant, boll weight and seed cotton yield per plant. Irrigation treatments were three; normal seven irrigations schedule upto 150 days of crop maturity, four irrigations (medium stress) upto 150 days of crop maturity and two irrigations upto 150 days of maturity (stress conditions). General and specific combining ability analysis revealed that the mean squares for GCA and SCA were significant for all the characters under all the irrigation treatments. The general combining ability estimates of parents for all the characters under study and under all the irrigation treatments were highest for CRIS-134 except for boll weight under four irrigations where CRIS-52 excelled all the parents. Similarly, CRIS-9 followed CRIS-134 in GCA estimates scoring, and ranked second in all irrigation treatments and for all the characters except for boll weight under seven irrigations (where MARVI was second highest), under four irrigations here CRIS-110 was second highest) and under two irrigations where CRIS-52 was second highest. Thus GCA estimates of parents for boll weight are affected by drought conditions and therefore in the selection of desirable parents to give desirable combinations for boll weight, only those combinations be selected with highly significant difference for boll weight towards bigger boll size. Testing of such combinations is recommended to continue upto F5 and F6 generations to get homogeneity of high performing lines/advance strains. As regards to specific combining ability estimates, hybrid CRIS-9 x CRIS-134 gave highest SCA value of 11.54 for seed cotton yield under seven irrigations treatment, while CRIS-9 x CRIS-191 gave highest SCA value of 9.91 under four irrigations treatment for seed cotton yield. Under stress conditions (two irrigations), CRIS-9 x CRIS-134 gave highest SCA value of 12.35 for seed cotton yield. As the seed cotton yield is the main and important attribute for almost all the stakeholders, therefore it is suggested that the particular hybrid CRIS-9 x CRIS-134 may be produced which in present study, has been isolated to give highest SCA values under normal as well as under drought conditions (only two irrigations).
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