JOURNAL OF AGRICULTURE & SOCIAL SCIENCES 1813–2235/2005/01–4–313–315 http://www.ijabjass.org Genetic Behaviour and Analysis of Quantitative Traits in Five Wheat Genotypes M. FAISAL ANWAR MALIK, SHAHID IQBAL AWAN 1 AND SHIRAZ ALI Barani Agricultural Research Station, Fatehjang 1 Corresponding author’s email: shahid1857@yahoo.com ABSTRACT General combining ability (GCA), specific combining ability (SCA) and reciprocal effects were computed from all possible crosses of five widely adapted local wheat varieties viz., Maxipak 65, Pak. 81, Potohar 93, Kohistan 97 and Margalla 99. Mean squares for all characters were highly significant. Mean squares for GCA were highly significant for plant height and number of tillers per plant, significant for days to flowering, spike length and number of spikelets per spike while non- significant for flag leaf area, days to maturity, 1000-grain weight and grain yield per plant. However, mean squares for specific combining ability and reciprocals were found to be non-significant for all the characters studied. All investigated features were determined by additive gene action. Margalla 99 was the best general combiner for most of the traits studied, while the cross Pak. 81 x Margalla 99 proved to be the best specific combiner. Key Words: Trticum aestivum; Specific combining ability; General combining ability; quantitative traits INTRODUCTION Improvement in crop plants depends upon the extent of genetic variability present or induced through hybridization and other methods. As the new variability for the quantitative traits is generated it is likely to alter the pattern of variability of its component traits as well. So it is very important for the development of productive cultivars that the estimates of combining ability, type of gene action and magnitude of genetic variances for various plant characters in a particular set of a cross are known. This information provides a guideline for selecting elite parents and desirable cross combinations which could be taken forward to later segregating generations for the development of new cultivars. The technique of combining ability is being utilized by many research workers to predict the behavior of cross combinations in segregating generations Khaliq et al. (1991) stated that GCA and SCA variances were significant while Sattar et al. (1992) reported that additive gene effects were more prominent for yield and yield components Kalwar et al. (1995) indicated that GCA variances were significant for grain yield and highly significant for plant height Bhutta et al. (1997) indicated the preponderance of additive type of gene action for flag leaf area Mahmood and Chowdhry (2000) reported that the parents LU 26S and 4072 were good general combiners for traits like flag leaf area Saeed et al. (2001) reported that about 67% of the hybrids showed positive SCA effects for flag leaf area and number of tillers per plant Mahmood and Chowdhry (2002) showed that the additive variance was greater than dominance one for flag leaf area, tillers plant 1 , 1000-grain weight and grain yield plant 1 . The present studies were conducted to determine the combining ability estimates of parents and to ascertain the type of genetic mechanism involved in the expression of yield related traits. MATERIALS AND METHODS To evaluate the combining abilities of different wheat varieties, studies were carried out at Barani Agricultural Research Station, Fatehjang during the year 2003-04. The experimental material comprised of five wheat varieties viz; Maxipak 65, Pak. 81, Potohar 93, Kohistan 97 and Margalla 99. The varieties were sown and crossed in all possible combinations. The F 1 seed along with their parents were sown in randomized complete block design with three replications. Three rows of five-meter length served as experimental unit keeping row-to-row and plant-to-plant distances of 30cm and 20cm respectively. The data were recorded from ten randomly selected plants from each experimental unit for various plant characters like flag leaf area, days to flowering, days to maturity, plant height, number of tillers per plant, spike length, number of spikelets per spike, 1000-grain weight and grain yield per plant. The means of the selected plants were analyzed for each trait using standard method of Steel and Torrie (1984). Parameters exhibiting significant differences among genotypes were subjected to combining ability analysis by using Griffing’s Method I, Model II (1956). RESULTS AND DISCUSSION The data revealed that mean squares for general combining ability were greater than the mean squares for specific combining ability and reciprocals for all the