| Gene action effects in wheat under different soil fertility
levels A.J. MALIK, A.R. CHOWDHRY1 and M.M. RAJPUR Dept, of Plant Breeding & Genetics, Sind Agr. Univ. Tandojam, Pakistan Grain yield and most of the yield components are complex characters and are polygenic (BHATT 1973, SINGH 1978, RAO 1977), and manifestation of these characters is greatly determined by interaction of genotype and the environment complex in which these develop (ANTOUN 1977, KUMAR 1979). As such, various studies on the nature of gene action have invariably reported a preponderance of additive effects for yield and the components of yield, although non-additive effects were also important in several cases (BHULLAR et al. 1979, ALI & EL-HADDAD 1978, JAIN & SINGH 1976). ALLARD (1956) and TSIL'KE et al. (1979) emphasised the usefulness of diallel crosses for investigating the effect of environment on the component of genetic variation. These components were shown as environments, dominance, array, environment x dominance, environment x array, and dominance x array and that significance of first five parameters was of great use in such studies. Furthermore the technique provides information right in early generation on the genetic mechanism controlling the phenotypic expression of plant characters. The present studies, therefore elucidates information on the gene action mechanism controlling the differential response of various wheat varieties to higher doses of Nitrogen application Materials and Methods A 4 x 4 diallel cross on wheat under two nitrogen fertilizer levels, 90 1bs. and 180 1bs. N per acre was conducted in the department of Plant Breeding and Genetics, Agricultural University Faisalabad. The data for F1 and F2 and parents was recorded on the following characters. KERNELS PER SPIKE : Kernels per spike were determined by actual counting of the seeds per spike. 100 KERNEL WEIGHT : 100- Kernel weight in grams was measured with Mettler's balance upto two dicimal places from three 100- grain samples at random from the bulk produce of each plot. GRAIN YIELD : Grain yield per plant in grams was estimated by dividing the total weight of grains from each plot by the number of harvested plants in the plot. The analysis of gene action for the diallel crossing system was done using the technique developed by HAYMAN (1954) and JINKS (1954, 1955, 1956) and used by WHITEHOUSE et al. (1958) for genetic analysis. |
| 1 Dean, Faculty of Agriculture, University of Agricultue Faisalabad. (Pakistant) |
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