Pattern of quantitative inheritance of yield and component traits in opium poppy (Papaver somniferum L.)

Generation mean analysis of cross NB-5x58/1 and its reciprocal cross was carried out to understand the nature of gene action in opium poppy. The significance of A, B, C and D scaling tests indicated presence of non-allelic interaction in the inheritance of traits except capsule size and husk yield/plant for reciprocal cross. Additive as well as dominance components of gene action were found in both the crosses. Most of the traits had greater non fixable dominance ?h? and dominance x dominance effects ?l? than fixable additive (d) and additive x additive effects (i) except leaves/plant, branches/plant, capsules/plant, stem diameter, capsule weight/plant, husk yield/plant, opium yield/plant, codeine and narcotine content which showed greater importance of additive (d) and additive x additive effects (i) effects. Inter-mating of the best parents, diallel selective mating or biparental mating in early segregating generations followed by recurrent selections were suggested for genetic improvement of opium poppy.

Estimation of genetic variance and allied parameters through biparental mating in opium poppy (Papaver somniferum L.)

Genetic variances and allied genetic parameters were estimated for eight economic traits through biparental mating designs in two populations: (i) a local land race, and (ii) a segregating F2 population of Indian opium poppy. Estimates of additive variance were larger than the dominance variances (o2A > o2D) or environmental variance (+-R > n�2) for the majority of the eight traits examined. Narrow sense heritability (h2NS) estimates were high (60-89%) for five traits, moderate (28.3%) for peduncle length and low (< 13%) for capsule index and morphine content in the local land race, and high (57-93%) for all the eight characters in the F2 population. Average degree of dominance in the local population leaned heavily towards overdominance (G > 1 .O) for six charcters (four in negative and two in positive directions) and towards partial dominance (G < 1.0) for the remaining two traits: latex yield and flowering time (both in negative direction). Accordingly, combination breeding for latex yield and flowering duration, (F1) hybrid breeding for seed yield, morphine content and capsule number and/or population breeding for other traits, were suggested for rapid genetic improvement of opium poppy.

Linked digenic epistasis in the inheritance of tillering and yielding ability in a cross of wheat

The nature of genetic variation in an intervarietal cross ('WG 377' × 'Sonalika') of bread wheat (Triticum aestivum L. em Thell.) was determined for grain yield and tillers per plant by analyzing 21 generation means and 36 family variances. For both traits, duplicate epistasis of linked loci in the pairs and gene dispersion was observed through the analysis of 21 generation means. The analysis of generation variances further suggested repulsion phase linkages for the gene pairs. The additive genetic component was significant for both traits in each of the analyses. Prevalence of gene dispersion suggested the possibility of high transgressive segregation. However, the task of exploiting additive genetic variation would be difficult because of duplicate epistasis and repulsion phase linkages. Considering these results a breeding procedure like biparental mating among a large number of superior F2 plants which encourages crossing-over is suggested.Key words: Triticum, linked epistasis, quantitative traits, additive effects, tillering.