| Estimation of heterosis in wheat populations derived
from intercultivaral hybridization A.S. LARIK, H.M.I. HAFIZ* and A.M. KHUSHK Department of Plant Breeding and Genetics, Sind Agriculture University, Tandojam, Pakistan With the realization of the possibility of producing hybrid seed on a large scale considerable emphasis has been given to the exploitation of heterosis in self-pollinated crops (BEHL 1985) and has been the object of considerable study as a means of increasing productivity of wheat (Triticum aestivum L.). It is now well established that heterosis does occur with proper combination of parents and is the result of allelic or non-allelic interaction of genes under the influence of a particular environment. Although the reports on yield heterosis in bread wheat are available (BEHL 1985, AL-SAHEAL & GAMIL 1981, UDDlN & JOARDER 1986) but the data for superiority over commercial check are scarce. Hence the present study was initiated to elucidate the nature and magnitude of heterosis over better parent and commercial check in wheat populations derived from intercultivaral hybridization. Materials and Methods Seeds of four cultivars (Pak-70, Sonalika, Pak-81 and T.J.-83) selected on the basis of diversity for their various economic traits alongwith F1 seeds of their crosses were grown during winter 1985-86 in a randomized complete block design with three replications at the Botanical Garden, Department of Plant Breeding and Genetics, Sind Agriculture University, Tandojam, Pakistan. The sub-plots had 3.5m long five rows. The seeds were planted at commercial sowing density, i.e., at distance of 15 cm plant to plant and 30 cm row to row. Standard cultural practices were followed throughout the growing season. Eight pre- and post harvest characters were recorded on 20 random plants in each entry (Table 1). Heterobeltiosis and "Commercial heterosis", i.e., heterosis over regional check (Pak-70) were calculated for each character separately. Results and Discussion Deviation from mid parent values signifies the expression of heterosis, but in our study the main aim was to define heterosis in terms of net economic gain. So the evaluation was carried out in comparison with better parent and the commercial check Pak-70. Mean performance of the parents and their F2 hybrids is presented in Table 1. Heterosis for days to flowering and days to maturity was low and negative. This is expected as heterosis for these traits have mostly been reported for either photoinsensitive or qualitatively photosensitive crops (BANGA & LABANA 1984). Wheat on the other hand, is quantitatively photosensitive crop which flowers when the total photoperiodic requirements are met. All the hybrids flowered and matured earlier than their parents. Hybrid Sonalika x Pak-70 matured 9.53 days earlier than their better parent (Table 2). It appeared that due to interaction of genes and partial dominance, the hybrids matured earlier. |
| * Department of Botany, New Campus, Punjab University, Lahore, Pakistan |
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