| I. Research Notes Expression of heterosis and combining ability for grain protein in a diallel wheat cross I. MIHALJEV, B. VULIC and Mirjana DJOLAI Faculty of Agriculture, Novi Sad, Yugoslavia Improvement of the nutritional value of common winter wheat by breeding new varieties or creating hybrid wheat, which is one of the main tasks in many wheat breeding programmes, requires good knowledge and data on expression of heterosis and combining ability for grain protein content, since the protein content in wheat grain is an important constituent in determining the nutritional quality of wheat. The purpose of the present study was to investigate heterosis and combining ability for protein content in wheat grain and to evaluate parents and F1 hybrids in two different environments (two years), as well as to relate the findings to breeding practice. Materials and Methods Three winter wheat varieties Sava, Bezostaja-1 and Kavkaz, and one spring wheat variety Cajeme 71 were crossed by hand in a diallel system excluding reciprocals in 1972 and 1974. The wheat varieties were chosen on the basis of both assumed genetic differences for grain protein content and genetic diversity of origin. In each of the six possible cross combinations enough seed was produced to set up a replicated trial with normal sowing density. The four parental varieties and the resulting six F1 hybrids were grown in field in a randomized complete block trial with three replications during 1973 and five replications during 1975. The plot unit was one row, 1 m long with 0,2 m between rows. An standard agricultural practice was applied. In each year the trial was hand harvested and the seeds from all the plants of the F1 hybrids and parental varieties in each replication were mixed to form a composite sample. Protein percentage determinations were made on all samples by a colorymetric method using the apparatus Prometar MK-2. Combining ability variances and effects were obtained by analysing the diallel table following GRIFFING (1956), method 2, model 1. |
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