Inheritance of manganese efficiency in durum wheat

Manganese (Mn) deficiency is a widespread problem on the alkaline soils, particularly for durum wheat (Triticum turgidum L. var. durum), which is more sensitive than either bread wheat or barley. The existence of considerable genetic variation in current germplasm of durum wheat (a relative yield of 58% in Stojocri 2 compared to 15% in check cv Yallaroi) and the development of a consistent selection criterion (Mn content of 35-day-old seedlings) has made breeding for Mn efficiency feasible. The development of Mn-efficient durum wheat would be facilitated if the mode of inheritance was well understood. F1 hybrid, F2, and F2-derived families from a cross between Stojocri 2 (moderately efficient) and Hazar (inefficient) were studied under controlled-environment conditions. F1 hybrid was intermediate to the parents, indicating incomplete dominance and dependence on external Mn concentration. Analysis of 110 F2 and 220 F3 single plants (including 20 F2-derived F3 families) showed that the observed variance was in agreement with the expected variance of a population segregating for two genes. Chi-square analysis of the segregation ratios of F3 families also supported the digenic segregation hypothesis. Currently Stojocri 2 is used in a breeding program for the transfer of Mn efficiency to commercial varieties, by backcrossing (two backcrosses retain about 88% of recurrent parent genotype).