Inheritances of Fusarium Head Blight Resistance in a Cross Involving Local and Exotic Durum Wheat Cultivars.

Fusarium head blight (FHB) has recently become d major disease in durum wheat {Triticum turgiqum L. subsp. durum (Desf.) Husn. [syn. Triticum turgidum L. var. durum (Desf.) Bowden]} in Tunisia. Although partial resistance to FHB is found in durum wheat landraces, little is known about resistance genes and their effectiveness. lihe objective of this research was to evaluate potential resistance or tolerance to FHB using a cross between two partially resistant durum v~iheat cultivars, Divide, a North Dakota State University (NDSU) cultivar, and Tun7, a Tunisian landrace. Seven populations (P1, P2, F1, F2, F3, BC1, and BC2) were evaluated in the greenhouse. Percentages of infected spikelets (PIS) v~'ere evaluated at 7, 14, and 21 d postinoculation (DPI) and area under disease progress curve (AUDPC) and Fusarium-damaged kernels (FDK) were measured. Mean generations analysis indicated that dominance effect (h) and dominance x dominance epistasis effect (!) contributed largely to the expression of partial resistance to FHB as measured by the PIS observed at 7 DPI (h = -8,9 and I = 10.4), 14 DPI (h = -28 and I = 33.7), and AUDPC (h = -300.5 and! = 340). Vanànce components indicated that additive effect (d) and additive x additive epistasis effect (I) are predominant components in the disease development at 21 DPI (d 8.5 and I = -9). Additive effect (d) appeared to condition the expression of FDK (d = -3). Heritability estimates were 0.42 for PIS observed at 21 DPI and 0.84 for FDK. These results suggest that disease scoring at 21 DPI and FDK could be used to screen for FHB in early generations. [ABSTRACT FROM AUTHOR]