Inheritance of Resistance to Head Smut Disease in Corn

Abstract

The inheritance in corn (Zea mays L.) of resistance to head smut disease incited by Sphacelotheca reiliana (Kuhn) Clinton was studied in the field on crosses of resistant dent corn line N6 with two susceptible sweet corn (su1) inbred lines. Disease incidence in the resistant parent (Pr) was 0% to 4%, and 83% to 96% in the susceptible parent (Ps). Predisposition of seedlings by clipping just above ground level increased percent infected in progeny populations by as much as 4-fold, but did not affect disease incidence in the, parents. At the lower disease incidence of unclipped plots, the F1, F2, and BCr means were close to the mean of Pr, suggesting dominance of resistance. At the high disease incidence of clipped plots, the relationship of parent and progeny means “suggested additive inheritance. Epistasis was also generally present with a higher level indicated for unclipped plots. Inheritance was concluded to be quantitative. Reciprocal differences were observed only in backcrosses. In the F2 and BCs populations, plants grown from dent (Su1) seed were lower in disease incidence than plants grown from su1 seed.