THE GROWTH PATTERN OF CORN IN RELATION TO RESISTANCE TO ROOT AND STALK ROT

Abstract

Single-cross hybrids resistant to root and stalk rot generally had greater growth rates, leaf areas, and stalk densities than susceptible single crosses. Differences in dry weight of tops were evident by the time of silk emergence and these differences became more pronounced as the hybrids approached maturity. Susceptible hybrids were characterized by a cessation of vegetative growth at pollination and a rapid senescence of leaves at or shortly after physiological maturity. Hybrids resistant to root and stalk rot were characterized by a continued increase in vegetative dry matter for several weeks after pollination, resulting in relatively heavy lower stalks and a high ratio of vegetative tissue to grain. The density of pith tissue from the lower stalk at physiological maturity was negatively correlated with subsequent stalk rot incidence.