Effects of Rust on Yield and Quality of Pearl Millet Forage1

Abstract

Rust (Puccinia substriata var. indica) occurs on pearl millet [Pennisetum americanum (L.) Leeke] in most years. Visual effects of the rust are severe, ranging from death of young plants from early infection to premature desiccation and/or death of leaves with later infection. There is a lack of quantitative data on the effects of rust on yield and quality of pearl millet. This study was initiated to assess the effect of rust on yield and quality of individual resistant and susceptible plants. Comparisons of 205 resistant with 173 susceptible plants showed significant reductions in dry matter (DM) concentration, DM yield, and in vitro dry matter digestibility (IVDMD) in diseased plants. The combined effects of lower yields and lower IVDMD led to a mean 51% reduction in digestible dry matter yield from the infected plants. The yield of leaves was reduced less by rust than was the yield of stems, but the opposite was true for IVDMD concentrations. Total sugars in the forage of infected plants were 64% less than in forage of resistant plants. Crude protein concentration was slightly higher in diseased plants. The results clearly demonstrated the benefits to be derived from incorporation of rust resistance into existing or new cultivars of pearl millet.