STABILITY OF FORAGE YIELD AND QUALITY IN PEARL-MILLET HYBRIDS HETEROGENEOUS FOR RUST RESISTANCE

The susceptible pearl millet hybrid 'Tifleaf 1', the resistant hybrid 'Tifleaf 2', and two experimental 3-way hybrids with different proport ions of resistant and susceptible plants were evaluated for rust resis tance and forage yield and quality in 1990, 1991, and 1992. Different environmental conditions were obtained by varying planting date, plant ing density, and fungicide applications across three years of evaluati on in the field. Rust severity of forage was negatively correlated wit h late season green yield, dry matter yield, in vitro dry matter diges tibility, and digestible dry matter yield. The stability across enviro nments of the 3-way hybrids was intermediate between resistant 'Tiflea f 2' and susceptible 'Tifleaf 1' for rust severity and the yield and q uality measurements negatively correlated with rust severity. Mixtures of resistant and susceptible plants would probably provide greater co ntrol of rust than measured in these small-plot experiments. Although a mixture of resistant and susceptible plants appears to provide an al ternative to monogenic control of rust in forage pearl millets, identi fication and utilization of additional sources of resistance would be beneficial to improve the performance of 3-way hybrids.