THE VALUE OF TRIPLOID, TETRAPLOID, AND HEXAPLOID NAPIER GRASS DERIVATIVES AS BIOMASS AND (OR) FORAGE

Pennisetum purpureum Schum. (Napier grass or elephantgrass) and hybrid s of P. glaucum (L.) R. Br. (pearl millet) x P. purpureum have been ev aluated for in vitro organic matter digestibility (IVOMD), neutral det ergent fibre (NDF), lignin, crude protein (CP), and biochemical methan e potential (BMP). Objectives of the study were to determine if the se lected lines differed, and also how the plant components were differen t. Although Napier grass and the triploids and hexaploids derived from crosses to pearl millet have high biomass production, the quality of the feedstock is variable. To understand how plant components (leaf bl ades, sheaths, stems, and meristematic regions) differ in forage quali ty, four Pennisetum lines were harvested at four different dates. The meristematic zone (tissue above and including the most recent fully ex panded leaf blade) was always the highest in IVOMD and CP (673 and 148 g kg-1), with declining IVOMD and CP values for blades, stems, and sh eaths. Bottom sheaths were consistently lowest in both IVOMD and CP (3 54 and 29 g kg-1). Large differences in quantity of stem and leaf mate rial and their ratios were observed between lines tested, but the qual ity of the various components from the triploid, tetraploid, and hexap loid lines were very similar.