Effect of Weed Control Management on Herbage Yield, Quality and Wintering Ability in the Established Dwarf Napiergrass (Pennisetum purpureum Schumach)

Abstract

In our previous extension activity of dwarf variety of late-heading type (DL) napiergrass (Pennisetum purpureum Schumach) to southern Kyushu, weed control was found to be a crucial factor for obtaining good establishment and considerable herbage dry matter (DM) yield in an established year. The objective of this study was to examine the effect of several weed control practices, i. e. mixed sowing of annual setaria, which has no regrowth ability in stem-elongated tillers, paper-mulching and hand-weeding, compared with no weeding control on DM yield, quality and wintering ability of this species in 2008 and 2010. Growth attributes including herbage yield, in vitro DM digestibility (IVDMD) and crude protein (CP) content as herbage quality and percentage of overwintered plants (POP) as wintering ability of this species were determined in both years. Weed control practices had a significantly (P < 0.05) positive effect on plant height, tiller density, percentage of leaf blade and leaf area index in DL napiergrass, compared with no-weeding control, and paper-mulching had the highest yields in both years and highest POP at 100% in 2008-2009. Setaria-sowing had a partially mitigating effect of weed damage on growth of DL napiergrass, while additive DM gain from setaria could compensate the yield decrease in DL napiergrass. Neither IVDMD nor CP was affected by any weed control practice in either year. Thus, paper-mulching and annual setaria-sowing could be a good proposal in weed control management of DL napiergrass.