Dry matter production and in vitro dry matter digestibility of tillers among napiergrass (Pennisetum purpureum Schumach) varieties

Abstract

AbstractDry matter production and in vitro dry matter digestibility (IVDMD) of tillers in napiergrass (Pennisetum purpureum Schumach) were compared in twice‐cut field‐grown plants among three varieties with variable plant types, that is, Wruk wona of the tiller weight type, Taiwan A146 of the tiller number type and Merkeron of the intermediate type. The effect of the late July and the early September first cutting dates was also compared. Changes in the length and dry matter weight (DMW) of each tiller were investigated every month with some canopy structural characteristics and the IVDMD of the leaf blade (LB) and stem with leaf sheath (ST) of the harvested sample were determined at both the first cutting and the second cutting in early November. Annual total of herbage dry matter yield (HDMY) and in vitro digestible dry matter yield were the highest in Wruk wona, followed by Taiwan A146 and Merkeron in both cutting dates and the effect of the first cutting date on HDMY was dependent on plant type. The first cutting for the tiller weight type of Wruk wona should be favorable in early September due to the highest first‐cut HDMY, derived from the vigorous growth in each tiller. For the tiller number type of Taiwan A146, cutting was favorable in late July, due to the highest second‐cut HDMY by the largest number of regrown tiller. The DM production at the first and second cuttings positively correlated with leaf area development, mediated by the emerged individual leaf area on the tillers at the first cutting and by the tiller number on which several leaves attached at the second cutting. The IVDMD tended to be negatively related with DMW in both LB and ST of each tiller in each variety and this tendency reduced the varietal difference in IVDDMY, compared with that in HDMY.