Leaf blade nutritional quality of rhodes grass (Chloris gayana) as affected by leaf age and length

Abstract

A greenhouse experiment was performed to determine the effect of leaf age and length on neutral detergent fibre (NDF) and in vitro NDF digestibility (NDFD) during a vegetative regrowth of Chloris gayana. Dense micro swards were grown in two plots under non-limiting conditions of water, phosphorus and nitrogen. Plants were harvested at seven consecutive leaf appearance intervals. Leaf blades were dissected from individual tillers and separated into five age categories (from early growing to pre-senescence). Leaf blade and sheath length were measured and leaves of the same category were bulked for NDF and NDFD analysis. The leaf lifespan (LLS) was determined in 15 marked tillers per plot. Linear and curvilinear functions were used to describe the relationships between NDF and NDFD with leaf age and length. The NDF concentration increased until half of LLS, concomitantly with leaf expansion, and remained stable thereafter. However, NDFD declined curvilinearly through the complete LLS. The final length of consecutively formed leaves increased through regrowth, this change being associated with an increase in NDF and a decline in NDFD. Results were consistent with previous findings for temperate species and highlight the importance of leaf length, in addition to leaf age, to determine leaf blade digestibility.