Dynamics in tiller weight and its association with herbage mass and tiller density in a bahia grass (Paspalum notatum) pasture under cattle grazing

Abstract

Dynamics in tiller weight and its association with herbage mass and tiller density were investigated for 2 years in a bahia grass ( Paspalum notatum ) pasture under cattle grazing, in an effort to char- acterise the dynamics in tiller weight and its com- ponents (live laminae, dead laminae and stem with leaf sheaths), to compare contributions of tiller density and tiller weight to herbage mass and to examine the existence of the self-thinning rule in bahia grass. Tiller weight (range=67-257 mg DM/tiller) was high from late spring (May) to mid-autumn (October) and low in the other half of the year. The rate of change in tiller weight (range= − 4.28 to 4.31 mg DM/tiller/d) reflected high positive rates of change in live lamina weight in April-May and high negative rates of change in stem weight in October-November. The high positive rates in April-May represent a spring flush achieved by consuming reserve substances in stolons and roots as the main energy pools. The high negative rates in October-November may indicate the transloca- tion of reserve substances stored in stems during summer into stolons and roots before the dormant winter season. Variations in herbage mass (range=23-560 g DM/m 2 ) were largely explained by the variations in tiller weight, with no sig- nificant contribution by tiller density (range=3859-4875 tillers/m 2 ). The tiller weight:density relationship, when combined with previous data having a broader range of tiller density, was in close agreement with the − 3/2 self-thinning rule (slope= − 1.63).