Tropical Grasslands (2000) Volume 34, 7–13

Effects of nitrogen fertiliser rate and cutting height on leaf appearance and extension in bahia grass (Paspalum notatum) swards

M. HIRATA

Grassland and Animal Production Division, Faculty of Agriculture, Miyazaki University, Miyazaki, Japan

Abstract

An experiment was conducted to investigate the effects of N-fertiliser rate and cutting height on leaf appearance rate (LAR) and leaf extension rate (LER) of bahia grass (Paspalum notatum) swards in the low-altitude region of southern Kyushu, Japan (humid, subtropical climate). The swards were subjected to 4 rates of N (0–400 kg/ha/yr) and 4 cutting heights (2–17 cm above ground level). LAR was highest in April (spring), decreased in May, and levelled off until October, then decreased in November (late autumn). The correlation between LAR and air temperature was not significant (r = 0.378, P > 0.05). LAR increased only with the lowest cutting height. Increasing N rate slightly raised LAR. The leaves extended when they were the first to third-youngest leaves. LER was highest in June–August and lowest in November, resulting in a significant correlation with air temperature (r = 0.778, P < 0.05). LER increased as N rate and cutting height increased. Leaf size (LER per tiller/LAR) was high for May–August, and positively associated with N rate and cutting height. These results have been useful in understanding the mechanisms behind the dynamics in canopy structure and herbage quality in bahia grass swards, though further studies for collecting information on other morphogenetic components of sward are necessary to obtain a deeper understanding.

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