Factors affecting the growth of kikuyu. I. Potential growth and nitrogen supply

Abstract

The potential growth of kikuyu (Pennisetum clandestinum) with ample supplies of water and fertilizer, and the effect of varying nitrogen supply, were estimated from field measurements of growth rate. A model, incorporating the effects of light interception, temperature and nitrogen supply, was used to account for variation in canopy development and temperature under field conditions. The model predicted a peak growth rate of 234 kg DM ha-1 day-1 by a well-fertilized kikuyu sward with a yield of 3590 kg DM ha-1 (LAI = 5.4), and grown at maximum/minimum temperatures of 32.0/23.9¦C. Growth was not limited by the nitrogen supply, provided that the nitrogen concentration of recently grown foliage exceeded 3.5%. However, at lower concentrations, assimilation (net growth plus an allowance for maintenance respiration) declined by 36% per unit decline in nitrogen concentration.