New Zealand Journal of Agricultural Research abstracts
Effect of spring grazing management on perennial ryegrass
and ryegrass-white clover pastures
2. Tiller and growing point densities and population dynamics
A. HERNÁNDEZ GARAY1
C. MATTHEW
J. HODGSON
Department of Plant Science
Massey University
Private Bag 11-222
Palmerston North, New Zealand
1Present address: Programa de Ganaderia, Colegio de Postgraduados,
Montecillo, Texcoco Edo. de México, México. CP 56230.
Abstract The objective of this study was to investigate the
effects of timing and duration of lax spring grazing on tiller dynamics in
perennial ryegrass swards, with and without white clover. Two periods of lax
grazing--short release (SR) from 26 October to 8 December and long release (LR)
from 15 September to 8 December--were compared with a conventional hard
grazing--early control (EC). These treatments were applied to swards of
perennial ryegrass, with and without white clover, and grazed by sheep. Tiller
weight, tiller population density, tiller appearance and death, and stolon
population were analysed in a factorial design with three (Experiment 1) and
four (Experiment 2) replicates. Tiller weight was increased during the
reproductive period, particularly in SR and LR treatments. Also, tiller
appearance rate increased in all treatments from September to late January, and
was particularly high late in December after grazing of the apices of the main
group of reproductive tillers. Lax grazing management increased tiller
appearance rate by 53% (P <= 0.05) in Experiment 1 and 23% (P
>= 0.05) in Experiment 2, and tiller loss rate by 40% in Experiment 1
(P >= 0.05) and 23% in Experiment 2 (P <= 0.05). Over 6
weeks following the return to hard grazing, these effects were reflected in
increased tiller population densities of 170, 147, and 115% in LR, SR, and EC
treatments respectively in Experiment 1 (P >= 0.05), and 97, 110.5,
and 36.5% in LR, SR, and EC treatments respectively in Experiment 2 (P
<= 0.05). It is concluded that the increases in herbage production observed
in summer-autumn following imposition of managements which combined lax spring
grazing and hard grazing at the time of anthesis, can be attributed to
increased tiller densities. The increase was most marked when the period of lax
grazing was longer.
Keywords spring grazing management; tiller population
density; tiller appearance rate; tiller losses; perennial ryegrass; white
clover
New Zealand Journal of Agricultural Research, 1997, Vol. 40: 37-50
0028-8233/97/4001-0037 $2.50/0 (c) The Royal Society of New Zealand
1997
PDF file of entire paper: medium quality (1830K); (scanned from paper original: notes about this process)
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