New Zealand Journal of Crop and Horticultural Science abstracts
Maize production potential and climatic risk
in the South Island of New Zealand
D. R. WILSON
J. V. JOHNSTONE
New Zealand Institute for Crop & Food
Research Limited
Private Bag 4704
Christchurch, New Zealand
M. J. SALINGER
National Institute of Water
& Atmospheric Research Limited
P.O. Box 28 841
Auckland, New Zealand
Abstract Maize production is expanding in the South Island of
New Zealand even though the climate is cool and variable, and marginal for
reliable production of the crop. Its productivity in the region was assessed in
field experiments conducted at Lincoln, Canterbury, during three contrasting
seasons--two warmer and one cooler than average for the region. Three cultivars
with different maturity characteristics were sown on several dates in each
season. Even though the deviations from the long-term mean seasonal temperature
(14.5deg.C) were quite small (-0.6 to +0.7deg.C) they had large effects on crop
development and yield. Silage and grain yields were high (means 18.9 and 9.1
t/ha respectively) for all sowing dates of all cultivars in the warmest season,
indicating good production potential in favourable years. However, in the other
two seasons, yields were reduced in treatments that were sown late or where
late-maturing cultivars were used. In the coolest season, some crops failed to
start grain growth before the first autumn frost; their yields were low and
they produced poor quality silage. The climatic risk of growing maize in the
region was quantified by analysing historical temperature records from eight
locations together with a simple thermal-time phenology model. Probabilities of
failure to reach maturity were calculated for combinations of five cultivar
maturities and four sowing dates spanning the ranges likely to be used in the
region. The analysis confirmed that reliable maize silage or grain production
is marginal because of variability in temperature and frost occurrence among
seasons and the sensitivity of crop development rate to temperature. Crop
failures are likely in cool seasons or when early autumn frosts occur,
especially with late sowing or when late-maturing cultivars are used. Locations
differed in their suitability for maize production. Areas in the north
(represented by Riwaka and Blenheim) were the least risky, and were the only
places where both grain and silage production appear to be viable. At lower
altitude, coastal locations in central Canterbury (Rangiora and Lincoln),
levels of risk were acceptable for silage crops, but the area was beyond the
climatic limit for reliable grain production. Although some crops completed
grain growth, they probably would not have reached an ear moisture content low
enough for commercial machine harvesting of grain. Higher altitude, inland
locations and areas further south were not suitable for reliable silage
production because crops often failed to complete grain growth, even when
early-maturing cultivars were sown early.
Keywords maize; Zea mays L.; temperature; phenology;
climatic risk
New Zealand Journal of Crop and Horticultural Science, 1994, Vol. 22:
321-334
0114-0671/94/2203-0321 $2.50/0 (c) The Royal Society of New Zealand
1994
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