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Effect of solar radiation and temperature on potential maize yield

R.C. Muchow

CSIRO Division of Tropical Crops and Pastures, Cunningham Laboratory 306 Carmody Road, St Lucia, Queensland 4067

Potential crop yield has been shown to be closely related to the amount of radiation intercepted (1,2). Temperature affects the duration of crop growth (3) and hence the maximum time that the incident radiation can be intercepted. Temperature also influences the rate of leaf canopy development (3) and consequently the proportion of the incident solar radiation intercepted. The objective of this paper is to use crop growth simulation to assess the impact of different temperature and radiation regimes on potential grain yield of maize.

Methods

A simple, mechanistic crop growth model was developed where phenology and leaf growth were related to temperature (3); above-ground biomass accumulation was correlated with radiation interception with a maximum radiation use of efficiency of 1.6 g MJ (2); and grain growth was simulated using linear increase in harvest index during grain filling (4).

Results and discussion

There was close agreement between observed and simulated maize grain yield under favourable growing conditions, where observed yields ranged from 9.4 t ha at Katherine, Australia (14S; mean temperature 27.7C; mean radiation 24.1 MJ m d ) to 18.3 t ha at Grand Junction, Colorado (39N; 19.0C; 26.4 MJ m2 d-1).

Table 1. Predicted maize grain yield at 15.5% moisture 1 (t ha ) under constant daily mean temperature and incident radiation for the growing season

The mode1 predicts that the environment with the highest temperature and the least radiation would have the lowest yield, whereas the highest yield would be under the lowest temperature and highest radiation (Table 1). The response to temperature was associated with variation in the predicted length of the growing season. Simulated duration of growth was 148, 109 and 88 days for constant mean temperature of 20, 25 and 30C. The response to incident solar radiation was directly related to the relative increase in the amount of radiation intercepted by the crop.

The yield potential of maize growing in tropical environments is lower than that in temperate environments, despite high levels of solar radiation, since high temperature markedly decreases the duration of crop growth. Only at locations with low temperature and high solar radiation, will the yield of maize approach 20 t ha -1 using current commercial hybrids.

References

1. Loomis, R.S. and Williams, W.A. (1963), Crop Sci. 3, 67-72.

2. Muchow, R.C. and Davis, R. (1988), Field Crops Res. 18, 17-30.

3. Muchow, R.C. and Carberry, P.S. (1989), Field Crops Res. (In Press).

4. Muchow, R.C. (1988), Field Crops Res. 18, 31-44.

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