Maize crop growth and development related to solar radiation.
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Date
1976
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Abstract
The interception and reflection of solar radiant energy by maize
crops was measured at Cedara using tube solarimeters. From the
measured data the amount of PHAR that was intercepted was related
to the L value of the crop. K(v), the extinction coefficient of PHAR
thus obtained was found to vary with row spacing, plant population
density and cultivar, whereas growth stage, time of day and weather
conditions did not appear to effect the K(v) value markedly.
On clear days the albedo (R(v)) of a ma1ze crop was of the order of
0,05 to 0,08 during the middle of the day. However, at low sun
angles in the early and late hours of the day, R(v) increased to
values of the order of 0,2. On overcast days, the diurnal variation
was considerably lower.
The rate of photosynthesis in a ma1ze crop was measured using the
plastic enclosure technique. The rate of CO2
uptake was related to
the amount of PHAR absorbed by the crop. A rectangular hyperbola
(Eqn. 2. I) was found to describe this relationship well. The photosynthetic
response of a crop to population density, plant spacing
and temperature at different developmental stages is discussed.
The seasonal distribution of dry matter in the maize crop was studied
using normal growth analysis techniques. From these data functions
describing the partitioning of DM to the various plant organs (e.g.
roots, leaves, grain) at different growth stages were developed.
The functions describing the absorption of light by the crop canopy,
its photosynthetic rate and the partitioning of photosynthate were
incorporated in a computer simulation model, which was used to estimate
the growth of a maize crop from meteorological radiant flux
density and temperature data. The functioning of the model and its
possible use are discussed.
Description
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1976.
Keywords
Corn--Growth., Corn--Effect of temperature on., Plants--Effect of solar radiation on., Theses--Crop science.