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Field beans are an indeterminate crop, thus producing flowers, pods
and seed over a period of time throughout crop development whilst
vegetative growth is continuing. This may be a benefit to a crop
that is sensitive to drought such that later formed pods may compensate
for poor growth of earlier produced pods. Temperature is the main
determinant of crop development and determines the duration of each
developmental phase (Figure 1). However, high temperatures may be
linked with drought conditions, which shorten developmental periods
and may reduce yield (Figure 2).
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Figure
1. Duration of various phases
of growth of field beans cv. Ascott grown at Rennes,
France from 1953 to 19853.
[redrawn from data from Poulin et.al.,
1989. Ag. & Forest Met. (45) 159-67]
Click
here for a larger image
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Figure
2. Effect of evapotranspiration
on various phases of crop development in field beans
cv. Ascott grown at Rennes, France from 1953 to 19853.
[redrawn from data from Poulin et.al.,
1989. Ag. & Forest Met. (45) 159-67]
Click
here for a larger image
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The response of
field beans to soil moisture may explain why soil conditions are
an important determinant of yield. Research at Nottingham University
during the 1980’s showed that crops established in compacted
soils develop small, shallow root systems that exploit a smaller
volume of soil and take up less water than those grown in a well
structured soil. Yields were reduced by up to 15% in experiments
over a number of seasons.9 Winter
beans are suited to soils with good water holding capacity and generally
yield better in heavy clays than on light, drought prone land.
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