A physiological study of shading and density effects on the growth and the efficiency of solar energy conversion in some field crops
1959
Kamel, M.S.
The growth and the efficiency (E s ) of conversion of solar energy were greatly affected in barley by both shading and density, although not always similarly in 1957 and 1958. Observations were made on: height; internode length; shoot diameter; shoot and leaf number; number and percentage of dead leaves; leaf length, breadth, ratio, thickness and area; spike development; awn emergence; spike length; number of heads per plant; number of grains per head and per plant; fresh and dry weights of roots, stem, leaves, heads, seeds, tops and entire plant; 1000-grain dry weight; and the root/top relation. The relation nonphotosynthetic tissues to photosynthetic tissues increased with increasing light intensity and with time. With increasing density this ratio decreased in the early stages but increased in the later ones. E s increased in the early and late stages with decreasing light intensity, in the middle stages the reverse occurred. In natural field conditions E s was maximum in the middle of the growing period. E s first (until 56-70 days) increased with density, later on medium density was more efficient. In both seasons proportion of grain and heads increased with density. Shading prolonged vegetative growth and diminished seed production.In mangold, E s increased for each period as well as on average with density. The highest E s values also persisted over a longer period in this crop.
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