You are looking at 1 - 3 of 3 items for
- Author or Editor: G. Stanhill x
Covering the ground between the hedge rows of an ‘Orleans’ apple orchard with a laminated plastic film vacuum-coated with aluminum significantly increased the average weight, diameter, color and sugar content of fruit harvested from the lower half of the canopy. The total weight of fruit harvested per tree was not affected until the following season when a large increase was recorded.
Measurements of global radiation above, and net solar radiation below, the roof of a glasshouse were both highly correlated on a daily and hourly basis with the water loss from a flowering rose crop as measured with a weighing lysimeter. The relationship can be used for an automatic system of irrigation control. Under local glasshouse, soil, and crop response conditions such a system would require an application of 6 liters of water per square meter of bed for every 730 cal cm2 global radiation above the glasshouse. Alternatively, a foliage spray irrigation system to ensure that the upper part of the canopy is kept continuously moist, would require applications of at least 0.4 liters per square meter at radiation intervals between 15 and 4 cal cm2 of global radiation outside the greenhouse, the exact figure depending mainly on the rate of air movement around the foliage. The latent heat equivalent of the crop water loss was 87% of the global radiation incident on the canopy, a figure similar to those listed for other, tall glasshouse crops.
The use of a highly reflecting layer of aluminized polyester to increase the amount of downward solar radiation in a rose glasshouse was investigated during midwinter. Solar radiation at the south end of the untreated glasshouse was 20% higher than that at the north end during this season, corresponding to similar differences in the number of flowers produced in mid-winter. Covering the north wall with a reflecting layer increased the solar radiations flux density above a roe crop canopy by 7.5% for about half the length of the cropped area. Covering the paths with the same material increased the downward solar radiation by an average of 3%, the effect being twice as great adjacent to the south wall. Much larger increases were inferred in the flux of upward solar radiation reaching the under surfaces of the canopy. Carbon dioxide fixation of the upper leaves of the rose canopy was linearly related to incident solar radiation. The effect of the reflecting surfaces on rose yield calculated from this relationship was in general agreement with that previously derived from the seasonal correlation between flower production and solar radiation.