The relation of photosynthesis by phytometers in the profiles of kale crops to leaf area index above them.
Abstract
To estimate the effect of foliage at different positions in the profiles of kale crops on the rate of photosynthesis below it, crop LAI was varied by topping or by removing some of the plants; the NAR of phytometers (sugar-beet seedlings supplied with nutrient solution) placed at different depths in the profiles was then measured. Phytometer NAR at a given height in the profile increased with decreasing plant population or decreasing height of topping; these changes were almost completely explained by changes in LAI above the phytometers, but leaves near the bottom of the canopy decreased phytometer NAR slightly less than equal areas of leaves higher in the crop, although they did not intercept less light. Phytometer NAR became nil when crop LAI above the phytometer was about 4, a value in agreement with other measurements.-R.B.