Plant-Water Measurements on Soybeans Sheltered by Temporary Corn Windbreaks
1973
Radke, J. K. | Hagstrom, R. T.
Double rows of corn (Zea mays L.) spaced at regular intervals in a soybean (Glycine max (L.) Merr.) field served as temporary windbreaks at two locations in western Minnesota. In 1969 at Dumont, Minnesota, corn windbreaks were placed between every 14 rows of soybeans (every 11.4 meters), and in 1970 at Lamberton, Minnesota, 22 rows of soybeans (17.5 meters) separated the corn windbreaks. Moisture stress was high in 1969, but moisture was adequate in 1970. Small, white evaporimeters provided estimates of potentlal evaporation, soybean plant potometers furnished information on potential transpiration, and the stomatal resistances of the soybean leaves were measured by a porometer and from leaf impressions. Windspeed and potential evaporation were reduced significantly over the first seven or eight soybean rows on the lee side of the windbreaks. Potential transpiration .and stomatai resistance varied significantly among rows between corn windbreaks and in some cases showed cyclic trends over rows. Potential transpiration and stomatal resistance appeared to be directly related when moisture stress was low, but were inversely related when moisture stress was high. Sheltered soybean yield increases and variations over rows were largely an accumulation of the variations that occurred in the plant-water relations during the growing season.
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