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INFLUENCE OF SOYBEAN PUBESCENCE TYPE ON RADIATION BALANCE, PHOTOSYNTHESIS AND TRANSPIRATION
Abstract
Soybean (Glycine max L.) production in the central part of the United States reaches its western most extension in the eastern Great Plains. Soybean yields in this region are frequently limited by environmental stresses of high radiation, high temperature and limited moisture. Previous studies with soybeans and other species have shown plant pubescence (plant hairs) to be a morphological feature which makes a plant better adapted to these stressful conditions. Isogenic lines of two soybean cultivars (Clark and Harosoy) were grown during the 1980, 1981 and 1982 growing seasons near Mead, Nebraska. The isogenic lines of each cultivar varied only in the amount of pubescence (dense vs. normal pubescence). The dense isolines have approximately four times the pubescence density as the normal isolines. Measurements of net radiation, albedo, reflected photosynthetically active radiation (PAR) and longwave radiation were made over the crop surfaces. Canopy temperatures, spectral reflectance in two PAR bands and two near infrared (NIR) bands and profiles of within canopy net radiation were measured. The response of leaf photosynthesis to light level was determined. Plant water potential, stomatal resistance, soil moisture, crop height, leaf area index and final seed yield were also observed. Results show that increased pubescence slightly increases the albedo and decreases the net radiation over the crop surface, increases net radiation levels per unit leaf area in the lower canopy by decreasing the net radiation extinction coefficient, but does not alter leaf photosynthesis or canopy temperature. No distinct differences in water relations between the two isolines varying in pubescence were noted, but a trend was seen for greater leaf stomatal resistance and lower water use in the dense isoline. The dense pubescent isoline exhibited more vigorous growth habit (taller plants, greater leaf ara), but no significant yield differences between isolines were noted. These data suggested that the gene for increased pubescence density may offer a small but possibly useful morphological adaptation for soybeans grown in the eastern Great Plains.
Subject Area
Agronomy
Recommended Citation
NIELSEN, DAVID CHRISTOPHER, "INFLUENCE OF SOYBEAN PUBESCENCE TYPE ON RADIATION BALANCE, PHOTOSYNTHESIS AND TRANSPIRATION" (1983). ETD collection for University of Nebraska-Lincoln. AAI8318670.
https://digitalcommons.unl.edu/dissertations/AAI8318670