||Effects of Ultraviolet-B Irradiance in Soybean. 6. Influence of Phosphorus Nutrition on Growth and Flavoniid Content.
Murali, N. S. ;
Teramura, A. H. ;
||Maryland Univ., College Park. Dept. of Botany.;Corvallis Environmental Research Lab., OR.
Radiation effects ;
Soybean plants ;
Plant growth ;
Ultraviolet radiation ;
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Soybeans Glycine max Essex were hydroponically grown in a greenhouse at 2 levels of ultraviolet-B(UV-B) radiation and 4 levels of P. Plants were grown in each treatment combination to the complete expansion of the 4th trifoliolate leaf. UV-B radiation and reduced P supply generally decreased plant height, leaf area and total biomass, but increased specific leaf weight and flavonoid content (measured as absorbance of methanolic extracts). Although both UV-B radiation and low P supply produced deleterious effects on plant biomass, the effects were non-additive. The combination of UV-B and the lowest P level (6.5 micrometers) had no effect on total biomass or leaf area. This was at least partially due to the accumulation of flavonoids and leaf thickening. The results show that the sensitivity of soybean to UV-B radiation is dependent upon plant P supply.