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ARS Home » Midwest Area » Morris, Minnesota » Soil Management Research » Research » Publications at this Location » Publication #94430
Title: THE EFFECT OF VARYING LEVELS OF PHOTOSYNTHETICALLY ACTIVE RADIATION ON THE GROWTH AND N-FIXATION OF VETCH, VICIA SATIVA L.

Author
item HAUSE, BENJAMIN - UNIVERSITY OF MINNESOTA
item Olness, Alan
item KUCHENREUTHER, M - UNIVERSITY OF MINNESOTA

Submitted to: Minnesota Academy of Science Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/2/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Intercropping techniques are potentially a means whereby the total protein production and nitrogen use efficiency of an agronomic system can be increased. Many factors influence the success of the two intercropped species, including light interception. This experiment seeks to determine the effect of light as an energy limitation on biomass production of wheat and vetch and N-fixation of vetch. Wheat and vetch were grown in a greenhouse under varying degrees of shading, developed with commercial shadecloth (0 to 50 percent at about 10 percent intervals). Pots were treated before planting with dicyandiamide to prevent nitrification. All pots received 2.82 mg of N15 as (**15NH4)**2SO4-. In addition, wheat pots each received 80.3 mg of N as (NH4)**2SO4- and vetch pots each received 8.03 mg of N as (NH4)**2SO4-. Vetch was inoculated with Rhizobium leguminosarum before planting. Plants were harvested periodically and dry weights were regressed against time to estimate relative growth rates. Early growth rates (mg/planVday)increased with light intensity (Fc) for both wheat (y=6.50+.00281x[r**2=0.825])and vetch (y=0.863+.00226x[r**2=0.549l]). The coefficient of light intensity, while similar for both species, may reflect the transfer of photosynthetate to the symbiont, Rhizobium, in vetch. Light use efficiency for N accumulation (mg/N/planT/Fc) was similar for wheat (y=1.21 +2.61e-4x [r**2=0.399]; 32 days after planting (dap), and y=3.45+2.04e-4x [r**2=0.148]; 46) dap and vetch (y=0.199+1.45e-4x[r**2=0.306]; 32 dap, and y=0.186+2.72e-4x [r**2=0.739]; 46 dap). When light is limiting, growth rates show similar responses to increased light intensity.