Low Red to Far-Red Light Environment Alters Nitrogen Assimilation in Corn (Zea mays)

Kramer, William
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University of Guelph

In the absence of direct resource competition, far-red light reflected from neighbouring weeds compromises light quality (red to far-red ratio; R/FR) which inactivates phytochrome (Phy) resulting in the regulation of various physiological processes. The main objective of this research was to investigate the effects of low R/FR light on nitrogen assimilation in corn. To explore this, changes to the nitrogen assimilation pathway were measured in corn seedlings nine days post-emergence under low R/FR and control light conditions. The observed results indicate that nitrate levels increased and ferredoxin-dependent glutamine:2-oxoglutarate aminotransferase activities decreased under low R/FR light, however, no other pathway enzymes were affected. Changes in the pathway appear to be PhyB-independent, as Arabidopsis phyB mutant did not change the nitrate levels compared to wild-type Arabidopsis. The research indicates the importance of mitigating early-season weed competition and offers insight into the early physiological mechanisms involved in nitrogen utilization under resource-independent competition.

Corn, Nitrogen, Plant Physiology, Weeds, Light Interactions, Low Red to Far-red Ratio