Abstract Detail

Ecological Section

Ma, li [1], Swanton, Clarence [2], Upadhyaya, Mahesh [1].

Effect of red/far-red ratio on the response of corn seedlings to UV-B radiation.

In order to determine if red/far-red (R/FR) ratio influences the response of corn plants to UV-B radiation and if a change in anthocyanin concentration induced by exposure to low R/FR ratio is involved in this effect, corn seedlings were grown under two different (1.1 and 0.3) R/FR ratios for one week in growth chambers and then transferred to three levels of UV-B radiation (for 10 days) in the greenhouse. Different levels of UV-B radiation were achieved by filtering radiation from ten 40 W UVB-313 fluorescent tubes with 1 (high UV-B), 2 (medium UV-B) and 3 (low UV-B) layers of cellulose acetate film. The anthocyanin concentration in corn stems was 60% lower (p ≤ 0.01) (at the beginning of the UV-B treatment) in plants grown at 0.3, compared to 1.1 R/FR ratio. The magnitude of this difference diminished during the course of UV-B treatment. UV-B exposure influenced a variety of corn growth parameters. For example, compared to the low and medium UV-B radiation levels, plant height decreased slightly (7%) but significantly upon exposure to the high level of UV-B radiation. Shoot fresh and dry weights and plant biomass decreased by 23, 19 and 17%, respectively. Root dry weight, leaf dry weight, leaf area, and stem dry weight also decreased by 26, 16, 24 and 19%, respectively. Both leaf weight ratio (leaf dry weight/shoot dry weight) and specific leaf weight (leaf dry weight/leaf area) increased slightly in plants exposed to high level of UV-B radiation. Leaf area ratio (leaf area/shoot dry weight) was not affected. Interestingly, R/FR treatments prior to UV-B exposure and the associated change in anthocyanin concentration in corn stems did not modify the response of corn plants to UV-B radiation on these growth parameters. This suggests that differences in R/FR ratio, which can result from a change in planting density or shading, and the associated change in anthocyanin pigment concentration, do not influence the response of corn seedlings to subsequent exposure to elevated levels of UV-B radiation. This finding is significant to our understanding of the ecophysiology of ecosystems, where both R/FR ratio and UV-B levels are fluctuating.

1 - University of British Columbia, Faculty of Land and Food Systems, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada
2 - University of Guelph, Plant Agriculture, 50 Stone Road E, Guelph, ON, N1G 2W1, Canada

Keywords:
red/far-red ratio
ultraviolet-B
Corn
Anthocyanin.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PEC021
Abstract ID:462
Candidate for Awards:None