Gas Exchange Characters with SO₂ Fumigation of Different Concentration and Time in Soybean

Abstract:

The low concentration of SO₂ in the air can promote stomata opening of plants and improving plant photosynthetic rate, but the gradual accumulation of SO₂ on plant leaves can convert the chlorophyll into phaeophytin, which has no photosynthetic activity, and then affect the plant growth and crop production. After Fumigation with SO₂ in soybean under several different concentrations (4 µl/l,10 µl/l,20 µl/l,40 µl/l) and time spans(1h,2h,4h) respectively, the photosynthesis and gas exchange characteristics were determined. The experimental data showed: (1) with the increasing of concentration and time for fumigation, SO₂ had a great adverse effect on photosynthesis in soybean. Such as the light saturation point of plants decreased, the light compensation point increased, and the maximum net photosynthetic rate reduced significantly (e.g., fumigation with SO₂,4-40 µl/l-4 h, Anmax reduced 29.5% to control) compared with the control plants’. (2)After all kinds processing time, low concentration of fumigation (4µl/l) caused larger stomatal conductance than control. However, the other treatments caused smaller gs than control. (3)gs revealed significant positive correlation with transpiration rate(E), each treatment and control shows r ≥0.9,P2. (5)Concentration of chlorophyll was no insignificant differences with the control at different treatments. After fumigation, the range of chlorophyll a / b was 1.39~1.61 and there was no big difference from control (chlorophyll a / b is 1.49), except the treatment of 20µl/l-1h, which had a significant decline in chlorophyll b (chlorophyll a / b is 1.71).Results: (1) SO₂ concentration had greater impact on soybean than time of fumigation, and the impact of high concentration in short time on soybean was obviously significant. (2) SO₂ fumigation in short time and low concentration can promote stomata open, however SO₂ also can damage the photosynthetic activity of chlorophyll. After a long time of fumigation, photosynthetic rate decreased rapidly, even if gs increased.

• Periodical: Advanced Materials Research (Volumes 518-523)
• Pages: 5450-5454
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.518-523.5450
• Online since: May 2012
• Authors: Jing Li, Da Long Jiang, Xiao Ming Li
• Keywords: Gas Exchange, Photosynthesis, SO₂, Stomatal Conductance

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