Poster: Photosynthesis (light)
Abs #
215: Photosynthesis and biomass production of corn sown under plastic.
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Presenter: |
Olowoyeye, Kehinde I, Kehinde.Olowoyeye@ucd.ie |
Authors | Olowoyeye, Kehinde I (A) Osborne, Bruce (A) Keane, George (A) | | Affiliations: |
(A): University College Dublin, Dept. of Botany and Crops Science
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The establishment of potentially important crops such as maize under temperate condition is often limited by low temperature. Experiments have shown that the use of photodegradable plastic coverings has resulted in an increased performance of maize under temperate conditions. This study examines photosynthetic and fluorescence responses of three maize varieties, Justina and Hudson, regarded as chilling-tolerant and Ethiopian a chilling-sensitive variety subjected to two treatments of complete plastic and no plastic covering. Experiment was set up in growth cabinet at constant 10oC and 70% relative humidity with 18/6hrs photoperiod and PAR of 450-650μmol m-2 s-1 of which 85-90% penetrates the plastic. There was 1-3oC and 13-23% increase in temperature and humidity below the plastic. Photosynthetic responses to light measured between 0-1400μmol m-2 s-1 of all varieties from both treatments was determined from gas exchange measurements 6 weeks after planting along with chlorophyll fluorescence, shoot height and leaf area. There was no light saturation and no net photosynthesis in seedlings from both treatments except in Hudson under plastic, with insignificant rate of photosynthesis. Efficiency of PS11 was higher in plants under the plastic relative to those without the plastic covering. To simulate the period maize plants pushes through photodegradable plastic on the field plastics were perforated at 6 weeks exposing plants to lower temperature and higher light intensity in the cabinet. Measurements on gas exchange and fluorescence showed depression in PS11 efficiency and CO2 assimilation of all three varieties from both treatments. Rates of shoot elongation and leaf expansion were higher in varieties under the plastic than those without the plastic covering.
