ISHS Acta Horticulturae 624: XXVI International Horticultural Congress: Elegant Science in Floriculture
TEMPERATURE EFFECTS ON PHOTOSYNTHESIS, GROWTH RESPIRATION, AND MAINTENANCE RESPIRATION OF MARIGOLD |
| Authors: | M. van Iersel, L. Seymour |
| Keywords: | Tagetes patula, carbon use efficiency, relative growth rate, carbon exchange rate |
| DOI: | 10.17660/ActaHortic.2003.624.76 |
| Abstract:
Marigolds (Tagetes patula) were grown from seed to flowering at either 20 or 30 °C, and the CO2 exchange rate of the plants was measured throughout the 60-day growing period. Plants grew faster at 30 than at 20 °C, because of higher whole-plant photosynthesis (Pnet) from 5 to 40 days after seeding. The maintenance respiration coefficient (rm) was lower at 20 than at 30 °C (Q10 = 1.3), while the growth respiration coefficient was not affected by temperature (0.51 g·g-1). The ratio of maintenance respiration to total respiration increased throughout plant development and reached 43 and 55% at 20 and 30 °C, respectively. Carbon use efficiency (CUE) of the plants increased during germination, and then decreased throughout the remainder of the growing period. This decrease in CUE was the result of a decrease in relative growth rate (RGR). Plants grown at 20 °C had a higher CUE than those at 30 °C from 40 to 51 days after seeding, which was the result of a lower RGR and higher rm at 30 °C. Although plants grown at 20 °C had equal or higher CUE, a lower rm, and less dark respiration (Rdark), their growth was less than that of plants at 30 °C, suggesting that whole-plant Pnet is a more important determinant of growth than CUE, rm, or Rdark | |
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