Biernacki, Maciej .
Quantification of plant phenology.
Temperature and day length data were used to quantify plant growth and development. A new measure of heat accumulation, daylight degree-hours was developed, to quantitatively model plant growth and development from seedling to maturity. Watermelon (Citrullus lanatus) was used as a model plant. Plants were seeded in pots at 12 weekly intervals in a greenhouse from April through June. Plants accumulated 419 degree-days and 5652 daylight degree-hours at maturity. At maturity, heat accumulation was significantly associated with fruit mass per plant. In general, plants became established after accumulation of c. 10 % of total heat accumulated, flowered at c. 35 %, and fruited at c. 45 %. Coefficient of determination for daylight degree-hours was 98 % vs 90 % for degree-days. In mature plants, dry weight was dominated by fruit and increased significantly with increased temperature. Root growth was optimal at temperatures significantly lower than that associated with optimal growth of above-ground structures. Mean leaf surface area per plant increased over all seeding occasions, to nearly 3500 cm2, while root surface area increased over the first seven seeding occasions, to 2000 cm2 and then decreased. Root surface area was significantly affected by changes in the length of small roots (with diameter <0.5 mm). Roots with diameter <0.5 mm, and root tips were most responsive to temperature, compared to other roots. Water use per unit leaf area increased from 0.2 mL.cm-2 at 14 oC, to about 1.5 mL.cm-2 at 45 oC. It increased even more per unit root surface area from 0.3 mL.cm-2 at 14 oC, to about 3.2 mL.cm-2 at 45 oC.
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1 - University of Memphis, Biology, Memphis, TN, 38152, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Williford B/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:15 AM