Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 10, 2004
Publication Date: N/A
Technical Abstract: Two methods are being evaluated for quantifying potato canopy leaf appearance rate as a function of air temperature. The first method uses a thermal time approach, and the second uses a non-linear temperature response function. Data for the models was obtained from SPAR (soil-plant-atmosphere research) chambers at USDA-ARS, Beltsville, MD, where potatoes (Solanum tuberosum L. cv. Kennebec) were grown in one of six temperature treatments ranging from 14/10°C to 34/29°C. Main stem leaf number increased linearly with accumulated thermal time which supports use of the first method. However, significantly different phyllochrons were obtained for each treatment (9.3, 11.9, 14.4, 17.9, 21.4, and 32.7 GDD leaf-1 at 14/10°C, 17/12, 20/15, 24/19, 28/23, and 34/29°C respectively with a base temperature of 8°C). These findings indicate that the use of a constant phyllochron will lead to errors when estimating foliar development in environments with fluctuating temperatures. In the second method, a beta-distribution function, which has been shown to be superior to thermal time methods with other crops, was fit (r2=0.996) to the relationship between leaf appearance rate and daily average temperature. The suitability for using these models for the field will also be tested using field data obtained during the summer of 2003 at USDA-ARS, Belstville, MD.