Yield and quality of 'Atlantic' and 'Harley Blackwell' potatoes as affected by multiple planting dates, nitrogen rates and growing degree days

Christine M. Worthington, Chad M. Hutchinson


Potato (Solanum tuberosum L.) production in Northeast Florida's Tri-County Agricultural Area (St. John, Putnam, and Flagler counties, TCAA) typically begins mid to late Jan. through the 1st week of March. Six planting dates (11, January 2005 and every two weeks, thereafter, to 22, March 2005) and two potato varieties ('Atlantic' and 'Harley Blackwell', were evaluated to determine key development stages (emergence and full flower) using accumulated growing degree days (GDD7C base) calculated throughout each of the six planting dates. Two N rates (168 and 224 kg ha-1) were also evaluated for the effects on yield as well and the occurrence of internal heat necrosis. The GDD to emergence and full flower for 'Atlantic' and 'Harley Blackwell' for all planting dates (1-6) were approximately 200 and 800 accumulated GDD, respectively. The main effects of planting date main effect were significantly different. Tuber total and marketable yields were significantly higher in planting date 4 with (35.3 and 32.5 t ha-1), respectively compared to all other planting dates. 'Harley Blackwell' had significantly higher total and marketable yields (26.1 and 20.0 t ha-1), compared with 'Atlantic' (23.6 and 18.6 t ha-1), respectively. The three way interaction between planting date variety N rate was significant. 'Harley Blackwell' in planting date 3 had significantly higher marketable yields with the (168 kg N/ha) rate compared with 'Atlantic' (28.8 and 23.6 t ha-1), respectively. Total and marketable tuber yields decreased on average 33 and 56%, respectively, as accumulated GDD at harvest exceeded 2200.


Solanum tuberosum; developmental stages; multiple planting dates

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283