Simulation of Potato Crop Growth and Development1

Abstract

Potato (Solanum tuberosum L.) crop yield is the result of net crop dry matter assimilation (NDMA) and fraction of NDMA partitioned to tubers (α) integrated from the day of tuber initiation onset (TIO) through the day of tuber growth cessation (M). These four physiological yield parameters respond to environment and crop development by complex and poorly understood relationships. A crop growth and development model was constructed to determine the integrated temperature sensitivity of the four yield parameters and to test the hypothesis that temperature effects on α may be explained by growth temperature responses of different potato crop components. The crop was divided into three components, canopy, roots, and tubers. Model inputs were daily mean air temperature, soil temperature at 10 cm, solar radiation, and initialization parameters. Simulation began at emergence and continued through three developmental phases, canopy growth, tuber initiation, and tuber growth, which were demarked by four events, emergence, TIO, tuber initiation end, and M. Simulated TIO wau a function of temperature, whereas tuber initiation end and M were indirectly related to both temperature and radiation. Net crop dry matter assimilation was a direct function of incident solar radiation, canopy light interception, and tuber growth rate. Temperature affected NDMA indirectly through effects on canopy light interception and tuber growth rate. Assimilate partitioning was modeled as a function of available assimilates and empirically derived functions of the relationship between potential growth and temperature for each crop component. Potential growth of root and canopy had a 22 to 24°C optimum, whereas potential tuber growth had a 14 to 16°C optimum. Simulated leaf duration decreased as temperature increased. The model appropriately responded to temperature and solar radiation inputs to simulate cultivar Sebago growth in North Florida. In simulations, the most temperature sensitive yield parameter was TIO, with cool temperatures generally causing earlier TIO. Both M and NDMA were relatively insensitive to temperature with α having intermediate temperature sensitivity. Maximum simulated yield was at 15°C which corresponded with earliest TIO and maximum α. We conclude that temperatureffects on assimilate partitioning may be explained by differential temperature growth responses of potato crop components.