The Effect of Temperature on Sweetpotato Growth and Development.

Ten field experiments were conducted on 'Jewel' sweetpotato [Ipomoea batatas L. (Lam.)] crop at three experimental stations from the International Potato Center (CIP): La Molina (12°05’ S, 76°57’ W, 240 m asl), San Ramon (11°07’ S, 75°21’ W, 770 m asl), and Yurimaguas (5°45’ S, 76°05’ W, 184 m asl), Peru. La Molina is located in a coastal alluvial valley, San Ramon in the jungle Pie de Monte, and Yurimaguas in the Amazon rainforest. The objective of these field experiments was to collect data to construct a crop growth and development model. The present study showed the crop sensitivity to temperature. Non- and destructive growth analyzes were performed every 7 and 21 days, respectively. The evaluated parameters were: plant cover, fresh and dry weight of leaves, petioles, stems, fiber roots, storage roots, and sweetpotatoes; number of leaves, stems, storage roots and sweetpotatoes; stem length, leaf area, and leaf area index (LAI). Each location had both a conventional and an automatic weather station within the range of 500 m around the field experiments. Irrigation was applied based on the information registered by volumetric lysimeters. The results showed an inverse relationship between temperature and number of stems and leaves, whereas a direct relationship was found between temperature and plant cover, stem length and storage roots initiation. Canopy growth, growth stages and leaf longevity responded to cumulative temperatures. High temperatures promoted a reduced number of storage roots becoming sweetpotatoes. This condition also affected the dry matter allocation, where stems became a dominant sink.