Quantifying Growth and Developmental Responses of Sweetpotato to Mid- and Late-Season Temperature

The growth and developmental responses of sweetpotato [Ipomoea batatas (L.) Lam.] to a wide range of temperatures have not been addressed extensively. The objectives of this study were to quantify temperature effects on growth, development, and biomass yield of sweetpotato during mid and late season. Four day/night temperature treatments, 25/17, 30/22, 35/27, and 40/32 degrees C, were imposed aft er the storage root initiation stage, 17 d aft er transplanting (DAT). Growth and developmental parameters were recorded from plants harvested at 91 DAT. Vine length and nodes showed sigmoidal and linear patterns, respectively, with time across all temperatures. The vine elongation rate during the linear growth phase and node addition rate during the whole season increased linearly with temperature. Temperature optimum for whole-plant leaf area was 26.7 degrees C. Leaf area declined more sharply at higher than at lower temperatures relative to rates at the optimum temperature. The total biomass showed a quadratic trend with maximum biomass yield at optimum temperature, 26.5 degrees C, and declined linearly at higher temperatures. The optimum temperatures for storage root fresh and dry weights were 24.0 and 25.6 degrees C, respectively, and weights declined by 101.5 and 13.1 g degrees C-1, respectively, at temperatures higher than optimum. The fraction of biomass partitioned to various plant parts showed quadratic trends. High temperatures during mid and late season promoted more shoot but less root growth, affecting the final storage root yield. The quantified temperature-dependent growth and developmental responses will be useful for crop production management decisions and for the development of sweetpotato crop models.