Climate Change and Sweetpotato Growth and Development.

Crops grown in the future climate will be grown in different environment than to day.  Several experiments were conducted to understand sweetpotato, a storage root crop, responses to a range of temperatures, elevated carbon dioxide, drought, and ultraviolet-B radiation either alone or in combination under sunlit plant growth chamber facilities. Temperature effects on early, mid- and late-season sweetpotato growth and developmental responses were quantified under optimum water and nutrient conditions. Vine length and nodes showed sigmoidal and linear patterns, respectively, over time across all temperature treatments. Vine elongation rate estimated during the linear growth phase and node addition rate during the whole season, increased linearly as temperature increased with rates for node addition being much steeper than for vine elongation. Internodal length, the product of vine length and number of nodes declined linearly with increase in temperature. Whole plant leaf area showed a quadratic trend with temperature and maximum leaf area was achieved at 26.7°C. Leaf area declined more sharply at higher than at lower temperatures, relative to rates at optimum temperature. Total, stem, and root biomass increased quadratically with an increase in temperature and the optimum temperature varied significantly among plant components; 26.5°C total, 29.2°C for stems, 26.7°C for leaves, and 25.6°C for root dry weights. Root fresh and dry biomass started to decline comparatively at lower temperatures (24.0 and 25.6°C, respectively) than other components; the rates of decline for fresh and total storage root dry weights were 101.5 g and 13.1 g 1°C^-1, respectively, from to optimum temperature. Since storage root bulking was affected by temperature, partitioning to stems and leaves increased quadratically with temperature with less biomass partitioned to roots at the two higher temperatures compared to optimum and lower temperatures tested in this study. Our results suggest that, temperature higher than 24°C had a detrimental effect on the mid- and late-season growth and development of storage roots. Elevated carbon dioxide modified sweetpotato growth processes including total and storage root biomass.