Effect of soil temperature on growth and yield of sweet potato (<I>Ipomoea batatas</I> L.) under cool climate

In cool climates, low temperature is critical for growth and yield of sweet potato (Ipomoea batatas L.). Despite its negative effects, few studies have quantified the impact. We evaluated effects soil (Ts) on in from 2-year field trials northern Japan. Ts was controlled by three steps using plastic mulch at different colors (green, black white) with ranged 21~24°C especially early before surface covered plant canopy. Higher significantly increased vine elongation, branching, leaf appearance, magnitude higher decreased proceeding stages. Increasing chlorophyll content stomatal conductance. Across treatments years, aboveground biomass linearly positively correlated Ts, 58 g m-2 observed per 1°C increase Ts. However, final storage root fresh not affected high over years. Increased individual weight offset number. The present quantitative study tested Japan showed that, enhanced during did contribute to yields climates.