Effects of gravity direction on water transport in sweetpotato plants

Abstract

This study is a fundamental research for understanding water transport of plants under low gravity in space. To demonstrate the suppressive effect of gravity on transpiration and sap flow, we assessed transpiration rates and (T_l–T_r) as indicators of sap flow rates using the difference in the surface temperatures at 1 mm from the heated points on both sides of the petioles of sweetpotato plants under different gravity directions on Earth. Transpiration and sap flow in the plants were promoted at the inverted position. The finding in this study suggests that gravitational potential could not be ignored in water transport in plants.