Abstract

The effect of different harvest stages on photosynthetic characteristics and yield of purple yam was studied in the open field. The results showed that the chlorophyll content of purple yam decreased continually with the extension of the harvest stage, which led to the decrease of photosynthetic rate. The moisture content of purple yam aboveground reduced, leading to plant wilted gradually. Moreover, the inflation of tuberous root lasted throughout whole harvest stage. And the tuberous root yield was the highest during the third harvest stage. However, yield of purple yam had reached approximately maximum, due to the rapid increase of dry matter accumulation of purple yam tuberous root during the first harvest stage to the second harvest stage, and then slowed down. In consideration of nutritional components of purple yam and the cultivation of next crop, we drew a conclusion that the date between September 30th and October 15th was the best harvest stage.