Effects of irrigation on growth dynamic and yield of Glycyrrhiza uralensis in Minqin Oasis

An experiment of randomized block design was conducted to study the effect of irrigation on growth dynamic and yield of Glycyrrhiza uralensis. The six levels of irrigation, 2 700 (W1), 3 600 (W2), 4 500 (W3), 5 400 (W4), 6 300 (W5) and 7 200 (W6) m3/ha, were applied. The plant height, root length, root diameter, aerial dry weight and root dry weight were promoted with different irrigation levels. The results indicated that plant height with W4, W5 and W6 treatments were significant higher (P0.05) than these with W1, W2 and W3 treatments. Growth rate of W6 main stem was 60％ faster than W1 and 33％ than W2 and W3. The aerial dry weight of W3, W4, W5 and W6 were significant significant higher (P0.05) than W1 and W2. The accumulation rate of the dry matter with W3 was 11％ faster than W1. The root length, root diameter and root dry weight increased with increasing irrigation levels, but decreased when irrigation levels were more than 5 400 m3/ha. The root dry weight of W3 and W4 were significant higher (P0.05) than others. The accumulation rate of dry matter of annual and biennial roots with W3 and W4 were faster 50％ and 35% than W1, respectively. It was concluded that the yield of annual and biennial roots were higher with 4 500 and 5 400 m3/ha irrigation levels, respectively. However, the irrigation efficiency with 4 500 m3/ha was higher than with 5 400 m3/ha treatment.