Allelopathic Effect of Decomposed Garlic (allium Sativum L.) Stalk on Lettuce (l. Sativa Var. Crispa L.)

Garlic (Allium sativum L.) stalk is a byproduct and normally the waste of garlic production but now is thought a good biological resource. It is necessary to utilize this resource efficiently and reasonably to reduce environment pollution and achieve agricultural sustainable development. The allelopathy of decomposed garlic stalk at different ratios (0:100, 1:100, 3:100 and 5:100) was investigated in this study using lettuce (L. sativa var. crispa L.) as the allelopathic test plant. The results are as follows: (1) Lower concentration of decomposed garlic stalk promoted lettuce plant growth, but higher concentration inhibited growth. (2) The highest ratio of stalk to soil (5:100) significantly increased the root length and fresh weight of lettuce but decreased the shoot length and fresh weight. (3) Lower ratio of stalk to soil significantly increased the content of protein and chlorophyll and the activity of plant enzymes. (4) Increasing the concentration of decomposed garlic stalk increased the activity of soil urease and sucrase. It was concluded that the decomposed garlic stalk with lower concentration could promote lettuce plant growth. This result provides a scientific basis for allelopathic study and application of decomposed garlic stalk.