Allelopathic Potential and Chemical Components of Aqueous Extract from Soil-Like Substrate

Abstract

. Rice and wheat are the traditional food for Chinese people, as well as the main crop candidates for space bioregenerative life support systems. Recycling of inedible parts of rice and wheat is an important issue concerning the system. In order to determine whether the mixed-substrate of rice and wheat’s inedible parts is suitable for plant cultivation, soil-like substrate made from rice and wheat was tested in an aqueous extract germination experiment. The effects of different concentrations of aqueous extract on seed vigor, seedling growth and development situations and the physiological and biochemical characteristics of wheat, lettuce and pumpkin were studied, and the presence and degrees of allelopathic effects were analyzed. The test results show that this type of soil-like substrate can exert different degrees of allelopathic effect on wheat and lettuce; this allelopathic effect is related to the concentration of soil-like substrate aqueous extract. With the increase of extract concentration, the seed germination, root length and shoot fresh weight of wheat decreased; and every concentration of aqueous extract showed significant inhibition on the root length and root fresh weight of lettuce. However, this type of soil-like substrate showed few effect on the growth of pumpkin seedlings. Content changes of chlorophyll and endogenous hormones in wheat and lettuce seedlings, and the chemical compositions of soil-like substrate were measured. Besides, the mechanism of allelopathic effect was analyzed.