Allelopathic Effects of Cotton Straw Extract on Seed Germination and Seedling Growth of Wheat

To define the allelopathic effect of cotton straw on wheat,an experiment using the seeds of wheat cultivar Yangmai 13 treated with different concentration of water extract of cotton straw was carried out to study the effects of cotton straw extract on seed germination and seedling growth of wheat.The results showed that when the concentration of extract was below 7.0%,germinating time of wheat seed was delayed while its germination rate was not affected,yet when the concentration was over 7.0%,germination time was delayed and germination rate was decreased.There were differences between the effects of extract of cotton stalk on shoot and root of wheat.For roots,when the extract was below 1.0%,minor effect on root development was observed,when the concentration was over1.0%,the total length,surface area and vigor of root were all decreased,but lipid peroxidation was increased,which caused the decrease in absorption capacity of water and nutrient of root and transport capacity to shoot.For shoots,when the concentration of extract was less than 4.0%,the absorption ofnitrogen,phosphorus,potassium and water was facilitated in wheat seedling shoot,the effects was gradually weakening as the increase of the concentration of extract,till to inhibiting effect.The extract was quite high in total phenolic content,which reached 124.0mg·L-1.Total phenolic acid content was significantly and negatively correlated to germination rate,germination potential,germination index,whole plant fresh weight,root/shoot,root water content,total root length,root surface area and root vigor index,while positively correlated to contents of nitrogen,phosphorus,potassium and malondialdehyde content in roots.The allelopathic effects of the extract were related to the total phenolic content,which could influence the uptake and transport of water or nutrient.