Influence Of No-tillage On Root Growth, Physiological Characters And Rhizhospheric Micro-ecosystem In Rice

In order to investigate influence of no-tillage on root growth, physiological characters and rhizhospheric micro-ecosystem in Rice, rhizobox experiments with three treatments, no-tillage, conventional tillage and root separation tillage, were conducted with Jinyou 253 as experimental materials in the late season of 2006 and early season of 2007, respectively. The dry weight, activity of SOD, POD and CAT as well as MAD content of the root were determined at the elongation and grain-filling stage, respectively. In the meantime, the nutrients contents and enzymes activities of the rhizhophere and bulk soil were determined. And the yield was measured at the maturing stage. The results were showed as follows:The biomass of no-tillage rice was lower than that of conventional tillage rice at various growth stages, and the differences were significant expect that at the maturing stage in the early season of 2007. And the yield of no-tillage rice was higher than that of conventional tillage rice in both the late season of 2006 and the early season of 2007, but the difference was not significant.The dry weight of the roots of no-tillage rice was small and its root/shoot ratio was significantly lower than that of conventional tillage rice at the early stage, while the root/shoot ratio of no-tillage rice was equal to or even higher than that of conventional tillage rice at the later stage. At the elongation stage, the activities of SOD, POD and CAT in the roots of no-tillage or no-tillage area of root separation tillage were lower than that of conventional tillage or conventional tillage area of root separation tillage, respectively, while the content of MDA in the roots of no-tillage or no-tillage area of root separation tillage was higher than that of conventional tillage or conventional tillage area of root separation tillage, respectively. At the grain-filling stage, the activities of SOD, POD and CAT in the roots of no-tillage or no-tillage area of root separation tillage were higher than that of conventional tillage or conventional tillage area of root separation tillage, respectively, while the content of MDA in the roots of no-tillage or no-tillage area of root separation tillage was lower than that of conventional tillage or conventional tillage area of root separation tillage, respectively. Therefore, root superiority were observed at the early growth period for convensional tillage rice, while it appeared at middle or late growth period for no-tillage rice.The pH in rhizhophere soil was significantly lower than that in bulk soil of paddy fields. The pH in rhizhophere soil of no-tillage rice was significantly lower than that of conventional tillage rice at elongation stage, while the pH in rhizhophere soil of no-tillage rice was significantly higher than that of conventional tillage rice at grain-filling stage. The available N and P in rhizhophere soil were lower than that in bulk soil of paddy fields, while the available K in rhizhophere soil was higher than that in bulk soil of paddy fields. The available N was higher and the available P and K were lower in the in rhizhophere soil of no-tillage rice compared with that of conventional tillage rice.The changing trend of invertase (protease, urease, amylase) activity in bulk soil was similar with that in rhizhophere soil. The invertase activity in bulk soil of conventional tillage was higher than that of no-tillage at both jointing and grain-filling stages. In the root separating cultivation, the invertase activity of conventional tillage was higher than that of no-tillage.