Effects of soil water content on growth, tillering, and manganese uptake of lowland rice grown in the water-saving ground-cover rice-prodluction system (GCRPS)

摘要

A 2-year field experiment and a pot experiment were carried out to compare Mn uptake, tillering, and plant growth of lowland rice grown under different soil water conditions in the ground-cover rice-production system (GCRPS) in Beijing, North China. The field experiment was conducted in 2001 and 2002, including two treatments: lowland-rice variety (Oryza sativa L. spp. Japonica) grown under thin (14 gm) plastic-film soil cover (GCRPS(plastic)) at 80%-90% water-holding capacity (WHC) and traditional lowland rice (paddy control) grown with 3cm standing-water table. The pot experiment was conducted in a greenhouse with four treatments: (1) traditional lowland rice: paddy control; (2) GCRPS, water-saturated soil: GCRPS(saturated); (3) GCRPS at 90% water-holding capacity (WHC): GCRPS(90%WHC); and (4) GCRPS at 70% WHC: GCRPS(70%WHC). Results of the field experiment showed that dry-matter production, number of tillers, as well as N and Mn concentrations in rice shoots of GCRPS were significantly lower than in paddy control, while there was no significant difference in shoot Fe, Cu, Zn, and P concentration and nematode populations. In the pot experiment, shoot Mn concentration significantly decreased with decreasing soil water content, while soil redox potential increased. Shoot-dry matter production and tiller number of GCRPSsaturated were significantly higher than in other treatments. Significant correlations were observed between the shoot Mn concentration and tiller number at maximum tillering stage in the field and pot experiment, respectively. We therefore conclude that the limitation of Mn acquisition might contribute to the growth and yield reduction of lowland rice grown in GCRPS. The experiment provides evidence that GCRPSplastic combined with nearly water-saturated soil conditions helps saving water and achieving optimum crop development without visual or latent Mn deficiency as observed under more aerobic conditions.