水稻-雍菜间作系统中种间关系和水稻的硅、氮营养状况

Interspecific relationship and Si,N nutrition of rice in rice-water spinach intercropping system

间作是一种优良的生态农业模式,但以水稻为主的水生作物间作研究很少.本试验以水稻和雍菜为研究对象,开展了连续两年(2014—2015年)四季的大田试验,研究水稻和雍菜间作条件下产量、种间关系以及水稻的硅、氮营养状况.试验共设置5个处理,包括水稻单作、雍菜单作、水稻-雍菜2∶2间作、3∶2间作、4∶2间作.结果表明:水稻和雍菜间作显著增加水稻的产量,其中2∶2间作、3∶2间作和4∶2间作在单位面积上的增产幅度分别为77.5%~120.6%、64.9%~80.9%、37.7%~56.0%,但间作显著降低了雍菜的产量.从土地当量比(LER)来看,水稻和雍菜间作可增加系统的综合产量,3种间作的LER全部大于1,其中3∶2间作模式最佳.从竞争指数来看,在间作系统中,水稻比雍菜有更强的竞争能力,特别是在早季.与水稻单作相比,水稻-雍菜间作显著增加水稻叶片对硅和氮的吸收量以及成熟期水稻叶片的硅含量,但是并没有增加水稻叶片的氮含量,甚至在成熟期略低于单作;而对土壤有效硅、铵态氮和硝态氮含量没有显著影响.在整个试验期间,与水稻单作和间作相比,雍菜单作始终有最高的土壤有效硅、铵态氮和硝态氮含量.本研究表明,水稻和雍菜间作可以促进水稻对硅和氮的吸收,增加水稻的竞争能力.

Intercropping is a sound eco-agricuhure model, but aquatic crops （e.g., rice） intercropping is seldom researched. In the present study, rice and water spinach were chosen as the research objects, a field trial was conducted to explore the yields, interspecific relationship and Si, N nutrition of rice under rice-water spinach intercropping for four seasons during two consecutive years （2014-2015）. The experiment had five treatments ： rice monocuhure, water spinach monoculture, and rice-water spinach intercropping ratios of 2 ： 2, 3 ： 2, 4 ： 2, respectively. The results showed that rice-water spinach intercropping significantly increased rice yield, and the increase rates of 2：2, 3：2 and 4：2 intercropping per unit area were 77.5%-120.6%, 64.9%-80.9%, 37.7%-56.0%, respectively. However, intereropping resulted in reduction of water spinach yield. Intercropping sig- nificantly increased total yield of rice and water spinach from land equivalent ratios （LER） analysis. The values of LER were more than 1.0, and the ratio of 3 ： 2 intercropping had the best effect. As for the competitive index, rice was more competitive than water spinach in intercropping system, especially in early season. Compared with rice monoculture, rice-water spinach intercropping significantly increased the absorption of Si and N in rice leaves, and Si content of rice leaves during ripe- ning stage, but didn＇t increase its N content and even slightly reduced it during ripening stage. In- tercropping had no significant effect on available Si, ammonium N and nitrate N content in soil.Compared with rice monocuhure and intercropping, water spinach monoculture had always the highest available Si, ammonium N and nitrate N contents in soil through the experiment period. The results suggested that rice-spinach intercropping could promote rice to absorb silicon and nitrogen and increase the competitive ability of rice.