水磷供应对柳枝稷和达乌里胡枝子生物量、水分利用效率及种间关系的影响

明确水磷供应对柳枝稷（Pancium virgatum L.）和达乌里胡枝子（Lespedeza davurica S.）生物量、水分利用效率（Water use efficiency，WUE）和种间关系的影响，可为黄土丘陵区二者混播草地建设提供依据。本研究采用盆栽试验，分析了2种水分水平（充分供水和干旱处理），3个磷处理（0，0.05和0.1 g P₂O₅·kg^-1干土）和5种组合比例12：0（柳枝稷：达乌里胡枝子），8：4，6：6，4：8和0：12]下二者的生物量、WUE和种间关系。结果表明：二者混播相对总生物量（Relative yield total，RYT）为0.91~1.34；不论施磷与否，柳枝稷竞争攻击力系数（Aggressivity，A）和达乌里胡枝子相对竞争强度（Relative competition intensity，RCI）在干旱处理下显著低于充分供水（P<0.05）；2种水分下，施磷（0.1 g·kg^-1）显著降低柳枝稷A值，对达乌里胡枝子RCI无影响。干旱处理下，4：8比例（柳枝稷：达乌里胡枝子）下RYT最高且WUE较高，施磷显著提高混播总生物量和WUE，且0.05和0.1 g·kg^-1间均无显著差异，表明采用4：8比例并施磷0.05 g·kg^-1可提高生物量和WUE。

Effects of Water and Phosphorus Supply on Biomass Production,Water Use Efficiency and Interspecific Relationship of Switchgrass and Bushclover

This study was aimed to clarify the effects of water and phosphorus (P) supply on biomass production,water use efficiency (WUE) and interspecific relationship of switchgrass (Pancium virgatum L.) and bushclover (Lespedeza davurica S.) and to provide the basis for the artificial grassland construction of these two species in loess hilly-gully region. A pot experiment was conducted with two soil water regimeshigh water (75%±5% field capacity,FC) and low water (35%±5% FC)],three P treatments (0,0.05 and 0.1 g P₂O₅·kg^-1 dry soil) and five mixture ratios12:0(switchgrass:bushclover),8:4,6:6,4:8,4:8 and 0:12]. Results showed that the relative yield total (RYT) values of switchgrass and bushclover mixtures were between 0.91 and 1.34. Regardless of P treatments,the aggressivity (A) values of switchgrass and the relative competition intensity (RCI) values of bushclover were significantly lower under low water regime than those under high water regime (P<0.05). Under both water regimes,P supply (0.1 g·kg^-1) significantly decreased the A values of switchgrass (P<0.05) while had no significant effect on the RCI values of bushclover. Under low water regime,the highest RYT values and a higher WUE were obtained at 4:8 mixture ratio of switchgrass to bushclover;P supply significantly increased total biomass production and WUE in their mixtures (P<0.05),while no significance difference between P concentrations were detected,implying that switchgrass and bushclover can be intercropped in the region,and 4:8 mixture ratio of switchgrass to bushclover with 0.05 g P₂O₅·kg^-1 dry soil supply could help to improve total biomass production and WUE.