关键词: 冬小麦, 群体分布, 灌溉, 群体结构, 光能利用率, 土壤有机碳, 根系生物量, 土壤含水率, 种间关系, 干旱区, 沙枣-芨芨草群落

Abstract: A field experiment was conducted in 2006〖KG-*2〗-〖KG-*7〗2008 to study the effects of different population distribution pattern and irrigation schedule on the radiation utilization in a winter wheat farmland at the same population density (204×106 plant·hm-2). Four population distribution patterns were designed, i.e., row spacing (cm) × plant spacing (cm) 7×7 (A), 14×3.5 (B), 24.5×2 (C), and 49×1 (D), and each pattern had four irrigation schedules, i.e., no-irrigation, irrigation at jointing stage, irrigation at jointing and heading stages, and irrigation at jointing, heading and filling stages. The irrigation amount was 060 m3 each time. In the patterns A and B, the tiller number and leaf area index (LAI) were significantly higher than those in C and D (P<005). With the increase of row spacing, the photosynthetically active radiation (PAR) transmittance ratio increased gradually, while the PAR capture ratio had a decreasing trend. Increasing irrigation times increased the tiller number and LAI, but decreased the transmittance ratio of PAR, resulting in a significant increase of PAR capture ratio (P<005). The PAR capture ratio in the crop canopy was higher in upper layers, compared with that in lower layers. Relatively uniform population distribution and irrigation increased the PAR capture ratio in the upper 40 cm canopy layers significantly. The radiation use efficiency (RUE) decreased with increasing row spacing, with the two year's average total RUE in A, B, C, and D being 124%, 127%, 121% and 106%, respectively, and that in B was 521% and 1956% higher than that in C and D, respectively, with the difference being significant. It was suggested that relatively uniform population distribution improved the winter wheat population structure and PAR capture, being beneficial to the fully use of radiation, and irrigation also had positive effects on the population structure, being helpful to the increase of crop RUE.

Key words: winter wheat, population distribution, irrigation, population structure, radiation use efficiency, soil organic carbon, root biomass, soil moisture content, interspecific relationship, arid area, Elacagnus angustifolia-Achnatherum splendens community.