西北地区盐碱地柳枝稷生物质形成规律与水肥调控效应研究

There are a large number of saline-alkali lands in northwest of China. Low productivity and ecological fragility has been the bottleneck of agriculture development and ecological construction in saline regions. The emergence of modern biomass economy pointed out the direction for saline-alkali land resources utilization and regional agricultural sustainable development. Switchgrass has been introduced into China as an ideal energy crop, and relevant researches mainly focused on its ecological adaptability, yield, quality and salt-tolerance physiology characteristics. However, there were fewer studies on biomass production and irrigation-fertilization management of switchgrass in saline-alkali land. Therefore, Long-term stationary experiments, pot experiments combined with mathematical model analysis were used to study biomass formation process and yield limiting factors of switchgrass in saline-alkali land. In this program, biomass formation laws for different ecotypes of switchgrass in saline-alkali land were studied, the effects of irrigation and fertilization management on water, N and salt movement in soils were analyzed. Biomass yield formation, photosynthetic physiology, water and fertilizer utilization characteristics were investigated under different irrigation and fertilization managements. The objective is to definite the potential productivity of switchgrass in saline-alkali land, reveal the regulation mechanism of irrigation and fertilization management, and establish water-fertilizer-salt management mode suitable for switchgrass. The results would provide theoretical basis and technical support for high-yield cultivation and large scale planting of switchgrass in saline-alkali land.

我国西北地区有大量的盐碱地，这类土地生产力低下，生态脆弱，一直是区域农业发展和生态建设的瓶颈。现代生物质经济的出现为盐碱地资源开发和农业可持续发展指明了方向。柳枝稷作为一种理想的能源作物已被引入我国，并在生态适应性评价、产量品质和耐盐生理等方面开展了相关研究，但盐碱地条件下柳枝稷生物质生产与水肥调控方面的研究较少。因此，本项目采用田间定位试验、盆栽试验与数学模型分析相结合的研究方法，从西北干旱半干旱区盐碱地柳枝稷的生物质形成过程及其产量限制因子出发，研究不同生态型柳枝稷在盐碱地种植的生物质形成规律，并研究水肥调控对盐碱土水肥盐运移、柳枝稷生物质产量形成、光合生理和水肥利用特性的影响，探明西北地区盐碱地柳枝稷生产能力及其调控机理，建立适合当地的作物-水-肥-盐管理模式，为盐碱地柳枝稷规模化种植提供理论依据与技术支撑。

本项目采用田间定位试验、盆栽试验与数学模型分析相结合的研究方法，研究了不同生态型柳枝稷在宁夏银北盐碱地种植的生态适应性、生产能力以及水肥调控效应，建立了盐碱地柳枝稷水肥调控模型，为西北地区盐碱地柳枝稷规模化种植提供了理论与技术支撑。主要研究结果如下：（1）柳枝稷在盐碱地均表现出良好的生态适应性，不同品种柳枝稷均可以安全越冬，其最高生物质产量可达20.5 t·hm-2，总体上低地型品种的生物质产量高于高地型品种，柳枝稷产量形成受土壤水分和盐分影响较大。不同品种柳枝稷光合能力、生理抗逆性和水肥利用特性都存在明显差异。经综合评价，Alamo、Cave-in-Rock在西北盐碱地区具有较高的产量潜力，其光合潜力大，水肥利用效率较高。（2）水肥盐对柳枝稷植株生长有明显耦合效应，其中土壤含水量和土壤盐分是影响柳枝稷株高、分蘖、叶面积、叶片数和干物质产量的主要因素，但是施氮能够在一定程度上减轻水盐胁迫对柳枝稷生长和产量的不利影响。随着水盐胁迫加重，柳枝稷Na+、K+含量升高，生理活性减弱，光合降低，生长受到明显抑制。水肥调控能够缓解土壤盐分胁迫，增强柳枝稷的生理抗逆性，保持较高光合能力，从而促进柳枝稷生长和生物质产量形成。（3）水肥调控对盐碱地柳枝稷产量具有显著影响，灌水对柳枝稷产量的影响大于施肥。随着灌水量的增加柳枝稷产量显著升高；随着施氮量增加，柳枝稷产量呈先升高后降低的趋势。高水中氮处理有利于降低土壤盐分，保持土壤水分和养分平衡，提高水肥利用效率。盐碱地条件下，充足的灌水和适量的氮肥投入是柳枝稷高产和水肥高效利用的保证。试验建立了柳枝稷水肥调控模型，通过模型求得，施氮量和灌水量分别为 130.65 kg·hm-2和1982.25 m3·hm-2时，可获得最高生物质产量。