气候变化对农业产生了重大影响。但大多数研究基于历史气象数据的分析，缺乏与作物生长发育和土壤水分相关联的长期监测。本研究收集了甘肃省农业科学院镇原试验站1957-2020年气象数据和1981-2019年作物生育期数据，并在陇东和宁南开展了相关田间长期试验。研究结果表明，60年来，每10年平均气温增加0.36°C和降水减少11.2mm；1981-2019年的39年间旱地冬小麦田间耗水量平均362.1mm，呈现出每10年减少22.1mm的趋势，但1985-2019年的35年间春玉米耗水量平均405.5mm，保持基本稳定。气候干暖化导致旱地作物生育期发生了明显变化，每10年冬小麦和春玉米生育期缩短5.19天和6.47天，播前推迟3.56天和1.8天，成熟期提前1.76天和5.51天。全膜双垄沟集雨种植使小雨量在垄沟集雨效率达到65.7-92.7%，水分向土壤深层入渗，作物根域水分成倍增加，作物水分满足率提高110-160%，连续15年全膜双垄沟较半膜平作覆盖旱地玉米增产19.87%。旱地玉米群体大小是影响产量和水分利用效率的关键因素，种植密度从3000提高到4500株/亩，玉米产量和水分利用效率增加20.6%和17.4%，从4500提高到6000株/亩再增加12.0%和12.7%。然而，不同降水量地区旱地玉米产量与种植密度均呈现二次曲线关系，曲线性状、最高产量对应的最大密度在地区之间差异很大。在300-500mm年降水量地区，种植密度随降水量的增加而增加，适水种植密度为每1mm降水可种植玉米12株/亩，但超过500mm时种植密度随降水量变化不大。因此，旱地农田抗旱节水应集中在压夏扩秋适水型种植结构建立、垄沟覆盖集雨种植、以水定密适水种植等，以减少气候变化引起的负面影响，增强旱地玉米生产的可持续。

The essential and toxic element concentrations in buckwheat were analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES). The concentration data were subjected to common chemometrics analyses, including correlation analysis (CA), principal component analysis (PCA) and hierarchical cluster analysis (HCA), to gain better understanding of the differences among the tested samples. Our results indicated that the essential and toxic element concentrations were not different between Fagopyrum tataricum (L.) Gaertn and F. esculentum Moench. The element concentrations varied among buckwheat samples from different sources. Commercial tartary buckwheat tea contained several essential elements, thus, could be used as the source of essential elements. The detection of toxic heavy metals in commercial tartary buckwheat tea suggested that safety issue of such buckwheat products should be seriously concerned. Our results also revealed that the place of origin and the processing protocol of tartary buckwheat affected the element concentrations of the commercial form. The implications to the quality control and safety evaluation of buckwheat were extensively discussed.

For quality control of buckwheat, fingerprint-efficacy study of buckwheat was carried out in this work. 2,2´-Bipyridyl,2,2- diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activity of the buckwheat was measured using UV spectrometer. Chemical fingerprints of tartary buckwheat from 29 different sources were determined by HPLC-UV and investigated by similarity analysis and hierarchical clustering analysis. The fingerprint-efficacy relationship between chemical fingerprint and DPPH radical scavenging activity of tartary buckwheat were established by multi-linear regression analysis. The results showed that the sources of buckwheat had some important influence on the chemical fingerprints and DPPH radical scavenging activity. DPPH radical scavenging activity of tartary buckwheat was stronger than that of common buckwheat, rutin, and kaempferol and some unknown compound might be the major effective components for quality control of tartary buckwheat for its antioxidant activity.