地下滴灌苜蓿种子田土壤养分及盐碱分布规律

为探明地下滴灌模式下多年生苜蓿种子田土壤中的养分和盐碱分布规律,为科学利用地下滴灌进行苜蓿种子生产提供指导。本研究以滴灌带正上方地面为起始点,对垂直方向0~60 cm、水平方向0~40 cm范围内的土壤取样分析。结果表明地下滴灌4年淋洗导致了新牧4号紫花苜蓿种子田土壤中的养分与盐碱存在异质性分布,养分主要分布于垂直距离0~30 cm、水平距离0~20 cm的土壤;盐分主要聚集于距地表垂直距离30~40 cm、距滴灌带水平距离30~40 cm的土壤;土壤碱性较强区域为距地表垂直距离30~60 cm、距滴灌带水平距离20~40 cm的土壤。

放牧对新疆天山山地草甸土壤团聚体和土壤呼吸潜力的影响

放牧是新疆山地草甸重要的利用方式,探明放牧对草地土壤呼吸的影响机制,可为深入了解草地碳汇功能,合理的利用草地提供参考依据。本研究在天山北坡中段山地草甸开展,以长期放牧和围封草地(CK)的土壤为研究对象,采用干筛法将土壤筛分为<0.25 mm,0.25~1 mm,1~2 mm,2~4 mm粒径的土壤团聚体,并测定了各粒径团聚体的比例、土壤β-葡萄糖苷酶、土壤β-木糖苷酶、土壤N-乙酰-β-D葡萄糖苷酶活性及其21天的CO_(2)释放量。研究结果表明:放牧显著增加了<0.25 mm粒径的团聚体比例,降低了<0.25 mm,1~2 mm土壤团聚体的CO_(2)释放量;<0.25 mm粒径土壤团聚体CO_(2)释放量均显著高于其他粒径;三种土壤酶活性在<0.25 mm,1~2 mm粒径的土壤团聚体中与土壤呼吸表现出显著的正相关。综合分析表明,在天山北坡中段山地草甸,放牧会抑制<0.25 mm,1~2 mm团聚体酶活性,降低土壤呼吸,使得草地整体代谢速率降低。

建植密度和施氮水平互作对老芒麦农艺性状和种子产量的影响

探究建植密度和施氮水平对老芒麦农艺性状和种子产量的影响,为新疆地区种植老芒麦提供生产理论基础。通过裂区试验设计,设置2个密度处理:低密度(25.87万株/hm^(2))、高密度(71.52万株/hm^(2)),下设5个施氮水平:0 kg/hm^(2)、30 kg/hm^(2)、60 kg/hm^(2)、90 kg/hm^(2)、120 kg/hm^(2),并在成熟期对老芒麦株高、茎粗、旗叶长、旗叶宽、倒二叶长、倒二叶宽等农艺性状及种子生产相关指标进行了测定。建植密度对老芒麦农艺性状和种子生产指标均具有显著影响,表现为高密度处理的老芒麦株高、倒二叶长、单位面积生殖枝数均显著高于低密度处理;施氮水平对老芒麦茎粗、旗叶长、旗叶宽、倒二叶长、倒二叶宽、单位面积生殖枝数、穗长、千粒重及种子产量均有显著的影响。建植密度和施氮水平对老芒麦种子产量具有显著的交互作用,低密度处理下随施氮量增加老芒麦种子产量增加,120 kg/hm^(2)施氮量下可获得最高的种子产量,高密度处理下随施氮量增加,老芒麦种子产量呈现先增加后降低趋势,施氮水平阈值为90 kg/hm^(2)。老芒麦建植密度为25.87万株/hm^(2),120 kg/hm^(2)施氮水平可获得较高的种子产量。

The cross-sectional and longitudinal association of the BODE index with quality of life in patients with chronic obstructive pulmonary disease

Background The body mass index, airflow obstruction, dyspnea, and exercise capacity （BODE） index was shown at predicting the risk of death, exacerbation and disease severity among patients with COPD, but few studies verified relationship between BODE index and health related quality of life （HRQoL） among Chinese COPD patients. The objective of this study was to evaluate the relationship between BODE index and HRQoL in cross-sectional and longitudinal association analyses. Methods A multi-center prospective cohort study was initially conducted in 491 stable COPD patients in Beijing, China. Health status （HRQoL） was assessed by St. George＇s Respiratory Questionnaire （SGRQ）; the BODE index was calculated for each patient; dyspnea was assessed using the 5-grade Medical Research Council dyspnea scale. Other measurements included socio-demographic, body mass index （BMI）, lung function test and 6-minute-walk test （6MWT）. Patients were then followed monthly for 12 months. Results Only 450 patients completed the 1-year follow up and were enrolled in our present analyses. Mean age was （65.2 ±10.6）years,＇ men 309 （68.7%）. The BODE index was categorized into 4 subgroups： 0-2, 3-4, 5-6 and 7-10. At baseline BODE index was gradually increased with baseline total SGRQ and SGRQ subscales （P trend 〈0.001）. For individual components of BODE index, with the decrease of airflow limitation, and 6MWD, and with the increase of Medical Research Council （MRC） dyspnea grade, total SGRQ and SGRQ subscales were increased correspondingly, P trend 〈0.05, respectively. Similar association patterns were found between baseline BODE index and its individual components and mean SGRQ scores at the end of 1-year follow up. By multiple linear regression analyses, baseline BODE index was not only significantly associated with SGRQ score at baseline but also with SGRQ score at the end of 1-year follow up after adjustment for age, male, current smoking, 13s being 0.434 and 0.378, respectively. Conclusions BODE index is associated with SGRQ score cross-sectionally and longitudinally among stable COPD patients. BODE index might have potential to be used as a sensitive tool to assess the status of quality of life and to monitor disease progression among stable COPD patients.