CO2超临界萃取沙棘油酸价测定

通过对CO2超临界萃取沙棘油酸价的测定，发现不同分离条件所得的沙棘油酸价差别较大；相同分离条件所得的沙棘油，由于样品取样后放置时间不同，所测的酸价大不相同，从中发现了CO2超临界萃取沙棘油酸价变化规律及CO2对沙棘油酸价测定的影响规律。     

雷林1号桉叶片营养诊断研究

对雷林１号桉叶营养诊断的采样时间、诊断方法，用临界值法和诊断施肥综合法诊断雷林１号桉施肥“中试的营养状况。结果表明：；雷林１号桉叶片营养诊断的最佳采样时间是８月龄，其Ｎ、Ｐ、Ｋ临界浓度为１７．２、１．３、４．９，ＤＲＩＳ参数为Ｋ／Ｐ、Ｐ／Ｎ和Ｎ／Ｋ。     

福建早稻测土配方施肥指标体系研究

根据近年来完成的135个氮、磷、钾肥效试验结果,建立福建早稻测土配方施肥指标体系。结果表明,土壤对稻谷的平均贡献率为73.5%,施用氮、磷、钾平均增产18.1%、5.4%和8.6%,土壤贡献率和氮、磷、钾增产效果与肥力等级成正比。山区早稻高产临界指标分别为碱解氮212 mg/kg、Olsen-P26 mg/kg和速效钾116 mg/kg,沿海早稻则分别为碱解氮203 mg/kg、Olsen-P 22 mg/kg和速效钾104 mg/kg,明显低于山区稻田。早稻最高施肥量平均为N166 kg/hm2、P2O569 kg/hm2和K2O 113 kg/hm2,经济施肥量平均为N 134 kg/hm2、P2O535 kg/hm2和K2O 78kg/hm2,但不同生产区域和土壤肥力等级的氮、磷、钾推荐用量有一定差异。建立了土测值与氮、磷、钾推荐用量的回归方程式,从而达到因土施肥的目的。     

基于叶面积指数构建滴灌玉米营养生长期临界氮稀释曲线

明确宁夏引黄灌区基于叶面积指数(leaf area index,LAI)的滴灌玉米临界氮稀释曲线模型及其适用性,探讨以氮营养指数(nitrogen nutrition index,NNI)为监测指标对滴灌水肥一体化模式下玉米氮素营养状况诊断的可行性。该研究于2017-2018年开展了不同施氮量(0~450 kg/hm^2)下4个田块的试验,采用系统分析和统计建模的方法,分析了LAI和植株氮浓度(plant nitrogen concentration,PNC)的定量关系,构建和验证基于LAI的临界氮稀释曲线模型,并建立理论框架,将基于LAI的临界氮曲线与基于植株干物质(plant dry matter,PDM)的临界氮浓度曲线关联,比较基于LAI和PDM的临界氮曲线之间的差异。结果表明,玉米营养生长期临界氮和LAI符合幂函数关系,拟合模型的评价指标均方根误差(root mean square error,RMSE)和标准化均方根误差(normalized RMSE,n-RMSE)的结果分别为0.09和4.13%,模型具有较好的稳定性。在试验氮素水平范围内,不同生育时期NNI随施氮量的增加而增加,变化范围为0.53~1.34,NNI可以准确地反映滴灌玉米氮素营养状况。在非限氮处理下,玉米植株氮素吸收与LAI成正比,LAI与PDM的异速生长参数接近理论值2/3。构建的基于LAI的临界氮曲线可以有效地识别玉米拔节期至吐丝期植株所需的氮状态,为宁夏滴灌玉米氮肥精确管理提供了一种新的评价方法。     

基于鱼类游泳能力的鱼道设计流速解析

短须裂腹鱼（Schizothorax wangchiachii）是黑水河流域生态修复重要的保护鱼类,为了使过鱼设施取得最佳过鱼效果,鱼类有更好的上溯路径,需要针对性探究过鱼对象的游泳能力指标;基于鱼道的水力学特性,对短须裂腹鱼感应流速、临界游泳速度、爆发游泳速度以及游泳耐力进行研究。结果表明,短须裂腹鱼的感应流速为（0.09±0.03）m/s,相对感应流速为（0.39±0.15）BL/s,流速0.04~0.14 m/s,趋流率（F）随流速（V）增大而显著增大,F=0.7576lnV+2.485（R2=0.97,P＜0.01）;临界游泳速度（Ucrit）为（1.41±0.18）m/s,相对临界游泳速度（U’crit）为（6.27±1.14）BL/s;递增流速法测得的爆发游泳速度(Uburst)为（1.83±0.23）m/s,相对爆发游泳速度(U’burst)为（7.95±1.04）BL/s;固定流速法测得爆发游泳速度为1.8 m/s,持续游泳速度为1.2 m/s,在1.2~1.8 m/s耐久游速区间,持续游泳时间（T）随游泳速度（V）增大而减小,lgT = -4.5015V+9.468 (R2=0.69,P＜0.01)。结合鱼道水力学特性,推荐鱼道最小流速为0.20 m/s,高速区流速小于1.44 m/s,鱼道进口部分流速为1.20~1.44 m/s,休息池段流速为0.20~1.16 m/s。     

关中平原冬小麦临界氮稀释曲线建模

临界氮稀释曲线可诊断植株氮营养状况,针对国内目前普遍存在的建模品种单一,可能造成模型普适性偏差的问题,以陕西关中平原主栽的6个冬小麦品种为研究对象,分别设置4个（0、105、210 kg·hm^-2和315 kg·hm^-2）施氮量水平,以两季4个冬小麦品种田间数据,建立了冬小麦花期前地上部干物质临界氮稀释曲线,曲线服从负幂指数函数;进一步通过另外2个冬小麦品种共计两季数据对模型进行了验证,验证结果表明,采用临界氮稀释曲线可以较好地区分独立样本中的氮营养亏缺和氮营养过剩数据。依据临界氮稀释曲线建立的氮营养指数和累计氮亏缺模型,可分别用于诊断植株的氮营养状况和量化氮素盈亏量,诊断结果表明施氮量为0 kg·hm^-2和105 kg·hm^-2条件下植株氮营养亏缺,210 kg·hm^-2和315 kg·hm^-2条件下小麦氮营养盈余,0~315 kg·hm^-2施氮量下的累计氮亏缺量-33.2~50.9 kg·hm^-2。通过建立氮营养指数与施氮量之间的线性关系,得出关中平原冬小麦适宜施氮量约为162 kg·hm^-2。     

Determining the optimum range of soil Olsen P for high P use efficiency, crop yield, and soil fertility in three typical cropland soils

Soil Olsen P level has a major influence on crop yield, efficient P utilization, and soil fertility. In this study, the optimum Olsen P range was determined from long-term (1990-2012) field experiments in three typical soil types of China under single cropping of maize or double cropping of maize and wheat. The critical soil Olsen P value for crop yield was evaluated using three different models, and the relationships among P use efficiency (PUE), Olsen P, and total P were analyzed. The agronomic critical soil Olsen P values obtained from the three models for the neutral soil of Gongzhuling and the calcareous soil of Zhengzhou were similar; however, the values from the linear-linear and linear-plateau models for both maize and wheat were substantially lower than those from the Mitscherlich model for the acidic soil of Qiyang. The PUE response change rates (linear equation slopes) under different soil Olsen P levels were small, indicating slight or no changes in the PUE as the soil Olsen P increased in all three soils. A comparison of the Olsen P levels that achieved the maximal PUE with the agronomic critical values derived from the three models indicated that the linear-plateau model exhibited the best performance. The regression equation coefficients of Olsen P response to total P decreased as follows:Zhengzhou (73 mg g^-1) > Qiyang (65 mg g^-1) > Gongzhuling (55 mg g^-1). The Olsen P level increased as the total P increased, which may result in a decrease in PUE. To achieve a relatively high crop yield, PUE, and soil fertility, the optimum Olsen P range should be 13-40, 10-40, and 29-40 mg kg^-1 at Gongzhuling, Zhengzhou, and Qiyang, respectively.     

Effects of Loma morhua (Microsporidia) infection on the cardiorespiratory performance of Atlantic cod Gadus morhua (L).

The microsporidian Loma morhua infects Atlantic cod (Gadus morhua) in the wild and in culture and results in the formation of xenomas within the gill filaments, heart and spleen. Given the importance of the two former organs to metabolic capacity and thermal tolerance, the cardiorespiratory performance of cod with a naturally acquired infection of Loma was measured during an acute temperature increase (2 °C h^?1) from 10 °C to the fish's critical thermal maximum (CT_Max). In addition, oxygen consumption and swimming performance were measured during two successive critical swimming speed (U_crit) tests at 10 °C. While Loma infection had a negative impact on cod cardiac function at warm temperatures, and on metabolic capacity in both the CT_Max and U_crit tests (i.e. a reduction of 30–40%), it appears that the Atlantic cod can largely compensate for these Loma‐induced cardiorespiratory limitations. For example, (i) CT_Max (21.0 ± 0.3 °C) and U_crit (~1.75 BL s^?1) were very comparable to those reported in previous studies using uninfected fish from the same founder population; and (ii) our data suggest that tissue oxygen extraction, and potentially the capacity for anaerobic metabolism, is enhanced in fish infected with this microsporidian.     

基于临界氮浓度的滴灌棉花氮素营养诊断模型研究

在新疆滴灌棉田,选择新陆早45号作为试验材料,设置5个施氮水平(0、120、240、360、480 kg/hm2),研究滴灌棉花各器官氮素吸收分配规律及生物量和氮浓度的动态变化,并建立滴灌棉花的临界氮浓度稀释模型,确定临界氮营养指数,实现对滴灌棉花氮素营养丰缺程度的诊断。结果表明,滴灌棉花生物量随施氮量的增加而增加,氮浓度随滴灌棉花的生长进程而降低;滴灌棉花临界氮浓度与地上部生物量间符合幂函数关系,其相关系数为0.906。通过均方根误差RMSE对模型进行验证,验证结果表明,所得模型的模拟性能较好。基于临界氮浓度建立的氮素营养指数模型(NNI)可作为滴灌棉花氮素营养状况的判别指标,由氮营养指数得到滴灌棉花的适宜施氮量为240~360 kg/hm2。