冀西北高寒区地膜覆盖对小南瓜生育及水分利用效率的影响

研究了地膜覆盖对旱砂地小南瓜生育特性和水分利用效率的影响.试验结果表明,地膜覆盖后,创造了适合于小南瓜生育的土壤温度和湿度条件,加快了其生育进程,单产量、单果鲜重和干重都优于对照,提高了对土壤水分的利用效率.     

A predictive model of burn severity based on 20-year satellite-inferred burn severity data in a large southwestern US wilderness area

We describe and then model satellite-inferred severe (stand-replacing) fire occurrence relative to topography (elevation, aspect, slope, solar radiation, Heat Load Index, wetness and measures of topographic ruggedness) using data from 114 fires > 40 ha in area that occurred between 1984 and 2004 in the Gila Wilderness and surrounding Gila National Forest. Severe fire occurred more frequently at higher elevations and on north-facing, steep slopes and at locally wet, cool sites, which suggests that moisture limitations on productivity in the southwestern US interact with topography to influence vegetation density and fuel production that in turn influence burn severity. We use the Random Forest algorithm and a stratified random sample of burn severity pixels with corresponding pixels from 15 topographic layers as predictor variables to build an empirical model predicting the probability of occurrence for severe burns across the entire 1.4 million ha study area. Our model correctly classified severity with a classification accuracy of 79.5% when burn severity pixels were classified as severe vs. not severe (two classes). Because our model was derived from data sampled across many fires over a 20-year period, it represents average probability of severe fire occurrence and is unlikely to predict burn severity for individual fire events. However, we believe it has potential as a tool for planning fuel treatment projects, in management of actively burning fires, and for better understanding of landscape-scale burn severity patterns.     

乐东拟单性木兰光合、蒸腾及水分利用效率研究

运用Li-6400光合测定仪对乐东拟单性木兰的光合蒸腾特性进行了初步研究。结果表明：（1）乐东拟单性木兰的光补偿点为65.5μmol•m-2•s-1,光饱和点为1467μmol•m-2•s-1,表观量子效率为0.024;（2）乐东拟单性木兰在晴天条件下光合日变化为双峰曲线,分别在10和16时达到峰值,而在14时到达谷底,表现出午休现象。相关分析表明其影响因子主要是蒸腾速率、气孔导度和光合有效辐射;（3）乐东拟单性木兰蒸腾速率日变化近似单峰型,其主要影响因子为大气温度、叶面温度和光合有效辐射;（4）乐东拟单性木兰水分利用效率日变化为倒单峰型曲线变化。     

Modelling nitrogen stress with probe genotypes to assess genetic parameters and genetic determinism of winter wheat tolerance to nitrogen constraint

Environmental and economical constraints in Europe will favour low nitrogen (N) input systems and wheat varieties adapted to moderate N deficiency. In this context, we studied the dynamics of genetic parameters according to N stress intensity and characterized the genetic determinants for plant tolerance to N deficiency. Thus, we combined N stress modelling with a genetic approach. Two hundred and twenty-two doubled haploid lines were experimented in the field for a range of nitrogen conditions. Those conditions were characterized by the Nitrogen Nutrition Index (NNI) of Récital. Grain Yield (GY) and Kernel Number (KN) were assessed. For GY and KN, and for each line, factorial regressions using NNI of Récital as environmental index were performed. In addition, we assessed the sensitivity to N stress (slopes of the regression) and the performances under low N conditions (predicted values for a NNI of 0.5). QTL detection was performed on these parameters as well as on KN and GY measured in each environment. G × N variance increased with N stress intensity whereas heritability and genetic variance decreased. 11 QTL regions were detected: 3 were N supply-specific QTL (on linkage groups 2A2, 3A and 4B) while 4 contained QTL detected under N⁺ and under N⁻ (2D1, 4B and 5A1). Out of these four, 2 coincided with QTL for factorial regression parameters (2D1 and 4B). Finally, 4 QTL were specific for factorial regression parameters (3B, 5A2 and 7B2). The role of genes commonly used in breeding programs (rht-B1 on 4B, and Ppd1 on 2D1) in plant adaptation to nitrogen constraint was highlighted. Future studies should focus on grain protein yield, another target for low-N breeding scheme.     

不同类型地膜覆盖对玉米农田水热状况及产量的影响

为提高我国北方旱地作物的水分利用效率,探索可降解类型地膜的应用前景,在山西省农科院东阳试验基地,于2015年和2016年连续定点定位设置普通地膜、渗水地膜、生物降解地膜、光降解地膜4种不同类型地膜覆盖模式,以不铺膜为对照,研究不同类型地膜覆盖模式对农田水热效应和玉米产量的影响。研究结果表明:4种覆膜处理下的土壤温度在生育前期土表处分别较不铺膜处理高3.1~5.9℃;渗水地膜和生物降解地膜处理的水分利用效率显著高于其他处理(P0.05),光降解地膜和普通地膜处理次之,不铺膜对照处理最低,渗水地膜、光降解地膜、生物降解地膜、普通地膜处理的水分利用效率分别较对照高11.0、5.9、12.8、5.4 kg/(mm·hm~2)。产量方面,与对照相比较,渗水地膜、光降解地膜、生物降解地膜、普通地膜处理2015年的增产率分别为20.3%、0.1%、15.4%、8.8%;2016年的增产率分别达到44.8%、36.1%、53.6%、31.6%,表现为生物降解地膜渗水地膜普通地膜光降解地膜。地膜增温保墒作用下,处理之间的增产效果与水分利用效率变化协同,其中生物降解地膜能够显著提高玉米的水分利用效率及产量,在未来可替代普通地膜推荐应用到旱地玉米中,同时达到缓解农田残膜污染的效果。     

上海市青浦区土地利用时空格局模拟研究

基于CLUE-S 模型,结合区域总体规划和生态保护红线管控方案,对青浦区进行了2040 年土地利用格局模拟预测,最后从最小累积阻力模型出发,对其生态阻力进行了比较分析,结论如下：（1）对CLUE-S模型适用性进行验证,经过计算,Kappa 精度达到95%以上,表明CLUE-S模型在青浦区具有良好的土地利用格局模拟能力;（2）青浦区土地利用格局空间差异显著,工业用地、交通用地、居住地、城市绿地和林地的面积增加,农业用地和水域的面积有所减少;（3）生态保护红线约束下,青浦东部地区生态阻力减小,西部地区保持稳定,土地利用空间格局变化更趋于合理。结论可为青浦区未来土地利用规划、管理及政策制定等提供参考依据和决策支持。     

河西古浪县沙漠绿洲边缘土地合理利用对策

通过对河西古浪县腾格里沙漠南缘新垦绿洲区农业生产、土地与水资源利用现状,区域种植结构、经济发展水平与生态环境建设等内容进行调查分析,结果显示：项目区农业用地资源有限,水资源短缺,农作物品种单一产业结构简单,经济作物种植面积小,严重制约了区域生态农业整体发展水平。为了改善绿洲边缘生态环境和发展新垦人工绿洲农业生产,提高区域土地利用效率,推广节水型生态农业,增加区域经济收益,采用在项目区增加种植经济植物、节水型农作物品种的种植面积,发展优质牧草和地膜种植面积,扩大养殖业等试验研究的方法和措施,调整区域产业种植结构,改革现行农田耕作技术,改善绿洲边缘生态环境,提高区域土地利用效率和增强土壤肥力,达到明显的经济效益,为沙漠绿洲边缘发展生态农业和促进区域农业可持续发展起到示范作用。     

烤烟钾素吸收利用效率研究现状与展望

简介了烤烟常用的钾肥类型及其特点,综述了烤烟钾素吸收利用机理和积累分配规律,分析了钾肥种类、烟草品种、气候条件、土壤环境、施钾技术和调控措施等对烤烟钾素吸收利用效率的影响,并讨论了提高烤烟钾素利用效率和烟叶含钾量的途径。     

春玉米行间覆膜田间土壤水分时空动态及水分高效利用机理研究

在不同覆膜方式下对春玉米田间土壤水分时空运移规律、耗水特征和水分利用效率进行了系统研究。结果表明:行间覆膜全生育期0～100cm土层土壤贮水量明显高于行上覆膜和不覆膜。不同覆膜方式下,春玉米全生育期土壤水分状况可分为土壤水分大量损耗期和土壤水分收支平衡期,且0～100cm土层可分为急变层、活跃层和相对稳定层;不同覆膜方式下膜内外土壤水分差异主要体现在0～60cm土层,行间覆膜使玉米根系长期生长在土壤含水量较高的区域,促进了玉米的生长发育和土壤水分的直接有效利用;不同覆膜方式的土壤水分利用效率、产量和产量水平的水分利用效率皆表现为行间覆膜>行上覆膜>不覆膜。行间覆膜较高的水分利用效率主要是充分有效地运用了降水和灌溉水。     

食用红甜菜的性状调查及保健利用价值

利用19个形态学性状对5个食用红甜菜材料分别在生长的不同时期进行了调查,对食用红甜菜的形态特征进行了描述;初步调查分析了3个材料的叶丛高度、叶片数、叶长、叶宽和叶片叶绿素含量的动态变化;探讨了食用红甜菜的营养保健功能和加工利用价值。