AquaCrop作物模型在黄土塬区夏玉米生产中的适用性评价

为评价Aqua Crop作物模型在黄土塬区的适用性,基于Hsiao等人推荐的玉米参数对模型参数进行调试及验证。在陕西长武地区模拟2003、2004、2005、2007、2008、2010年玉米生育期内生物量、蒸发蒸腾量的变化过程及收获时产量、地上部生物量,将模拟值与收集到的实测值进行对比、分析。结果表明,这6年模拟产量与实测产量间的校正决定系数(Adj)R2为0.9270,相对误差在-2.479至11.182之间;模拟地上部生物量与实测地上部生物量间的Adj.R2为0.7842,模型对产量的模拟效果优于对生物量的模拟;2005年和2008年模拟蒸散量与实测蒸散量间的Adj.R2分别为0.6229和0.7973。模拟效果较好,对黄土塬区夏玉米水分优化管理模拟有重要意义。     

基于CROPWAT模型的非充分灌溉研究

为验证FAO的CROPWAT模型在非充分灌溉中的适用性和精确性,将民勤棉花和春小麦非充分灌溉的试验方案及当地气象资料输入模型,分析CROPWAT模型在模拟作物蒸发蒸腾量和非充分灌溉对产量影响的模拟效果。结果显示,棉花各生育期日平均蒸发蒸腾量的模拟值和实测值表现出相同的分布规律,但模拟值整体高于实测值0.15~1 mm;模拟非充分灌溉对棉花和春小麦产量的影响时,模拟值和实测值显示出一致的变化规律,将结果进行统计分析,棉花和春小麦的RMSE、EF、CRM分别为20.62%和10.35%、0.98和0.856、-0.00051和-0.0155,说明CROPWAT模型总体模拟效果较好,但模型的执行值较实测值偏高。模拟结果表明,模型在非充分灌溉的研究中有着较好的适用性,但为了使模拟结果更准确,使用前需根据当地实测资料对Kc、Ky等参数进行校正。     

黄土高原一年生饲草作物产量与水分利用效率

一年生饲草作物是补充黄土高原地区冬春季家畜饲草供应的重要来源,而水分利用效率是评价饲草作物适应区域气候环境的重要表征。采用大田试验研究了甘肃陇东黄土高原雨养农业区9种春播一年生饲草作物〔玉米(Zea mays)、苏丹草(Sorghum sudanense)、大豆(Glycine max)、谷子(Setaria italica)、糜子(Panicum miliaceum)、箭筈豌豆(Vicia sativa)、豌豆(Pisum sativum)、燕麦(Avena sativa)和春小麦(Triticum aestivum)〕的饲草干物质产量土壤水分亏缺值和水分利用效率。结果表明:除苏丹草外,其余8种饲草作物的土壤水分亏缺值均呈现"V"型。出苗后6周,春小麦的水分利用效率最高;出苗后15周,玉米的水分利用效率高于其他饲草作物,而谷子和糜子的水分利用效率变幅比其他饲草作物小。在春播条件下,9种一年生饲草作物中,可优先选择玉米、春小麦、谷子和糜子。     

甘肃省粮油产量对气候变暖的敏感性研究

为揭示甘肃各地粮食和油料作物产量对大尺度气温变化响应的程度，利用1981～2000年甘肃省各地小麦、玉米、马铃薯、糜子、谷子等粮食作物和胡麻、油菜等油料作物产量和相应4～10月的气温数据，采用EOF分析方法，研究了甘肃粮油产量对气候变化的敏感性。结果表明：小麦、玉米、胡麻产量对气候变化比较敏感，敏感区主要在河西地区，黄土高原地区对气候变化的敏感性不强；糜子、马铃薯、油菜在大部分地方不敏感，谷子基本不敏感。提出了农业产业结构调整的一些建议。     

TRMM数据应用于降雨量和降雨侵蚀力估算的适宜性研究

USLE/RUSLE模型的模拟精度在很大程度上依赖于各个土壤侵蚀因子的准确估算,降雨侵蚀力因子R作为其最重要的因子之一,由于降雨实测资料不足而使其计算精度存在偏差.TRMM数据已被广泛应用于降雨数据估算,为解决这一难题提供了新的思路.文中基于2008 ～ 2009年TRMM 3B42数据集,采用已有计算方法,对我国2008 ～ 2009年降雨量和降雨侵蚀力进行了估算.并根据2008年实测降雨量以及已有研究成果对估算结果进行了对比分析和验证.结果表明:1)基于TRMM数据的降雨量估算值与实测数据具有较好的一致性,能够很好地反映降水变化过程,但与实测值之间仍存在一定偏差.2)2008年各月降雨量估算值与实测值之间的Nash-Sutcliffe系数E与均方根误差RMSE表现出相反的季节变化.3)多年平均R值与2008年和2009降雨侵蚀力估算值之间的相关系数分别为0.85和0.76,表现出较好的一致性.4)由于数据本身的局限性,TRMM数据对某些地区某些时段的降雨侵蚀力估计值普遍偏高.     

旱作覆膜玉米生长和水分利用对气候变化的响应

基于3 a连续冬小麦-夏玉米覆膜轮作试验校准和验证AquaCrop模型的适用性,模拟研究了气候变化对夏玉米生长、产量和水分利用的影响,分析了覆膜措施对气候变化的应对效果。结果表明:关中地区(以武功、宝鸡和西安地区为例)年平均温度呈逐年递增趋势,温度增加幅度由高到低依次为宝鸡、西安和武功,增温速率分别为0.20、0.12℃·10a~(-1)和0.09℃·10a~(-1);降雨量呈逐年递减趋势,减少幅度大小依次为西安、宝鸡和武功,减小量分别为3.59、3.23 mm·10a~(-1)和2.64 mm·10a~(-1)。AquaCrop模型在关中地区表现出了良好的适用性,可以较好地模拟连续覆膜条件下作物的产量指标、水分利用和生长的动态变化,冠层覆盖度模拟值和实测值之间的均方根误差(RMSE)介于1.1%～15.3%,生物量模拟值和实测值之间的RMSE介于0.626～2.540 t·hm~(-2),土壤贮水量模拟值和实测值之间的RMSE介于12.6～47.4 mm。模拟研究表明,上世纪60年代以来,随着气温不断升高,武功、宝鸡和西安地区的夏玉米生育期均呈逐年缩短趋势,特别是1980s以来,减少幅度达2.76、4.82 d·10a~(-1)和5.94 d·10a~(-1);在不同的降水年型下,覆膜处理产量均高于裸地处理,且其变异系数较小;在干旱气候条件下,覆膜处理依然可以获得一定的籽粒产量,与裸地处理相比,覆膜处理表现出了较好的稳产效应。同时,覆膜处理有效减少了玉米苗期土壤表层蒸发(平均减少7.6 mm),从而在土壤中保蓄更多的降雨;覆膜处理虽然增加了土壤耗水量,但其通过保蓄土壤水分,稳定作物产量,有效提高了玉米的水分利用效率。因此,关中地区旱作覆膜可以有效适应当地气候变化,在一定程度上应对干旱气候,具有较好的增产稳产效应。     

天山北坡融雪期雪层含水率、密度和雪层温度研究

利用DELTA T自动气象仪和Snow Folk积雪特性仪等观测分析整个融雪期阴阳坡雪层含水率、密度与雪层温度的时间变化特征和垂直变化特征并分析与气温、雪深、风速、空气湿度、露点温度（[WTBX]DP）、湿球温度（WB[WTBZ]）等的相关性。结果表明：① 融雪期雪层温度的变化,总的来说阳坡雪层温度大于阴坡。前期阳坡雪层平均温度大于阴坡,后期阴坡积雪平均温度大于阳坡。阴阳坡平均温度在上层最高,中层最低。融雪期温度梯度变化,阴坡总的温度梯度值为负,阳坡为正。② 融雪期含水率的变化,阳坡雪层平均含水率大于阴坡,阴阳坡下层含水率最大,上层次之。融雪期含水率梯度的变化,融雪期阴坡的含水率为正梯度,阳坡的含水率为负的含水率梯度。③ 融雪期密度初期密度梯度较大,后期密度梯度减小。阳坡平均密度大于阴坡,阳坡较阴坡会出现较大的密度值。阴坡密度每日拐点比阳坡早2 h。     

干旱对太行山山前平原雨养农田产量影响的模拟研究

以多时间尺度标准化降水蒸散指数（SPEI）作为干旱指标,利用APSIM模型（农业生产系统模拟模型）模拟太行山山前平原雨养旱作农田冬小麦-夏玉米近30 a产量变化,分析干旱对作物产量的影响。结果显示：APSIM模型对模拟雨养条件下作物产量具有良好的适用性,玉米产量年际波动较大、变异系数为51.2%,易受降雨因素影响;小麦产量波动相对较为稳定,变异系数为26.4%。干旱指数与作物产量极显著相关（P<0.01）,其中小麦产量与SPEI-3-Apr相关系数达0.79,玉米产量与SPEI-3-Sep相关系数达0.88,适宜干湿状态在0～2之间;所建立的回归方程分别可以解释61.8%的小麦产量变异和87.7%的玉米产量变异。研究表明,SPEI-3-Apr、SPEI-3-Sep可分别作为该地区雨养农田小麦、玉米产量的估计指标。     

六盘山区旱作春玉米养分投入与肥料生产效率

为了明确半干旱地区玉米生产养分投入状况及肥料生产效率,提高旱地农业资源效率,连续三年对宁夏六盘山区不同类型旱地玉米施肥及生产状况进行调查。调查结果显示:六盘山区玉米生产中的氮肥(纯N)、磷肥(P_2O_5)和钾肥(K_2O)的平均投入量分别为323.7、210.1 kg·hm~(-2)和28.6 kg·hm~(-2),氮、磷、钾比例为1∶0.64∶0.08,磷的比例偏高,而钾肥比例偏低;氮、磷肥施肥量明显偏高,分别集中在高于330 kg·hm~(-2)和高于165 kg·hm~(-2)水平的农户比例高达48.5%和70.1%,造成了浪费和环境污染,钾肥用量偏低,集中处于低于42 kg·hm~(-2)水平,样本比例高达69.3%;施肥基追比大致为6∶4,追肥主要为尿素,平均用量为121.9 kg·hm~(-2),适宜玉米生长,但施追肥量处于两个极端,大多数追肥量或者很高或者很低;调研区玉米三年平均产量为9 864 kg·hm~(-2),由于降雨不足与施肥不合理,玉米产量呈逐年递减趋势;氮肥、磷肥和钾肥的三年平均偏生产力分别为30.7、47.8 kg·kg~(-1)和391.3 kg·kg~(-1),氮肥和磷肥的偏生产力偏低。该区域玉米生产有机肥投入以牛羊粪便为主,投入量偏低。综上所述,调研区施肥方面存在投入量和比例不合理问题,需进行科学指导与调整。     

基于AquaCrop模型的夏玉米生长模拟及灌溉制度优化

为评价AquaCrop模型在关中地区的适用性并寻求最佳的灌溉制度,对夏玉米在不同灌溉与施氮水平下的生长进行模拟和验证,并利用校验后的模型研究了3种不同降雨年型以及11种灌溉模式下夏玉米产量和水分利用效率的变化特征。结果表明：AquaCrop模型可以较好地模拟关中地区不同灌溉与施氮水平下夏玉米产量和生物量,模型模拟的产量与实测值之间的决定系数（R²）、均方根误差（RMSE）、标准均方根误差（NRMSE）、符合度指数（d）和纳什效率系数（E_NS）分别为0.919、0.249 t·hm^-2、4.112、0.977和0.915;对于地上部生物量,模拟值与实测值的R²、RMSE、NRMSE、d和E_NS分别为0.860、0.977 t·hm^-2、6.407、0.933和0.694。利用校验后的模型分析了试验区内3种不同降水年型条件下11种灌溉模式的夏玉米产量和水分利用效率的变化特征,依据模拟结果及夏玉米生理需水规律,同时为了实现高产和高水分利用效率,得出不同年型的优化灌溉制度为：若能保证出苗整齐,湿润年可不灌水,此时也能获得较高产量和水分利用效率;平水年推荐在拔节期灌水60 mm,能节约50%水资源,亦能保证稳产;干旱年推荐在拔节期和抽雄期各灌水60 mm,可获得高产和高水分利用效率。     

Model of crop:weed competition applied to maize:Abutilon theophrasti interactions. I. Model description and evaluation

A complex set of interactions among crops, weeds and their environment determines the impact of weed interference on crop productivity. These interactions can be simulated with dynamic crop:weed competition models, such as ALMANAC. In this study, ALMANAC was modified to simulate maize: Abutilon theophrasti competition. In the modified ALMANAC model, daily increases in leaf area index (LAI), height and rooting depth are attenuated on the basis of accumulated above-ground biomass and by environmental stress. Also, a simple, flexible method is adopted to partition radiation in a mixed canopy. A maize: A. theophrasti competition study conducted near Aurora, NY, in which a range of weed densities (0–16 plants m⁻²) were established in a maize crop, was used to evaluate the model. The modified ALMANAC proved to be a useful tool for segregating the maize response to competition in 1991 (simulated loss of 35% at the highest weed density) from those in 1992–94 (simulated losses not greater than 16%). Based on these findings, the modified ALMANAC model is judged to be capable of distinguishing between environmental conditions that facilitate large yield losses and those that allow maize to outcompete A. theophrasti .     

A simple tentative model of the losses caused by the Senegalese grasshopper,Oedaleus senegalensis (Krauss 1877) to millet in the Sahel

Oedaleus senegalensis is a serious pest of millet in the Sahel, but the correlation to crop loss remains largely unknown. Therefore, the correlation between densities of O. senegalensis, defoliation level and millet yields was investigated in Niger in 2008, and a simple model to foresee the yield based on these parameters was developed. The yield was significantly correlated to both the density of O. senegalensis and the defoliation level on 17 September. The best model to foresee millet yield involved grasshopper density and cumulated rainfall and may be regarded a tentative method in O. senegalensis control.     

连作对谷子土壤酶活性及养分的影响

为探明谷子连作对土壤环境的影响,分析不同连作年限对谷子土壤养分和酶活性的影响,本研究在4a不施肥定位试验的基础上,设置连作2 a(T1)、连作3 a(T2)、连作4 a(T3)和轮作(CK)4个处理,分别测定了土壤养分、土壤脲酶、碱性磷酸酶、蔗糖酶和过氧化氢酶活性及其变化。试验结果表明,与轮作(CK)相比,连作2 a(T1)、连作3 a(T2)和连作4 a(T3)分别减产6.9%、12.7%和35.6%,随着连作年限增加,减产幅度加大;连作土壤氮、磷含量降低,其中速效氮含量降低最为显著(P0.05),速效钾含量变化不显著(P0.05),土壤p H升高。连作条件下,土壤脲酶、碱性磷酸酶、蔗糖酶和过氧化氢酶活性均呈现逐年降低的趋势,且随着连作年限增加,降低越显著,连作4 a(T3)显著低于其它处理(P0.05)。     

Competition of sorghum cultivars and densities with Japanese millet (Echinochloa esculenta)

Field studies were conducted at two locations in southern Queensland, Australia during the 2003–2004 and 2004–2005 growing seasons to determine the differential competitiveness of sorghum (Sorghum bicolor L. Moench) cultivars and crop densities against weeds and the sorghum yield loss due to weeds. Weed competition was investigated by growing sorghum in the presence or absence of a model grass weed, Japanese millet (Echinochloa esculenta). The correlation analyses showed that the early growth traits (height, shoot biomass, and daily growth rate of the shoot biomass) of sorghum adversely affected the height, biomass, and seed production of millet, as measured at maturity. “MR Goldrush” and “Bonus MR” were the most competitive cultivars, resulting in reduced weed biomass, weed density, and weed seed production. The density of sorghum also had a significant effect on the crop's ability to compete with millet. When compared to the density of 4.5 plants per m², sorghum that was planted at 7.5 plants per m² suppressed the density, biomass, and seed production of millet by 22%, 27% and 38%, respectively. Millet caused a significant yield loss in comparison with the weed‐free plots. The combined weed‐suppressive effects of the competitive cultivars, such as MR Goldrush, and high crop densities minimized the yield losses from the weeds. These results indicate that sorghum competition against grass weeds can be improved by choosing competitive cultivars and by using a high crop density of >7.5 plants per m². These non‐chemical options should be included in an integrated weed management program for better weed management, particularly where the control options are limited by the evolution of herbicide resistance.     

Manipulating inoculum densities of Verticillium dahliae and Pratylenchus penetrans with green manure amendments and solarization influence potato yield

We used cover crops with demonstrated efficacy against Verticillium dahliae and Pratylenchus penetrans in combination with the biocidal practice of solarization to determine the importance of targeting both organisms for managing potato early dying, an issue relevant to the search for alternatives to soil fumigation. Two experiments were conducted in commercial fields using a split-plot design with cover crop treatments of rapeseed, marigold, forage pearl millet, sorghum-sudangrass, and corn as the main plot factor and solarization as the subplot factor. Cover crops were grown and solarization applied in year one, followed by potato in year two. The main effect of solarization was significant for reduced inoculum levels of both organisms in year two and increased tuber yields. The main effect of cover crop was also significant with lower population densities of P. penetrans following the marigold and millet treatments and of V. dahliae following rape and sorghum-sudangrass. The cover crop treatments influenced yield in only one of the experiments in the absence of solarization. The combinatorial effect of cover crops and solarization resulted in a wide range of pathogen population densities. Mean soil inoculum levels were negatively related to yield for V. dahliae in experiment 1, and for P. penetrans and the P. penetrans × V. dahliae interaction in both experiments.     

宁南旱区沟垄微型集水种植谷子最优沟垄宽度的确定

研究宁南旱区沟垄微型集水种植谷子比较适宜的沟垄宽度,是为了进一步提高降水利用率和产量.以大同14号谷子为材料,设计垄沟比值为1,四种不同宽度的带型.结果表明:在2004～2005年的试验中,微集水处理的蓄水量在谷子不同生育期均比对照增加,水分利用效率平均分别比对照高10.30 kg/(mm·hm2)(2004)、6.76 kg/(mm·hm2)(2005);由于降雨量不同且降雨分布不均匀,使2004～2005年度沟垄微型集雨种植谷子产量有所差异,但在两年试验中,谷子增产趋势基本一致,不同带型的产量分别比对照平均提高108.48%(2004)和135.28%(2005).通过回归分析,得出在宁南半干旱地区微集水种植谷子比较适宜的沟垄宽度为45 cm.     

模拟降雨条件下谷子和冬小麦植株对降雨再分配过程的影响

以谷子（ Setaria italica）、冬小麦（ Triticum aestivum Linn 。）为研究对象,利用人工模拟降雨测定了不同降雨强度和生长阶段两种作物植株的穿透雨,采用人工喷雾法测定了不同生长阶段的冠层截留,根据水量平衡法计算了不同观测阶段的茎秆流。结果表明：谷子、冬小麦冠层对降雨的再分配作用显著,谷子冠下穿透雨率平均约为79％,茎秆流率平均约为20％,冠层截留率平均约占1％;冬小麦冠下穿透雨率平均约为79％,茎秆流率平均约为19％,冠层截留率平均约占2％。在其全生育期内,两种作物冠下穿透雨与茎秆流呈彼此消长趋势。穿透雨量和茎秆流量与降雨强度呈显著正相关关系,但是穿透雨率和茎秆流率与降雨强度的关系不显著。茎秆流量和冠层截留量及其二者占总降雨量的比率均与作物叶面积指数呈显著正相关关系,但穿透雨量及穿透雨率随叶面积指数增加呈显著下降趋势。     

甘肃省小杂粮产业竞争优势度及影响因素分析

以资源禀赋系数、成本收益、综合比较优势指数3个指标为基础,比较分析了甘肃小杂粮产业竞争优势度;通过对消费者和农户的深入调查,并建立计量经济模型对影响甘肃小杂粮产业竞争优势的主要因素进行了实证分析.结果表明,甘肃谷子、糜子、荞麦、蚕豆的资源禀赋系数分别为1.53、6.64、8.72、3.9,比较优势指数分别为1.23、2.57、2.95、1.97,小杂粮从资源的丰富程度、成本收益、种植规模、产出水平等方面具有竞争潜力;消费者收入水平、认知程度、年龄、受教育程度对甘肃小杂粮的市场竞争力有显著影响;家庭耕地面积、小杂粮收入占家庭收入比例对农户扩大生产规模的意愿有显著影响.     

Effects of moisture and septoria tritici blotch stresses on wheat yields under semi-arid conditions: A Simulation study

The effects of Septoria tritici blotch on spring wheat were incorporated into a crop growth simulator and the model was then used to evaluate the interrelationships between moisture and disease stresses on wheat yields under semi-arid conditions. Simulation experiments revealed that moisture availability plays a role in determining the relationship between disease and yield. In a season when precipitation was distributed evenly, a non-diseased crop yielded more than diseased crops. Yield reductions in diseased crops were related to the severity of epidemics; the relationship between disease and yield was inverse and linear. In a season when water was scarce during the stage of kernel-filling, crops with mild or moderate disease epidemics (apparent infection rate of a logistic model,r, of 0.025 or 0.05 per unit) yielded more than the non-diseased crop. The yield of the crop with a severe epidemic (r of 0.1 per unit) was reduced substantially and the relationship between disease and yield was parabolic. The parabolic relationship was linearized when additional precipitation was simulated in the model.     

Purple witchweed (Striga hermonthica) germination and seedbank depletion under different crops,fallow, and bare soil

Seedbank density is an important aspect that determines the amount of damage that the parasitic weed, purple witchweed (Striga hermonthica; hereafter, called “Striga”), causes on its crop hosts. The seedbank depletion of Striga was measured in Mali and Niger during the 2004 rainy season under the host crops, pearl millet and sorghum, the non‐host crops, cowpea and sesame, the intercrops of pearl millet or sorghum with cowpea or sesame, and fallow with or without weeding. Two methods were used and compared; namely, a seed bag method and a soil‐sampling method. The fate of the seeds was assessed by a seed press test. Seed germination, as determined by the presence of empty seed coats, contributed most to the seedbank depletion of Striga under a variety of crop covers and fallow. The highest seedbank depletion was found under the monocultures of the host crops. The intercrops of the host and non‐host crops caused less seedbank depletion, followed by the monocultures of the non‐host crops, fallow, and bare soil. The seed bag method and the soil‐sampling method yielded similar percentages of seedbank depletion, while the former allowed for distinguishing between the germinated and diseased seeds. The results suggest that, although all the tested crop species can cause the seed germination and seedbank depletion of Striga, management by using host cereal crops causes the highest amount of germination and has the highest potential to deplete the soil seed bank, provided that seed production is prevented.