苹果花生间作系统土壤水分动态及主要竞争区域

以晋西黄土区典型苹果-花生间作系统为研究对象,研究间作系统界面土壤水分动态变化以及土壤水分的主要竞争区域,旨在提高该地区果农间作系统降水生产力、土壤水分利用效率。采用烘干称重法对苹果树行(行距为5 m)距苹果树不同距离处0~60 cm土层的土壤水分含量进行监测,利用移动窗口法对土壤水分的主要竞争区域进行分析。研究表明:花生的苗期、开花期、结荚期和成熟期,土壤水分含量较低,均未超过20%,且各时期土壤水分含量差异显著,苗期和成熟期土壤水分含量高于开花期和结荚期,开花期土壤水分含量最低;以距苹果树南北两侧各2.5 m为分界线,距离果树越远,土壤水分含量先降低再升高,最低点在距树行1.2 m左右;在花生各生育期,与花生单作比较,间作系统土壤水分皆呈现出负效应,分别是-25.16%、-20.26%、~(-1)2.97%和~(-1)1.13%;苹果-花生间作系统苗期的主要竞争区域是距树南侧0.8~2 m和距树北侧0.8~1.8 m,竞争宽度2.2 m;花生开花期的主要竞争区域为距树南侧0.8~1.8 m和距树北侧1~2 m,结荚期和成熟期土壤水分的主要竞争宽度最小,为1.8 m,主要竞争区域分别是距树南侧0.8~1.8 m、距树北侧0.8~1.6 m和距树南侧0.8~1.6 m、距树北侧0.8~1.8 m。     

玉米行距对大豆/玉米间作产量及种间竞争力的影响

为明确大豆/玉米间作体系中玉米最佳种植行距,通过设置5个间作玉米种植行距(D10:10 cm、D20:20 cm、D45:45 cm、D60:60 cm、D70:70 cm),研究不同玉米种植行距对作物产量、体系生产力、种间相对竞争力的影响。结果表明:玉米行距改变不影响间作产量优势,土地当量比(land equivalent ratio,LER)均大于1;随玉米行距的增加,间作大豆产量随之下降,间作玉米产量随之升高,系统生产力(system production,SP)随之提升;间作玉米行距改变显著影响了间作大豆的结荚数和单株粒数,单株结荚数从D10处理的38.5荚·株-1下降为D70处理的15.8荚·株-1,单株粒数从D10处理的66.6粒·株-1下降为D70处理的26.4粒·株-1;随玉米行距的增加,间作玉米穗粒数呈现先增加后减小的趋势,D60处理穗粒数最大,达606粒;间作玉米行距改变显著影响了种间相对竞争力,随间作玉米种植行距的增加,大豆相对于玉米的竞争力Asm逐渐弱化,竞争力平衡点出现在D45处理,采样期平均Asm为0.01。因此,综合考虑间作体系产量,作物产量和种间竞争力,D45处理为大豆/玉米间作体系间作玉米的最佳行距配置。     

晋西黄土区苹果花生间作系统小气候效应

苹果花生间作是晋西黄土区主要的农林复合配置模式,但常常因为间作系统结构设计不合理而导致间作系统内作物生长和产量受到影响。为了定量解析果农间作系统对小气候,进而对其间作作物生长发育和产量的影响,本文深入研究果农间作系统的小气候状况,为优化当地果农间作系统结构提供理论支持。以晋西黄土区吉县7年生苹果(Maluspumila)+花生(Arachis hypogaea)间作系统及花生单作系统(对照)为研究对象,首先在果树与作物间布设根障,以消除果树地下部分对作物的影响。在此基础上,对距树行不同距离处作物行的小气候因子(光合有效辐射(PAR)、大气温度、空气相对湿度和风速)及作物生长进行监测,经数学模拟分析得出:(1)苹果+花生间作系统的光合有效辐射相对指数为49.39%~88.07%,大气温度相对指数为92.74%~97.32%,空气相对湿度相对指数为112.36%~123.72%,风速相对指数为70.58%~74.22%,且距树行越近小气候效应越显著;(2)果农间作系统对小气候的影响进而造成对间作系统中花生生长发育及产量的负面影响,间作系统内花生的净光合速率和产量均低于对照的单作花生,且表现为距树行越近下降越多;(3)各小气候因子对花生生长的影响程度不同,光合有效辐射、大气温度和空气相对湿度对花生净光合速率和产量的贡献率分别为62.48%、20.71%、16.45%和53.48%、16.45%、30.07%。     

晋西黄土区核桃-谷子间作系统水肥影响域

为了定量判定晋西黄土区果农间作系统水肥主要竞争区域,以核桃-谷子间作系统为研究对象,对土壤水分和土壤养分进行定位监测,采用移动窗口法定量判定间作系统中土壤水分和土壤养分的影响域。结果显示:当窗口宽度为2时,移动窗口法能有效地判定出土壤水分和土壤养分的影响域。40~100 cm土层,距树行不同距离处的土壤水分和土壤养分含量相异性较小,难以判定影响域;综合0~40 cm、0~100 cm土层的土壤水分状况,土壤水分的影响域范围是距树南侧1.75 m到距树北侧1.25 m,影响宽度为3 m,即主要竞争区域为距树南侧1.75m到距树北侧1.25 m;不同的土壤养分指标影响域的范围不同,综合考虑土壤养分的四个不同指标(有机质、全氮、速效磷和速效钾)及其在0~40 cm、0~100 cm两个土层的分布情况,土壤养分的影响域是距树南侧2.25 m到距树北侧2.25 m,影响宽度为4.5 m,即主要竞争区域为距树南侧2.25 m到距树北侧2.25 m。建议在土壤水分和土壤养分的主要竞争区域,采取改变垄沟、起垄覆膜、选择性施肥等措施,缓解核桃、谷子之间的竞争,提高资源利用效率,增加当地农民经济收入。     

玉米‖棉花的作物生理特性及根系特征研究

为探究不同种植模式对作物生理特性及根系形态特征的影响,本试验以玉米‖棉花为研究对象,试验设置3种种植模式处理,分别为单作玉米、单作棉花、玉米‖棉花。通过对作物株高、叶绿素含量、田间温湿度、根系长度变化及产量等的测定,探究不同种植模式下作物的生长状况及土地当量比。结果表明:单作玉米功能叶叶片平均SPAD值高于间作6.78%,间作棉花功能叶叶片平均SPAD值高于单作1.12%。玉米间作株高平均增长率为83%,单作平均增长率为82.9%,表明了玉米间作模式更有利于株高的增长;单、间作玉米田间温度分别为30.9℃、32.47℃;单、间作棉花田间温度分别为31.6℃、32.95℃,间作模式在一定程度影响根系分布,不同土层间作作物根长显著增加4.7%。     

水分胁迫下间作棉田土壤水分及产量分析

2012—2013年在阿拉尔垦区间作棉田中设置试验,分析间作系统中棉花种植模式和水分胁迫对土壤水分、产量的影响。研究表明:1 0~100 cm土层,蕾期和吐絮期田间土壤含水量表现出先降低再升高的趋势,含水量最低值出现在40~60 cm土层。花铃期田间土壤含水量先降低再升高,而后又降低,拐点分别为40~60 cm土层和60~80 cm土层。2蕾期,M2W4、M2W2、M2W3、M1W4土壤含水量较高。花铃期,M2W2含水量较高。吐絮期M2、M3模式土壤含水量整体较高。3同一模式下,棉花单株产量最高的是W2水分处理(4 500 m3·hm-2);同一灌水量处理下,单株产量经济效益最高的是M2模式(距红枣行距1.0 m处种植棉花)。综合考虑,距幼龄红枣行距1.0 m处种植棉花,配合滴灌水量4 500 m3·hm-2利于棉田发挥最大生产潜力,也利于单株棉花产量的提高。     

南疆地区田间配置对枣棉间作耗水特性的调控效应

为探明农果间作水分高效利用机理，提出适合南疆地区最优的农果间作模式，在大田试验条件下对枣棉间作系统进行研究，以种植模式（枣棉间作和枣、棉单作）和田间配置（棉花种植行数分别为2、4、6行；棉花株距分别为10 cm和12.5 cm）为参试因子，共9个处理，田间随机排列，共27个小区，小区面积为3 m×10 m。测定了各处理的耗水特征、产量、水分利用效率（WUE）和水分当量比（WER）等指标。结果表明：种植模式显著影响复合群体的耗水特性，枣棉间作耗水量较单作加权平均增加9.5%，棵间蒸发量降低11.4 mm，蒸散比降低13.5%。棉花种植行数显著影响复合群体的耗水特性，间作6行棉花较间作2行棉花耗水量增加9.1%~13.9%；间作6行棉花分别较间作4行和2行棉花提高土壤贮水消耗量35.2 mm和66.3 mm，棵间蒸发量分别降低24.2 mm和33.7 mm，蒸散比分别降低16.0%和22.2%；棉花株距变化仅对土壤贮水消耗量有显著影响，I3处理（间作棉花4行）土壤贮水消耗量较I4（间作棉花2行）高24.4 mm，I1（株距10 cm）较I2(株距12.5 cm)高14.7 mm。枣棉间作群体对40~60 cm土层土壤贮水消耗量最高，20~40 cm土层次之，80~100 cm土层最低；单作枣树对土壤深层水分利用较多，单作棉花则主要消耗浅层土壤中的水分，枣棉间作能够较好地利用土壤各层的水分。就土壤贮水利用而言，增加棉花行数或减小株距有助于促进40~80 cm土层土壤贮水的利用。不同枣棉间作处理的WER都大于1，说明枣棉间作较单作提高了农田WUE。间作棉花种植行数为4行、株距为12.5 cm时，枣棉间作综合效益最优，产量为7 460 kg·hm^-2，WUE为11.37 kg·mm^-1·hm^-2，WER为1.34。     

枣棉间作中利用光合数据筛选棉花种植模式

相关研究表明,用光合速率可以较好地模拟测算作物经济产量。为全面快捷高效地筛选出更高效更适合南疆推广的枣棉间作棉花种植模式,以不同的行间距并结合差异化灌水对枣棉间作环境下的棉花进行处理,以此产生的不同光热环境为基础,建立叶片水平的净光合速率分析图。利用净光合速率折线图,结合使用棉花整个生长季实测的叶片相关生理数据,对所建图示进行比较。结果发现,M3（距红枣行0．5 m种植棉花,枣行间种6行棉花）、W3（按350 m3·667m-2灌水）处理的净光合速率与大田棉花的净光合速率相似度最高。两者相交,M3W3处理的净光合速率平均值也最大,最终产量也最高,符合实验设想。由本试验结果可以看出,利用净光合速率能提前预计作物的经济产量,节约研究时间,在枣棉间作种植生产中,可以筛选出更好的棉花种植模式。     

1980-2015年宁夏农作物种植结构时空变化特征分析

以1980-2015年宁夏农业统计资料为数据源,运用数理统计和GIS空间分析方法,分析了宁夏农作物种植结构的时空变化特征。结果表明:1)36年来宁夏农作物总种植面积增长显著,但粮食作物种植面积增长不明显。其中小麦种植面积呈快速降低趋势,玉米、薯类、蔬果等作物种植面积均呈快速增长趋势。2)宁夏主要农作物在空间分布上具有明显的地域特点。水稻主要分布在引黄灌溉区且种植比例和空间分布变化不明显;随着玉米种植比例和种植范围的迅速扩张,小麦的种植比例和分布区域明显缩小;薯类作物主要分布于宁夏南部山区,随着种植结构调整,逐步扩展到中部干旱区;蔬果类作物种植比例和分布区域扩张最为迅速。3)宁夏农作物种植结构类型逐渐从单一型向多元组合型发展,种植结构类型更加丰富,布局更加合理。     

晋西黄土丘陵区植被生态需水研究

以水量平衡关系为理论基础,采用1961-2007年晋西黄土丘陵地区14个气象站的气象资料,在GIS技术支持下估算该地区的植被需水量,分析植被需水量的时空变化以及缺水量。研究结果表明:晋西黄土丘陵地区现有植被适宜需水量为40.759×108m3,最小生态需水量为24.784×108m3,从北到南呈递增趋势;适宜和最小亏缺水量分别为5.581×108m3和0.414×108m3,区域分布是中部最多,南部次之,北部最少;植被生态需水和缺水表现出不同的年变化和月变化趋势和空间分异规律。生态需水量与亏缺水量的计算结果为改善晋西黄土丘陵区生态环境,合理利用水资源和植被资源,提高生态、经济与社会效益提供参考依据。     

Weed competition in willow coppice crops: the cause and extent of yield losses

Growth in 2-year-old willow Salix spp., grown in the short-rotation coppice (SRC) system on agricultural land, was compared in 30 weeded and 30 unweeded plots in each of 2 years after cutting. Non-destructive assessment methods of both crop and weed biomass were used. Coppice growth in year I was greater in the weeded plots than in the unweeded plots. In year II, coppice growth was not different between plots so that, over the 2-year study period, the coppice yield reductions with weeds reflected the losses in year I only. There was considerable variation in the amount of weeds in the unweeded plots. The relationship between the volume of weeds present and the extent of the coppice yield reduction over 1 and 2 years after cutting are described by linear models. Soil moisture and nutrient content, when measured in mid-summer, were not different between plots in either year. In year I, mid-summer coppice height was greater in the weedy plots, while stem numbers in both years and canopy density in year II were lower in the weedy plots. These results indicate that tall weeds competing for light and space in the first year of growth, rather than moisture or nutrient stress, caused fewer (and taller) stems to grow from the coppice stools, leading to the observed reductions in biomass.     

Shade-induced plasticity in invasive Impatiens glandulifera populations

Phenotypic plasticity, which confers a fitness advantage under heterogeneous and novel environments, has been commonly suggested to contribute to the success of invasive plants in their introduced range. For example, plasticity in response to changes in light availability could facilitate invasiveness by allowing plants to both rapidly establish in unshaded, disturbed habitats, and tolerate shaded or crowded environments. The plastic responses of invasive plants to shade were mostly studied in morphological traits. However, plasticity in physiological traits might provide more rapid and reversible responses and thus be more effective in environments with rapid temporal variations. Here, we compared plasticity in a range of morphological and physiological traits that provide shade avoidance or tolerance between two native and six introduced populations of Impatiens glandulifera. In a common garden, we subjected second-generation siblings of native and invasive plants to two light availability treatments and measured their morphological, physiological and performance responses. Impatiens glandulifera from invasive populations exhibited greater phenotypic plasticity in response to light availability in four out of 12 measured traits. Moreover, this greater plasticity was mostly limited to physiological traits associated with photosynthetic acclimation. These results suggest high phenotypic plasticity in response to light availability could have facilitated I. glandulifera's spread in both disturbed habitats and woodlands or under intense light competition. The results of this study highlight the importance of considering physiological traits when studying the role of plasticity in the success of invasive plants.     

氮肥追施模式对遮阴下棉花光合效率及产量的影响

通过探讨果棉间作下棉花适宜的氮肥追施模式,为间作棉田合理氮肥施用提供理论依据。以中棉所49为试验材料,设置不遮阴(CK)和遮阴50%处理,每个处理3个氮肥追施模式N_1(氮肥前移)、N_2(正常追肥)、N_3(氮肥前移比例较N_1大),研究氮肥追施对遮阴膜下滴灌棉花光合特性和产量的影响。结果表明:与CK相比,遮阴50%处理下棉花叶片叶绿素含量和叶面积指数增加,净光合速率下降,伏前桃比例减少,秋桃比例增加。遮阴50%处理下,氮肥追施适当前移(N_1),可提高棉花光合速率,促进光合产物的形成与积累,增加伏桃比例,显著提高了单株铃数、单铃重和皮棉产量。因此,可以考虑将氮肥适量前移(N_1),作为果棉间作下棉花提高光能利用率和产量的有效途径。     

Growth and reproductive success of the seed‐derived plants of Sagittaria trifolia emerging at different times

In order to clarify the growth and reproductive success of seed‐derived Sagittaria trifolia individuals emerging at different times within a season, seeds were sown on May 16, June 16 and July 22 2010 and allowed to grow in pots under shaded and unshaded conditions. The timing of when the first inflorescence of each seedling appeared was recorded, as well as the number of seeds and tubers produced and the dry weight of each organ. In total, 220 seedlings were used, 23–59 in each treatment. As the sowing time was delayed, so too was the appearance of the first inflorescence. Additionally, the number of inflorescences, fruits and seeds produced by the unshaded plants significantly decreased with the sowing time. The total dry weight was significantly greater in the unshaded than in the shaded plants: the July‐sown, shaded plants grew very poorly. The relative resource allocation to the tubers was greater in the late‐emerging, shaded seedlings. Even in the shaded groups, except for the July‐sown plants, most of the plants set seed. Therefore, when addressing weed control in paddy fields, one should keep seedlings in mind, in addition to plants that have grown from tubers.     

Morphological and physiological responses of the invasive weed Isatis tinctoria to contrasting light, soil-nitrogen and water

We evaluated the morphological and physiological responses to contrasting above- and below-ground resources for the invasive weed, Isatis tinctoria L. (dyer's woad). Plants were grown under low and high levels of light [shade (50% of ambient) and full sun], soil water (50 and 100 mL day⁻¹), and soil nitrogen (N) (0 and 20 mg N kg⁻¹ soil) in 8 L pots in 63 day glasshouse experiments conducted during winter and spring. Soil-N enrichment did not increase any of the growth variables (shoot and root dry mass, shoot:root ratio, leaf area, and specific leaf area) or physiological variables (stomatal conductance and ¹³C discrimination) in either experiment. The absence of plasticity in response to changes in soil-N supply suggests that I. tinctoria may survive and persist in nutrient-poor conditions by having low-N requirements, low-N productivity, or both. In contrast, plants compensated for shaded conditions by altering leaf area, specific leaf area, and shoot:root ratio to improve light capture. We discuss the potential mechanisms whereby response to these variable resources may be associated with a series of adaptations that favour the ability to tolerate and colonize harsh, nutrient-poor conditions, as well as invade shaded and undisturbed sites.     

The importance of reduced light intensity on the growth and development of six weed species

Crops limit light for photosynthesis and growth of weeds. We studied the effect of reduced light on performance of six weed species [one invasive species (Amsinckia micrantha), three common species (Veronica persica, Capsella bursa‐pastoris, Viola arvensis) and two less common weeds (Anagallis arvensis and Scleranthus annuus)]. In two glasshouse experiments, six light levels were achieved aiming at 0%, 20%, 50%, 80%, 90% and 95% reduction of light and corresponding with daily light integrals (DLI) of 12.4, 9.63, 7.13, 2.74, 0.95 and 0.69 mol m^?2 day^?1 in experiment 1 and 21.2, 18.0, 10.7, 3.71, 1.64 and 1.20 mol m^?2 day^?1 in experiment 2. The number of leaves was strictly controlled by DLI. Chlorophyll content index, maximum photochemical efficiency of photosystem II (F_v/F_m), stomatal conductance, flowering and dry matter were strongly reduced when DLI was reduced to 0.69–3.71 mol m^?2 day^?1 for all species. Threshold DLI for flowering was ca. 3.71 mol m^?2 day^?1 for S. annuus, V. arvensis, A. arvensis and V. persica, while C. bursa‐pastoris deviated by flowering at DLI of 0.95 mol m^?2 day^?1. This may explain why C. bursa‐pastoris is common in the seedbank of Danish arable soils in spite of intensive farming with well‐fertilised and dense crops.     

核（桃）麦间作系统内小气候特征的初步研究

对墨玉县两种核(桃)麦间作模式小气候因素调查分析表明,小麦间作较单作成熟期推迟4~6 d,群体内CO2浓度和温度分别降低25.33~28.73μmol·mol-1和0.23℃~0.43℃,相对湿度增加4.38~5.32个百分点,产量降低42.2%~74.5%。在间作区域内,拔节到抽穗,是核桃叶幕迅速形成期,遮荫率为52.22%~60.32%,重度遮荫率(光照强度≤1/2空地光照强度)为29.77%~34.09%,至扬花期的遮荫率最大,达52.21%~71.51%,重度遮荫率达37.15%~38.39%,并一直持续到小麦成熟,全期弱影响阶段(光照强度1/2空地光照强度)50天左右,强影响阶段(光照强度≤1/2空地光照强度)45天左右,间作小麦群体内CO2浓度和温度大小顺序为顶部中部底部,距离树行越近,群体内平均CO2浓度越少,平均相对湿度越高,平均温度越低。9 m×3 m的核桃配置的综合小气候条件和产量构成优于6 m×4 m核桃配置,是值得推广的核(桃)麦间作模式。     

生殖生长期光富集和遮阴对大豆干物质分配及产量品质的影响

大豆冠层截获的太阳辐射强度是决定大豆生长发育和产量的重要环境因素.通过对蛋白质、脂肪含量不同的三个大豆品种在生殖生长期进行光处理,研究田间条件下,群体光富集和遮阴对大豆干物质分配、产量及品质的影响.结果表明:与自然光照相比,光富集后大豆积累的光合产物更多地分配到库;而遮阴后大豆积累的光合产物更多地分配给了源.光富集显著增加大豆单株产量、荚数和粒数,不同品种(系)单株产量增加幅度为27.7%～71.7%、单株荚数增加幅度为33.3%～71.1%、单株粒数增加幅度为35.5%～85.7%;遮阴显著减少大豆单株产量、荚数和粒数,不同品种(系)单株产量降低幅度为34.4%～49.7%、单株荚数降低幅度为43.0%～47.7%、单株粒数降低幅度为33.4%～52.6%.生殖生长期光富集有增加籽粒蛋白质含量和降低籽粒脂肪含量的趋势,而遮阴有降低籽粒内蛋白质含量和增加籽粒脂肪含量的趋势,品种间有一定差异.     

采用树轮图像分析法重建过去气候变化

通过分析温泉气象站的气候资料与博尔塔拉河流域3个采点的树轮灰度参数相关关系发现,树轮的最大灰度参数与降水相关性较高,最高单相关系数达0.502.并利用该灰度参数构建方程,重建了近百年来温泉气象站冬春季(1～5月)的降水序列,并通过检验证明该方程是稳定可靠的.由此说明,利用树轮灰度参数重建历史时期气候变化具有可行性.     

Shading and the growth and photosynthetic responses of Ammannia coccinnea

The effects of shade on the growth and CO₂ exchange rate (CER) of Ammannia coccinnea Wild., a noxious weed in water-seeded rice, were determined under glasshouse conditions. Shade substantially reduced A. coccinnea growth when imposed early and maintained throughout the growing season. However, plants transferred from full light to 18% or 50% sunlight 30 or 45 days after seeding had only slightly less dry weight than unshaded plants. Constant shade reduced growth severely (94%). In contrast, plants that were shaded for 45 days and then placed in full light largely recovered from the effects of shading by final harvest. The ability of A. coccinnea to reduce the effects of shade appears related to increased partitioning to leaves, increased specific leaf area and decreased dark respiration rates. The ability of the weed to recover from shade appears related to its ability to greatly increase CER in new leaves in response to increased light. Plasticity in A. coccinnea morphology and physiology appears to explain its persistence in California rice fields and suggests that management strategies that rely on shade alone may not improve control of this weed.