基于小麦群体图像的田间麦穗计数及产量预测方法

在田间小麦测产时,需人工获取田间单位面积内的麦穗数和穗粒数,耗时耗力。为了快速测量小麦田间单位面积内的产量,该文利用特定装置以田间麦穗倾斜的方式获取田间麦穗群体图像,通过转换图像颜色空间RGB→HSI,提取饱和度S分量图像,然后把饱和度S分量图像转换成二值图像,再经细窄部位粘连去除算法进行初步分割,再由边界和区域的特征参数判断出粘连的麦穗图像,并利用基于凹点检测匹配连线的方法实现粘连麦穗的分割,进而识别出图像中的麦穗数量;通过计算图像中每个麦穗的面积像素点数并由预测公式得到每个麦穗的籽粒数,进而计算出每幅图像上所有麦穗的预测籽粒数,然后计算出0.25 m2区域内对应的4幅图像上的预测籽粒数;同时根据籽粒千粒质量数据,计算得到该区域内的产量信息。该文在识别3个品种田间麦穗单幅图像中麦穗数量的平均识别精度为91.63%,籽粒数的平均预测精度为90.73%;对3个品种0.25 m2区域的小麦麦穗数量、总籽粒数及产量预测的平均精度为93.83%、93.43%、93.49%。运用该文方法可以实现小麦田间单位面积内的产量信息自动测量。     

Dry-Matter Partitioning across Parts of the Wheat Internode during the Grain Filling Period as Influenced by Fertilizer and Tillage Treatments

Dry-matter transportation and redistribution is an important factor influencing grain weight during the grain filling period. This study, carried out over two consecutive winter wheat growth seasons (2010/2011 and 2011/2012), examined how dry-matter partitioning across segments of the wheat internode during grain filling period is influenced by fertilizer and tillage treatments. The contributions of current assimilates and remobilization of dry matter to final grain weight were calculated. To precisely illustrate the changes in dry matter during the grain filling period, the whole wheat stem was divided into two parts, the top three part and bottom two part. The former included three segments: the exposed part of the uppermost internode (EXUI), the enclosed part of the uppermost internode (ENUI), and the penultimate internode (PI). The latter included two segments: the lower internode (ERI) and the lowest internode (ESTI). During postanthesis, two different phases characterized by different rates of dry-matter accumulation could be distinguished. The first phase was the dry-matter accumulation; the second phase was mobilization to grains. The bottom two parts contributed more dry matter during pre-anthesis to the final grain; on the other hand, the top three parts contributed more dry matter to the final grain during postanthesis. On average, for the bottom two parts, the ERI segment had the greatest contribution of pre-anthesis dry matter to grain weight (CRAP) (3.68% in 2010/2011 and 5.31% in 2011/2012 growth seasons). For the top three parts, the EXUI segment had the greatest contribution of postanthesis photosynthetic assimilate to grain weight (CAPA) (99.71% in 2010/2011 and 99.08% in 2011/2012 growth season). The top three parts achieved maximum dry weight at 15 days after anthesis (daa), 5 days earlier than the bottom two parts. The heavy rainfall in the late grain filling period of 2011/2012 growth season inhibited postanthesis dry mobilization, and to maintain the grain filling requirements, more dry matter stored during pre-anthesis was redistributed. The present results suggest that rainfall occurring late in the grain filling period may have adverse impact on postanthesis accumulation. To avoid this phenomenon, early sowing with plastic film cover and split nitrogen application may be recommended. Fertilizing with 195 kg hm^?2 (120 + 75) N plus 45000 kg hm^?2 of ox manure and 120 kg hm^?2 phosphate with wheat straw retention during the summer fallow period under conservation minimum tillage produced the greatest stem dry matter at anthesis.     

Plant and soil fertility characteristics of different winter wheat fields in the Huang-huai-hai plain of China

High-profile nutrient accumulation has caused low nutrient use efficiency and environmental pollution. A total of 140 points in farmers’ wheat fields were investigated and sampled under a typical winter wheat and summer maize rotation system in the Huang-huai-hai Plain of China (HPC). The average wheat yield in the high-yield field is more than 10% relative to the mid-low-yield areas based on historical data. The results showed in the high-yield wheat field the effective spike number was the main yield component, followed by 1000-grain weight. Uptake contents and ratios of N, P₂O₅ and K₂O in the whole wheat plant were also examined. Along the soil depth, organic matter (OM), alkali-hydrolyzable N (AN), available P (AP) and available K (AK) concentration gradually decreased. Soil critical values of AN, AP and AK in the 0–20?cm depth needed to achieve the maximum grain yield were 85.9, 17.7 and 114.2?mg kg^?1 calculated by the significant linear-plus-plateau model between wheat grain yield and soil nutrient concentration at harvest, respectively. These results indicated that the rational application of fertilizer based on the soil nutrient supply capacity and residual nutrients in root zone and optimum planting density are key determinants of grain production in the HPC.     

砂土麦田追施硫肥对冬小麦产量和质量的影响

在砂质土壤条件下,研究了追施硫肥对冬小麦产量和品质的影响。结果表明:拔节期追施硫肥显著提高小麦子粒产量,千粒重随着追施硫肥用量的增多而提高,不同追硫处理与对照相比均达到差异极显著水平;追施硫肥显著提高了小麦子粒容重和子粒硬度,改善了小麦的磨粉品质和面团流变学特性,尤其对小麦的淀粉糊化特性指标影响较大,高峰粘度、低谷粘度、最终粘度、稀懈值与对照相比均达到极显著水平。比较不同硫肥追施量对产量和品质的调控作用以及投入成本来看,以拔节期每公顷追施30kg纯S的效果较好。     

A comparison of two methods to predict the landscape-scale variation of crop yield

Landscape-scale variation is a source of information that increasingly is being taken into consideration in agricultural and environmental studies. Models that encompass and interpret this variation in fields and across contrasting management practices have the potential to improve the landscape management of agroecosystems. Our objective was to compare the results of two approaches, analysis of covariance (ANCOVA) and state-space modeling, to determine the factors affecting grain yield in three crop rotations [pea (Pisum sativum L.)–wheat (Triticum aestivum L.)–barley (Hordeum vulgare L.), canola (Brassica napus L.)–wheat–barley, and wheat–wheat–barley] at two sites in Saskatchewan, Canada. Crop rotations were established in adjacent 30 m×80 m plots arranged in a randomized complete block with five replicates. Variables that were expected to affect resource availability and pest infestations in wheat (second rotation phase) or barley (third rotation phase) were measured. Each sampling point was classified according to landscape position as either a shoulder or footslope. Landscape position was considered as a cross-classified treatment along with crop rotation, and analyzed using ANCOVA procedures. State-space modeling was conducted on a single transect connecting sampling points across all of the rotations and replicates at each site. ANCOVA frequently indicated that grain yield and other measured variables differed between landscape position across all rotations, or in a specific crop rotation. For example, grain yield, soil water content, soil N availability during the growing season, and the incidence of common root rot were higher in the footslopes than the shoulders in all of the crop rotations at one of the sites. However, the landscape position effect for grain yield was never fully explained by the landscape position effects detected for the other variables (e.g., higher soil water content in the footslopes did not correspond with higher grain yields in footslope positions at both sites). State-space modeling indicated that most of the measured variables contributed to the prediction of landscape-scale variation for grain yield in the pea–wheat rotation; whereas only leaf and root disease incidences explained landscape-scale variation in the wheat–wheat rotation. The selective omission of data indicated that state-space modeling was accounting for the varied importance of the predictors across the landscape; i.e., localized response functions. The major reason that ANCOVA did not explain landscape-scale variation of grain yield across the different crop rotations may be because it was unable to account for highly localized variation. However, there is evidence from other studies that the ANCOVA approach is appropriate when the response functions explaining grain yield do not vary significantly within the study area. This situation is most likely to occur in studies with smaller experimental areas. Future research conducted at scales reflecting ‘real world’ field conditions (i.e., study units representative of producer’s fields) should consider the use of state-space modeling or alternative statistical techniques that are designed to address and predict the complex and dynamic nature of landscape-scale processes.     

长效氮肥一次基施对覆膜冬小麦的肥效研究

针对地膜覆盖栽培作物因追肥困难引起的生育后期脱肥问题 ,对不同种类的长效氮肥在覆膜冬小麦上一次基施的肥效进行了田间试验。结果表明 ,两种长效尿素一次基施分别比普通尿素增产1 0 .5 %和 1 2 .4 % ,籽粒氮素利用率提高 1 0 .1和 1 0 .9个百分点 ,氮素生产指数提高 3.9kg和 4 .6kg。长效碳铵的肥效和普通尿素相当 ,比普通碳铵增产 6.6% ,籽粒氮素利用率提高 5 .8个百分点 ,氮生产指数增加2 .3kg。在收获前 2周进行的部分生物学性状调查结果表明 ,两种长效尿素处理的小麦绿叶指数和旗叶面积分别比普通尿素增加 1 8.5 %、2 5 .9%和 34 .8%、34 .5 % ;长效碳铵比普通碳铵增加 1 2 .3%和 4 2 .9%。长效氮肥通过缓慢释放氮素 ,延缓叶片衰老和增大功能叶面积 ,从而提高小麦籽粒产量和对化学氮肥的氮素利用率。     

Protein and lysine content, grain yield, and other technological traits in durum wheat under Mediterranean conditions

A major problem for durum wheat production in the Mediterranean region is yield fluctuation. This fluctuation is a result of year-to-year variation in precipitation and heat stress during grain growth, which is typical of the Mediterranean climate. Both yield stability and good quality are needed in adapted durum wheat ideotypes. Ten durum wheat cultivars differing in drought resistance were grown during 1998, under both rainfed and irrigated conditions, at three sites in southern Spain. The main traits studied were protein and lysine content, grain yield, test weight, SDS sedimentation, semolina color, and grain vitreousness. Results show a high influence of site on all traits. Only test weight (TW), SDS sedimentation, grain vitreousness, and protein per kernel appeared to be determined also by cultivar effect. Vitreousness was positively correlated with TW (r = 0.48**) and semolina color (r = 0.46**). An inverse relationship was found between grain yield and protein content. Regression of cultivar mean values of protein content and grain yield showed a negative correlation (r = -0.72***), probably due to dilution of protein by non-nitrogen compounds and reduced starch accumulation in the grain under drought conditions. Lysine content was negatively associated with protein content (r = -0.86***), indicating the difficulty of a simultaneous breeding for both characteristics.     

砂姜黑土强筋小麦施肥技术研究

通过田间试验研究了施用不同肥料和不同施肥方法等对强筋小麦养分吸收和产量品质的影响。结果表明:在氮肥用量相同时,氮肥后移小麦产量和品质均好于全部基施(习惯施肥)处理;高氮和硫酸铵处理能提高强筋小麦的品质。磷酸二铵提高小麦产量效果好于过磷酸钙,而对子粒品质影响则过磷酸钙好于磷酸二铵;高量磷肥虽然不能进一步提高小麦产量,但能改善小麦的品质。增施有机肥和钾肥可促进小麦对N、P、K养分的吸收,显著提高小麦产量和品质,是砂姜黑土区优质高产强筋小麦重要施肥技术。锌肥能提高小麦产量和品质,含硫肥料有改善小麦品质的作用。试验表明,在砂姜黑土上,施用有机肥,稳定磷肥用量,加大氮、钾肥用量,配施锌肥和硫肥,分期施用氮肥(追肥量占总氮量比例在40%以上)有利于强筋小麦的优质高产。     

不同氮肥管理方式对华北粮田2排放和作物产量的影响分析

通过华北小麦和玉米田已发表文献分析,明确不同施氮量、氮肥基追比及氮素调控措施对土壤N2O排放和作物产量的影响。结果表明：高氮水平下减少氮肥用量并调整基追比有助于减少土壤N2O排放;添加硝化抑制剂双氰胺（DCD）对小麦和玉米产量的提高和土壤N2O的减排效果均较好。兼顾华北粮田N2O减排和作物产量,小麦季推荐合理施氮量167~174 kg·hm-2,基追比1：1,添加DCD,土壤N2O总排放量为0.31 kg·hm-2,籽粒产量6200 kg·hm-2以上;玉米季推荐合理施氮量177~181 kg·hm-2,基追比2：3~1：2,添加DCD,土壤N2O总排放量1.70 kg·hm-2,籽粒产量9000 kg·hm-2以上。     

不同秸秆还田技术模式对冬小麦强弱势粒灌浆特性的影响

为揭示砂姜黑土区不同秸秆还田技术模式对冬小麦籽粒灌浆进程的影响,该研究基于农业农村部华东地区作物栽培科学观测站15a的长期定位试验,设置单季小麦秸秆全量粉碎覆盖还田（T1）、小麦秸秆全量粉碎覆盖还田+玉米秸秆全量粉碎翻埋还田（T2）、单季玉米秸秆全量粉碎翻埋还田（T3）和小麦玉米秸秆全年不还田（CK）4种不同秸秆还田技术模式,采用Richards方程模拟冬小麦籽粒灌浆过程,研究不同秸秆还田技术模式对冬小麦强弱势粒灌浆特征参数的调控效应。结果表明：1）相较于秸秆不还田,秸秆还田处理能提升冬小麦强、弱势粒的籽粒体积、千粒质量和产量,T1、T2、T3处理下强势粒千粒质量和籽粒产量较CK分别显著提升11.02%、10.63%、13.75%和16.28%、14.29%、13.94%,弱势粒千粒质量和籽粒产量较CK分别显著提升9.73%、6.64%、7.57%和19.24%、23.25%、11.50%。Richards方程能极显著模拟不同秸秆还田技术模式下冬小麦籽粒灌浆过程,拟合方程决定系数（R²）均在0.997以上。2）对冬小麦强势粒,秸秆还田可延长小麦强势粒灌浆时间,主要通过缩短灌浆渐增期持续时间和提高其灌浆速率,延长灌浆缓增期的持续时间来提升强势粒千粒质量。其中T1、T3处理下冬小麦强势粒灌浆持续时间较CK分别延长2.137 d和4.443 d,T1、T2处理下强势粒单粒最大灌浆速率较CK分别显著提高了7.81%和12.26%。3）对冬小麦弱势粒,T1处理下弱势粒灌浆持续时间较CK延长1.477 d,T1、T2、T3弱势粒单粒最大灌浆速率较CK分别显著提升16.46%、22.69%和17.13%。该研究表明秸秆全量还田可提升砂姜黑土区冬小麦籽粒库容和籽粒灌浆速率,最终增加粒质量。研究可为砂姜黑土区秸秆资源的高效利用提供理论指导和技术支撑。     

不同小麦品种(品系)耐缺锰能力的比较研究

在四川平原水旱轮作的缺锰土壤上,采用田间和盆栽试验相结合的方法研究了15个不同小麦品种（品系）的耐缺锰能力。结果表明,不同小麦品种的耐缺锰能力存在很大差异。多数小麦品种对缺锰敏感,少数品种具有较强的耐性。其中,小麦品系80-8既具有较强的耐缺锰能力,也是供试小麦品种中产量最高的,在缺锰土壤上具有很好的推广应用价值。通过盆栽试验可对不同小麦品种进行初步筛选。在缺锰条件下,不同小麦品种间地上部锰浓度没有显著差异,不宜作为判别小麦耐缺锰能力的指标。缺锰可见症状与缺锰耐性有较好的一致性,可作为初步筛选指标。田间试验相对产量是最可靠的鉴定指标。根系发达,根冠比较高是小麦耐缺锰的一个重要因素。     

地形对漫川漫岗黑土区大豆产量的影响

为研究黑土区田块尺度地形对大豆产量造成的影响,在海伦东兴合作社具有明显地形起伏的地块,采集大豆田间试验数据,考虑温度、太阳辐射、坡度、土壤养分等因素,运用作物生长模型DSSAT(Decision Support Systemfor Agrotechnology Transfer)模型对各样点进行参数率定及验证,得出以下结论:1)DSSAT模型的模拟产量与实际产量的相对均方根误差为7.9%,模拟结果表现为优,表明运用作物模型模拟不同地形上的产量变异具有可行性;2)地形通过影响作物生长环境因子的时空差异决定产量差异,田块尺度温度、水分和坡度是影响产量差异的主要因素;3)坡顶和坡底的产量相对较高,且产量变异性较小,阳坡虽然接收到更多的光照,却由于水分胁迫造成减产,坡底和平缓坡顶水肥保持较好,易获得高产。研究成果为田间精细管理与田块尺度耕地高效利用提供科学依据。     

影响我国主要麦区小麦籽粒硫含量的品种(系)与土壤因素

【目的】明确我国主要麦区小麦主栽品种(系)籽粒硫含量差异,研究地点、年份、品种(系)对小麦籽粒硫含量的影响,为科学施肥和选育优质稳产小麦品种提供依据。【方法】于旱作区、麦玉区和稻麦区共47个地点种植当地主栽品种(系),测定了小麦生物量、收获指数、产量及其构成、籽粒硫累积量,并对籽粒硫含量与小麦生物量、收获指数、产量构成、硫累积量、籽粒养分含量、土壤肥力指标间的相互关系进行分析。【结果】旱作区、麦玉区和稻麦区主栽小麦品种(系)籽粒硫含量分别介于1.73～2.27、1.59～2.01和1.42～1.73 g/kg,平均值分别为1.98、1.78和1.53 g/kg。同一麦区内籽粒硫含量主要受品种(系)、地点和年份影响。旱作区,品种(系)对籽粒硫含量变异的贡献率最高,为13.1%;麦玉区和稻麦区地点对籽粒硫含量变异的贡献率最高,平均分别为34.2%和52.0%,品种(系)对籽粒硫含量变异的贡献率平均分别为25.4%和7.1%。收获指数和籽粒硫吸收量对小麦籽粒硫含量的影响大于产量构成要素、硫收获指数和地上部硫吸收量。旱作区籽粒硫含量与千粒重、地上部硫吸收量显著正相关,麦玉区与产量显著负相关,与...     

基于APSIM模型旱地春小麦产量对温度和CO2浓度升高的响应

为了探索气候变化对旱地春小麦生长的影响机理,在田间试验的基础上通过调试APSIM模型参数,并对模型进行检验,用APSIM模型模拟7个温度水平和7个CO2浓度水平组合设计下的春小麦产量,并采用二次多项回归和通径分析研究春小麦产量对温度和CO2浓度升高的响应。结果表明:当温度不变,CO2浓度每升高100 mol·mol-1,春小麦平均增产4.9%,最大增产可达到14.6%;春小麦产量随CO2浓度升高呈递增型二次抛物线变化,但春小麦产量会出现报酬递减。当CO2浓度不变时,温度每升高1℃,春小麦平均减产6.1%,最大减产幅度高达14.2%;春小麦产量随温度升高呈递减型二次抛物线变化。温度和CO2浓度同时升高对春小麦产量存在正的协同作用,但温度对春小麦产量负效应大于CO2浓度对春小麦产量的正效应。温度和CO2浓度同时升高会对旱地春小麦产量形成不利。     

变量施肥条件下冬小麦长势及品质变异遥感监测

卫星遥感数据能够在作物生长期内获取大范围“面状”地物光谱信息,反映作物的长势变异情况,以2005－2006年度国家精准农业研究示范基地冬小麦变量施肥试验为基础,以高空间分辨率卫星遥感影像Quickbird为数据源,结合地面获取的冬小麦品质、产量等数据,研究冬小麦长势及品质的变异情况。研究结果表明,Quickbird光谱参数能够反映冬小麦不同施肥处理小区的长势变异,而冬小麦早期的空间长势变异与其最终产量、品质变异有着密切的关系;冬小麦孕穗后期长势光谱信息与其产量有着很好的正相关关系,而与其品质信息存在着显著的负相关关系,其中OSAVI与产量的相关性达到0.536、GNDVI与冬小麦籽粒蛋白质及湿面筋含量的相关性分别达到了-0.531和-0.535;研究还发现,不同植被指数所反映的作物长势存在一定差异,反映冬小麦群体长势的植被参数和反映冬小麦叶绿素密度的植被指数在指示作物空间长势变异上有所不同。因此,利用遥感影像监测作物长势及其品质空间变异在技术上是可行的。     

煤矿沉陷区沉陷裂缝对土壤特性和作物生长的影响

为了研究煤矿沉陷区沉陷裂缝对土壤特性和作物生长的影响,通过野外调查和室内分析,对沉陷裂缝周围土壤水氮含量、微生物学特性和作物生理、产量特性进行了研究。结果表明,沉陷裂缝导致了土壤水、氮的流失。距沉陷裂缝越近,土壤含水量和有效氮含量越低,当距裂缝距离超过120 cm时,沉陷裂缝对土壤含水量和有效氮含量影响不显著。土壤水肥特性改变也导致了土壤微生物特性的改变,距沉陷裂缝越近,土壤酶(脲酶、蔗糖酶)活性和土壤呼吸速率越低。当距裂缝距离超过90 cm时,沉陷裂缝对土壤微生物的特性影响不显著。沉陷裂缝通过影响土壤中水分和矿物营养的含量,进而影响到植物叶片的叶绿素含量和光合特性。当裂缝距离超过60 cm时,沉陷裂缝对小麦叶片的叶绿素含量影响不显著。在拔节期,沉陷裂缝对光合作用的影响主要在距裂缝0~60 cm范围内,当距裂缝距离超过60 cm时,沉陷裂缝对小麦光合作用的影响不显著。但到花期时,当距裂缝距离超过90 cm时,沉陷裂缝对光合作用的影响不显著。沉陷裂缝对小麦各产量性状也造成了不同程度的影响。在距裂缝0~60 cm范围内,沉陷裂缝对株高、单茎重和穗粒数均有显著影响,当距裂缝距离超过90 cm时,则影响不显著。沉陷裂缝导致小麦穗数和产量的下降,距裂缝越近,小麦穗数和产量下降幅度越大,与距裂缝120 cm处小麦相比,裂缝边缘0~30 cm范围内小麦穗数和产量分别降低43.7%和53.3%。总之,开采沉陷产生的裂缝(隙),导致附近土壤水分蒸发增强和养分流失加剧,降低了土壤质量,影响到作物的生长,最终导致作物产量显著降低。     

中低分子量腐殖酸提高冬小麦磷吸收和产量的机理

  【目的】  研究不同分子量腐殖酸与磷肥复合制备的腐殖酸磷肥对作物和土壤磷有效性的影响,为腐殖酸磷肥研发和磷素高效利用提供理论依据。  【方法】  利用超滤分级方法,将风化煤腐殖酸分子量分为 > 100 kDa、10～100 kDa和 < 10 kDa 3个部分,获得高 (HA_H)、中 (HA_M)、低 (HA_L) 不同分子量的腐殖酸,采用磷酸与KOH反应法制备普通磷肥 (P)、未分级腐殖酸磷肥 (PHA)、高分子量腐殖酸磷肥 (PHA_H)、中分子量腐殖酸磷肥 (PHA_M) 和低分子量腐殖酸磷肥 (PHA_L) 5种磷肥。采用深100 cm、内径25 cm的土柱进行冬小麦栽培试验,按等磷量原则,设置P、PHA、PHA_H、PHA_M、PHA_L 5个施磷处理,同时设置与4个施磷处理对应的等量腐殖酸处理 (HA、HA_H、HA_M、HA_L),以不施磷肥为对照CK。测定小麦产量及产量构成因素、植株磷含量及不同层次土壤有效磷含量。  【结果】  1) 与CK相比,腐殖酸处理 (HA、HA_H、HA_M、HA_L) 小麦增产不明显。与普通磷肥相比,PHA、PHA_M和PHA_L处理产量显著提高了14.73%、18.84%、21.37% (P < 0.05),3 个处理间产量差异不显著,PHA_H增产不明显。PHA_L处理千粒重显著高于普通磷肥处理,其余3个腐殖酸磷肥处理增幅未达显著水平。2) PHA、PHA_M和PHA_L处理籽粒吸磷量较普通磷肥处理分别显著提高14.97%、19.45%、22.68%,而PHA_H增幅未达显著水平;腐殖酸磷肥处理间秸秆吸磷量没有显著差异。3) 与普通磷肥相比,PHA、PHA_H、PHA_M、PHA_L磷肥偏生产力和农学效率分别提高14.71%、6.01%、18.82%、21.35%和14.95%、1.66%、20.18%、23.03%,磷肥表观利用率分别提高2.93、0.51、4.52、5.41个百分点,也以中、低分子量腐殖酸磷肥效果最为明显,腐殖酸中的氧烷基碳、羧基/酰胺基碳、烷基碳结构与小麦籽粒产量和磷肥利用率具有正相关性,与芳香碳、芳香C―O负相关。4) 4个腐殖酸磷肥处理间及其与普通磷肥处理间 0—20、20—40、40—60 cm 土层土壤有效磷含量差异不显著。  【结论】  田间土柱栽培条件下,单施腐殖酸对小麦没有表现出明显的增产效果。腐殖酸中的氧烷基碳、羧基/酰胺基碳、烷基碳结构与小麦磷素吸收具有正相关性,低分子量腐殖酸具有较多的烷基碳、氧烷基碳、羧基/酰胺基碳结构,因而低分子量腐殖酸提高磷肥中磷素利用率的作用好于中分子量腐殖酸,而高分子量腐殖酸的效果不显著。     

2003-2011年中国粮食增产的贡献因素分析

理清2003年以来中国粮食产量增加的主要贡献因子及其贡献率,对于及时调整农业政策,保持和提升粮食生产能力有重要的意义。该文利用2003-2011年中国粮食及其各构成品种(根据国家统计局,粮食作物包括稻谷、小麦、玉米、薯类、豆类和其他谷物)的产量和播种面积数据,采用贡献因素分解的研究方法,研究了2003年以来中国粮食增产的作物和地区贡献,以及面积、单产和种植结构调整对于粮食增产的贡献率,并对各增产主力省区和主要粮食作物的增产贡献因素进行了分析,划定了增产主导类型。结果显示:研究期粮食增产全部来自3大粮食作物,其中玉米贡献了一半以上的增产量;杂粮、豆类和薯类总产均出现下降,其播种面积则分别下降了25.7%、17.4%和8.2%。地区贡献以黑龙江和河南最为突出,累积贡献率超过1/3;累积贡献率超过90%的13个省区,除新疆外其余都是粮食主产省区。作为传统农区的四川,其粮食增产贡献率仅为1.6%,与山西、陕西和甘肃等非主产区基本相当;全国粮食增产的面积贡献率最大,达到46.3%,其次是单产贡献率(44.2%),结构调整的贡献率将近10%,其中一半以上来自豆类向稻谷和玉米的调整;稻谷、玉米和春小麦的增产为面积主导型,而冬小麦的增产为单产和面积共同作用型;除河南和安徽为单产主导型,吉林和河北为面积单产共同作用型,其他增产主力省区的增产类型均为面积主导型。综合来看,2003-2011年中国粮食增产是以面积增加主导的外延式增产方式。由于粮食消费结构和国际粮食贸易容量的限制,今后结构调整的潜力已经很小。因此,在稳定粮食播种面积的基础上,进一步提高粮食作物的单产水平是今后稳定和提高粮食生产能力的重要举措。研究结果可为今后农业政策的调整提供决策依据。     

剪叶对不同土壤类型及不同品种小麦产量和品质的影响

为探究不同土壤条件下剪叶对不同品种小麦植株性状、籽粒产量和品质的影响,采用盆栽试验,在土壤肥力较高的黑土和土壤肥力较低的潮土条件下,以强筋春小麦品种津强8号和中筋春小麦农麦5号为供试品种,于小麦旗叶展开时,进行不同叶位剪叶处理。结果表明,在其他处理相同时,黑土条件下小麦株高、穗长、千粒重和籽粒产量均显著(P < 0.05)优于潮土条件下的小麦,其中产量提高44.8%,说明土壤肥力对小麦植株性状和产量有重要影响;剪叶处理的穗粒数、千粒重和产量均低于不剪叶(CK)处理,其中剪旗叶的产量较CK降低25.4%,剪倒2叶的产量较CK降低21.8%,且差异显著(P < 0.05),说明剪叶对小麦产量性状有不利影响。黑土条件下籽粒总蛋白质及组分含量均高于潮土,其中总蛋白质含量、球蛋白和醇溶蛋白含量分别较潮土条件下高出1.88个百分点、0.34个百分点、1.06个百分点,且均达到显著水平(P < 0.05),说明土壤肥力对小麦品质有重要影响;津强8号的总蛋白质含量、球蛋白、醇溶蛋白和谷蛋白含量均高于农麦5号,其中谷蛋白含量显著高出1.38个百分点(P< 0.05);而农麦5号的清蛋白含量较津强8号显著高出0.68个百分点(P< 0.05),说明强筋小麦品种并非每项品质指标都优于中筋小麦品种。本研究结果为进一步开展小麦优质高产栽培研究提供了理论依据。     

Effects of tree species and topography on soil chemistry, litter quality, and decomposition in Northeast Turkey

Leaf litters from beech (Fagus orientalis Lipsky.) and oak (Quercus robur L.), and needle litters from fir (Abies nordmanniana Spach.) and pine (Pinus sylvestris L.) trees were collected from north-facing site and south-facing site and at three slope positions (top, middle and bottom) on each aspect that varied in soil chemical characteristics (soil pH, cation exchange capacity and base saturation). The litters were analysed for initial total carbon, nitrogen, acid detergent fibre, lignin and cellulose concentrations. Nitrogen, acid detergent fibre and lignin concentrations and carbon:nitrogen and lignin:nitrogen ratios varied significantly within and between species according to soil chemical characteristics on aspects and slope positions. Litter decomposition was studied in the field using the litterbag technique. The litters were placed on two aspects and at three slopes on each aspect in October 2001, and were sampled every 6-month for 2 years. The main effects of aspect, species and slope position on decomposition rates were all statistically significant. Oak leaf litter showed highest decomposition rates, followed by pine, fir and beech litter, and the litters placed on north-facing site decomposed faster than those on the south-facing site. The litters placed at the top slope position decomposed slower than at those at either the bottom or middle positions. Initial lignin concentrations explained most of the variation in decomposition rates between species, and within species for the aspects and the slope positions, but the explained variance showed differences between aspects and slope positions. This result illustrates the important point that litter quality may define the potential rates of microbial decomposition but these are significantly influenced by the biotic and abiotic environment in which decomposition takes place.