不同施肥对春玉米源库特征及其关系的影响

采用田间小区试验方法研究了不同氮、磷、钾肥用量对春玉米源、库特征及源库关系的影响.试验设氮、磷、钾肥处理各4个(氮、磷、钾肥用量分别为:N:0、120、240、360kg hm-2;P2O5:0、75、150、225 kg hm-2;K2O:0、120、240、360kghm-2).研究结果表明,当N用量为240kg hm-2、P2O5;用量为150kg hm-2、K2O用量为240kg hm-2时,春玉米的叶绿素含量、叶面积指数、干物质积累量等源特性和穗粒数、百粒重、产量、经济系数等库特性均高于其它处理;表征源库关系的茎鞘物质输出率处于相对较低的水平,粒叶比最低.因此在N、P2O5、K2O用量分别为240kg hm-2、150kg hm-2 240kg hm-2时既可以保持较高的叶源性能,又能促进籽粒库容的增大,能够获得协调的源库关系.     

露地洋葱施肥、土壤养分及产量状况的分析研究

在农户调查和土壤测试相结合的基础上,分析了山东惠民县露地洋葱土壤养分状况、肥料投入及其对产量和养分平衡的影响。结果表明,施用有机肥农户占总调查户的44%,平均由有机肥带入的氮磷钾养分量分别为N 170kg hm-2、P2O5112 kg hm-2、K2O 223 kg hm-2。化肥氮、磷投入量较高,平均分别为N 458 kg hm-2和P2O5399 kg hm-2,是洋葱氮磷吸收量的4.0和6.0倍,化学钾肥不足(K2O 131 kg hm-2),占洋葱钾吸收量的55%。收获时0~30 cm土壤无机氮含量达到88 kg hm-2,O lsen-P(P)和速效钾(K)平均含量分别为25.5和104 mg kg-1。自春季返青前到收获期间,30~60 cm和60~90 cm土壤无机氮含量均有不同程度的提高,土壤氮表观损失量与氮素投入量呈显著直线相关,维持土壤氮素平衡的最大氮素供应量为290 kg hm-2。相关分析表明,无论是氮、钾化肥投入量还是各阶段土壤无机氮、速效钾含量都与洋葱产量无显著相关,而磷肥用量及0~30 cm土壤剖面O lsen-P含量与产量有显著正相关(p<0.05)。     

氮素水平对不同穗型水稻品种植株衰老和产量的影响

在大田条件下,研究了两种氮素水平对直、弯穗水稻品种植株生长、叶片衰老和产量的影响。结果表明,高氮条件下两品种的朱粗度和叶片性状均优于低氮条件。增施氮肥能提高剑叶的叶绿素含量,延长叶绿素含量缓降期,使植株在生育后期能保持较高的绿叶面积;同时能提高剑叶的全氮含量,延长光合速率高值持续期,增加植株的干物质积累和籽粒产量。在同一氮素水平下,直立穗型品种的植株粗度、剑叶活力、籽粒灌浆速率、千粒重、生物产量及籽粒产量均略优于弯曲穗型品种。     

江淮丘陵区水稻钾、氮吸收特性与施钾效应研究

江淮地区水稻田间小区施钾效应试验结果表明,施钾能明显提高水稻产量,改善水稻生育性状,在氮磷肥充足时,钾肥的增产效果极其显著。水稻钾吸收量明显以秸秆吸钾量为主,约为籽粒吸钾量的5倍。N来自土壤的数量为120.30 kg hm-2;K2O来自土壤的数量为72.83kg hm-2。NPK全素施钾处理吸钾总量平均高出NP处理48.79%,籽粒和秸秆分别平均增加9.21%和56.8%;说明钾吸收量增加对秸秆产量贡献明显小于对籽粒产量的贡献。除最高施钾量和不施氮处理外,其余处理均出现不同程度钾素亏缺,说明在不施氮肥或氮肥不足的情况下,水稻对肥料钾的吸收量也相应减少。本试验钾肥(K2O)产投比以NPK2处理最高为2.54。综上所述,本地区同等肥力土壤,水稻钾肥推荐用量为120kg hm-2,根据土壤钾素平衡状况,水稻施钾量可适当增加。     

不同肥料结构对水稻群体干物质生产及养分吸收分配的影响

大田试验研究结果表明:单施化肥的水稻植株干物质积累和养分吸收主要集中于生长中前期。而有机无机肥配施,特别是化肥与厩肥配合施用有利于水稻植株在中后期,尤其是灌浆期对养分吸收和干物质的积累,其中以植株对磷的吸收比例在各肥料结构间差异最大(p<0.01)。有机无机肥配施还可促进水稻植株养分向籽粒中转移和分配。从而明显增加了水稻结实率和千粒重,进而大大提高了水稻籽粒产量(p<0.05或p<0.01)。     

不同浓度钙营养液对烟草矿质营养吸收与积累的影响

本文采用温室水培的方法,研究了不同的钙素供应水平对烟草各种矿质养分的吸收与积累的影响。结果表明,在其它养分形态与浓度一致条件下,随着钙浓度从75mgL-1提高到900mgL-1,烟草生长量呈抛物线型变化。钙浓度为150mgL-1时烟株干物质量最大。超过150mgL-1,随钙的增加而下降,当钙素达900mgL-1(K/Ca为1/6)时,烟株生长严重受抑。随着供钙水平由低到高,烟株氮、磷、钾、锌、锰含量均呈抛物线型变化,含钙量呈直线上升关系,而镁和铜含量则随钙浓度提高而显著下降。烟株各养分积累量均随营养液钙浓度提高呈抛物线型变化,但不同养分出现最大积累量时的营养液钙浓度却不相同。不同供钙水平上烟叶中各元素含量的变化特征与全株的结果基本一致。在低钙浓度范围(75~300mgL-1),钙对钾有协合关系,增钙促进提钾,大于300mgL-1后有拮抗作用,提钙导致降钾。钙与镁、锌、铜、锰间也存在明显的交互作用。烟叶中各元素含量与积累量的变化趋势与整株基本一致。     

砂壤质棕漠土上葡萄滴灌施肥的NPK追肥配比研究

应用二次通用旋转组合设计,在砂壤质棕漠土上进行了葡萄滴灌施肥条件下的氮、磷、钾追肥配比试验,获得了相应的函数模型;通过对模型的优化和解析,得出了葡萄适宜的NPK滴灌追肥用量配比,在葡萄萌芽—开花期滴灌追施氮、磷、钾的比例以N∶P2O5∶K2O=1:0.26:0.12为好,在葡萄果实生长期滴灌追施氮、磷、钾的比例以N∶P2O5∶K2O=1:1.54:1.97较佳。     

氮肥不同施用方法对小麦生长、养分吸收利用的影响

以超高产强筋小麦为试验材料,探讨返青、拔节与孕穗肥施用比例对氮、磷、钾吸收利用、籽粒产量的调节效应。结果表明:拔节期追施氮肥,产量提高,后期施氮有利于磷、钾素吸收效率和运转效率提高。施氮量为300kghm-2条件下,以基肥、拔节肥比例为7∶3较为适宜。     

氮钾肥配施对番茄幼苗生长及前期产量构成的影响

以尿素和硫酸钾为主要氮、钾肥料,以草炭和蛭石为育苗基质进行番茄育苗试验,研究分析了育苗基质中不同氮、钾肥料配施方案对番茄幼苗生长及其前期产量构成的影响,结果表明:番茄育苗过程中氮、钾肥料不同配比对番茄幼苗生长及前期产量存在显著影响,偏施氮肥或钾肥均可降低番茄出苗率、抑制番茄幼苗生长与干物质积累,氮、钾肥料合理配施可明显提高番茄幼苗素质,增加番茄前期开花数与座果数从而增加番茄前期产量,番茄基质育苗过程中氮、钾(N∶K2O)肥料最佳配比为1∶1.2。     

土壤肥力对烟叶化学成份及品质的影响

采用典型相关分析和逐步回归分析讨论了贵州省主产烟区土壤养分对烟叶的化学成份和品质的影响。土壤养分选取反映土壤肥力的主要因素(有机质、速效氮、速效磷、速效钾、pH)作为指标,烟叶化学成份是通过主成分分析从15个因素中萃取出9个(总糖、还原糖、烟碱、蛋白质、K、Cl、Mg、Cu、Zn)作为指标,烟叶品质指标选用施木克值和糖碱比。典型相关分析结果表明:贵州主产烟区土壤各养分对烟叶化学成分作用的大小依次为:速效氮>速效磷>有机质>pH>速效钾;对烟叶化学成分的影响分别是:速效氮主要影响烟叶中糖组分含量,对还原糖的积累有利,对总糖积累不利;速效磷的作用与速效氮相反;有机质对矿质元素含量和含氮化合物影响较大,对Cu、烟碱的积累不利,对Zn、Cl的积累有利,并与糖碱比值呈负相关;由于研究区域中烟叶化学成分K变异较小,土壤速效钾对烟叶化学成分中的K没有明显的影响。逐步回归分析建立了土壤养分与烟叶化学成分的量化方程。     

设施黄瓜干物质累积及NPK吸收规律

以津研四号黄瓜为试材,研究设施黄瓜干物质累积及其N、P、K吸收规律。结果表明:黄瓜干物质积累主要集中在初瓜期和盛瓜期,约占全生育期干物质累积量的95%;植株与果实干物质累积的比例为1.5:1。苗期、初瓜期、盛瓜期和末瓜期N素吸收量占整个生育期吸收总量的百分比依次为2.1%、29.3%、65.2%和3.4%;P素为3.2%、32.8%、61.6%和2.4%;K素为2.3%、27.3%、66.8%和3.8%。当黄瓜的产量(鲜重)为142.5 t hm-2时,全生育期N、P、K吸收量分别为405.4、74.9和506.6kg,N、P、K吸收比例为1:0.18:1.25,生产1 t商品瓜吸收的N、P、K分别为2.84、0.53和3.55kg。     

肥水条件对不同类型水稻干物质积累与分配的影响

研究了肥水条件对不同类型水稻物质积累与分配的影响。结果表明：产量与总干物质积累量显正相关，杂交稻抽穗后的物质积累优势明显，而高产常规粳稻抽穗前干物质净积累量较大；肥水充足能促进干物质的再分配，增加籽粒产量，肥水不足会对干物质的输出产生抑制作用；水稻叶片的干物质输出和转换率高于茎鞘，对产量贡献较大；直立穗型品种叶片及茎鞘的干物质输出能力均较强，对高产有利。     

不同氮钾施用水平对番茄营养吸收和土壤养分变化的影响

以“辽园多丽”番茄为试材,在日光温室内桶栽条件下,研究不同氮钾水平对番茄养分吸收和土壤养分变化的影响。结果表明:在一定范围内,随着土壤中施氮量和施钾量的增多,番茄叶片和果实中含氮量、含钾量越高。说明氮、钾两种元素可互相促进彼此的吸收,但是,超过一定范围,会降低果实中氮素和钾素的比例。不同氮钾处理对植株磷素的吸收影响不大。土壤中增施钾肥在一定程度上抑制了番茄植株对钙素和镁素的吸收,土壤中氮素含量的高低对叶片中钙的吸收影响不大,土壤中适当氮水平可促进番茄叶片和果实中镁素的吸收和积累,施氮量过高则降低了果实中钙素、镁素的积累。随着土壤中氮肥和钾肥施入量的增多,土壤中碱解氮和速效钾的含量呈升高趋势,不同施钾水平条件下,中等钾素处理土壤中碱解氮含量较高。     

半湿润偏旱区冬小麦需肥特性研究

本试验主要研究了半湿润偏旱区冬小麦的干物质积累进程和不同生育期对氮、磷、钾的需求特点。     

设施栽培下仙客来的养分吸收规律研究

以设施栽培的仙客来‘NP3’为材料,探讨了仙客来的干物质积累和矿质养分吸收积累规律。结果表明,设施栽培条件下,成品时干物重为32.49g的仙客来单株矿质养分的需求总量为2.51g。越夏后10月份是仙客来干物质和养分积累的重要时期,N的吸收量最大,每日每株吸收11.36mg;K次之,9.56 mg;P为2.44 mg;Ca为3.83mg;Mg为2.36mg。不同生育期对矿质养分的吸收比例不同,但N/K基本平衡在1:1。     

Assessing growth and yield of wheat using remotely-sensed canopy temperature and spectral indices

Abstract

Prediction models were developed for wheat to assess crop growth in terms of leaf area index, dry matter production and grain yield from remotely-sensed temperature and spectral indices. The cumulative stress degree days (SDD) for the period of flowering to grain formation stage showed significantly higher correlation with dry matter (r= — 0940) and grain yield (r= —0-939) whereas that, for the period grain formation to harvest stage, showed significantly higher correlation lpar;r= —0-967) for crop water use. Significant and positive correlations between dry matter, leaf area and grain yield with infrared/red, normalised difference (ND), transformed vegetation index and greenness index were attained with the latter providing the highest degree of predictability. Spectral indices measured between flowering to milking stages gave the best prediction indicating the suitability of this period for crop growth assessment by this technique. Inter-stage sensitivity analysis by using multiple regression approach also revealed that greenness and transformed vegetation indices could provide better prediction of dry matter and grain yield. From the values of regression coefficients the jointing to beginning of milk formation period of the crop was found to be the most sensitive stage influencing the yield of crop.     

Relationships between radar backscatter and accumulation rates on the Greenland ice sheet

C-band radar backscatter generally seems to be inversely related to accumulation rate across Greenland's dry snow zone. A coupled snow metamorphosis-backscatter model was constructed in order to investigate the observation. Accumulation rate and mean annual temperature were the coupled-model inputs. In a local area where accumulation rate is known very accurately the model predicts the backscatter level along several transects within the calibration uncertainties of the ERS-1 SAR data. The analysis was applied to the remainder of the dry snow zone. The model showed that both accumulation rate and temperature can modulate surface backscatter across Greenland's dry snow zone with accumulation rate being the primary influence.     

Estimating dry matter content from spectral reflectance for green leaves of different species

Efficient and accurate detection of the temporal dynamics and spatial variations of leaf dry matter content would help monitor key properties and processes in vegetation and the wider ecosystem. However, leaf water content strongly absorbs at shortwave infrared wavelengths, reducing the signal from dry matter. The major objective of this study was to examine relationship between spectral reflectance of fresh leaves and the ratio of leaf dry mass to leaf area, across a wide range of species at the leaf scale. A narrow-band, normalized index combining two distinct wavebands centred at 1649 and 1722 nm achieved the highest overall performance and discriminatory power compared to either single band or first derivatives. The normalized index was evaluated using the PROSPECT (leaf optical properties spectra) simulated reflectance spectra and field measurements from the Leaf Optical Properties Experiment (LOPEX) data set. Both evaluations show that leaf dry matter contents were retrievable with R ² of 0.845 and 0.681 and regression slopes of 0.903 and 0.886. This study suggests that spectral reflectance measurements hold promise for the assessment of dry matter content for green leaves. Further investigation needs to be conducted to evaluate the effectiveness of this normalized index at canopy scales.     

Development of angle indexes for soil moisture estimation, dry matter detection and land-cover discrimination

A new index was proposed to estimate soil and vegetation moisture based on NIR (858 nm) and SWIR (1240 and 1640 nm) MODIS bands. The Shortwave Angle Slope Index (SASI) parameterizes the general shape of the NIR-SWIR part of the spectrum. We expand on the novel approach used to develop SASI by proposing another index, the Angle at NIR (ANIR). We use laboratory and simulation datasets to validate the ability of SASI to estimate soil and vegetation moisture, and evaluate the advantage for using both SASI and ANIR as land-cover discrimination tools. Our results demonstrate that SASI is a good indicator of soil and vegetation moisture. ANIR shows promise in discriminating dry plant matter from soil and quantifying the amount of dry matter irrespective of changes in soil moisture or green vegetation. When SASI is combined with ANIR, discrimination between soil, dry plant matter, and low to high amounts of green vegetation is significantly improved. Angle indexes are an exciting new way to engineer indexes that contain valuable environmental information not accessible from other indexes.     

Prediction of feed abrasive value by artificial neural networks and multiple linear regression

In order to evaluate rapid testing methods based on the relationship between feed abrasive value (FAV) and physicochemical properties (particle size, bulk density, dry matter (DM), soluble dry matter, water-holding capacity (WHC), ash, crud protein, neutral detergent fiber (NDF), physically effective NDF and non-fibrous carbohydrates (NFC)), 100 empirical dataset were used. Relationships were investigated using multiple linear regression (MLR) and artificial neural networks (ANNs). The mean relative error was significantly (P?<?0.01) lower for ANN than MLR model. Globally, the non-linear ANN model approach is shown to provide a better prediction of FAV than linear multiple regression.