Using multi-polarization C- and L-band synthetic aperture radar to estimate biomass and soil moisture of wheat fields

Biomass and soil moisture are two important parameters for agricultural crop monitoring and yield estimation. In this study, the Water Cloud Model (WCM) was coupled with the Ulaby soil moisture model to estimate both biomass and soil moisture for spring wheat fields in a test site in western Canada. This study exploited both C-band (RADARSAT-2) and L-band (UAVSAR) Synthetic Aperture Radars (SARs) for this purpose. The WCM-Ulaby model was calibrated for three polarizations (HH, VV and HV). Subsequently two of these three polarizations were used as inputs to an inversion procedure, to retrieve either soil moisture or biomass without the need for any ancillary data. The model was calibrated for total canopy biomass, the biomass of only the wheat heads, as well as for different wheat growth stages. This resulted in a calibrated WCM-Ulaby model for each sensor-polarization-phenology-biomass combination. Validation of model retrievals led to promising results. RADARSAT-2 (HH-HV) estimated total wheat biomass with root mean square (RMSE) and mean average (MAE) errors of 78.834 g/m² and 58.438 g/m²; soil moisture with errors of 0.078 m³/m³ (RMSE) and 0.065 m³/m³ (MAE) are reported. During the period of crop ripening, L-band estimates of soil moisture had accuracies of 0.064 m³/m³ (RMSE) and 0.057 m³/m³ (MAE). RADARSAT-2 (VV-HV) produced interesting results for retrieval of the biomass of the wheat heads. In this particular case, the biomass of the heads was estimated with accuracies of 38.757 g/m² (RSME) and 33.152 g/m² (MAE). For wider implementation this model will require additional data to strengthen the model accuracy and confirm estimation performance. Nevertheless this study encourages further research given the importance of wheat as a global commodity, the challenge of cloud cover in optical monitoring and the potential of direct estimation of the weight of heads where wheat production lies.     

Nutrient Recovery from Human Urine Using Pretreated Zeolite and Struvite Precipitation in Combination with Freezing‐Thawing and Plant Availability Tests on Common Wheat

The nutrient rich fractions in wastewater originating from human urine and can be recovered as solids for more efficient recycling, facilitated handling and storage for reuse in agriculture. Freezing and thawing can be used to concentrate the urine nutrients. Phosphorus (P) and nitrogen (N) can be precipitated as struvite [(Mg,Ca)(K,NH₄)(PO₄)·6H₂O] by adding MgO and additional nitrogen can be recovered by using zeolites. The zeolite in this study was pretreated in two ways: (i) washed and (ii) washed and thermally treated. The P recovery was high (> 97%) and the N recovery was ca. 50 to 60%. There was no significant difference in the nitrogen recovery among the different pretreated zeolites or between the pretreated and the untreated zeolite. Freezing had a positive effect on the nutrient concentration. The acute toxicity of the supernatants was tested on Daphnia magna to evaluate the possibilities of discharging the remaining supernatants to a recipient. The supernatants from the frozen treatments and from the unfrozen and washed zeolites were much less toxic than those of the original urine. The minerals acted as slow‐release fertilizers in climate chamber tests on spring wheat.     

1980-2011年阿勒泰市光热资源变化对春小麦发育期的影响

利用阿勒泰基准站1980-2011年观测资料,分析了阿勒泰市春小麦发育期和光热资源变化,及各发育期日期与≥0℃积温、日照时数的相关性研究。结果表明：全发育期天数的变化是呈减少趋势的,分蘖、乳熟期、全发育期天数均通过了（P＜0.01）显著性检验;全发育期的≥0℃积温和日照时数是呈线性减少趋势变化的,拔节、乳熟、成熟期的≥0℃积温与年份的相关系数通过了信度0.01的显著性检验;出苗、拔节、乳熟、成熟期和全发育期的日照时数与年份的相关系数通过了（P<0.01）的显著性检验。成熟期日期受成熟期间的日照时数的正相关影响(P＜0.05）,分蘖、乳熟期的日期受发育期间的≥0℃积温和日照时数的正相关影响（P＜0.01）。造成这些差异的主要原因可能是各年的气候条件不同,其次是各年份的栽培条件、田间管理( 如灌溉、施肥、病虫害防治)等非气象因子的不同所致,各年作物的生长及发育都是气象因子和非气象因子共同作用的结果。     

川东南小麦农业气候区划

本文根据川东南农业气候资源特点和小麦产量形成与气象条件的关系,用影响小麦产量及其分布的主要气象因子,进行模糊聚类分析,将川东南划分为6个不同的小麦气候生态区域。     

覆盖麦田的小气候特征

麦田进行秸杆覆盖后 ,由于地表热学性质和动力学性质的变化 ,使近地层水热状况发生改变 .1 997年 3月份小气候观测表明 :覆盖后白天能提高近地层的空气温度 ,减小近地层空气湿度 ,明显降低地温 ;覆盖后麦田乱流交换系数增大 ,显热通量增大 ,潜热通量减小 ,亦即用于土壤蒸发的能量减小 ,使土壤蒸发减小 ,从而从能量平衡角度解释了覆盖的保墒机理     

有限水分胁迫对小麦生长状况的影响及合理灌溉的土壤相对湿度指标

在人工控制水分条件下 ,通过田间小间隔不同水分等级和持续时间试验 ,分析了水分胁迫对小麦生理、生态及产量的影响 ,探讨了小麦对不同水分胁迫后复水的滞后作用和补偿效应 ,得出了有利于小麦高产、高效的轻度水分胁迫临界土壤相对湿度指标为 55% .     

化学融雪剂对小麦和玉米种子发芽的影响

研究了不同化学融雪剂浓度对小麦和玉米种子发芽的影响。结果表明:随着融雪剂处理浓度的增加,其对农作物种子发芽的抑制效应呈显著上升趋势,且不同融雪剂品种对同种农作物品种发芽的影响呈现较为明显的差异,不同农作物种子对同种融雪剂的反应差异也较大。在融雪剂胁迫下,小麦种子均表现出比玉米种子较强的发芽能力,且辽春9号比龙麦26号发芽能力更强。1#融雪剂对玉米种子发芽的影响无明显差别,但在2#融雪剂处理中,明玉2号较耐寒豫玉发芽能力强。与1#融雪剂相比,2#融雪剂处理种子的发芽率、发芽指数和活力指数相对较高。     

运城市2008年度小麦腥黑穗病发生的气候特征

运城是山西的小麦主产区,2008年是小麦腥黑穗病发生最为严重的一年,全市约5300hmz小麦发生了腥黑穗病。原因主要有：一是与小麦的品种抗病性有关,二是与2007年小麦播期的低温连阴天气有关,三是与2007年的小麦播期偏晚有关。从总体上来看,主要是由于2007年小麦播期的不良气候条件诱发了小麦腥黑穗病的发生,使得2008年发病小麦产量严重下降,损失较大。     

STEPWISE CANONICAL DISCRIMINANT ANALYSIS OF CONTINUOUS DIGITALIZED SIGNALS:APPLICATION TO CHROMATOGRAMS OF WHEAT PROTEINS

Continuous digitalized signals such as spectra,electrophoregrams or chromatograms generally have alarge number of data points and contain redundant information.It is therefore troublesome performingdiscriminant analysis without any preliminary selection of variables.A procedure for the application ofcanonical discriminant analysis(CDA)on this kind of data is studied.CDA can be presented as asuccession of two principal component analyses(PCAs).The first is performed directly on the raw dataand gives PC scores.The second is applied on the gravity centres of each qualitative group assessed onthe normalized PC scores.A stepwise procedure for selection of the relevant PC scores is presented.Themethod has been tested on an illustrative collection of 165 size-exclusion high-performance(SE-HPLC)chromatograms of proteins of wheat belonging to 55 genotypes and grown in three locations.Thediscrimination of the growing locations was performed using seven to nine PC scores and gave more than86% accurate classifications of the samples both in the training sets and the verification sets.Thegenotypes were also rather well identified,with more than 85% of the samples correctly classified.Thestudied method gives a way of assessing relevant mathematical distances between digitalized signalsaccording to qualitative knowledge of the samples.     

Bioavailability and toxicity of antimony

Antimony (Sb) is a toxic trace element widely distributed in the lithosphere and mainly associated with arsenic. Sb compounds are considered to be pollutants of high interest, however, the biogeochemical behaviour of Sb is still largely unknown, especially compared to other well-known toxic elements. In particular, questions remain about the availability of Sb to vascular plants. In this work, we focused on the following problems: (i) Sb uptake by plants; (ii) the availability of Sb to plants and (iii) variations in uptake and distribution of essential plant nutrients and trace elements resulting from bioaccumulation of Sb in Triticum aestivum (wheat) seedlings. The seedlings were either germinated or grown in media enriched with Sb. By the end of germination, concentrations of Sb in the seedlings germinated in Sb-amended media increased significantly. Sb content was highest in the roots and lowest in the leaves of the seedlings. After transfer of the seedlings germinated in an Sb-free medium to Sb-enriched media, Sb concentration in the seedlings increased with time, especially in the roots. Bioaccumulation of Sb influenced concentrations of different macro- and trace elements in all parts of the plants. The least variations were observed in the leaves, probably because the increase of Sb concentration in leaves was not as significant as in the seeds and roots.