Plant factors influencing enzyme retting of fiber and seed flax.

Retting, which is the microbial activity through which bast fibers are released from nonfiber tissues, is the limiting factor in flax processing. The objective of this work is to identify chemical and structural characteristics in a variety of fiber and seed flax types that influence enzyme retting in a recently developed method. Analyses of flax retted in a series of tests, including two enzyme rettings in some cases, indicated that lignin did not limit the separation of fibers from shive and showed that pectinases in enzyme-retting mixtures could ret fiber and seed flax. However, mature stems, such as that in flax produced for seed, had greater amounts of cutin and wax in the cleaned fiber product, suggesting that the cuticle could be a greater antiquality factor in seed versus fiber flax. With seed flax, the fraction of finer fibers produced during retting was significantly lower than with fiber flax. Results indicated that enzyme retting could be used to obtain flax fibers from seed flax stem residues and add value to this agricultural material.     

大麻鲜茎剥皮机的设计与试验

为了减轻大麻收获劳动强度、提高大麻鲜皮剥制效率,该研究根据大麻茎杆分枝多、皮骨结合紧密等特点,采取揉搓分离与梳理分离相结合的皮骨分离方法,设计出大麻鲜茎剥皮机。该样机主要由揉搓机构、梳理分离机构、纤维收集装置、传动系统、机架、行走装置等组成,样机具体结构紧凑、移动方便、皮骨分离能力强等特点。试验结果表明:样机的揉搓分离机构能够使大麻鲜茎破裂,皮骨初步分离;梳理分离机构能将揉搓后粘连在韧皮表面的大部分麻骨去除,起到梳理鲜皮上屑骨的作用。样机的鲜茎出皮率为10.90%~21.36%,剥净率为61.50%~78.33%,生产率为108.67~174.22 kg/h,纤维强度为4.90~5.61 cN/dtex,可实现大麻鲜茎的皮骨分离。     

Chemical composition of components comprising bast tissue in flax

Components from the bast region of flax (Linum usitatissium) were removed by hand from seed flax and fiber flax and analyzed by gas chromatography and mass spectrometry. Stems soaked in water were separated by hand into an outer layer, which consisted of epidermis with cuticle and parenchyma cells, and fiber bundles. Each of the two fractions were evaluated for chemical markers that could be used to predict the degree of retting and possibly fiber quality. The outer layer was subsequently treated with a mixed enzyme preparation to remove the carbohydrate portion, thus providing another fraction consisting primarily of cuticle. Four main constituent groups were investigated: dihydroxy fatty acids, long-chain fatty acids and alcohols, sterols, and aromatics. Long-chain fatty acids and alcohols located in the outer layer accounted for 80-92% of the total found in both fractions. Aromatics and sterols in the outer layer accounted for 29--72 and 27--67%, respectively, of the total and do not appear to be a reliable marker for the degree of retting. The best markers for retting were the dihydroxy fatty acids, of which 98--99% were accounted for in the outer layer. The main dihydroxy fatty acids were a mixture of 8,16- and 9,16-dihydroxyhexadecanoic acids and represented 87--89% of the total dihydroxy fatty acids measured. As a constituent of cuticle, this compound may serve as an excellent marker for indicating the degree of retting as well as a possible marker for fiber quality because this compound is almost always exclusively associated with the outer layer and not the fiber.     

Chemical and spectroscopic analysis of lignin in isolated flax fibers

The chemistry of pure flax fibers, free of contaminating nonfiber components, has not been determined. Fibers from the center sections of the stem of seed and fiber flax (Linum usitatissium L.), which had been retted after soaking in water and removal of the epidermis by hand, underwent chemical and spectroscopic analysis. Wet chemical analysis showed only trace indications of aromatics and no long chain fatty acids or alcohols in fibers. Pyrolysis mass spectroscopy (PyMS) and pyrolysis gas chromatography mass spectrometry (PyGCMS) showed only trace amounts of aromatic constituents that could be attributed to the presence of lignin. Mid-infrared (Mid-IR) and Raman spectroscopy of these fibers showed no aromatic compounds present. This study suggests that earlier work reporting the presence of lignin ranging from 1 to 4% may be the result of residual shive or epidermis/cuticle material remaining after the retting process which may be responsible for the favorable properties desired by the composites industry.     

抑制4CL基因表达的转基因毛白杨中木质素含量与茎杆颜色的关系

摘要： 将反义4CL（4-香豆酸辅酶A连接酶, 4-coumarate:CoA ligase）基因转入三倍体毛白杨（Populus tomentosa Carr.）可显著降低转基因植株的木质素含量。转基因植株茎杆在剥皮后呈现程度不等的红褐色,而对照为白色。茎杆全部为红褐色的转基因株系中木质素含量下降最多,茎杆局部为红褐色或呈现红褐色斑点的株系中木质素含量下降幅度减小。野生型对照茎杆的Wiesner反应为典型的紫红色,转基因植株红褐色茎杆的Wiesner反应为红色。茎杆为红褐色斑块的株系中,红褐色部分的Wiesner反应呈红色,白色部分与对照相同,呈典型紫红色,进一步证明颜色改变与转基因株系木质素含量的关系。茎杆颜色的改变可作为一个辅助指标筛选低木质素含量的转基因株系。     

香蕉茎纤维提取微生物初筛的一种新策略

我国是香蕉的主产国之一,随着香蕉茎杆的综合处理、利用技术的不断深化,香蕉纤维的开发和利用在我国呈现出良好的应用前景。然而目前香蕉纤维开发利用程度不高,主要原因是还没有获得高效的微生物提取菌株。本文以香蕉茎杆纤维脱胶为背景,采用脱胶菌侵染新鲜土豆片的方法,探讨了一种香蕉茎纤维提取微生物初筛的新策略,为香蕉纤维产业的开发利用提供了一个可资利用的新思路。     

刺五加在东北黑土区埂带上的生态适应性及水保效益研究

为了解决东北黑土区坡耕地治理中埂带植物品种少、水保效益差的问题,在黑龙江省牡丹江修建梯田埂和地埂试验区,在埂带上栽植长梗刺五加和短梗刺五加,设置径流小区,以自然裸露为对照。通过对埂带刺五加生物量、泥沙和径流量、对土壤含水量影响及经济效益观测,研究刺五加在东北黑土区埂带上的生态适应性及水土保持效益。结果表明:长梗刺五加和短梗刺五加在梯田埂和地埂上均有良好的适应性;埂带刺五加试验区土壤侵蚀量低于东北黑土区容许土壤流失量200 t/（km²·a）,满足水土保持功能要求;观测不同深度土壤含水量,刺五加埂带显著高于对照;栽植第三年的经济效益,梯田埂上短梗刺五加和长梗刺五加分别达到了96 880元/hm²和10 740元/hm²。地埂上短梗刺五加和长梗刺五加分别达到47 700元/hm²和10 665元/hm²,经济效益显著;二者相比,短梗刺五加在埂带上优于长梗刺五加。     

Field sampling considerations for the stem nitrate test in peppermint

Abstract

The stem nitrate test for peppermint (Mentha piperita var.) is a promising nitrogen (N) management tool. When used properly, this test may aid in obtaining significant savings of fertilizer costs and in the protection of groundwater quality. There are several factors related to environmental conditions, N management, and sampling procedures that have not been evaluated and may confound interpretation of test results. The objective of this study was to measure the response of stem nitrate concentrations to factors that would be expected to influence the test and develop guidelines for the collection of stem tissue. The factors considered here were i) solar radiation effects on both hourly and daily scales; ii) spatial variability; iii) differences between alternative plant materials; and iv) the temporal response of tissue nitrate concentrations to soluble N application. The most influential of these variables were the type of stem material (a 441% effect at p=3.55E‐6) and the number of stems collected to estimate the field mean concentration. It was found that the variance of the sample population and the number of stems required for a given sampling error could be greatly reduced by only collecting stems from within the plant canopy. Collecting only these stems, 30 stems were found to be adequate to estimate the field mean concentration within 10 to 15% of the true population mean (p<0.05). Statistically significant differences in stem nitrate concentrations were produced by variations in solar radiation on both hourly (p<0.05) and day length (p<0.01) scales. When measuring the diurnal response, a 17% reduction in stem nitrate concentration was observed over a nine‐hour period from 12:00 hours to 21:00 hours. On the day length scale, an 80% reduction in incoming solar radiation produced a 29% increase in stem nitrate concentrations after three days of shading. In the analysis of stem nitrate spatial variability, no discernable range of autocorrelation was detected indicating a purely random distribution of stem nitrate concentrations on the l‐150mscale. Given this finding and under the conditions of the analyses (late season with stem nitrate in excess of critical levels), it is not important that samples collected for this test fully cover the field being assessed, despite the intuitive appeal of full‐field sampling as a standard procedure. The response of stem nitrate concentrations to soluble N application was minimal, probably due to plant N status in the test plots being well above the critical deficiency content prior to application. With the data produced from these investigations, users of the peppermint stem nitrate test are presented with a method to collect data in the field whereby N management interpretations of the test can be more consistent and reliable. In addition, these results indicate the need for researchers to fully report the method of sampling employed when presenting finding for stem tissue tests.     

连续夹持输送式苎麻剥麻机研制

针对苎麻剥麻劳动强度大、作业工效低等问题,该研究基于横向喂入式剥麻技术的作业特点,结合苎麻剥麻的工艺要求,设计了一种连续夹持输送式苎麻剥麻机。通过对剥麻装置、夹持输送装置和换端夹持装置等关键部件的结构设计和理论分析,确定影响剥麻质量的关键因素及作业参数范围。以剥麻间隙、滚筒转速和输送速度作为影响因素,建立苎麻剥麻的鲜茎出麻率和原麻含杂率的数学模型,结合Box-Behnken试验方案进行多目标优化试验,寻求装置作业参数对苎麻剥麻的影响规律及最优参数组合。试验结果表明:滚筒转速、剥麻间隙和输送速度对鲜茎出麻率和原麻含杂率均具有极显著影响。通过多目标参数优化分析,确定最优作业参数组合:剥麻间隙4.0 mm、滚筒转速330 r/min和输送速度0.36 m/s。基于优化参数进行苎麻剥麻的生产验证试验,结果显示:鲜茎出麻率5.04%、原麻含杂率1.18%,各指标与模型预测值的相对误差均小于5%,验证了预测模型的准确性;整机生产效率142 kg/h,达到设计指标要求;苎麻纤维的含胶率22.85%,束纤维断裂强度4.56 CN/dtex,达到《苎麻》国家标准二等苎麻纤维等别。     

旱涝交替胁迫增强水稻抗倒伏性能

茎倒伏是水稻减产的重要影响因素。本文采用小区试验,分析了旱涝交替胁迫下旱后浅蓄（T1）、旱后深蓄（T2）与目前常用的浅水勤灌（CK,对照）模式下,水稻茎秆生长指标和抗倒伏指标的差异,并结合水稻茎秆的细观特征,对水稻抗倒伏能力的影响机制进行了探讨。结果表明,与对照相比,适宜的旱涝交替胁迫处理（T1）基部节间长度降低,茎粗、茎杆截面面积增加,但差异不显著;茎杆的抗弯截面模量和累积破坏能量分别增加12.4%和9.4%,差异达到显著水平;茎杆壁厚、维管束数量、维管束面积增加,维管束细胞趋于密实,使得茎杆的抗折力增加,倒伏指数下降。但旱后淹水深度过深（T2）,水稻抗倒伏指标下降。地上部分鲜重增加是 T2处理倒伏指数增加的主要原因。上述情况表明,适宜的干旱胁迫能够拮抗淹水胁迫造成的抗倒伏能力下降,提高后期抗倒伏能力。现有节水模式下适当加大雨后蓄水深度不会增加倒伏风险。     

Quantification of kavalactones and determination of kava (Piper methysticum) chemotypes using near-infrared reflectance spectroscopy for quality control in vanuatu

Kava ( Piper methysticum Forst f., Piperaceae) has anxiolytic properties and the ability to promote a state of relaxation without the loss of mental alertness. The rapid growth of the nutraceutical market between 1998 and 2000 has been stopped by a ban in Europe and Australia because of some suspicion of liver toxicity. It is now important to develop a fast, cheap, and reliable quality test to control kava exports. The aim of this study is to develop a calibration of the near-infrared reflectance spectroscopy (NIRS) using partial least-squares (PLS) regression. Two hundred thirty-six samples of kava roots, stumps, and basal stems were collected from the Vanuatu Agricultural Research and Technical Centre germplasm collection and from four villages. These samples, representing 45 different varieties, were analyzed using NIRS to record their absorption spectra between 400 and 2500 nm. A set of 101 selected samples was analyzed for their kavalactone content using HPLC. The results were used for PLS calibration of the NIRS. The NIRS prediction of the kavalactone content and the dry matter were in agreement with the HPLC results. There were good correlations between these two series of results, and coefficients ( R (2)) were all close to 1. The measurements were reproducible and had repeatability on par with the HPLC method. The NIRS system has been calibrated for the six major kavalactone content measurements, and it is suggested that this method could be used for quality control in Vanuatu.     

灭菌与未灭菌龙须草生物制浆比较研究

试验研究灭菌与未灭菌龙须草生物制浆过程中微生物生长及鼠李糖变化规律结果表明 ,龙须草非纤维素降解菌全发酵过程中其生长曲线符合一般微生物生长规律 ,未受到其他因素影响 ,灭菌与未灭菌龙须草发酵过程中鼠李糖浓度在龙须草纤维分散 (发酵工艺完成 )前一直增高 ,其峰值为 0 .35g/L左右 ,但灭菌龙须草发酵过程相对略长 ;应用龙须草非纤维素降解菌进行龙须草生物制浆 ,可不必对龙须草原料、自来水以及用于脱胶的设备等进行灭菌处理。     

不同辣椒品种镉吸收积累能力及关键期研究

  【目的】   比较不同辣椒品种植株Cd的吸收和积累动态差异,明确Cd积累关键期,为生产上规避辣椒Cd积累提供技术支持。   【方法】   以8个辣椒品种为材料进行了田间小区试验,供试土壤全镉含量为0.194 mg/kg。在辣椒苗期 (移栽当天)、壮苗期 (移栽后32 天)、结果期 (移栽后65 天)、成熟期 (移栽后111天) 采样,分析辣椒植株根、茎、叶及果实生物量、Cd含量,计算不同组织间的Cd运转系数。   【结果】   供试8个品种分为菜椒和朝天椒两类。4次采集的样品,叶部Cd含量均为菜椒 > 朝天椒,果实Cd含量在结果期菜椒高于朝天椒,成熟期朝天椒显著高于菜椒。朝天椒果实以品种艳椒425的Cd含量最低,菜椒以品种苏椒5号Cd含量最低。壮苗期为辣椒植株Cd的快速积累期,朝天椒根、茎和叶Cd含量移栽后0到32天分别增加了14.9、51.2和51.9倍,菜椒分别增加了8.9、25.6和39.9倍。结果期Cd积累变缓,移栽后65天朝天椒根、茎和叶Cd含量比移栽后32 天分别增加了0.35、0.55和–0.13倍,菜椒分别增加了0.20、0.01和–0.29倍;成熟期 (移栽后111 天) 朝天椒根、茎和叶Cd含量比结果初期 (移栽后65天) 分别增加了–0.29、0.44和–0.40倍,菜椒分别增加了–0.34、–0.14和–0.32倍。不同辣椒品种Cd在植株内的转运能力有差异,4次采样根–茎Cd转运效率菜椒 > 朝天椒,而茎–叶、叶–果和茎–果Cd转运效率则是朝天椒 > 菜椒。辣椒果实Cd积累量与壮苗期茎的Cd含量呈极显著正相关 (P < 0.01),与茎–果、叶–果Cd转运效率显著相关 (P < 0.05)。   【结论】   壮苗期前 (移栽后0～32天) 为辣椒植株Cd的快速积累期,该时期辣椒根茎叶中的Cd含量可以增加数十倍,进入结果期Cd含量的增加速率大大降低。壮苗期辣椒茎的Cd含量与果实Cd积累量呈极显著相关。菜椒根中的Cd向茎的转运能力较强,而朝天椒茎叶中的Cd向果实中转运能力较强,因而,朝天椒果实Cd积累能力高于菜椒。     

不同水分状况下施锌对玉米生长和锌吸收的影响

选择潮土(砂壤)和土(粘壤)两种质地不同的土壤,进行盆栽试验,研究不同土壤水分条件下施锌对玉米生长和锌吸收的影响。结果表明,施锌显著增加了玉米植株根、茎、叶以及整株干物质重;缺锌条件下玉米植株根冠比、根叶比和根茎比趋向增大。施锌显著提高了玉米植株各器官中锌的浓度和吸收量,并明显促进锌向地上部运移。干旱胁迫抑制了玉米植株生长,根冠比、根茎比、根叶比增大;随着土壤水分供应增加,植株生长加快,各器官生物量以茎和叶增加大于根。水分胁迫下,在潮土上玉米叶片中锌浓度上升;在土上叶片中锌浓度下降。但增施锌后,根和茎锌浓度增加幅度较大,叶片增加幅度较小;施锌和水分胁迫对根和茎锌浓度的交互作用极显著。水分胁迫下,玉米植株对锌的吸收总量减少。水分胁迫和锌肥施用对玉米叶片、茎锌吸收量的交互作用十分显著,但对根锌吸收量的交互影响不显著。     

机器学习结合高光谱植被指数与SPAD值估算冬小麦氮含量

冬小麦叶片氮含量与叶片光合作用和营养状况密切相关,直接影响植株生长发育,而茎秆中的氮含量与茎秆中纤维素、半纤维素和木质素的比例和含量密切相关,直接影响茎秆质量及植株的抗倒伏能力。然而,有关对冬小麦茎秆氮含量估算研究较为有限,限制了从氮含量角度判断茎秆质量及对倒伏的预测能力。为精准估算冬小麦不同器官（叶片、茎秆）氮含量,该研究通过2年田间试验,获取冬小麦4个关键生育期（拔节期、抽穗期、开花期、灌浆期）和3种施氮水平条件下（N1、N2和N3）的冠层光谱反射率、叶片、茎秆氮含量及叶片SPAD (soil and plant analyzer development, SPAD)值。分析了不同生育期和施氮水平条件下高光谱植被指数对叶片和茎秆氮含量的敏感性,并结合5种常用的机器学习算法：随机森林回归（random forest regression,RFR）、支持向量回归（support vector regression,SVR）、偏最小二乘回归（partial least squares regression,PLSR）、高斯过程回归（gaussian process regression,GPR）、深度神经网络回归（deep neural networks,DNN）构建冬小麦叶片和茎秆氮含量估算模型。结果表明：高光谱植被指数对叶片和茎秆氮含量的敏感性受到生育期和施氮水平的影响。在灌浆期,最佳植被指数双峰冠层植被指数 DCNI（double-peak canopy nitrogen index）对叶片氮含量的敏感性最高,R²为0.866。对茎秆氮含量,在抽穗期的敏感性最高,最佳植被指数归一化叶绿素比值指数 NPQI（normalized phaeophytinization index）与氮含量相关系数R²＝0.677。施氮水平的提升增加了光谱植被指数对茎秆氮含量的敏感性。结合SPAD值的机器学习算法提升了氮含量的估算精度,对叶片氮含量,在不同生育期和施氮水平条件下估算精度提升了1%～7%,其中在全生育期的归一化均方根误差NRMSE从0.254提升到0.214,抽穗期的NRMSE提升最大,从0.201提升到0.128。对茎秆氮含量,全生育期的NRMSE从0.443提升到0.400,抽穗期的NRMSE提升最大,从0.323提升到0.268。在全生育期,结合SPAD值的DNN模型对叶片（R²=0.782、NRMSE=0.214）和茎秆（R²=0.802、NRMSE=0.400）氮含量的估算精度最佳。研究说明,SPAD值与光谱植被指数结合有利于提升冬小麦不同生育期和施氮水平条件下叶片和茎秆氮含量的估算精度。     

Carbon mineralization patterns of cotton leaves and stems in vertisols and inceptisols

In India, cotton crop residues available after cotton picking are considered as waste materials and disposed off the field. For developing better residue management practices, knowledge of the decomposition kinetics is needed. Short-term laboratory incubations were conducted to determine the pattern of C mineralization from cotton leaves and stems [stem pieces (ca. 2 cm) vs. ground stem (0.25 mm)] in the two major soil groups (vertisols and inceptisols) on which cotton is grown to a large extent. The amount of C mineralized was significantly greater from leaf- (18.3% of added C) and ground stem-C (19% of added C) when compared to stem pieces-C (13.2% of added C). Differences between the residues were not seen in the inceptisols. The cumulative amount of C mineralized ranged from 9.6-11.5% of the added C. Narrowing the C:N ratio of stem did not enhance C mineralization.     

微灌旋流网式一体化水砂分离器试验

现有研究以及关注的过滤设备多集中于低含砂水水源,对于缺水地区以高含砂水为水源进行微灌的研究较少,该文提出一种新型微灌用网式一体化水砂分离器,并与常规水砂分离器进行试验对比分析,旨在解决以高含沙水为水源进行微灌的堵塞问题。该文在试验对比的基础上,分别计算网式一体化水砂分离器和常规水砂分离器的主要性能参数,包括溢流参数(溢流流量和溢流浓度)、底流参数(底流流量、底流浓度、底流分流比)以及分级分离参数(分离效率和分级效率)。结果表明,网式一体化水砂分离器和常规水砂分离器的溢流流量和底流流量均与进口压力呈正相关关系,而底流分流比与进口压力呈负相关关系;在进口压力为0.26~0.34 MPa时,网式一体化水砂分离器的分割粒度为20.0~25.0μm,分离极限为83.5~89.0μm,分离精度为0.40~0.43;而常规水砂分离器的分割粒度为24.5~27.5μm,分离极限为86.0~95.0μm,分离精度为0.27~0.42。如果以分离效率80%为评价指标,在进口压力为0.26~0.34 MPa时,常规水砂分离器的平均分离粒径为65μm,而网式一体化水砂分离器的平均分离粒径为45μm。研究可为高含砂水微灌用新型过滤器提供了试验方法、试验参数和理论依据。     

油菜联合收获机分离清选差速圆筒筛设计与试验

为减少油菜联合收获机旋风分离清选系统负载和提高清选性能,该文设计了一种与旋风分离清选装置配合使用、可对油菜脱出物进行初步筛分的差速圆筒筛。分析计算了筛网与助流装置转速范围,开展了基于EDEM的性能指标正交试验,以筛分损失率与筛下物清洁率为指标,以筛网转速、助流装置转速和助流装置投影面齿数为影响因素,得出了最佳参数组合,并开展了台架及田间验证试验。仿真结果表明:最佳参数组合为筛网转速35 r/min,助流装置转速80 r/min,助流装置投影面锯齿数6个。台架验证试验表明:整机喂入量3 kg/s、脱出物喂入量为1 kg/s条件下,差速圆筒筛与旋风分离清选装置配合使用,清选系统油菜籽粒总损失率为4.83%,其中筛分损失率为3.97%,清洁率为85.7%,风机转速可降低36.9%。田间试验表明:清选系统损失率平均值为5.9%,籽粒清洁率平均值为84.4%,平均功耗为3.48 kW,差速圆筒筛作业顺畅。该研究可减少旋风分离清选负载,为油菜联合收获机清选系统的结构改进和优化提供参考。     

Role of the fermentation process in off-odorant formation in white pepper: on-site trial in Thailand

In white pepper samples, directly taken from a retting batch at a pepper production plant in Thailand, 3-methylindole, 4-methylphenol, 3-methylphenol, and butanoic acid, recently confirmed to be responsible for the characteristic fecal off-odor frequently detected in white pepper powders, were quantified by stable isotope dilution analyses. The results clearly showed that, in particular, 3-methylindole (fecal, swine-manure-like), 4-methylphenol (fecal, horse-like), and butanoic acid (cheese-like) were biochemically formed during retting, thus indicating that fermentation is the crucial step for off-odorant formation during white pepper processing. Model fermentation experiments performed with different manufacturing regimens revealed that white pepper, containing no substantial amounts of these odorants, can be produced from ripe starting material by a short fermentation under water and with frequent exchange of water. The overall aroma of such pepper was superior as compared to the aroma of white pepper produced according to the traditional procedure.     

根据植株茎直径变化诊断作物水分状况研究进展

植株茎直径膨胀和收缩与作物体内水分状况的关系一直是研究的热点问题。根据20世纪50年代以来的大量国内外文献,综述了茎直径变化法诊断作物水分状况的研究进展,阐明了从植株茎直径变化诊断作物水分状况方法的优势,指出了此项研究存在的问题,进而对其今后研究方向和发展趋势进行了展望。