机器人采摘中番茄力学特性与机械损伤的关系

为了减小机器人采摘中番茄的夹持损伤,通过加卸载正交试验对不同结构番茄力学特性与机械损伤的关系进行了研究。试验因素包括加载位置、探头类型、指面材料、压缩率和加载速度。试验结果表明：对番茄5个力学参数影响都显著且最大的因素为压缩率,并且番茄的力学特性参数之间存在一定的相关性。压缩率每增加1%,应变能、塑性应变能、峰值力和压缩斜率约分别平均增加26.16 mJ、19.04 mJ、4.62 N和0.16 N/mm,而弹性度平均减小0.88%。对番茄机械损伤度影响显著的因素依次为压缩率、球度、加载位置和加载速度。压缩率每增加1%,番茄的机械损伤度平均增加2.98%。番茄的机械损伤度与力学参数之间的回归系数为0.7214,其中与番茄机械损伤度最相关的力学参数是峰值力。该研究为采摘机器人夹持机构的设计和稳定夹持控制策略的实现提供了理论依据。     

采收成熟度对晚熟W.默科特柑橘贮藏期品质的影响

W.默科特(Citrus reticulata Blanco)是中国重要的晚熟柑橘品种,为探究成熟度对果实品质及耐贮性的影响,以7个不同采收期(分别为11月25日,12月10日,12月24日,翌年1月7日,1月21日,2月7日以及2月19日采样)的W.默科特果实为试验材料,对采收点及冷库贮藏期间(0～150 d)的色泽...     

Water soluble carbohydrates and growth potential of winter wheat as influenced by weather conditions during winter

Abstract

Although winter survival of winter wheat most often is recorded qualitatively by rating dead or living plants, the surviving plants may differ extensively in vigour and degree of carbohydrate reserves left at the end of winter. This factor is yet not accounted for in existing models of winter wheat yield and crop performance. A quantitative measure of plant vigour at spring arrival, as influenced by the prevailing winter weather and the plants’ concentration of water soluble carbohydrates, would hence make a useful supplement to such models. Two cultivars of winter wheat were grown in boxes over 2 years at three sites in Norway with contrasting winter climates. Plants were sampled monthly for measurements of growth potential and analyses of reserve carbohydrates. Fructan constituted the main part of water soluble carbohydrates (WSC). The concentration of fructan fell throughout winter, but increased rapidly after snow thaw in spring when a positive carbon balance was restored. Daily global radiation at plant level and soil temperature (2 cm) were the only two climatic factors found to have significant effects on periodic changes in fructan concentration in a stepwise regression analysis. Still, number of days with snow cover had a causal effect through its impact on soil temperature and radiation at plant level. In neither of the 2 years was there any significant correlation between plant carbohydrate concentration and growth potential at the different sites. The results implied that plant vigour at the end of winter was strongly related to plant condition in late autumn and duration of snow cover in winter. Plants that had been covered with snow for a long time period showed significantly lower growth at the samplings in March and April than plants from the location with a shorter duration of snow cover.     

Retention of phenylalanine ammonia-lyase activity in wheat seedlings during storage and in vitro digestion

The retention of phenylalanine ammonia-lyase (PAL) activity in Red Spring wheat seedlings during storage and in vitro protein digestion was evaluated toward assessing the efficacy of plant PAL as a dietary supplement for patients suffering from the metabolic disease, phenylketonuria. Retention of PAL activity in freeze-dried wheat seedling tissues following three months of storage at -20 degrees C ranged from 62% in the leaf to 89% in root/residual seed tissues. After a 3-h two-stage ("gastric-intestinal") in vitro digestion, 36% and 42% recovery of PAL activity was associated with chopped fresh leaf and root/residual seed tissues respectively; however, no activity was recovered from freeze-dried tissues. High performance liquid chromatographic analysis of the residual phenylalanine (Phe) after in vitro digestion confirmed that the fresh tissues effected a significantly higher conversion of exogenous Phe than freeze-dried tissues. These results demonstrate that the plant cell walls provide protection of PAL during in vitro digestion. In cases where exogenous Phe (100 mg; 24 mM) was supplied to the tissues, the product of the reaction, trans-cinnamic acid, may have exerted a significant inhibitory effect on PAL activity.     

电子束辐照对小麦储藏抑菌及加工品质的影响

该文研究了不同剂量电子束辐照对储藏小麦微生物菌落的抑制作用,以及辐照后对小麦主要储藏指标与加工品质的影响。试验结果表明,电子束辐照对储藏小麦菌落总数有明显的抑制作用（P＜0.01）,且辐照剂量越高菌落总数越低;不同剂量辐照后,对所有霉菌属的抑制效果均达极显著水平（P＜0.01）。经0～5.1 kGy剂量辐照后,小麦感官及基本营养成分没有太大变化;面团流变学特性表明,除稳定时间和断裂时间随着剂量的增加略增外,评价值与弱化度呈负相关,其他吸水率、形成时间的变化并不十分明显;但高剂量照射使其面筋指数、α-淀粉酶活性迅速降低,经5.1 kGy剂量辐照的比未经辐照的小麦降落数值下降了56.12%。馒头制品品尝评分也随着辐照剂量的增大而降低。     

田间集雨对冬小麦生理、生长和产量的影响

依据在北京昌平2004～2005年冬小麦田间集雨试验,研究了该措施对土壤水分、冬小麦生理生长及产量的影响。结果表明：在集雨面积占总种植面积40%、降雨接近常年水平的条件下,集雨明显改善了田间水分状况,0～160 cm土壤冬小麦耗水增加6.5%～9.8%,且对深层水的利用是对照的6.9～7.3倍,小麦抗旱能力增强。集雨处理的冬小麦叶片光合强度和蒸腾强度较对照分别提高10.1%～46.4%和21.5%～60.5%,气孔阻力则降低23.3%～45.3%,光系统PSII的最大光能转换效率和潜在活性分别提高2.1%～42.6%和10%～353%。集雨处理的冬小麦生长得到增强,株高和叶面积指数比对照分别增加15%～39%和58.2%～112%,收获时干物质增加27%～44%,最终产量增加36%～42%。耗水深度按1 m和1.6 m计算时,相应的水分生产效率提高39.5%～50.5%和23.5%～33.5%。尽管保水剂处理的土壤水分和植株生长总体上较单独集雨效果好,但产量效应不明显。     

Derivation of site-related measures to minimise soil erosion on the watershed scale in the Saxonian loess belt using the model EROSION 3D

The Saxonian loess belt is one of the areas in Germany most endangered by water erosion. As consequence of extreme rainstorms, farmland and adjacent areas, e.g. villages, roads, biotopes and watercourses, are repeatedly damaged. Estimating soil loss is a crucial factor for sustainable land use planning in this region. Since soil erosion measurements are usually conducted at the scale of plots, thereby being both costly as well as time-consuming, erosion models are substantial tools for soil protection policies. This paper summarises and integrates the results of a research project aimed at assessing the present situation as well as that of future landscape planning alternatives, using the physically based EROSION 3D simulation model on a catchment scale. EROSION 3D can estimate the yields of sediment for small watersheds and enables environmental researchers and planners to locate the main areas of soil loss and deposition. Five different scenarios based on past and present land use information as well as future landscape 2 planning alternatives were simulated.The modelling results showed that scenarios based on only one option for minimising soil loss were not sufficiently effective in reducing sediment production. However, the combination of active soil protection measures such as conservation tillage with passive measures like grassed waterways or buffer strips resulted in an adequate soil protection. In contrast to passive protection measures, best management practices like non-tillage systems are commonly used in the Saxonian loess belt already. Thus, the implementation of passive measures is an important future task in land use planning. Simulation models like EROSION 3D can provide the information needed for the adequate localisation and the dimensioning of site-specific measures.     

Contribution of wheat endogenous and wheat kernel associated microbial endoxylanases to changes in the arabinoxylan population during breadmaking

Wheat kernel associated endoxylanases consist of a majority of microbial endoxylanases and a minority of endogenous endoxylanases. At least part of these enzymes can be expected to end up in wheat flour upon milling. In this study, the contribution of both types of these endoxylanases to changes in the arabinoxylan (AX) population during wheat flour breadmaking was assessed. To this end, wheat flour produced from two wheat varieties with different endoxylanase activity levels, both before and after sodium hypochlorite surface treatment of the wheat kernels, was used in a straight dough breadmaking procedure. Monitoring of the AX population during the breadmaking process showed that changes in AX are to a large extent caused by endogenous endoxylanases, whereas the contribution of microbial endoxylanases to these changes was generally very low. The latter points to a limited contamination of wheat flour with microbial enzymes during milling or to an extensive inactivation of these wheat flour associated microbial endoxylanases by endoxylanase inhibitors, present in wheat flour. When all wheat kernel associated microbial endoxylanases were first washed from the kernels and then added to the bread recipe, they drastically affected the AX population, suggesting that they can have a large impact on whole meal breadmaking.     

不同采收期对苹果常温贮藏品质和衰老的影响

以通辽地区的‘塞外红’苹果为试材,研究了生长发育期在116~134 d内的3个采收期果实常温(20±1)℃贮藏品质和软化衰老的变化,以确定‘塞外红’苹果的最佳采收成熟度和适宜采收期。结果表明,随着采收期的推迟,果实硬度逐渐降低,可溶性固形物和可滴定酸含量逐渐升高,种子颜色逐渐变褐到全褐。随着贮藏时间的延长,3个采收期果实的硬度、维生素C和可滴定酸含量均逐渐下降,从采收到贮藏结束,采期Ⅰ果实的硬度一直保持最高,采期Ⅱ保持了果实较高的维生素C和可滴定酸含量,采期Ⅲ果实的可溶性固形物含量SSC一直保持最高。结果还表明,采期Ⅰ的果实常温贮藏期间虽然具有较高的原果胶和纤维素含量,而且抑制了可溶性果胶的生成,推迟了果实多聚半乳糖醛酸酶PG活性和纤维素酶活性高峰,延缓了果实呼吸高峰和乙烯释放高峰的出现时间,但果实的外观色泽、口感和风味相对较差;采期Ⅲ的果实丙二醛和乙醇含量积累较多,果实衰老快。综合分析,采期Ⅱ的‘塞外红’苹果具有良好的内在品质、外观色泽和贮运性能。因此,建议通辽地区‘塞外红’苹果的采收期以9月5—10日为宜(可适当晚采1~2 d),采收成熟度参考标准为:果实生长发育天数123~128 d、果肉硬度11.0~11.5 kg/cm^2、SSC≥16.5%、种子的颜色3/4左右变褐、淀粉染色为4.5级左右。     

Effects of harvesting date and storage on the amounts of polyacetylenes in carrots, Daucus carota

The amounts of three main polyacetylenes in carrots; falcarinol, falcarindiol, and falcarindiol-3-acetate, were determined by HPLC, during three seasons, in carrots harvested several times per season and at different locations in Sweden. The amounts of falcarindiol first decreased from a relatively high level and then increased later in the harvest season. The amounts of falcarindiol-3-acetate showed similar variations, whereas the amounts of falcarinol did not exhibit any significant variation during the harvest season. During storage the amount of polyacetylenes leveled off, increasing in samples initially low and decreasing in samples initially high in polyacetylenes. The amounts of all polyacetylenes varied significantly due to external factors and between stored and fresh samples. This variation opens up possibilities to achieve a chemical composition of polyacetylenes at harvest that minimizes the risk of bitter off-taste and maximizes the positive health effects reported in connection with polyacetylenes in carrots.     

The impact of water harvesting on soil properties in the island of Fuerteventura, Spain

Abstract. In the extremely arid island of Fuerteventura (Canary Islands, Spain), a traditional water harvesting practice has evolved in slightly sloping areas, which receive runoff water from time to time. The system is particularly effective in the rehabilitation of saline–sodic soils where the improved fertility allows certain crops to be grown, which would not be possible without water harvesting. The influence of the water harvesting on soil fertility was investigated by comparing the properties of the cultivated soils receiving periodic runoff with those of natural control soils that did not receive runoff. The saline–sodic characteristics of the four uncultivated soils were absent from the four cultivated soils which, on average, contained only one quarter of the exchangeable sodium and more than twice the exchangeable calcium content. The clay and silt content of all four of the cultivated soils had been substantially enhanced relative to the control soils, by sediment contained in the runoff.     

Comparative study of the effect of incorporated individual wheat storage proteins on mixing properties of rice and wheat doughs

The aim of this work was to compare the effects of incorporated wheat storage proteins on the functional properties of rice and wheat flours. The advantage of rice as a base flour compared to wheat is that it does not contain any wheat flour components and, therefore, has no interactive effect between wheat glutenin proteins. The incorporation of individual HMW glutenin subunit proteins (Bx6, Bx7, and By8) in different ratios had significant positive effects on the mixing requirements of both rice and wheat doughs. Reconstitution experiments using two x+y type HMW-GS pairs together with a bacterially expressed LMW-GS have been also carried out in this study. The largest effects of polymer formation and mixing properties of rice flour dough were observed when Bx and By subunits were used in a 1:1 ratio and HMW and LMW glutenin subunits in a 1:3 ratio. However, using the same subunit ratios in wheat as the base flour, these synergistic effects were not observed.     

冬小麦灌溉制度对土壤贮水利用的影响

足墒条件下冬小麦播种时200cm土体总贮水量为619.6mm,有效贮水量为329.5mm。冬小麦播种～拔节期主要消耗0～100cm土层内土壤有效贮水;由于有效贮水能满足作物需水,因此拔节期不出现土壤水分亏缺。拔节～开花期对照(CK)耗水深度为200cm土层,起身期灌1水(Ⅰ-1)处理为160cm,其他处理为130cm;至开花期CK和Ⅰ-1处理0～60cm土层内已呈现一定程度的水分亏缺。开花～成熟期各处理200cm 土体内土壤有效水含量均呈不同程度下降,但主要供水层为0～130cm土层;冬小麦成熟期除春后起身～孕穗～灌浆期(Ⅲ-1)、拔节～开花～灌浆期(Ⅲ-2)灌3水和起身～拔节～开花～灌浆期(Ⅳ)灌4水处理外,大部分处理0～80cm或0～60cm土层内均呈明显的水分亏缺。随灌水次数或灌水量的增加,土壤贮水利用率呈明显下降趋势。     

Characterization using Raman microspectroscopy of arabinoxylans in the walls of different cell types during the development of wheat endosperm

The time course and pattern of arabinoxylan deposition in the wheat (Triticum aestivum) endosperm during grain development were studied using Raman spectroscopy. The presence of arabinoxylans (AX) is detected at the beginning of grain filling. At this stage, AX appear more substituted than at the later stages. Feruloylation of AX increases during the grain-filling stage, especially in the case of the aleurone layer. Whatever the stage of grain development, four populations of cells could be defined according to Raman arabinoxylan signatures. In the walls of the aleurone cells, AX appeared to be little substituted and highly esterified with phenolic acids. In the walls of prismatic cells, AX were found to be highly substituted and poorly esterified. Apart from aleurone and prismatic cells, the substitution degree of AX in endosperm was in the same range. Cells in the crease region were distinguished from cells in the starchy endosperm by their lower amount of esterified phenolic compounds.     

单果真空袋包装处理对冷藏酥梨品质的影响

为提高酥梨冷藏后的品质,将果实经单果真空袋包装后于0～2℃条件下贮藏,分别于包装后的1、2、3和4周后对包装袋进行刺孔,使袋内气体成分几乎与常规空气相同,并继续冷藏至120 d。结果表明,单果真空袋包装前处理能够减缓梨果硬度的下降,抑制腐烂率和失重率的上升,使酥梨含有较高的可溶性固形物和可滴定酸质量分数,能很好地保持果皮绿色,提高了酥梨的贮藏品质,其中最佳的真空袋密封包装前处理时间为2周。与传统冷藏方法相比,该处理能够更好地保持酥梨果实良好的冷藏品质,是一种可行的酥梨果实保鲜处理方法。     

利用冬小麦作物生长模型对产量气候风险的评估

以北京地区冬小麦生产为例，介绍了两种作物生长模型——小麦生长模拟模型WheatSM和农业生产模拟系统(小麦模型)APSIM-Wheat在作物生产气候风险评估中的应用研究。在对WheatSM和APSIM-Wheat进行参数调试和验证的基础上，用北京地区1955～2000年的历史时期气候资料，以日为时间步长，进行多年冬小麦生产的模拟，分析不同气候年型下冬小麦产量的风险。其中，利用WheatSM的模拟结果评估了北京地区热害对冬小麦产量造成的风险，结果表明，5月平均气温≥21℃时为灌浆期高温年型，热害造成的减产至少在13.1%以上；利用APSIM-Wheat的模拟结果评估了北京地区干旱造成的冬小麦产量风险，结果表明，当全生育期降水量<100 mm，缺水量>169.40 mm时，北京冬小麦全生育期严重干旱，冬小麦产量在4 t·hm^-2以下。以上研究结果符合生产实际，可为北京地区不同气候年型下冬小麦生产的动态决策和减轻灾害损失提供科学依据和技术支持。     

基于自然分区的1960—2018年中国气候变化特征

  目的  基于东北不同积温带的差异,探究不同时期深松对春玉米田土壤物理特性和产量的影响。  方法  于2014年在低积温带（齐齐哈尔）、中积温带（洮南）和高积温带（沈阳）开展深松试验。设置秋季30 cm深松（AS）、春季30 cm深松（SS）和常规15 cm旋耕（CT）3个处理,比对分析不同时期深松对土壤含水量、土壤容重、土壤硬度和玉米产量的影响。  结果  深松对不同积温带土壤物理特性改善和产量提升具有积极效果。各处理对土壤水分提高的总体效果为SS > AS > CT,深松对提高低、高积温带吐丝期(R1)、中积温带6叶期（V6）和R1期土壤水分最为显著。SS对改善低积温带和高积温带土壤容重效果明显,低积温带SS与CT相比,在10 ~ 20 cm、20 ~ 40 cm土壤容重分别降低8.23%和11.12%（P < 0.05）;高积温带SS在0 ~ 10 cm、10 ~ 20 cm和20 ~ 40 cm的土壤容重分别较CT低7.28%、5.68%和2.02%。SS对低、高积温带土壤硬度改善效果显著,低积温带SS与CT相比,在0 ~ 10 cm、10 ~ 20 cm和20 ~ 40 cm土壤硬度分别降低32.26%、27.46%和33.77%;高积温带SS在0 ~ 10 cm、10 ~ 20 cm和20 ~ 40 cm土壤硬度分别较CT低9.50%、8.63%和5.29%（P < 0.05）。深松对百粒重影响显著,AS和SS与CT相比,在中、低积温带粒重分别提高2.77%和5.14%、8.48%和8.48%（P < 0.05）。在产量上,AS和SS与CT相比,在低积温带和高积温带分别提高8.57%和11.43%、15.46%和12.37%（P < 0.05）。  结论  深松能显著改善不同积温带土壤物理特性,且提高玉米产量。秋季深松和春季深松对不同积温带土壤水分提升效果明显,春季深松对土壤容重和硬度改善效果在整体上优于秋季深松。从改善土壤物理特性和玉米增产的角度考虑,推荐春季深松为东北地区最佳深松选择。