Restriction of nyctinastic movements and application of tensile forces to leaves affects diurnal patterns of expansion growth

2002 ◽  
Vol 29 (11) ◽  
pp. 1247 ◽  
Author(s):  
Achim Walter ◽  
Regina Feil ◽  
Ulrich Schurr
Keyword(s):  
Ricinus Communis ◽  
Leaf Growth ◽  
Starch Content ◽  
Tensile Force ◽  
Soluble Sugars ◽  
Leaf Expansion ◽  
Leaf Vein ◽  
Tensile Forces ◽  
Biomechanical Forces ◽  
The Impact

Leaves of Ricinus communis L. show strong nyctinastic movements as well as diurnal variations of growth activity, combined with prominent basipetal gradients of relative growth rate. A novel technique, using digital image sequence processing, is able to resolve such spatio–temporal patterns of leaf growth with high resolution. In this paper we analyse the impact of prevention of nyctinastic movements, and the potential of tensile forces to overcome the retarding effects. Tensile forces affected leaf expansion and tissue expansibility in a dose–response relation. In a comparison with freely-growing leaves, an appropriate, optimal tensile force was identified that rebuilt the natural diurnal course of leaf expansion. With this tensile force, undisturbed patterns of temporal and spatial growth distribution as well as undisturbed concentrations of major cations, amino acids or soluble sugars were observed. However, diurnal fluctuations in starch content of almost fully-grown leaves were affected by the treatment and could not be compensated by tensile forces. This effect might point to a connection between diurnal growth variations of the leaf vein, biomechanical forces that synchronize growth within the vein, and metabolism of carbohydrates as growth substrates of the vein. We therefore hypothesize that interveinal tensions, which are produced during nyctinastic leaf movements, are (i) required for undisturbed leaf growth and (ii) can be simulated by application of adequate tensile forces.

scholarly journals Cable Tensile Forces Associated to Winch Design in Tethered Harvesting Operations: A Case Study from the Pacific North West

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 827
Author(s):  
Omar Mologni ◽  
Eric D. T. Nance ◽  
C. Kevin Lyons ◽  
Luca Marchi ◽  
Stefano Grigolato ◽  
...  
Keyword(s):  
Endurance Limit ◽  
Tensile Force ◽  
Force Analysis ◽  
North West ◽  
The Pacific ◽  
Work Tasks ◽  
Tensile Forces ◽  
System Activation ◽  
The Impact

Cable tensile forces in winch-assist harvesting have been investigated in order to assess the safety concerns of the technology. However, the literature is lacking, particularly in regards to the impact of winch design. In this study, a Summit Winch Assist tethering a feller-director on ground slopes up to 77% was monitored for four days. The cable tensile forces were simultaneously recorded at the harvesting and anchor machine at a frequency of 100 Hz. Cameras and GNSS devices enabled a time study of the operations and the recording of machine positions. Winch functionality and design were disclosed by the manufacturer and used for the interpretation of the results. The cable tensile forces reached 296 kN at the harvesting machine and 260 kN at the anchor machine. The slow negotiation of obstacles while moving downhill recorded the highest peaks, mainly due to threshold settings of the winch in the brake system activation. Lower but significant peaks were also recorded during stationary work tasks. The peaks, however, were limited to a few events and never exceeded the endurance limit of the cable. Overall, the study confirmed recent findings in cable tensile force analysis of active winch-assist operations and provided evidence of the underlaying mechanisms that contribute to cable tensile forces.

scholarly journals Determination of the Impact of Weft Density on Fabric Dynamic Thickness under Tensile Forces

2019 ◽  
Vol 27 (6(138)) ◽  
pp. 46-53
Author(s):  
Željko Penava ◽  
Diana Šimić Penava ◽  
Željko Knezić
Keyword(s):  
Axial Strain ◽  
Tensile Force ◽  
Woven Fabric ◽  
Uniaxial Tensile ◽  
Measuring Apparatus ◽  
Thickness Change ◽  
Fabric Thickness ◽  
Axial Forces ◽  
Tensile Forces ◽  
The Impact

This paper deals with the impact of fabric density on fabric thickness change when samples are subjected to uniaxial tensile forces in the weft direction. During stretching, fabric thickness changes depending on the value of the tensile force. In an effort to be as precise as possible in measuring fabric dynamic thickness changes and the area on which the tensile force acts, a new measuring apparatus was designed and constructed. This measuring apparatus allows the simultaneous measurement of fabric dynamic thickness, related tensile axial forces and extension. Measurements of the fabric dynamic thickness, breaking force and breaking extension during the stretching process were carried out on five samples of cotton woven fabric with a constant warp density and different weft densities in the same structural plain weave. Based on the experimentally obtained values, the paper presents diagrams of the relationship between dynamic changes in fabric thickness in relation to the tensile force and extension. The research presented in this paper shows that an increase in the tensile force increases fabric thickness for all weft densities. Also, the out-of-plane woven fabric ratio was calculated as a relation between the relative thickness strain and relative axial strain. The characteristic curve shows this ratio.

Investigation of Workpiece Distortion During the Photopolymerization of a PAAW Joint

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Kristopher R. Doll ◽  
Edward C. De Meter
Keyword(s):  
Residual Stresses ◽  
Adhesive Joint ◽  
Load Capacity ◽  
Tensile Force ◽  
Empirical Models ◽  
Thickness Reduction ◽  
Joint Thickness ◽  
A Value ◽  
Tensile Forces ◽  
The Impact

As a workpiece is bonded to a photo-activated adhesive workholding (PAAW) fixture, the adhesive shrinks during photopolymerization. This leads to the buildup of residual stresses that may distort the workpiece or reduce the external load capacity of the adhesive joints. This research quantifies the impact of adhesive shrinkage on fractional thickness reduction and residual tensile force for a commercially available adhesive and gripper. These variables are quantified for typical ranges of adhesive joint thickness and workpiece interface stiffness. Empirical models are presented for relating these variables. This research reveals that once photopolymerization ceases, workpiece distortion and residual stresses are permanent, and are not diminished by adhesive stress relaxation. It also reveals that the fractional thickness reduction of a PAAW joint can range from close to zero to a value equivalent to the fractional volumetric shrinkage of the adhesive. Furthermore, it decreases with increasing workpiece interface stiffness and increasing adhesive joint thickness following a power law relationship. It is believed that necking within the adhesive joint has a significant influence on this relationship. For stiff workpiece interfaces, residual tensile forces can grow larger than 25% of the tensile break strength of an adhesive joint formed without restraint.

Seasonal Nonstructural Carbohydrate Patterns in Dewberry (Rubus spp.) Roots

Weed Science ◽  
2021 ◽  
pp. 1-23
Author(s):  
Katherine M. Ghantous ◽  
Hilary A. Sandler
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
Soluble Sugars ◽  
Leaf Expansion ◽  
Control Measures ◽  
Growth Stages ◽  
Phenological Stages ◽  
Long Term Storage ◽  
Nonstructural Carbohydrate ◽  
Fruit Maturity

Abstract Applying control measures when carbohydrate levels are low can decrease the likelihood of plant survival, but little is known about the carbohydrate cycles of dewberry (Rubus spp.), a problematic weed group on cranberry farms. Weedy Rubus plants were collected from areas adjacent to production beds on commercial cranberry farms in Massachusetts, two locations per year for two years. For each site and year, four entire plants were collected at five phenological stages: budbreak, full leaf expansion, flowering, fruit maturity, and after onset of dormancy. Root sections were analyzed for total nonstructural carbohydrate (TNC; starch, sucrose, fructose, and glucose). Overall trends for all sites and years showed TNC were lowest at full leaf expansion or flowering; when sampled at dormancy, TNC concentrations were greater than or equal to those measured at budbreak. Starch, a carbohydrate form associated with long-term storage, had low levels at budbreak, leaf expansion and/or flowering with a significant increase at fruit maturity and the onset of dormancy, ending at levels higher than those found at budbreak. The concentration of soluble sugars, carbohydrate forms readily usable by plants, was highest at budbreak compared to the other four phenological samplings. Overall, our findings supported the hypothesis that TNC levels within the roots of weedy Rubus plants can be predicted based on different phenological growth stages in Massachusetts. However, recommendations for timing management practices cannot be based on TNC cycles alone; other factors such as temporal proximity to dormancy may also impact Rubus plants recovery and further research is warranted. Late-season damage should allow less time for plants to replenish carbohydrate reserves (prior to the onset of dormancy), thereby likely enhancing weed management tactics effectiveness over time. Future studies should consider tracking the relationship between environmental conditions, phenological stages, and carbohydrate trends.

The effect of long-term fertilization on forage crop productivity and quality in the North

2020 ◽  
Author(s):  
Н.Т. Чеботарёв ◽  
Н.Н. Шергина
Keyword(s):  
Crop Rotation ◽  
Starch Content ◽  
Crop Productivity ◽  
Komi Republic ◽  
Perennial Grasses ◽  
Organic Fertilizers ◽  
Nitrate Content ◽  
Mineral Fertilizers ◽  
Forage Crop ◽  
The Impact

В условиях Республики Коми в полевом стационарном опыте на дерново-подзолистой легкосуглинистой почве изучена эффективность различных доз органических и минеральных удобрений, а также совместного их применения. Исследования проводили в 1978–2019 годах на опытных полях Института агробиотехнологий ФИЦ Коми НЦ УрО РАН. Целью проводимых исследований было изучение влияния комплексного применения удобрений на продуктивность и качество кормовых культур в шестипольном севообороте. Кормовой севооборот имел следующее чередование культур: картофель, викоовсяная смесь с подсевом многолетних трав, многолетние травы 1 г.п., многолетние травы 2 г.п., викоовсяная смесь, картофель. В результате научных исследований (более 40 лет) установлено, что наиболее эффективной была органоминеральная система удобрений, особенно при внесении 80 т/га торфонавозного компоста (ТНК) и минеральных удобрений. Многолетние исследования показали, что наиболее значительные урожаи кормовых культур (в среднем за три ротации) получены при использовании 80 т/га ТНК и NPK: однолетних трав — 4,4 т/га; многолетних трав — 6,2 и картофеля — 7,1 т/га сухого вещества высокого качества. Содержание сухого вещества в клубнях картофеля в вариантах с NPK составило 18,0–18,8%, на органическом фоне — 18,4–18,9 и при комплексном применении удобрений — 17,1–17,7; в контроле — 19,6%. Количество крахмала в картофеле незначительно различалось по вариантам опыта и равнялось 12,6–13,1%. Содержание нитратов не превышало ПДК (250 мг/кг сырой массы). Количество сухого вещества в однолетних и многолетних травах изменялось незначительно и составляло 19,0–19,8 и 25,0–26,8% соответственно. Установлено, что удобрения способствовали повышению содержания сырого протеина в однолетних и многолетних травах до 13,1–15,0% (в контроле — 11,2%) и 8,8–10,6 % (в контроле — 8,1%) соответственно. The impact of various rates of organic and mineral fertilizers was analyzed in the Komi Republic on sod-podzolic soil with low loam content. The research took place at the Institute of Agricultural Biotechnology in 1978–2019. The goal was to test forage crop productivity and quality under fertilization and six-field crop rotation. Crop rotation happened as follows: potatoes, vetch-oat mixture overseeded by perennial grasses, first-year perennial grasses, second-year perennial grasses, vetch-oat mixture, potatoes. For 40 years the combination of mineral and organic fertilizers was the most effective. The highest yields for three rotations were observed under the application of 80 t ha-1 of peat-manure compost and NPK: annual grasses produced 4.4 t ha-1; perennial grasses — 6.2, and potatoes — 7.1 t ha-1 of high-quality dry matter (DM). Potato tubers accumulated 18.0–18.8% of DM under NPK application, 18.4–18.9 — under organic nutrition, 17.1–17.7 — when using complex fertilization, and 19.6% — in the control. Starch content varied within 12.6–13.1% in potatoes. Nitrate content did not exceed the maximum acceptable concentration (250 mg/kg of raw mass). DM concentrations amounted to 19.0–19.8 and 25.0–26.8% in annual and perennial grasses, respectively. Fertilization increased crude protein amount in annual and perennial grasses up to 13.1–15.0% (versus 11.2% in the control) and 8.8–10.6 % (versus 8.1%), respectively.

scholarly journals Primary metabolite mobilization during germination in rosewood (Aniba rosaeodora Ducke) seeds

2008 ◽  
Vol 32 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Renata Braga Souza Lima ◽  
José Francisco de Carvalho Gonçalves ◽  
Silvana Cristina Pando ◽  
Andréia Varmes Fernandes ◽  
André Luis Wendt dos Santos
Keyword(s):  
Seed Germination ◽  
Amylase Activity ◽  
Starch Content ◽  
Initial Period ◽  
Soluble Sugar ◽  
Soluble Sugars ◽  
Alpha Amylase ◽  
Primary Metabolite ◽  
Radicle Growth ◽  
Starch Mobilization

This study aimed to characterize protein, oil, starch and soluble sugar mobilization as well as the activity of alpha-amylase during rosewood seed germination. Germination test was carried out at 25°C and the following parameters were analyzed: percentage of germination, initial, average, and final germination time. Seed reserve quantification was monitored in quiescent seeds and during different stages of radicle growth. Starch mobilization was studied in function of a-amylase activity. Germination reached 87.5% at the initial, average, and final time of 16, 21 and 30 days, respectively. Oil mobilization showed a negative linear behavior, decreasing 40% between the first and the last stage analyzed, whereas protein levels increased 34.7% during the initial period of germination. Starch content (46.4%) was the highest among those of the metabolites analyzed and starch mobilization occurred inversely to the observed for soluble sugars; alpha-amylase activity increased until the 15th day, a period before radicle emission and corresponding to the highest starch mobilization. The high percentage of rosewood seed germination may be related to the controlled condition used in the germination chamber as well as to high seed reserve mobilization, in special oil and starch.

scholarly journals Falling weight impact test of a new-type flexible rock-shed

2018 ◽  
Vol 38 (2) ◽  
pp. 242-252
Author(s):  
Jianrong Yang ◽  
Zhiyu Zhang
Keyword(s):  
Experimental Studies ◽  
Steel Tube ◽  
Time Interval ◽  
Explicit Finite Element ◽  
Numerical Studies ◽  
Structural Details ◽  
Tensile Forces ◽  
New Type ◽  
Falling Weight ◽  
The Impact

A new concept of a flexible rock-shed is presented for protection of the railway from falling rocks. The flexible rock-shed is made of flexible nets connected by specific spring spacer bars to an array of reinforced concrete portable frames which are linked by a longitudinal steel tube truss. To evaluate the performance of the flexible rock-shed, experimental and numerical studies are carried out in the present study. Impact tests are conducted on a full-scale partial model of the prototype structure when it is subjected to a falling block of 340 kg. The impact time interval, maximum deflection of the flexible net, tensile forces in the supporting ropes, and axial strains of spring spacer bars are recorded. To further examine the dynamic behavior of the flexible rock-shed, numerical simulations are also carried out by using the explicit finite element code ANSYS/LS-DYNA. It is found that the numerical results coincide well with the experimental data and both the numerical and experimental studies reveal that the structure can withstand impact energy of 50 kJ with all the materials working in the elastic range. The structural details are improved and the basis for the design and construction of similar structures in the future is provided.<br>

scholarly journals Dynamics of Polysaccharides and Neutral Lipids during Anther Development in Castor (Ricinus communis)

2015 ◽  
Vol 140 (4) ◽  
pp. 356-361 ◽  
Author(s):  
Dongmei Wei ◽  
Huimin Xu ◽  
Ruili Li
Keyword(s):  
Neutral Lipids ◽  
Ricinus Communis ◽  
Starch Content ◽  
Single Layer ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Tapetal Cells

Anthers contain starch and neutral lipids, which have key roles in microspore ontogeny and gametophyte development. In this study, we observed the dynamic changes in starch and neutral lipids in the anther developmental processes of castor (Ricinus communis) by cytochemical methods. Starch grains and neutral lipids presented a regular dynamic distribution during anther development. In young anthers, some neutral lipids accumulated in sporogenous cells, whereas neutral lipids disappeared with microspore growth. At the late microspore stage, starch grains began to accumulate in microspores, and the starch content of bicellular pollen significantly increased after microspore mitosis. At anthesis, starch grains and neutral lipids accumulated in the mature pollen grains. Visible changes occurred in anther wall cells. The epidermis, middle layer, and tapetum were degenerated, and only a single layer of endothecium remained at anthesis. The dynamic variation of starch grains and neutral lipids in tapetal cells was consistent with the changes in microspores and pollen during anther development. All these findings demonstrated that tapetal cells directly interacted with the developing gametophytes. The tapetal cells play an important role in supplying nutritional substances for microspore absorption. Moreover, the endothecium protects the pollen and contributes to anther dehiscence. The results of this study provide a foundation for the further research on sexual reproduction in angiosperms.

scholarly journals Monitoring the Impact of Electromagnetic Waves on Yield and Quality in Maize

2011 ◽  
Vol 68 (1) ◽  
Author(s):  
Florin IMBREA ◽  
Branko MARINCOVIC ◽  
Valeriu TABĂRĂ ◽  
PAUL PÎRŞAN ◽  
Gheorghe DAVID ◽  
...  
Keyword(s):  
Protein Content ◽  
Quality Indicators ◽  
Electromagnetic Waves ◽  
Starch Content ◽  
New Technology ◽  
Low Frequency ◽  
Cultivation Method ◽  
Yield And Quality ◽  
The Impact ◽  
Starch Yield

Experimenting new technology of cultivating maize is an important step forward in order to optimise the yielding capacity if a crop that ranks second among crops cultivated worldwide and first among crops cultivated in Romania. Using low frequency radiations to stimulate yield and quality in maize allows increases in yield between 10 and 15% compared to the classical cultivation method and an improvement of the quality indicators (protein content increased with 6-11% determining an increase of the protein yield per ha; starch content increased with 7-14%, which also determined an increase of the starch yield per ha; while fat content, another indicator we monitored, increased with 2-6%).

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