scholarly journals Plant composition and species relations on the Huntingdon Marsh, Quebec

1973 ◽  
Vol 51 (6) ◽  
pp. 1231-1247 ◽  
Author(s):  
Allan N. Auclair ◽  
André Bouchard ◽  
Josephine Pajaczkowski
Keyword(s):  
Water Depth ◽  
Plant Biomass ◽  
Dry Weight ◽  
Weight Basis ◽  
Species Variation ◽  
Species Relationships ◽  
Sedge Meadow ◽  
Calamagrostis Canadensis ◽  
Meadow Communities ◽  
Eleocharis Palustris

The purpose of this study was to identify significant species relationships and underlying ecological gradients characteristic of the Huntingdon Marsh, Quebec. In 1970, one hundred and seven 1-m2 samples of plant biomass were obtained from the marsh in conjunction with environmental measurements. These data were later analyzed using principal-components analysis.The marsh complex divided unambiguously into emergent aquatic and sedge meadow communities on the basis of distinct environmental and compositional differences. Equisetum fluviatile, Scirpus fluviatilis, Eleocharis palustris, and Scirpus validus were major species in the emergent aquatic community. Respectively, these species dominated 29, 25, 16, and 14% of 51 quadrats on a dry weight basis. Water depth accounted for almost one-third of the species variation in this community. Interaction between submerged and floating forms and competitive exclusion between dominant species explained much of the remaining species variance.On a dry weight basis, Carex aquatilis, C. lacustris, Calamagrostis canadensis, and Typha angustifolia dominated 36, 16, 16, and 11% of the 56 quadrats on the sedge meadow. As a group, Carex spp. dominated 63% of the quadrats. Disturbance related to chance perturbations, water depth, and the incidence of fire accounted for much of the variation in this community.The organization of emergent and sedge meadow communities was discussed in relation to continuum and community concepts with particular reference to relative changes in discontinuity of species relationships across the environmental gradient.

Time-course accumulation of flavonoids in hydroponically grown Achillea millefolium L.

2014 ◽  
Vol 94 (2) ◽  
pp. 383-395 ◽  
Author(s):  
Karine Pedneault ◽  
Martine Dorais ◽  
Sébastien Léonhart ◽  
Paul Angers ◽  
André Gosselin
Keyword(s):  
Time Course ◽  
Plant Biomass ◽  
Dry Weight ◽  
Hydroponic Culture ◽  
Weight Basis ◽  
Early Flowering ◽  
Achillea Millefolium ◽  
Phenological Stage ◽  
Stage 4 ◽  
Hydroponically Grown

Pedneault, K., Dorais, M., Léonhart, S., Angers, P. and Gosselin, A. 2014. Time-course accumulation of flavonoids in hydroponically grown Achillea millefolium L. Can. J. Plant. Sci. 94: 383–395. In recent decades, the use of plant-based medicines as health products has increased considerably all over the world. As greenhouse hydroponic culture allows standardized cultural methods to be used, it may be valuable for reducing the risks associated with harvesting medicinal plants from the wild, such as species dissemination, species misidentification, adulteration, and non-hygienic handling, while allowing the production of high yields of clean, standardized biomass year-round. To evaluate the potential of hydroponic culture for medicinal plant production, the present study investigated the accumulation patterns of apigenin, luteolin, apigenin glycosides, and the chlorogenic acid 5-caffeoylquinic acid in the plant organs of A. millefolium at five phenological stages from 35 to 102 d after sowing, and drew a comparison with outdoor-grown plants at 122 d after sowing. The results showed two flavonoid accumulation peaks: one at the early growth stage (35 d after sowing) and one at early flowering (87 d after sowing). At 87 d after sowing, most of the apigenin glycosides were concentrated in the roots (3.80% wt/wt, dry weight basis), whereas free apigenin and luteolin were located mainly in the flower heads (1.25 and 0.86% wt/wt, dry weight basis, respectively). Early flowering was the best harvesting stage for optimal flavonoid production in terms of active compounds per plant and kilograms of plant biomass per cultivated area. At 122 d after sowing (phenological stage 4), the outdoor-grown plants were nine times smaller than the early flowering plants (87 d after sowing) from the hydroponic system and had a root-tissue apigenin glycoside level that was five times lower than that of the hydroponically grown plants. In conclusion, the use of a hydroponic growing system reduced by 29% the time required to reach phenological stage 4, which corresponds to maximum plant bioactive concentration, in comparison with field production. Therefore, hydroponic culture represents an effective alternative to outdoor production and can result in standardized, high-quality medicinal plant biomass with potential flavonoid yields approximating 515 mg per plant.

ERRORS ASSOCIATED WITH HERBAGE DISSECTION ANALYSES 2. Problems of species identification

1976 ◽  
pp. 213-225
Author(s):  
I.M. Ritchie ◽  
C.C. Boswell ◽  
A.M. Badland
Keyword(s):  
New Zealand ◽  
Dry Weight ◽  
Analytical Tool ◽  
Species Level ◽  
Weight Basis ◽  
Plant Identification ◽  
Leaf Fragment ◽  
Research Division ◽  
Or Groups ◽  
Botanical Analysis

HERBACE DISSECTION is the process in which samples of herbage cut from trials are separated by hand into component species. Heavy reliance is placed on herbage dissection as an analytical tool ,in New Zealand, and in the four botanical analysis laboratories in the Research Division of the Ministry of Agriculture and Fisheries about 20 000 samples are analysed each year. In the laboratory a representative subsample is taken by a rigorous quartering procedure until approximately 400 pieces of herbage remain. Each leaf fragment is then identified to species level or groups of these as appropriate. The fractions are then dried and the composition calculated on a percentage dry weight basis. The accuracy of the analyses of these laboratories has been monitored by a system of interchanging herbage dissection samples between them. From this, the need to separate subsampling errors from problems of plant identification was, appreciated and some of this work is described here.

Evaluation of Nurse Crops for Weed Control and Plant Establishment in Prairie Restoration

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 485b-485
Author(s):  
Lisa M. Barry ◽  
Michael N. Dana
Keyword(s):  
Plant Biomass ◽  
Spring Barley ◽  
Dry Weight ◽  
Site Quality ◽  
Prairie Restoration ◽  
Plant Establishment ◽  
Significant Difference ◽  
Nurse Crops ◽  
Partridge Pea ◽  
Prairie Plant

Nurse crops are often recommended in prairie restoration planting. This work investigated several alternative nurse crops to determine their utility in prairie planting. Nurse crops were composed of increasing densities (900, 1800, or 2700 seeds/m2) of partridge pea, spring oats, spring barley, Canada wild rye, or equal mixtures of partridge pea and one of the grasses. The experimental design was a randomized complete-block set in two sites with three blocks per site and 48 treatments per block. Each 3 × 3-m plot contained 1 m2 planted in Dec. 1995 or Mar. 1996 with an equal mix of seven prairie species. The nurse crops were sown over each nine square meter area in April 1996. Plots lacking nurse crops served as controls. Evaluated data consisted of weed pressure rankings and weed and prairie plant dry weight. Nurse crop treatments had a significant effect on weed pressure in both sites. Barley (1800 and 2700 seeds/m2) as well as partridge pea + barley (2700 seeds/m2) were most effective at reducing weed pressure. When weed and prairie plant biomass values were compared, a significant difference was observed for site quality and planting season. Prairie plant establishment was significantly greater in the poorly drained, less-fertile site and spring-sown plots in both sites had significantly higher prairie biomass values. Overall, after two seasons, there was no advantage in using nurse crops over the control. Among nurse crop treatments, oats were most effective in reducing weed competition and enhancing prairie plant growth.

Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the Brisbane River (Australia) – Preliminary Results

1989 ◽  
Vol 21 (2) ◽  
pp. 161-165 ◽  
Author(s):  
S. I. Kayal ◽  
D. W. Connell
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
River Estuary ◽  
Dry Weight ◽  
Weight Basis ◽  
Sediment Samples ◽  
Preliminary Results ◽  
Treated Sewage ◽  
Polycyclic Aromatic ◽  
Petroleum Refineries

Results of the analysis of twenty-three composite sediment samples revealed that PAHs are widely distributed in the Brisbane River estuary. Mean concentrations for individual compounds, on a dry weight basis, ranged from 0.03 µg/g for dibenz [ah] anthracene to 2.34 µg/g for fluoranthene. Observed PAH assemblages were rich in compounds having pyrolytic origins. However, the presence of petroleum derived compounds was indicative of the importance of petroleum as a PAH source in the estuary. Petroleum refineries, a coal loading terminal and a major treated sewage outfall located at the mouth were not indicated as major contributing sources of PAH pollution in the estuary.

Mineral nutrition, dinitrogen fixation, and growth of Alnuscrispa and Alnusglutinosa

1985 ◽  
Vol 15 (5) ◽  
pp. 855-861 ◽  
Author(s):  
G. Prégent ◽  
C. Camiré
Keyword(s):  
Mineral Nutrition ◽  
Dry Weight ◽  
Optimal Growth ◽  
Maximum Growth ◽  
Dinitrogen Fixation ◽  
Weight Basis ◽  
Critical Levels ◽  
N Status

Invitro cultures of Alnuscrispa (Ait.) Pursh and Alnusglutinosa (L.) Gaertn. were used to estimate critical foliage levels of selected nutrients for optimal growth and dinitrogen (N2) fixation. For A. crispa to obtain 90% of maximum growth and N2 fixation, foliar levels of 0.12% P, 0.13% Mg, <0.31% K, and <0.04% Ca on a dry weight basis were needed. For A. glutinosa, the critical levels were 0.138% P, 0.10% Mg, 0.29% Ca, and ~0.20% K. From all the deficiencies observed, P had the more pronounced effects on N status of both species.

SOLUBLE SUGAR CHANGES OCCURRING DURING COLD HARDENING OF SPRING WHEAT, FALL RYE AND ALFALFA

1983 ◽  
Vol 63 (2) ◽  
pp. 415-420 ◽  
Author(s):  
D. G. GREEN
Keyword(s):  
Spring Wheat ◽  
Soluble Sugar ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Weight Basis ◽  
Cold Hardening ◽  
Spring Type

Alfa, a relatively nonhardy alfalfa cultivar continued to accumulate, on a dry weight basis, fructose, α- and β-D-glucose, sucrose and maltose during the latter stages of cold hardening. Rambler, a hardier alfalfa cultivar conversely showed a decrease for these soluble sugars with hardening. Frontier rye, a very hardy winter habit cereal showed decreases in these soluble sugars plus melibiose during the same hardening period. These results support the hypothesis that hardy cereals and alfalfa undergo a decrease in soluble sugars with hardening, while less hardy cereals and alfalfa continue to increase in content of soluble sugars. Manitou wheat appeared not to fit this hypothesis and showed the decreased soluble sugars usually associated with hardy cultivars. Although Manitou is a spring type wheat, one of its parents, Thatcher, does contain gene(s) for the winter habit.Key words: Sugar, cold hardening, wheat, rye, alfalfa

scholarly journals THE MOLECULAR WEIGHT OF RHODOPSIN AND THE NATURE OF THE RHODOPSIN-DIGITONIN COMPLEX

1954 ◽  
Vol 37 (3) ◽  
pp. 381-399 ◽  
Author(s):  
Ruth Hubbard
Keyword(s):  
Molecular Weight ◽  
Single Molecule ◽  
Extinction Coefficient ◽  
Dry Weight ◽  
Weight Basis ◽  
Sedimentation Behavior ◽  
A Value ◽  
Wet Weight ◽  
Single Boundary ◽  
Stoichiometric Complex

The sedimentation behavior of aqueous solutions of digitonin and of cattle rhodopsin in digitonin has been examined in the ultracentrifuge. In confirmation of earlier work, digitonin was found to sediment as a micelle (D-1) with an s20 of about 6.35 Svedberg units, and containing at least 60 molecules. The rhodopsin solutions sediment as a stoichiometric complex of rhodopsin with digitonin (RD-1) with an s20 of about 9.77 Svedberg units. The s20 of the RD-1 micelle is constant between pH 6.3 and 9.6, and in the presence of excess digitonin. RD-1 travels as a single boundary also in the electrophoresis apparatus at pH 8.5, and on filter paper at pH 8.0. The molecular weight of the RD-1 micelle lies between 260,000 and 290,000. Of this, only about 40,000 gm. are due to rhodopsin; the rest is digitonin (180 to 200 moles). Comparison of the relative concentrations of RD-1 and retinene in solutions of rhodopsin-digitonin shows that RD-1 contains only one retinene equivalent. It can therefore contain only one molecule of rhodopsin with a molecular weight of about 40,000. Cattle rhodopsin therefore contains only one chromophore consisting of a single molecule of retinene. It is likely that frog rhodopsin has a similar molecular weight and also contains only one chromophore per molecule. The molar extinction coefficient of rhodopsin is therefore identical with the extinction coefficient per mole of retinene (40,600 cm.2 per mole) and the E(1 per cent, 1 cm., 500 mµ) has a value of about 10. Rhodopsin constitutes about 14 per cent of the dry weight, and 3.7 per cent of the wet weight of cattle outer limbs. This corresponds to about 4.2 x 106 molecules of rhodopsin per outer limb. The rhodopsin content of frog outer limbs is considerably higher: about 35 per cent of the dry weight, and 10 per cent of the wet weight, corresponding to about 2.1 x 109 molecules per outer limb. Thus the frog outer limb contains about five hundred times as much rhodopsin as the cattle outer limb. But the relative volumes of these structures are such that the ratio of concentrations is only about 2.5 to 1 on a weight basis. Rhodopsin accounts for at least one-fifth of the total protein of the cattle outer limb; for the frog, this value must be higher. The extinction (K500) along its axis is about 0.037 cm.2 for the cattle outer limb, and about 0.50 cm.2 for the frog outer limb.

Influence of Temperature and Water Activity on Aflatoxin Production by Aspergillus flavus in Cowpea (Vigna unguiculata) Seeds and Meal

1985 ◽  
Vol 48 (12) ◽  
pp. 1040-1043 ◽  
Author(s):  
P. E. KOEHLER ◽  
L. R. BEUCHAT ◽  
M. S. CHHINNAN
Keyword(s):  
Heat Treatment ◽  
Water Activity ◽  
Aspergillus Flavus ◽  
Vigna Unguiculata ◽  
Dry Weight ◽  
Aflatoxin Production ◽  
Weight Basis ◽  
Influence Of Temperature

Experiments were done to determine the influence of temperature (21, 30 and 37°C) and aw (0.76 to 0.98) on aflatoxin production by Aspergillus flavus on cowpea (Vigna unguiculata) seeds, meal and meal supplemented with onion. Larger quantities of aflatoxin were produced at 21 and 30°C than at 37°C. The highest amount of aflatoxin (2777 μg/20 g, dry weight basis) was observed in meal containing onion at aw 0.98 after 20 d of incubation at 21°C. A level of 870 |μg/20 g was detected in seeds at aw 0.95 after 14 d of incubation at 30°C. Meal at aw 0.96 supported production of 551 μg of aflatoxin per 20 g after 20 d at 30° C. Temperature had little influence on the optimal aw for aflatoxin production in cowpea meal. However, an increase in temperature resulted in a decreased optimal aw for aflatoxin production on whole cowpeas. When known quantities of aflatoxin were added to cowpea meal which was subsequently steamed for 5 min, only 29% was extractable using a variety of procedures, indicating that the toxin may be bound in some manner to cowpea constituents as a result of heat treatment.

Low K+ in Paphiopedilum leeanum leaf epidermis: implications for stomatal functioning

1977 ◽  
Vol 55 (4) ◽  
pp. 489-495 ◽  
Author(s):  
Sherman D. Nelson ◽  
James M. Mayo
Keyword(s):  
Dry Weight ◽  
Atomic Absorption Spectrophotometry ◽  
Weight Basis ◽  
Leaf Epidermis ◽  
Photometric Analysis ◽  
Abaxial Epidermis ◽  
Absorption Spectrophotometry ◽  
Stomatal Functioning ◽  
Low K ◽  
Stomatal Mechanism

Abaxial epidermal strips from leaves of Paphiopedilum leeanum were analyzed via sodium cobaltinitrite staining and atomic absorption spectrophotometry for the presence and location of potassium. On a dry weight basis K content of the abaxial epidermis was found to be 103 times less than has been reported in other species, and unlike other species no localization of K+ in guard cells of open stomata could be detected via the sodium cobaltinitrite stain for potassium.Flame photometric analysis of the mesophyll indicated that it contained normal amounts of K+ (about 1.87% on a dry weight basis). Analysis showed that the K+ content of the abaxial epidermis (0.032%) was considerably less than that of the mesophyll, a situation unlike previous reports for other species in which the epidermal concentration was found to be greater than the mesophyll. A process for exclusion of K+ from the abaxial epidermis is suggested, as is the lack of involvement of K+ as the major osmoticum in the stomatal mechanism of this species.

scholarly journals Responses of Tomato to Potassium Rates in a Calcareous Soil

HortScience ◽  
2017 ◽  
Vol 52 (5) ◽  
pp. 764-769 ◽  
Author(s):  
Qiang Zhu ◽  
Monica Ozores-Hampton ◽  
Yuncong Li ◽  
Kelly Morgan ◽  
Guodong Liu ◽  
...  
Keyword(s):  
Calcareous Soil ◽  
Plant Biomass ◽  
Winter Season ◽  
Calcareous Soils ◽  
Leaf Tissue ◽  
Dry Weight ◽  
The United States ◽  
Ammonium Bicarbonate ◽  
Soluble Solids ◽  
Postharvest Quality

Florida produces the most vegetables in the United States during the winter season with favorable weather conditions. However, vegetables grown on calcareous soils in Florida have no potassium (K) fertilizer recommendation. The objective of this study was to evaluate the effects of K rates on leaf tissue K concentration (LTKC), plant biomass, fruit yield, and postharvest quality of tomatoes (Solanum lycopersicum L.) grown on a calcareous soil. The experiment was conducted during the winter seasons of 2014 and 2015 in Homestead, FL. Potassium fertilizers were applied at rates of 0, 56, 93, 149, 186, and 223 kg·ha−1 of K and divided into preplant dry fertilizer and fertigation during the season. No deficiency of LTKC was found at 30 days after transplanting (DAT) in both years. Potassium rates lower than 149 kg·ha−1 resulted in deficient LTKC at 95 DAT in 2014. No significant responses to K rates were observed in plant (leaf, stem, and root combined) dry weight biomass at all the sampling dates in both years. However, at 95 DAT, fruit dry weight biomass increased with increasing K rates to 130 and 147 kg·ha−1, reaching a plateau thereafter indicated by the linear-plateau models in 2014 and 2015, respectively. Predicted from quadratic and linear-plateau models, K rates of 173 and 178 kg·ha−1 were considered as the optimum rates for total season marketable yields in 2014 and 2015, respectively. Postharvest qualities, including fruit firmness, pH, and total soluble solids (TSS) content, were not significantly affected by K rates in both years. Overall, K rate of 178 kg·ha−1 was sufficient to grow tomato during the winter season in calcareous soils with 78 to 82 mg·kg−1 of ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extracted K in Florida.

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