Reproductive ecology of Ochetophila trinervis in Northwest Patagonia

2011 ◽  
Vol 38 (9) ◽  
pp. 720 ◽  
Author(s):  
M. Fernanda Reyes ◽  
Miriam E. Gobbi ◽  
Eugenia E. Chaia
Keyword(s):  
Reproductive Ecology ◽  
Field Studies ◽  
Plant Size ◽  
Rainfall Gradient ◽  
Dry Land ◽  
North West ◽  
Seed Biology ◽  
Ochetophila Trinervis ◽  
Actinorhizal Species ◽  
Discaria Trinervis

Native actinorhizal species Ochetophila trinervis (Gillies ex Hook. & Arn.) Poepp. ex Miers, also known as Discaria trinervis (Kellermann et al. 2005), grows along watercourses and distant from them, along a rainfall gradient in north-west Patagonia. We studied the reproductive ecology of this species under different macro- and micro-environmental conditions, in three zones in a rainfall gradient (western, intermediate and eastern) with two sites for each one, near and distant to a watercourse (riparian and dry-land). We performed field studies and germination trials. Plant size, reproductive effort (seed abundance per branch) and seed bank size of O. trinervis, were favoured by the proximity of streams in the drier environments of the gradient. The abundance of seedlings and saplings in the field was very low, which was in agreement with a lack of germination in the field, despite the good germination capacity of seeds. Sexual reproduction of O. trinervis was affected by the low abundance of seedlings. Lower rainfall, higher temperatures and a longer growing season along the gradient favour the potential regeneration of the species. Because of its nitrogen-fixing capacity and other features, O. trinervis has potential for reclamation of eroded lands in Patagonia. Patterns of seed biology and regeneration presented in this study will aid in the use of O. trinervis in the reclamation of disturbed lands.

Temperature affects the dormancy and germination of sympatric annual (Oryza meridionalis) and perennial (O. rufipogon) native Australian rices (Poaceae) and influences their emergence in introduced para grass (Urochloa mutica) swards

2015 ◽  
Vol 63 (8) ◽  
pp. 687 ◽  
Author(s):  
Sean M. Bellairs ◽  
Penelope A. S. Wurm ◽  
Beckie Kernich
Keyword(s):  
Soil Surface ◽  
Field Studies ◽  
Oryza Rufipogon ◽  
Oryza Species ◽  
Northern Australia ◽  
Seed Biology ◽  
Oryza Meridionalis ◽  
Native Grasslands ◽  
Wild Rice Species ◽  
Soil Temperatures

The seed biology of two ecologically and genetically important sympatric wild rice species from northern Australia was compared – perennial Oryza rufipogon Griff. and annual Oryza meridionalis N.Q.Ng. The aim was to determine mechanisms of dormancy exhibited at seed shed and to identify factors that trigger or inhibit germination. This information was used to investigate the ecology of in situ Oryza populations in introduced para grass swards (Urochloa mutica (Forssk.) T.Q. Nguyen) and to understand interactions between the two sympatric Oryza species. Primary dormancy in the two species is similar, namely, non-deep physiological dormancy, determined by external maternal structures and broken by warm temperature treatments equivalent to dry season soil temperatures. Light quality, smoke water, gibberellic acid and nitric acid treatments had minor influences on germination. Changes to the soil profile and aboveground biomass structure due to swards of U. mutica significantly affected emergence of O. meridionalis. Thus the influence of soil temperature explains the results of previous field studies in which biomass or litter on the soil surface prevented germination. This has implications for biodiversity management on monsoonal floodplains of northern Australia, where introduced pasture species produce greater biomass than native grasslands, reduce soil temperatures and are displacing native rices. There were differences between the Oryza species – dormancy was more quickly broken in annual O. meridionalis, reflecting the reduced need for investment in seed bank persistence for annual species in annually inundated and climatically reliable wetlands.

Study on Energy Exchange of Dry-Land Spring Maize Field in Loess Plateau

2013 ◽  
Vol 726-731 ◽  
pp. 3771-3779
Author(s):  
Jia Xuan Guo ◽  
Xu Rong Mei ◽  
Yu Zhong Li
Keyword(s):  
Loess Plateau ◽  
Energy Exchange ◽  
Growth Period ◽  
Bowen Ratio ◽  
Heat Consumption ◽  
Field Energy ◽  
Growth Stages ◽  
Dry Land ◽  
North West ◽  
Spring Maize

Dry-land spring maize is a main cultivated crop in North-West China. To explore the mechanism for changes of evapotranspiration and heat consumption in dry-land spring maize, eddy covariance technique was used to monitor the energy-exchange characteristics of the crop in Eastern Loess Plateau field. The results showed that the field-energy-balance ratio of dry-land spring maize is in the 0.75 - 1.0 range during non-rainfall daily noon (12:00 - 14:00). The Bowen ratio exhibited "L-type" trend during the total growth stages, namely, the highest Bowen ratio was at seedling stage with phase average 4.85 ± 1.42. The evaporation fraction showed a single peak trend in August, and the higher evaporation ratio met with more precipitation with average values 0.55 ± 0.06. The Bowen ratio and average evaporation fraction at the entire growth period were 1.78 ± 1.71 and 0.40 ± 0.18, respectively. About 40% of surface energy obtained from drought agro-ecosystem was used for evapotranspiration and heat consumption.

Laboratory and field studies on the reproductive ecology ofParocneria orienta(Lepidoptera: Lymantriidae) in China

2015 ◽  
Vol 45 (2) ◽  
pp. 77-83
Author(s):  
Hua Yang ◽  
Kun-Sheng Zhang ◽  
Wei Yang ◽  
Chun-Ping Yang
Keyword(s):  
Reproductive Ecology ◽  
Field Studies

Response of phalaris to differing water regimes or grazing treatments as measured by basal bud weight, water-soluble carbohydrates, and plant tillers

2004 ◽  
Vol 55 (8) ◽  
pp. 879 ◽  
Author(s):  
G. M. Lodge
Keyword(s):  
Water Treatment ◽  
Stem Elongation ◽  
Field Studies ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Mean Values ◽  
North West ◽  
Management Intervention ◽  
The North

Studies of Phalaris aquatica L. were used to collect data for basal bud (all below ground shoot material) weights, their water-soluble carbohydrate (WSC) content, and green vegetative tillers. A glasshouse study of cvv. Australian and Sirosa was conducted on regrowth after 26 days of plants previously exposed to either non-limiting or limiting (simulated Mediterranean environment, and 3- or 6-week drought) watering treatments. The other studies were of Sirosa phalaris pastures that had previously been subjected to continuous or lenient (resting in both spring and autumn each year) grazing by Merino wethers. In the glasshouse study, weight of basal buds (g/plant) was highest (13.88 g/plant) for Australian plants in the non-limiting water treatment, but not significantly different among watering treatments for Sirosa plants. Basal bud WSC values ranged from 2126 mg/plant (Australian phalaris, non-limiting water) to <200 mg/plant in 6-week drought and Mediterranean watering treatments of both cultivars. Tiller regrowth was higher in Australian non-limiting water treatment compared with all other treatments. Post-drought field studies (6 weeks tiller regrowth in May–June 1995) showed that plants in continuously grazed treatments had basal bud weights <11 g/plant, basal bud WSC contents <600 mg/plant, and green vegetative tiller weights <2.5 g/plant, compared with values of >11 g/plant, >1300 mg/plant, and >3.6 g/plant, respectively, for treatments rested for 12 weeks in both autumn and spring. At the end of spring 1995, when plants were post stem elongation and anthesis, basal bud WSC (mg/plant) was significantly higher in autumn–spring rest treatments compared with plants that were continuously grazed (mean values for 2 sites of 2889 and 1458 mg/plant, respectively). From these data, threshold values of basal bud WSC contents of <600 mg/plant after 6 weeks of regrowth in autumn–early winter, or <2000 mg/plant in flowering plants in late spring in continuously grazed pastures >3 years old, were proposed as useful indicators that management intervention may be required to maintain Sirosa phalaris persistence on the North-West Slopes of New South Wales.

Effect of sowing time on the once-over harvest yield of broccoli cultivars in north-west Tasmania

1986 ◽  
Vol 26 (4) ◽  
pp. 497
Author(s):  
B Chung ◽  
HL Strickland
Keyword(s):  
Brassica Oleracea ◽  
West Coast ◽  
Continuous Production ◽  
Plant Size ◽  
Sowing Time ◽  
North West ◽  
Growing Period ◽  
The North ◽  
Brassica Oleracea L

The effect of sowing times between November and May on the maturity and once-over harvest yield of broccoli (Brassica oleracea L. var. italica Plenck) was studied on the north-west coast of Tasmania. Sowing times between November and January had little effect on the plant size and marketable spear yield of the cultivar Futura. However, delaying sowing from January to March reduced the plant size and marketable spear yield of 10 cultivars of different maturity types. The length of the growing period of all cultivars was increased for sowings after February. A continuous production of broccoli for once-over harvest can be maintained for March-August by a combination of cultivars and sowings from January to March. However, yields of less than 5 t/ha can be expected for the mid-May-August harvests compared with yields in excess of 10 t/ha for March and April harvests.

scholarly journals Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part A): tropospheric degradation of non-aromatic volatile organic compounds

2002 ◽  
Vol 2 (6) ◽  
pp. 1847-1903 ◽  
Author(s):  
S. M. Saunders ◽  
M. E. Jenkin ◽  
R. G. Derwent ◽  
M. J. Pilling
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Good Description ◽  
Field Studies ◽  
Companion Paper ◽  
Chemical Mechanism ◽  
North West ◽  
Radical Intermediates ◽  
Volatile Organic ◽  
Master Chemical Mechanism

Abstract. Kinetic and mechanistic data relevant to the tropospheric degradation of volatile organic compounds (VOC), and the production of secondary pollutants, have previously been used to define a protocol which underpinned the construction of a near-explicit Master Chemical Mechanism. In this paper, an update to the previous protocol is presented, which has been used to define degradation schemes for 107 non-aromatic VOC as part of version 3 of the Master Chemical Mechanism (MCM v3). The treatment of 18 aromatic VOC is described in a companion paper. The protocol is divided into a series of subsections describing initiation reactions, the reactions of the radical intermediates and the further degradation of first and subsequent generation products. Emphasis is placed on updating the previous information, and outlining the methodology which is specifically applicable to VOC not considered previously (e.g. a- and b-pinene). The present protocol aims to take into consideration work available in the open literature up to the beginning of 2001, and some other studies known by the authors which were under review at the time. Application of MCM v3 in appropriate box models indicates that the representation of isoprene degradation provides a good description of the speciated distribution of oxygenated organic products observed in reported field studies where isoprene was the dominant emitted hydrocarbon, and that the a-pinene degradation chemistry provides a good description of the time dependence of key gas phase species in a-pinene/NOX photo-oxidation experiments carried out in the European Photoreactor (EUPHORE). Photochemical Ozone Creation Potentials (POCP) have been calculated for the 106 non-aromatic non-methane VOC in MCM v3 for idealised conditions appropriate to north-west Europe, using a photochemical trajectory model. The POCP values provide a measure of the relative ozone forming abilities of the VOC. Where applicable, the values are compared with those calculated with previous versions of the MCM.

scholarly journals Calving Ice Walls

1989 ◽  
Vol 12 ◽  
pp. 74-80 ◽  
Author(s):  
T. Hughes
Keyword(s):  
Shear Bands ◽  
Ice Sheets ◽  
Field Work ◽  
Field Studies ◽  
Line Field ◽  
Dry Land ◽  
Water Trough ◽  
Ablation Mechanism ◽  
Shear Rupture ◽  
Made In

Calving ice walls are an important ablation mechanism for deglaciation of calving bays occupied by temperate tide-water glaciers and polar marine ice sheets. Dangers inherent in calving bays have precluded detailed field studies of these calving ice walls. However, calving ice walls also exist in sub-polar glaciers terminating on dry land, and an opportunity for detailed field work was afforded by the 12 August 1970 volcanic eruption on Deception Island (63.0°S, 60.6°W), where thawing of a surface blanket of ice-cemented ash produced solifluction ramps that made parts of the ice wall accessible. Measurements made in a melt-water trough incised into the ice wall, and in four tunnels cut into the ice wall, revealed numerous shear bands that rose almost vertically and curved forward. Shear offset increased upward and was greatest in shear bands that intersected the tips of ring-fault crevasses on the up-slope side of the ice wall. Near the base of the ice wall, other shear bands, possibly related to the slip-line field, intersected the ice wall at about 45°. Ice slabs separated by ring faults calved straight down as a result of shear rupture along these two sets of shear bands. Calving dynamics were analyzed and generalized for ice walls grounded in water.

scholarly journals Bioclimatic Impact on the Carob Seeds Morphological Diversity in Morocco

2021 ◽  
Vol 18 (1) ◽  
pp. 207-217
Author(s):  
Foughali Boubkar ◽  
Fghire Rachid ◽  
Anaya Fatima ◽  
Issa Ali Oudou ◽  
Tahrouch Saadia ◽  
...  
Keyword(s):  
Morphological Diversity ◽  
Annual Rainfall ◽  
Shape Parameters ◽  
The South ◽  
Rainfall Gradient ◽  
Dry Land ◽  
The North ◽  
Carob Tree ◽  
Length Width ◽  
Ceratonia Siliqua L

The carob tree, Ceratonia siliqua L., a typical thermophilic sclerophyllous species, is a multipurpose tree (agronomic, silvicultural and pastoral) with aromatic and medicinal properties. Due to its geographical distribution, it occupies different countries of the Mediterranean. In Morocco, this species spreads over the different bioclimatic from the arid in the south to the humid in the north. The present work, study the morphological diversity of the seeds of five carob tree ecotypes distributed along a rainfall gradient (from the arid in the south to the humid one towards the north of the country). The shape parameters studied are the length, width, thickness, weight, volume and density of the seeds.The results obtained show that the carob tree ecotypes are characterized by significant differences in the different morphological parameters of the seeds among the five ecotypes studied. Indeed, dry land seeds are generally reduced in length, volume and weight, while those in humid regions are larger in weight and size. Those of the dry sowing areas have moderate parameters. The variance analysis shows that the origin of the ecotypes hada significant effect on the various shape parameters. Moreover, the multiple comparison of averages revealed different distinct groups. ACP analysis revealed that seed weight and volume is strongly correlated with the first component (the bioclimatic origin and the annual rainfall of the site of origin). While the second component corresponds to the parameters of length, width and thickness of the seeds. As for the factor 3, it corresponds to the density of the seeds which is not dependent on the other variables.In terms of conclusion, it is deduced that in Morocco, the carob tree seeds are characterized by a large morphological diversity which varies according to the rainfall gradient.

Studies of Divers' Performance During the SEALAB II Project

1966 ◽  
Vol 8 (3) ◽  
pp. 183-199 ◽  
Author(s):  
Hugh M. Bowen ◽  
Birger Andersen ◽  
David Promisel
Keyword(s):  
Mental Arithmetic ◽  
Physical Nature ◽  
Field Studies ◽  
Base Line ◽  
Psychomotor Tests ◽  
Dry Land ◽  
Telephone Contact ◽  
Work Activities ◽  
Water Conditions ◽  
Water Work

Field studies of the three 10 men teams of divers participating in the SEALAB II project were undertaken. During each team's 15 day submergence at 205 feet, psychomotor tests and a vision test were conducted in the water, and a mental arithmetic test in the habitat. Compared to base line performance (dry-land and shallow water conditions), performance on the mental arithmetic test showed no deterioration while performance on the psychomotor tests showed considerable deterioration. Many divers found that their in-water work activities proceeded slowly; among other causes of a more physical nature, concern for one's safety may detract from the amount of attention one gives to the task at hand. The most active divers in the SEALAB group were those who indicated that they were least fearful and least aroused by the conditions and who were helpful, gregarious, and made least telephone contact with the outside world.

MIXED FARMING SYSTEMS IN TRANSITION: THE CASE OF FIVE VILLAGES ALONG A RAINFALL GRADIENT IN NORTH-WEST SYRIA

2003 ◽  
Vol 40 (1) ◽  
pp. 109-126 ◽  
Author(s):  
B. RISCHKOWSKY ◽  
E. F. THOMSON ◽  
R. SHNAYIEN ◽  
J. M. KING
Keyword(s):  
Crop Production ◽  
Crop Yields ◽  
National Policy ◽  
Farming Systems ◽  
Farm Income ◽  
Forage Crops ◽  
Rainfall Gradient ◽  
North West ◽  
Mixed Farming ◽  
The Many

The changes taking place in the mixed farming systems of northwest Syria were examined by re-visiting, in 1996 and 2000, five villages along a rainfall gradient. The villages had been surveyed first in 1977–79. In those villages with moderate rainfall, intensification of crop production, namely a trend towards cereal monoculture and the planting of tree crops, did not lead to specialization in cropping at the expense of sheep ownership. In contrast, households in the areas too dry for most rainfed crops except barley (Hordeum vulgare) were more likely to sell their sheep because they depended heavily on off-farm income. Increases in crop yields were found but these only benefited the families in villages in the higher rainfall zones. Conversely, with the exception of ewe fertility, there was little evidence of improvements in sheep productivity. The mixed farming systems in the five villages sampled are still passing through a period of transition, and the cropping component will undoubtedly continue to change. This is less likely to happen to the small ruminant component in the near future unless the sector is given higher priority in national policy. As a strategy to increase feed production and balance the crop rotations, the prospects for closer crop/livestock integration at the farm level are limited by the many difficulties associated with the introduction of leguminous pasture and forage crops.

Sign in / Sign up

Export Citation Format

Share Document