Ability to recover overrides the negative effects of flooding on growth of tropical grasses Chloris gayana and Panicum coloratum

2015 ◽  
Vol 66 (1) ◽  
pp. 100 ◽  
Author(s):  
José A. Imaz ◽  
Daniel O. Giménez ◽  
Agustín A. Grimoldi ◽  
Gustavo G. Striker
Keyword(s):  
Recovery Period ◽  
Growth Period ◽  
Early Spring ◽  
Early Summer ◽  
Late Winter ◽  
Negative Effects ◽  
Tropical Grasses ◽  
Panicum Coloratum ◽  
Flooding Event ◽  
Chloris Gayana

This study assessed the flooding tolerance of the tropical grasses Chloris gayana Kunth and Panicum coloratum L. at different times of the year: (i) late winter flooding for 50 days (WF), (ii) early spring flooding (SF) for 20 days, and (iii) long-term flooding covering both periods (WF + SF, 70 days). A growth period under well-watered conditions was allowed after each flooding event to assess recovery of plant species. Plants were harvested after each flooding event and at the end of the recovery period. Panicum coloratum had higher tolerance to WF than C. gayana. Treatment WF did not affect biomass in P. coloratum, whereas it reduced biomass of flooded plants by 38% in C. gayana. Treatment SF did not differentiate the species for tolerance; both registered moderate reduction in their growth (20–30%). Under WF + SF, C. gayana showed additional reduction in its growth over that observed when subjected separately to either WF or SF, whereas P. coloratum did not. Both species displayed remarkably fast recovery from flooding when temperatures rose during early summer, attaining biomass equivalent to that of non-flooded plants 1 month after water subsided. Therefore, although P. coloratum appears slightly more tolerant during flooding than C. gayana, both species are promising for introduction in temperate lowland grasslands.

scholarly journals Experimental studies on seed production tropical grasses in Kenya. 6. The effect of harvest date on seed yield in varieties of Setaria sphacelata, Chloris gayana and Panicum coloratum.

1973 ◽  
Vol 21 (1) ◽  
pp. 3-11
Author(s):  
J.G. Boonman
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Experimental Studies ◽  
The Other ◽  
Harvest Date ◽  
Tropical Grasses ◽  
Panicum Coloratum ◽  
Setaria Sphacelata ◽  
Chloris Gayana ◽  
Late Abstract

Setaria sphacelata cv. Nandi I and Nandi III, Chloris gayana cv. Mbarara, Masaba and Pokot, and Panicum coloratum cv. Solai were grown for seed and harvested on a range of dates beginning 3-4 weeks after initial head emergence (defined as 5-10 heads/m2). Harvesting date was not very critical, and harvesting could normally be spread over 1-2 weeks. The interval between initial heading and optimum harvest date was normally 6-7 weeks. In most crops considerable shedding of spikelets (up to 30-50% in P. coloratum, rather less in the other 2 species) could be tolerated before yield of pure germinating seed fell with delay in harvesting. It was suggested that most of the spikelets which were shed early were empty. Cultivars which headed early produced nearly twice as much seed as those which headed late. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Seasonal dynamics of Proteocephalus sagittus in the stone loach Barbatula barbatula from the Haná River, Czech Republic

2004 ◽  
Vol 78 (3) ◽  
pp. 225-229 ◽  
Author(s):  
J. Jarkovský ◽  
B. Koubková ◽  
T. Scholz ◽  
M. Prokeš ◽  
V. Baruš
Keyword(s):  
Czech Republic ◽  
Seasonal Cycle ◽  
Early Spring ◽  
Early Summer ◽  
Fish Host ◽  
Late Winter ◽  
Stone Loach ◽  
Barbatula Barbatula ◽  
Infection Parameters ◽  
First Time

AbstractThe seasonal cycle of the cestode Proteocephalus sagittus (Cestoda: Proteocephalidae) was studied for the first time in the stone loach Barbatula barbatula from the Haná River, Czech Republic. A total of 180 loaches were examined monthly from January to December 2001. The parasite occurred in loaches throughout the year but infection parameters differed significantly among seasons, with the highest values of prevalence and abundance from the late winter to the early summer. Parasite recruitment took place in the winter and early spring and the worms sexually matured in the late spring and early summer. In contrast to P. torulosus, the gravid worms of which laid eggs only at the end of the spring/beginning of the summer, gravid worms of P. sagittus were also found, although in low numbers, in the autumn and early winter. The rate of infection of loach with P. sagittus was neither dependent on the sex nor on the size of its fish host.

Population dynamics of three species of dasyurid marsupials in arid central Australia: a 10-year study

2001 ◽  
Vol 28 (5) ◽  
pp. 493 ◽  
Author(s):  
Christopher R. Dickman ◽  
Adele S. Haythornthwaite ◽  
Gayle H. McNaught ◽  
Paul S. Mahon ◽  
Bobby Tamayo ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Life Histories ◽  
Arid Zone ◽  
Early Spring ◽  
Early Summer ◽  
Late Winter ◽  
Sand Ridge ◽  
Red Foxes ◽  
Central Australia ◽  
Simpson Desert

This study investigated the population dynamics of three species of dasyurid marsupials in sand ridge habitat of the Simpson Desert, western Queensland, over a 10-year period between March 1990 and December 1999. The lesser hairy-footed dunnart (Sminthopsis youngsoni), was captured most consistently over the period of study, followed by the wongai ningaui (Ningaui ridei), and the mulgara (Dasycercus cristicauda). Rates of recapture were low (4.5–22.2%), probably because individuals of each species are very mobile. All species bred in late winter or early spring when animals were aged at least 8–10 months, and independent juveniles first appeared usually in summer. S. youngsoni reared a second litter in late spring or early summer in 3 of the 10 years studied, when the availability of food was likely to have been high; neither N. ridei nor D. cristicauda were known to attempt a second litter within a season. To explore factors that might influence population dynamics, we compared capture rates of each species with measures of rainfall, temperature, vegetation cover, abundance of predators [feral cats (Felis catus), red foxes (Vulpes vulpes), and goannas (Varanus spp.)], dragons, other dasyurids and indices of food abundance. The abundance of S. youngsoni appeared to depend primarily on the cover of spinifex 7–9 months earlier, that of D. cristicauda was related most strongly to rainfall 7–9 months earlier, while that of N. ridei was related to minimum temperature lagged by 1–3 months. While the dynamics of other arid-zone mammals are driven demonstrably by interactions between rainfall, resource availability and predation, our findings suggest that dasyurids have limited flexibility in their life histories and are influenced more subtly and by factors such as facilitation that are just beginning to become apparent.

The effects of submergence on anatomical, morphological and biomass allocation responses of tropical grasses Chloris gayana and Panicum coloratum at seedling stage

2012 ◽  
Vol 63 (12) ◽  
pp. 1145 ◽  
Author(s):  
José A. Imaz ◽  
Daniel O. Giménez ◽  
Agustín A. Grimoldi ◽  
Gustavo G. Striker
Keyword(s):  
Biomass Allocation ◽  
Seedling Recruitment ◽  
Morphological Changes ◽  
Biomass Accumulation ◽  
Seedling Stage ◽  
Tropical Grasses ◽  
Panicum Coloratum ◽  
Root Aerenchyma ◽  
Chloris Gayana ◽  
Water Response

Submergence is a major factor affecting seedling recruitment in lowland grassland ecosystems. Our aim was to evaluate the tolerance to increasing flooding intensity of the seedlings of tropical grasses Chloris gayana K. and Panicum coloratum L., whose use as a forage species is increasing in humid grasslands. For this purpose, 2-week-old seedlings of C. gayana and P. coloratum were subjected to control, partial submergence (PS) and complete submergence (CS) in clear water for 14 days and allowed to grow for a subsequent 12-day period to assess their recovery. The following responses were assessed: generation of root aerenchyma, morphological changes and emergence from water, biomass allocation in relation to plant size, and biomass accumulation. Results showed that constitutive root aerenchyma was high in both species. Under PS and CS, root aerenchyma increased by up to 50–55% in C. gayana and up to 40–48% in P. coloratum. Under PS, the increase in seedling height for both species was the same as for controls. Under CS, C. gayana further increased its height and emerged more quickly from water; P. coloratum was not able to increase its height, and therefore the seedlings always remained underwater. The escape-from-water response of C. gayana was associated with preferential biomass allocation towards shoots and with a marked lengthening of leaf blades. By contrast, there was no change in allocation in P. coloratum, and its leaves were shorter under CS. The final biomass of C. gayana under CS was similar to that under PS, and equivalent to 54% of its controls. In P. coloratum, biomass under PS and CS were 64 and 21% of its controls (respectively), which indicates that injury caused by CS persisted during the post-submergence period. In conclusion, both species are tolerant to PS at the seedling stage. However, when flood depth increases by submerging the seedlings, C. gayana is able to escape from water while P. coloratum is not, thus strongly affecting its recovery. Therefore, C. gayana appears to be a more promising species for cultivation in lowland grasslands prone to flooding of unpredictable intensity.

Late winter – early spring sedimentation off the Great Whale River, southeastern Hudson Bay

1988 ◽  
Vol 25 (6) ◽  
pp. 930-933 ◽  
Author(s):  
B. d'Anglejan ◽  
G. Biksham
Keyword(s):  
Algal Biomass ◽  
Sediment Traps ◽  
Early Spring ◽  
Early Summer ◽  
Late Winter ◽  
Hudson Bay ◽  
Sedimentation Rates ◽  
Summer Period ◽  
The Mean ◽  
Peak Runoff

Sediment traps were used to measure particle-settling fluxes in serial moorings offshore of Great Whale River (Hudson Bay), both under the late winter sea-ice cover and during and after breakup. Before breakup, the settling fluxes ranged between 0.25 and 2 g cm−2 100 a−1, increasing from April to May in response to the progressively larger under-ice algal biomass. Fluxes also increased with depth. During and after breakup, including the early summer period of peak runoff, sedimentation rates increased to values of up to 33 g cm−2100 a−1. These fluxes agree with the mean sedimentation rate determined from 210Pb activities in the underlying sediments.

Sea ice conditions during an early spring voyage in the eastern Weddell Sea, Antarctica

Polar Record ◽  
1988 ◽  
Vol 24 (148) ◽  
pp. 49-54 ◽  
Author(s):  
H. Eicken ◽  
T. C. Grenfell ◽  
B. Stonehouse
Keyword(s):  
Open Water ◽  
Early Spring ◽  
Early Summer ◽  
Weddell Sea ◽  
Late Winter ◽  
Main Body ◽  
Pack Ice ◽  
Large Populations ◽  
Differential Expansion ◽  
Ice Pack

AbstractDuring a late winter and early spring oceanographic voyage south into the Weddell Sea the icebreaker RV Polarstern first encountered patches and bands of loose floes in 58°S; these increased over the next 150 km to form closed ice pack which extended 1000 km to the coast. Along the coast the ship encountered almost continuous shore leads and polynyas that formed repeatedly despite persistently low air and sea temperatures. These areas of open water, which are generally visible in USA NOAA and USSR METEOR satellite photographs, form under the action of strong offshore winds that carry the main body of pack ice west and southwest. Grease ice, pancake ice and nilas spreading over the open water are rafted and ridged by windgenerated stresses to double thickness or more; these kinds of ice were continually driven westward, accumulating in a distinctive zone along the eastern edge of the pack ice. Polynyas and leads narrow and disappear temporarily only when winds with northerly or westerly components bring the pack ice toward the land, and reform as soon as offshore winds predominate. Open water, often more than 15 km wide, was present close to the ship throught the spring voyage, facilitating oceanographic work as far south as 77°S. Polarstern's full icebreaking capacity was needed only occasionally when winds temporarily pressed the pack ice against the coast. The presence throughout early spring of both fast and pack ice, separated by a zone of thin ice or open water, is essential to large populations of Weddell seals, emperor penguins and whales in the area. The transect from the continent included ice pack that was undergoing early summer decay, characterized by differential expansion and melting which brought about a gradual decrease in concentration toward the ice edge.

On the chronology of the Samian war

1979 ◽  
Vol 99 ◽  
pp. 7-19 ◽  
Author(s):  
Charles W. Fornara ◽  
D. M. Lewis
Keyword(s):  
Early Spring ◽  
Early Summer ◽  
The Other ◽  
Late Winter ◽  
Independent Data ◽  
Relative Chronology ◽  
The Subject ◽  
Historical Tradition ◽  
Mutually Independent ◽  
Critical Interest

Unlike much else in the Pentecontaetia, the chronology of the Samian War, its antecedents included, has apparently evoked such little critical interest that an almost casual treatment of the subject is observable in modern works. Nesselhauf, for example, annotated his brief discussion of the Samian War with a reference to Busolt and Beloch ‘for the details’. Each scholar provides a radically different chronology from the other. Indeed, the range of dates postulated by modern writers is remarkable considering the relatively small span of time, two years, in which the events appear to have unfolded. Beloch and the authors of ATL date the war between Samos and Miletus, which ultimately caused the revolt, in summer 441 B.C.; Busolt set the war in March-April 440 B.C., E. Meyer a shade earlier. Some scholars fail to specify the date (Nesselhauf, Meiggs). The beginning of the revolt itself has been placed in spring 440 B.C. by Sealey, among others; Gomme and Meiggs date it in early summer, Busolt, strangely, in early July. The direct cause of the revolt, the installation of the democracy at Samos (Thuc. i 115.3), is little discussed, much less fixed in date. The democracy was not established in a day: it therefore requires consideration in any chronological reconstruction. Finally, the end of the war has been variously set in late winter, early spring and early summer 439 B.C.Such uncertainty is surprising since our evidence is abundant and also specific enough to allow us to make reasonably firm chronological estimates. Indeed, our fortunate possession of mutually independent data—the historical tradition and the monumental evidence—provides us with the opportunity to attempt precision in a degree usually beyond our expectations. However we may separately interpret Thucydides' relative chronology or the random evidence of the stones, these data, when taken in combination, yield knowledge greater than the sum of its parts.

Differences in light and temperature responses determine autumn versus spring germination for seeds of Schoenolirion croceum

2004 ◽  
Vol 82 (10) ◽  
pp. 1429-1437 ◽  
Author(s):  
Jeffrey L Walck ◽  
Siti N Hidayati
Keyword(s):  
Soil Surface ◽  
Early Spring ◽  
Early Summer ◽  
Light Regime ◽  
Late Winter ◽  
Light Conditions ◽  
Germination Phenology ◽  
Temperature Requirements ◽  
Temperature Responses ◽  
Do So

Seeds of the southeastern North American Schoenolirion croceum (Michx.) Wood are dormant when dispersed in late spring to early summer. Fresh seeds buried in soil after dispersal germinate in autumn, whereas those sown on the soil surface do so the following late winter – early spring. To understand this difference in germination phenology, we examined the light and temperature requirements for dormancy break and germination. Seeds germinated to high percentages in darkness over 12:12 h thermoperiods ranging from 15:6 to 35:20 °C following warm stratification (25:15 °C) in darkness, whereas no seeds germinated in light following stratification in light. On the other hand, seeds germinated to high percentages in light and in darkness following cold stratification (5 °C) in light or darkness. Seeds exposed to light during autumn germinated in winter–spring regardless of the light regime in summer or winter–spring, whereas those in darkness during autumn germinated in autumn regardless of the light regime in summer. Thus, light conditions during autumn are critical for determining whether seeds will germinate in autumn versus early spring. In contrast with many other species in which germination phenology is mostly temperature controlled, timing of germination for S. croceum depends on the light conditions in relation to temperatures experienced during dormancy release.Key words: dark, germination phenology, Hyacinthaceae, negative photoblastic seeds, photoecology, seed dormancy.

scholarly journals Effects of deferred forage as winter cover on spring growth of the tropical grasses Chloris gayana and Panicum coloratum

2016 ◽  
Vol 5 (1) ◽  
pp. 29 ◽  
Author(s):  
José A. Imaz ◽  
Victor Merani ◽  
Daniel dos Santos ◽  
Marcelo Benvenutti ◽  
Daniel O. Giménez ◽  
...  
Keyword(s):  
Tropical Grasses ◽  
Panicum Coloratum ◽  
Chloris Gayana ◽  
Winter Cover

DYNAMICS OF BARLEY FLAVONOID AND PRODUCTIVITY UNDER UF-A RADIATION

1970 ◽  
pp. 14-18
Author(s):  
L. I. Goncharova ◽  
P. N. Tsygvintsev ◽  
О. А. Guseva
Keyword(s):  
Grain Yield ◽  
Defense Mechanisms ◽  
Antioxidant Defense ◽  
Malonic Dialdehyde ◽  
Growth Period ◽  
Negative Effects ◽  
Uv Spectrum ◽  
Quantum Energy ◽  
Dry Soil ◽  
Universal Mechanism

The effect of increased UV-A radiation during the ontogeny of barley plants of the Vladimir variety in the vegetation experiment was studied. Changes in the content of malonic dialdehyde, flavonoids and grain yield were revealed. UV-A radiation as compared to UV-B radiation, has lower quantum energy and can have both positive and negative effects on plant regulatory and photosynthetic processes. One of the most damaging effects of increased levels of UV-A radiation is oxidative stress, which causes lipid peroxidation of biological membranes. The existence of a plant cell in such conditions is possible only thanks to a system of antioxidant defense mechanisms. The accumulation of phenolic compounds under the action of UV radiation is a universal mechanism of protection against photodamage, which was formed in the early stages of the evolution of photoautotrophic organisms. Flavonoids are localized in the epidermis of plant tissues and act as an internal filter. The content of flavonoids is determined by the genotype and due to ontogenetic patterns. Plants were grown in a greenhouse, in vessels containing 4.5 kg of air-dry soil. The repetition is threefold (3 vessels in each variant). Sowing density - 13 plants in each vessel. As a source of UV-A radiation used lamps Black Light BLUE company Philips. Plants were irradiated for 5 hours a day from 10 to 15 hours at 13, 25, 34, 43 and 52 stages of organogenesis. The magnitude of the daily biologically effective dose of UV-A radiation was 60.7 kJ / m2. The solar part of the UV spectrum in the vegetation experiment was absent in the greenhouse. The nature of changes in the content of flavonoids under the action of UV-A irradiation during the growing season of plants with the dynamics of the oxidative process has been established. The first maximum was observed during the vegetative growth period, the second - at the earing stage. The data obtained indicate that flavonoids have ontogenetic conditionality and perform photoprotective functions. The increase in their content under the action of UV-A radiation is accompanied by an increase in resistance to photodamage, which is confirmed by the formation of grain yield.

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