scholarly journals Herbage accumulation, tiller population density, and sward components of prairie grass under different nitrogen levels

2001 ◽  
Vol 44 (1) ◽  
pp. 13-22 ◽  
Author(s):  
O. Scheneiter ◽  
P. Rimieri
Keyword(s):  
Population Density ◽  
Nitrogen Levels ◽  
Prairie Grass

scholarly journals Effects of soil characteristics and spring management on the persistence of 'Grasslands Matua' prairie grass

1990 ◽  
pp. 241-245
Author(s):  
C.J. Boom ◽  
G.W. Sheath
Keyword(s):  
Seed Production ◽  
Population Decline ◽  
Soil Survey ◽  
Research Centre ◽  
Late Winter ◽  
Seedling Vigour ◽  
Seed Vigour ◽  
Nitrogen Levels ◽  
Prairie Grass ◽  
Tiller Density

'Grasslands Matua' prairie grass was direct drilled into easy hill county at Whatawhata Research Centre. Establishment was excellent, but persistence was poor in most paddocks after 2 years. Site conditions associated with a range of Matua populations were surveyed. Matua population decline was greatest during spring. Spring soil nitrogen levels were associated with persistence, implying that nitrogen application in late winter may enhance persistence. In a trial to assess the effect of spring management on tillering patterns, seed production and seedling vigour, October closing resulted in the highest seed production, seed vigour and highest tiller density after herbage removal. It is proposed that a springsummer hay making policy will enhance the vigour of the existing population and provide adequate reseeding for new plant recruitment. Keywords Matua, persistence, soil survey, nitrogen, tiller density, closing date

Effects of density and soil nitrogen levels on growth of Galinsoga quadriradiata and G. parviflora in pure and mixed stands

1986 ◽  
Vol 64 (11) ◽  
pp. 2708-2715 ◽  
Author(s):  
J. P. N. Rai ◽  
R. S. Tripathi
Keyword(s):  
Population Density ◽  
Soil Nitrogen ◽  
Reproductive Effort ◽  
Plant Biomass ◽  
Northeast India ◽  
Nitrogen Level ◽  
Mixed Stands ◽  
Nitrogen Levels ◽  
Annual Weeds ◽  
Successional Communities

The responses of two sympatric annual weeds, Galinsoga quadriradiata Ruiz & Pavon (G. ciliata (Raf.) Blake) and G. parviflora Cav., which occur abundantly in croplands and early secondary successional communities of hill regions in northeast India, were studied in relation to population density, soil nitrogen, and nature of the stand (pure versus mixed stands). Both weeds exhibited density-dependent mortality which increased at a higher nitrogen level. In the case of G. quadriradiata more individuals survived in a mixture than in monoculture, whereas G. parviflora showed the reverse trend. Growth of both weeds was better at a higher soil nitrogen level. Increased mortality and suppression of growth caused by an increase in density was also minimized in G. quadriradiata at the higher level of soil nitrogen. With an increase in population density, per-plant biomass and capitula production in both weeds showed an increase in positive skewness which, however, decreased at an increased nitrogen level. Galinsoga quadriradiata was less sensitive to density than G. parviflora regardless of soil nitrogen. At lower densities, both weeds grew better in a mixture than in pure stands, but at higher densities G. quadriradiata suppressed the growth of G. parviflora. Although the crude reproductive effort of the two weeds was independent of soil nitrogen, G. quadriradiata, in contrast to G. parviflora, exhibited a greater crude reproductive effort when grown either at higher densities or in a mixture.

scholarly journals Role of Host Nutrition in Symbiont Regulation: Impact of Dietary Nitrogen on Proliferation of Obligate and Facultative Bacterial Endosymbionts of the Pea Aphid Acyrthosiphon pisum

2006 ◽  
Vol 73 (4) ◽  
pp. 1362-1366 ◽  
Author(s):  
T. L. Wilkinson ◽  
R. Koga ◽  
T. Fukatsu
Keyword(s):  
Population Density ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Buchnera Aphidicola ◽  
Nitrogen Levels ◽  
Dietary Nitrogen ◽  
Obligate Symbiont ◽  
Host Nutrition ◽  
Bacterial Endosymbionts ◽  
The Impact

ABSTRACT The impact of host nutrition on symbiont regulation in the pea aphid Acyrthosiphon pisum was investigated. The population density of the obligate symbiont Buchnera aphidicola positively correlated with dietary nitrogen levels. In contrast, the population density of the facultative symbiont Serratia symbiotica increased in aphids reared on low-nitrogen diets, indicating distinct regulatory mechanisms in the same insect host.

Convergence of regional population density in Russia over 120 years

2020 ◽  
pp. 133-158
Author(s):  
K. A. Kholodilin ◽  
Y. I. Yanzhimaeva
Keyword(s):  
Population Density ◽  
Spatial Dependence ◽  
Population Distribution ◽  
Regional Level ◽  
Capital City ◽  
County Level ◽  
Spatial Effects ◽  
Russian Regions ◽  
Regional Population ◽  
Regional Population Density

A relative uniformity of population distribution on the territory of the country is of importance from socio-economic and strategic perspectives. It is especially important in the case of Russia with its densely populated West and underpopulated East. This paper considers changes in population density in Russian regions, which occurred between 1897 and 2017. It explores whether there was convergence in population density and what factors influenced it. For this purpose, it uses the data both at county and regional levels, which are brought to common borders for comparability purposes. Further, the models of unconditional and conditional β-convergence are estimated, taking into account the spatial dependence. The paper concludes that the population density equalization took place in 1897-2017 at the county level and in 1926—1970 at the regional level. In addition, the population density increase is shown to be influenced not only by spatial effects, but also by political and geographical factors such as climate, number of GULAG camps, and the distance from the capital city.

Pasture species and cultivars used in New Zealand - a list

1999 ◽  
pp. 147-166 ◽  
Author(s):  
J.F.L. Charlton ◽  
A.V. Stewart
Keyword(s):  
New Zealand ◽  
Red Clover ◽  
Birdsfoot Trefoil ◽  
Reference List ◽  
Commercial Activity ◽  
Animal Products ◽  
Prairie Grass ◽  
Brome Grass ◽  
Industry Needs ◽  
Herb Species

In recent years, the number of pasture species and cultivars commercially available to farmers in New Zealand has increased significantly. Reasons for this include increased commercial activity in the development and supply of proprietary cultivars, and more specialisation in New Zealand's pastoral agriculture. In particular, pasture cultivars are increasingly marketed as proprietary products with associated technical support. This year there are 109 certified cultivars available, belonging to 23 grass, legume and herb species. As a result, farmers are now able to develop improved pasture feed supply, but they are somewhat confused about pasture species and cultivars, and this frustrates their aims to produce high quality animal products from productive pastures. Accordingly, the herbage seeds industry needs to work from a clear reference list, to avoid any confusion when supplying farmers and overseas clients with their seed requirements. Our list of pasture species, types and cultivars available within New Zealand aims to be that reference. Keywords: birdsfoot trefoil, brome grass, caucasian clover, chicory, clover, cocksfoot, cultivars, herbs, lotus, lucerne, pasture, phalaris, plantain, prairie grass, red clover, ryegrass, seeds, species, strawberry clover, sub clover, tall fescue, timothy, types, white clover, Yorkshire fog

THE PERFORMANCE OF 'GRASSLANDS MATUA' PRAIRIE GRASS IN THE SOUTHERN NORTH ISLAND

1977 ◽  
pp. 148-155
Author(s):  
G.J.Rys I.M. Ritchie ◽  
R.G. Smith ◽  
N.A. Thomson ◽  
G. Crouchley ◽  
W. Stiefel
Keyword(s):  
White Clover ◽  
Animal Health ◽  
Red Clover ◽  
Annual Production ◽  
Lower Yield ◽  
Prairie Grass

The performance of 'Grasslands Matua' prairie grass (Bromus catharticus) was compared with perennial ryegrasses under mowing or grazing in three trials conducted in the southern North Island. Production of Matua under mowing at Flock House and Waimate West was 13% and 19% greater than G.4708 and Nui ryegrass, respectively, with the extra production contributed in summer and winter. At Masterton no difference between Matua and Ariki ryegrass production occurred under grazing. A 31% increase in annual production was recorded for both Matua and G.4708 swards receiving N, compared with those sown with white clover, with the annual yield of G.4708 receiving N similar to Matua receiving no N. Less frequent defoliation increased production of Matua swards by 17% and the Matua component by 38%. Production of Nui in comparison with Matua swards was 14% lower under frequent and 9% lower under infrequent defoliation. Similar production was recorded from red clover under frequent, and infrequent defoliation for both Nui and Matua swards. A 48% lower yield of white clover occurred under infrequent defoliation of Matua swards. At Masterton a higher incidence of goitre in newborn lambs, accompanied by a 12% lower lamb liveweight at weaning, occurred on Matua- compared with Ariki-based swards. Aspects of seasonal production, fertility response, management, and animal health are discussed.

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