Structural characteristics of marandu palisadegrass swards subjected to continuous stocking and contrasting rhythms of growth

The concept of sward target has been used recently to characterise grazing management practices, but its efficiency to monitor and control sward structure questioned since it corresponds to a single sward structural feature, usually sward surface height. The objective of this experiment was to evaluate sward structure and its patterns of variation throughout the year on continuously stocked marandu palisadegrass swards maintained at 30 cm and subjected to contrasting rhythms of growth from January 2007 to April 2008. Treatments corresponded to three nitrogen application rates (150, 300 and 450 kg ha-1 of N) plus the control (no N fertilisation), and were allocated to experimental units according to a complete randomised block design, with four replications. Sward herbage mass, morphological composition, leaf area index (LAI), foliage angle and light interception were evaluated. The increase in nitrogen application rates resulted in increased sward herbage mass, proportion of leaf and stem, and reduction in the proportion of dead material. These modifications were in line with the increase in LAI and reduction in foliage angle, although they did not modify sward light interception. Despite the wide range of nitrogen application rates used, there was a common pattern of variation in sward structure. Overall, changes in sward structural characteristics generated by the range of growth rhythms studied were small, indicating that sward height corresponded to an efficient way to monitor and control the grazing process and sward structure, and can be used to define targets of grazing management.

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Use Patterns and Residual Levels of Organophosphate Pesticides on Vegetables in Trinidad, West Indies

Journal of AOAC International ◽

10.1093/jaoac/82.4.991 ◽

1999 ◽

Vol 82 (4) ◽

pp. 991-996 ◽

Cited By ~ 7

Author(s):

Ivan Chang Yen ◽

Isaac Bekele ◽

Carlyle Kalloo

Keyword(s):

Regulatory Agencies ◽

Organophosphate Pesticides ◽

Monitoring And Control ◽

Pesticide Application ◽

Use Patterns ◽

Application Rates ◽

Island State ◽

Wide Range ◽

Pirimiphos Methyl ◽

And Control

Abstract The twin-island state of Trinidad and Tobago produces much of the fresh fruit and vegetables consumed locally, although some are exported to Europe and North America. On average, approximately 1500 tons of pesticides are imported annually, of which about 10-15% are organophosphates. A survey of local farmers revealed that a wide range of pesticides are used and that the same pesticides are used on several crops to control different pests. Application rates exceeding manufacturers' recommendations are also common, as is the disregard of recommended preharvest intervals after pesticide application. Praedial larceny and subsequent sale of freshly sprayed crops also contribute to the risks posed to consumers by pesticide residues. A market basket survey of produce conducted between October 1996 and May 1997 in Trinidad for organophosphate pesticides showed that 10% of produce exceeded the internationally acceptable maximum residue limits (MRLs) for the respective pesticides. Celery constituted 6.5% of all such samples, with over 83% of celery samples exceeding the MRL. Organophosphate pesticides detected were methamidophos, triazophos, prophenofos, diazinon, ethion, pirimiphos methyl, malathion, and dimethoate, with the first 4 being the most commonly detected. There is an urgent need for comprehensive monitoring and control of pesticides on produce by local regulatory agencies, especially because the above data relate only to one class of pesticides. The education of farmers on safe operating practices regarding pesticide application and observation of recommended preharvest intervals for applied pesticides is also required.

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Effects of postgrazing residue on morphogenetic and structural characteristics of Tifton 85 pastures

Semina Ciências Agrárias ◽

10.5433/1679-0359.2016v37n4p2043 ◽

2016 ◽

Vol 37 (4) ◽

pp. 2043

Author(s):

Wilton Ladeira Silva ◽

Ana Cláudia Ruggieri ◽

Ricardo Andrade Reis ◽

Américo Garcia Silva Sobrinho ◽

Euclides Braga Malheiros

Keyword(s):

Structural Characteristics ◽

Stem Elongation ◽

Light Interception ◽

Climatic Conditions ◽

Leaf Length ◽

Elongation Rate ◽

Area Index ◽

Structural Variables ◽

Senescence Rate ◽

Leaf Appearance

The ideal time to start grazing is when pastures reach 95% light interception. The use of residual leaf area index (rLAI) to time the interruption of grazing under intermittent grazing has recently been studied in forage species in different climatic conditions in Brazil. However, studies evaluating the formation and development of leaves and tillers through morphogenetic and structural variables in functional rLAI are still lacking for Tifton 85 pastures. Therefore, the objective of this study was to evaluate the effects of varying rLAI in successive grazing cycles on morphogenetic and structural characteristics of Tifton 85 pasture grazed intermittently by sheep. Morphogenetic and structural characteristics were evaluated in three grazing cycles under three rLAI conditions (0.8, 1.6, and 2.4). The regrowth interval (time taken to return to 95% light interception) of pastures increased from 21.33 to 29.66 days with decreasing rLAI. The leaf appearance rate increased at a rate of 0.02 leaves tiller-1 day-1 and the number of live leaves per tiller increased by 0.41 with decreasing rLAI. Phyllochron, leaf elongation rate, final leaf length, leaf senescence rate, and stem elongation rate decreased linearly with decreasing rLAI. The number of live leaves per tiller was lower (7.97) in the third grazing cycle, probably owing to the higher senescence rate observed that same cycle, while the other variables had higher values. The 2.4 rLAI condition promotes excessive stem elongation, reduced leaf appearance, lower number of live leaves per tiller, and increased senescence of leaves, while the 0.8 and 1.6 rLAI conditions promote desirable morphogenetic and structural characteristics, which correlate directly with forage quality. In order to avoid excessive forage losses, grazing must occur preferentially by the end of March, when climatic conditions still support the appropriate development of the plants.

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Effect of residual leaf area index on spatial components of Tifton 85 pastures and ingestive behaviour of sheep

Animal Production Science ◽

10.1071/an15087 ◽

2017 ◽

Vol 57 (5) ◽

pp. 903 ◽

Cited By ~ 4

Author(s):

W. L. Silva ◽

J. P. R. Costa ◽

G. P. Caputti ◽

A. L. S. Valente ◽

D. Tsuzukibashi ◽

...

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Rainy Season ◽

Structural Characteristics ◽

Light Interception ◽

Dry Season ◽

Area Index ◽

Dead Material ◽

Point Quadrat ◽

Ingestive Behaviour

This study compared the effect of residual leaf area index (rLAI) on the spatial distribution of morphological components of Tifton 85 (Cynodon spp.) pastures and the ingestive behaviour of grazing sheep. Also, it was investigated whether any specific correlation could be found between pasture structural characteristics and sheep ingestive behaviour. Four rLAI treatments (0.8; 1.4; 2.0 and 2.6) with four replications were evaluated per period. Sheep grazed under rotational stocking management and they grazed for 4 days in each pasture while pasture regrowth period was determined by the 95% light interception requirement. Pasture structure was evaluated using inclined point-quadrat, LAI estimates, light interception and leaf : stem ratio. The 2.6 rLAI yielded the highest proportion of dead material in the lower canopy. In the post-grazing period the proportion of leaves increased with increasing rLAI, especially on the canopy surface during the rainy season. In the pre-grazing average pasture height ranged between 19 and 26 cm with dead material and stem observed up to the canopy surface in the dry season. The animals grazed longer on the last day (89.72%) compared with the first day (80.25%) in the dry season. However, they spent less time (11.45%) ruminating in the dry season compared with the rainy season (15.38%), regardless of the grazing day. Grazing time decreased and rumination time increased as rLAI increased. Sheep grazing time correlated negatively with pasture height, before and after grazing. The sheep tend to graze longer on Tifton 85 pastures when rLAI was lower and forage supply was possibly less as on the last grazing day and in the dry season.

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Ultrastructural observations of lethal yellow (Ay/Ay) mouse embryos

Development ◽

10.1242/dev.35.1.73 ◽

1976 ◽

Vol 35 (1) ◽

pp. 73-80

Author(s):

Patricia G. Calarco ◽

Roger A. Pedersen

Keyword(s):

Developmental Stages ◽

Inner Cell Mass ◽

Structural Characteristics ◽

Cell Mass ◽

Blastocyst Stage ◽

Cell Organelles ◽

Cell Stage ◽

Wide Range ◽

Lethal Yellow ◽

And Control

Ay/Ay embryos were identified by the presence of large excluded blastomeres (Pedersen, 1974) and examined cytologically and ultrastructurally. Cell organelles, inclusions and junctions in the excluded blastomeres were compared with those of non-excluded cells of Ay/Ay embryos and control embryos. Excluded blastomeres always had the fine structural characteristics of earlier developmental stages and may have arrested at the 4- to 8-cell stage or slightly later. Interior cells (inner cell mass) were observed in all mutant blastocysts. Nonexcluded cells of Ay/Ay embryos were normal until degenerative changes appear in the late blastocyst stage. The mode of action of the +Ay gene was not determined, but evidence from this study and others indicates that the effects of +Ay gene action occur over a wide range of time in early cleavage and implantation.

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The effect of a wide range of fertilizer nitrogen application rates and defoliation intervals on the dry-matter production, seasonal response to nitrogen, persistence and aspects of chemical composition of perennial ryegrass (Lolium perennecv. S.24)

The Journal of Agricultural Science ◽

10.1017/s0021859600037424 ◽

1977 ◽

Vol 88 (3) ◽

pp. 711-721 ◽

Cited By ~ 31

Author(s):

P. W. Bartholomew ◽

D. M. B. Chestnutt

Keyword(s):

Dry Matter ◽

Maximum Yield ◽

Ground Cover ◽

Growing Season ◽

Nitrate Content ◽

Nitrogen Application ◽

Fertilizer Nitrogen ◽

Application Rates ◽

Wide Range ◽

Small Plot

SUMMARYA small-plot experiment was made to assess the influence on dry-matter output from grass of a wide range of fertilizer nitrogen and defoliation interval treatments. There were five defoliation treatments, 22, 28, 45, 75 and 112-day regrowth intervalsroughout the growing season each at six levels of nitrogen application, ranging by 300 kg increments from 0 to 1500 kg/ha/year.There was a marked interaction effect between treatments; a positive dry-matter response was maintained to a higher level of applied nitrogen with more frequent defoliation. In 2 years out of 3 maximum dry-matter yield was produced under a 75·day defoliation interval although the mean yield advantage over a 45-day defoliation system was only 11%. Mean yield of digestible dry matter appeared to reach a maximum under a 45·day defoliation interval at 600 kg N/ha but at the lower levels of N the maximum yield was reached at the longest growth interval.Seasonal response to nitrogen under the 22–day and 28–day defoliation systems measured as the increase in yield resulting from increased N at each cutting date reached its peak in July–August. Application for these short growth periods early and late in the growing season appeared to be a relatively inefficient use of nitrogen.The less frequently the sward was harvested and the higher the nitrogen application the greater was the reduction in ground cover as estimated by eye at the end of the growing season, this reached an estimated 25% reduction under 112·day defoliation at 300 kg N/ha/year.In relation to published figures nitrate content of herbage did not reach dangerous levels until nitrogen application reached levels beyond those at which maximum dry·matter yield was achieved.

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Sward structural characteristics and herbage accumulation of Panicum maximum cv. Mombaça subjected to rotational stocking managements

Scientia Agricola ◽

10.1590/s0103-90162009000100002 ◽

2009 ◽

Vol 66 (1) ◽

pp. 8-19 ◽

Cited By ~ 61

Author(s):

Sila Carneiro da Silva ◽

Adriana Amaral de Oliveira Bueno ◽

Roberta Aparecida Carnevalli ◽

Marina Castro Uebele ◽

Fernando Oliveira Bueno ◽

...

Keyword(s):

Management Practices ◽

Transition Period ◽

Structural Characteristics ◽

Block Design ◽

Incident Light ◽

Grazing Management ◽

Panicum Maximum ◽

Area Index ◽

Horizontal Orientation ◽

Guinea Grass

Grazing strategies promote changes in sward structure that can affect patterns of herbage accumulation and sward flexibility to management. This experiment evaluated sward structural characteristics and herbage accumulation of Mombaça guinea grass (Panicum maximum Jacq. cv. Mombaça) subjected to rotational stocking managements. Treatments involved grazing when swards reached either 95 or 100% interception of the incident light (LI), to post-grazing heights of 30 and 50 cm, and were allocated to 2,000 m² paddocks according to a randomised complete block design in a 2 × 2 factorial arrangement with four replications, from January 2001 to February 2002. Sward canopy changed from a vertical to a more horizontal orientation as the light interception area index and height increased from post to pre-grazing. Leaf canopy height pre-grazing was stable throughout the year and around 90 and 115 cm for the 95% and 100% LI treatments respectively, indicating a potential for development and use of target-based grazing management practices. Herbage mass pre and post-grazing was lower for the 95% than the 100% LI treatments, but with higher proportion of leaf and lower proportions of stem and dead material. Treatment effects on herbage accumulation were cumulative and became more evident as the experiment progressed, with up to 6 t ha-1 DM advantage to the 95/30 treatment. Although based on a single year experiment, grazing management should aim for low herbage mass during the transition period from winter to spring in order to allow fast recovery of swards and favour herbage accumulation during the following growing season.

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A Novel Approach to Mitigate DDoS Attack Using Gateway Mechanism

International Journal on Recent and Innovation Trends in Computing and Communication ◽

10.17762/ijritcc.v7i2.5226 ◽

2019 ◽

Vol 7 (2) ◽

pp. 18-20

Author(s):

Satvir Kaur, Gureshpal Singh, Baljinder Singh

Keyword(s):

Denial Of Service ◽

Secret Information ◽

Ddos Attack ◽

Wireless Links ◽

Novel Approach ◽

Wide Range ◽

And Control ◽

Monitor And Control

Intelligent and economical sensors, connected to the network via wireless links and distributed in large quantities, offer unprecedented opportunities to monitor and control homes, cities and the environment. In addition, sensors connected to the network use a wide range of applications within the defence area, generating new features for recognition and surveillance and various tactical applications. Denial of service is one of the most terrible attacks is the cloning attack of the node, where the attacker captures the knot and extracts its secret information, create replicas and enter them in the network field other malevolent behaviour. To detect and mitigate this attack, this paper proposed a Gateway based technique.

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003 Epidemiology and Control of Pepper Stip

HortScience ◽

10.21273/hortsci.34.3.441b ◽

1999 ◽

Vol 34 (3) ◽

pp. 441B-441

Author(s):

Richard Smith ◽

Robert Mullen ◽

Tim Hartz

Keyword(s):

Total Nitrogen ◽

Mineral Nutrition ◽

No Reduction ◽

Nitrogen Nutrition ◽

Field Studies ◽

Nitrogen Application ◽

Physiological Disorder ◽

Resistant Cultivars ◽

Application Rates ◽

And Control

Pepper stip is a physiological disorder manifested as gray-brown to greenish spots occurring on the fruit of bell, pimento, Anaheim, and other types of peppers, most noticeably on red fruit that mature under fall conditions. Most hybrid bell cultivars are resistant to the malady; the problem is most severe for pepper growers reliant on less-expensive, open-pollinated cultivars. In 1995, we initiated studies to evaluate the possible link between mineral nutrition and this disorder. Two susceptible open-pollinated cultivars and two resistant hybrid cultivars were grown in randomized plots at seven sites. Significant correlations were seen between the levels of potassium (r = 0.59) and calcium (r = -0.37) in whole leaves and the incidence of stip (P = 0.05). The stip-resistant cultivars also maintained less total nitrogen in the whole leaves than susceptible cultivars (P = 0.05). In 1996 and 1997, we undertook field studies to evaluate the effects of varying calcium and nitrogen application rates. Inconsistent results were observed with calcium applications. Moderate reductions in stip incidence was observed at some sites and no reduction at others following foliar calcium applications. Nitrogen nutrition had no effect on stip severity. In 1998, evaluation of a large number of open-pollinated cultivars was undertaken; `Gusto' showed excellent tolerance to pepper stip, followed by `Taurus' and `Cal Wonder 300'. We conclude that growers that are reliant on open-pollinated cultivars can utilize these cultivars to minimize the incidence of pepper stip.

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