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levels in female house mice at high population density. Physiol. Behav. 64 , 529–533. Michael S. D. Analysis of steroid hormone levels in female house mice at high population density

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Cereal Research Communications
Authors: Oscar Moreno-Ramos, Julio Rodríguez-Casas, Donald Johnson, Eduardo Canseco-Vilchis, Thomas Thompson, and Jesús Salazar-Gómez

del trigo y del triticale a la fecha y al método de siembra. Tesis Lic. Univ. Aut. Chapingo. Chapingo, Mex. Salazar G.,M., O.H. Moreno, R. Cruz, and R. Salazar. 1998. Plant population density x sowing date

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Cereal Research Communications
Authors: Julio Rodríguez-Casas, Oscar Moreno-Ramos, Donald Johnson, Eduardo Canseco-Vilchis, Thomas Thompson, and Jesús Salazar-Gómez

Salazar, G.M., O.H. Moreno, R.I., Cruz, and R. Salazar. 1998. Plant population density x sowing date interaction in wheat. Cereal Res. Comm. 26: 225–232 Salazar R. Plant population

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Cereal Research Communications
Authors: Oscar Moreno-Ramos, Julio Rodríguez-Casas, Donald Johnson, Eduardo Canseco-Vilchis, Thomas Thompson, and Jesús Salazar-Gómez

Under the use of the new irrigated wheat production method on raised beds in NW Mexico, it is necessary to re-define the components of the traditional production technology, focused on population density (PD) and number of rows per bed (RPB). At the Yaqui Valley Agricultural Experiment Station an experiment was carried out during fall-winter 1991–1992, which consisted of a complete factorial of three plant arrangements: one, two, and three rows per raised bed (RPB), and seven population densities (PD): 20, 40, 80, 160, 240, 320 and 800 thousand plants per hectare (TPPH), in a randomized complete block design with four replications. Results indicated that average wheat grain yields were 730 and 250 kg ha −1 higher when seeded at two RPB compared with one and three RPB, and PD had no significant effect. At PD higher than 80 TPPH, yields increased consistently. The response to PD was consistent up to around 240 TPPH. Differences in optimum PD were not so large and it is not necessary to change the recommendations when the plant pattern arrangement (RPB) is modified.

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. Individuals-area relationships: The relationship between animal population density and area. Ecology 81:734–748. James M. Y. Individuals-area relationships: The relationship between animal

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The western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is one of the most important maize pests, and was introduced to Slovenia in 2003 by natural spread from both the East and West. In Slovenia, as in other European countries, different patterns of spread and population growth of the WCR have been observed in maize growing areas, depending on the density of maize fields in the area and the frequency of maize in the crop rotation. In this study, the spread, population growth and impact on agriculture practice of the WCR have been analysed using GIS tools. In the period from 2003 to 2007, the spread and population growth were observed to be different between western and eastern Slovenia due to differences in population pressure from neighbouring areas and the portion of maize in the area. In the West, the distribution and prevalence of WCR has remained approximately unchanged since the first year of introduction, while in the East, both spread and population growth have become more progressive. However, both parameters showed only moderate progress up to 2006, while in 2007, conditions became more favourable for WCR development and spread. Spread was influenced significantly, although there were only 45 captured imagos per positive PAL pheromone trap per year after 4 years of presence, on average. Moderate growth of the WCR population was a consequence of the implementation of area-wide containment measures in a delimited area, which resulted in a considerable decrease of monoculture maize growth. This altered pattern of agricultural practice was confirmed with GIS analysis in areas that were demarcated in 2004 and 2005. In the maize growing area in the East, the portion of area under monocultural maize cultivation decreased from 28% to 5% in demarcated areas of WCR from 2004 and 2005, and decreased from 18% to 2% in 2007. In the area demarcated in 2004 in the West, the portion of monocultural maize is decreased in 2007 to only 3%, compared with 34% in 2003. Obviously Slovenian farmers have followed the legislation to a great extent and adopted crop rotation as the main WCR control measure. Implementation of area-wide containment measures from the first year of WCR infestation resulted in slower population growth and expansion.

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Trichoderma harzianum is a potential biocontrol agent against Sclerotinia sclerotiorum in soybean. Information is needed on the compatibility of this biocontrol agent and the post-emergent herbicides used in soybean cropping.Haloxyfop R Methyl (EC 10.4%), Glyphosate (SL 48%), Imazamox (WG 70%) and Imazethapyr (SL 10%) were evaluated for their effects on the mycelial growth of T. harzianum on in vitro agar plates. Glyphosate (2000 ppm), Imazethapyr (500 and 250 ppm) and Haloxyfop R Methyl (1000, 500 and 100 ppm) reduced the mycelial growth of T. harzianum . Imazamox had no effect at any concentration.Subsequently, all the herbicides were assessed for their effect on soil populations of T. harzianum . Greenhouse assays conducted with non-sterile soil inoculated with T. harzianum and a specific herbicide were sampled before pesticide application and after 30 days. The number of colony forming units per gram of soil (c.f.u./g of soil) was evaluated with a soil dilution technique using Trichoderma selective medium (TSM). No detrimental effect was revealed.

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Community Ecology
Authors: J. Herrmann, U. Kormann, C. Schüepp, Y. Stocker, F. Herzog, and M. Entling

fragmentation, population density, and prey availability on body condition of two orb-weaving spiders. Ecol. Entomol. 36: 680–685. Entling M.H. Contrasting effects of habitat fragmentation

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The spatial distribution of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) was analysed in ornamental crops (roses and spray-type carnations) and horticultural crops (pepper and strawberries), inside greenhouses, using sticky traps. In ornamental crops, at low population densities, during the winter, there was not a constant location of the isolated foci of infestation, from one week to the next, or a specific pattern of variation in that location. In spray-type carnations, pepper and strawberries, at higher population densities, in spring and summer, the basic units of distribution were the individuals, and they were aggregated. For roses, at those population levels, a random distribution was observed, with a tendency for aggregation. The number of traps needed to estimate population densities, in each crop, was evaluated for two fixed levels of precision (0.10 and 0.25) and results are indicated and discussed.

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Abstract  

Over the last decades the acceleration of the industrialization and urbanization processes together with the intensive agricultural practices have resulted in an impact on the Piracicaba river basin, state of São Paulo, Brazil. The source rivers drain from an area of low population density, absence of heavy industries, non-significant agriculture, native forest and reforestation, the opposite is found in the middle part of the basin. Samples of riverbed sediments were collected along the basin for chemical analysis. Results showed that the source rivers still preserve their natural characteristics, while the Atibaia river in the middle part shows signs of pollution from the agricultural activity, industrial effluents and urban sewage.

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