WINTER ACTIVITY OF THE ROOTS OF PERENNIAL WEEDS

Science ◽  
1929 ◽  
Vol 69 (1785) ◽  
pp. 299-300 ◽  
Author(s):  
C. F. Rogers
Keyword(s):  
Winter Activity ◽  
Perennial Weeds

EFFECT OF NITROGEN FERTILIZER DOSE AND ROW SPACING ON AMARANTH PRODUCTIVITY

2019 ◽  
Keyword(s):  
Animal Husbandry ◽  
Dry Weight ◽  
Nitrogen Fertilizers ◽  
Row Spacing ◽  
Cereal Aphid ◽  
Perennial Weeds ◽  
Food And Feed ◽  
Leaf Surface Area ◽  
Cultivation Technology ◽  
Photosynthetic Potential

Amaranth is a valuable food and feed crop that can solve the problem of vegetable protein in animal husbandry. The aim of the research was to study elements of amaranth cultivation technology: the dose of nitrogen fertilizers (without fertilizers, N15, N20, N25) and the row spacing (15, 30, 45 cm). The work was carried out on sod-podzolic medium loamy gleyic soil on the experimental field of FSBEI HE Yaroslavl State Agricultural Academy in 2018. The studied parameters were determined according to generally ac-cepted methods. The use of nitrogen fertilizers contributed to a significant increase in leaf area and pho-tosynthetic potential of amaranth crops at the highest values of the background N20 – 4.7 thousand m2 / ha and 324.08 thousand m2 / ha × days, respectively. Increase in row spacing when sowing amaranth raised the leaf surface area value, accumulation of dry aboveground mass, photosynthetic potential, ger-mination and safety at maximum values in the variant with a row spacing of 45 cm. abundance of weed flea, cereal aphid and sunflower fire. Sowing amaranth with a width of 45 cm between rows caused a sta-tistically significant decrease in the number of studied pests, as well as the number and dry weight of young and perennial weeds. The use of nitrogen fertilizers in a dose of 25 kg AI / ha contributed to a sig-nificant decrease in the yield of amaranth green mass from 145.12 q / ha on the «no-fertilizer» variant to 127.93 q / ha, with maximum values for the background N20 – 156, 55 kg / ha. Thus, the greatest effi- 128 ciency was shown by the introduction of nitrogen fertilizers at a dose of 20 kg ai / ha when sown with a row spacing of 45 cm.

scholarly journals Effects of disk tillage on soil condition, crop yield and weed infestation

2011 ◽  
Vol 48 (No. 1) ◽  
pp. 20-26
Author(s):  
M. Birkás ◽  
T. Szalai ◽  
C. Gyuricza ◽  
M. Gecse ◽  
K. Bordás
Keyword(s):  
Winter Wheat ◽  
Crop Yield ◽  
Field Experiments ◽  
Soil Layer ◽  
Soil Condition ◽  
Perennial Weeds ◽  
Weed Infestation ◽  
Set Up ◽  
Different Levels

This research was instigated by the fact that during the last decade annually repeated shallow disk tillage on the same field became frequent practice in Hungary. In order to study the changes of soil condition associated with disk tillage and to assess it is consequences, long-term tillage field experiments with different levels of nutrients were set up in 1991 (A) and in 1994 (B) on Chromic Luvisol at Gödöllö. The effects of disk tillage (D) and disk tillage combined with loosening (LD) on soil condition, on yield of maize and winter wheat, and on weed infestation were examined. The evaluation of soil condition measured by cone index and bulk density indicated that use of disking annually resulted in a dense soil layer below the disking depth (diskpan-compaction). It was found, that soil condition deteriorated by diskpan-compaction decreased the yield of maize significantly by 20 and 42% (w/w), and that of wheat by 13 and 15% (w/w) when compared to soils with no diskpan-compaction. Averaged over seven years, and three fertilizer levels, the cover % of the total, grass and perennial weeds on loosened soils were 73, 69 and 65% of soils contained diskpan-compaction.

Seasonal dynamics of carbohydrate and nitrogenous components in the roots of perennial weeds

1990 ◽  
Vol 13 (4) ◽  
pp. 359-365 ◽  
Author(s):  
D. R. CYR ◽  
J. D. BEWLEY ◽  
E. B. DUMBROFF
Keyword(s):  
Seasonal Dynamics ◽  
Perennial Weeds

scholarly journals Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

2016 ◽  
Vol 94 (12) ◽  
pp. 829-836 ◽  
Author(s):  
B.J. Klüg-Baerwald ◽  
L.E. Gower ◽  
C.L. Lausen ◽  
R.M. Brigham
Keyword(s):  
Heat Loss ◽  
Barometric Pressure ◽  
Myotis Lucifugus ◽  
Energetic Cost ◽  
Cold Temperatures ◽  
Bat Activity ◽  
Environmental Correlates ◽  
Interspecific Differences ◽  
Winter Activity ◽  
Species Specific

Winter activity of bats is common, yet poorly understood. Other studies suggest a relationship between winter activity and ambient temperature, particularly temperature at sunset. We recorded echolocation calls to determine correlates of hourly bat activity in Dinosaur Provincial Park, Alberta, Canada. We documented bat activity in temperatures as low as −10.4 °C. We observed big brown bats (Eptesicus fuscus (Palisot de Beauvois, 1796)) flying at colder temperatures than species of Myotis bats (genus Myotis Kaup, 1829). We show that temperature and wind are important predictors of winter activity by E. fuscus and Myotis, and that Myotis may also use changes in barometric pressure to cue activity. In the absence of foraging opportunity, we suggest these environmental factors relate to heat loss and thus the energetic cost of flight. To understand the energetic consequences of bat flight in cold temperatures, we estimated energy expenditure during winter flights of E. fuscus and little brown myotis (Myotis lucifugus (Le Conte, 1831)) using species-specific parameters. We estimated that winter flight uses considerable fat stores and that flight thermogenesis could mitigate energetic costs by 20% or more. We also show that temperature-dependent interspecific differences in winter activity likely stem from differences between species in heat loss and potential for activity–thermoregulatory heat substitution.

Seed germination strategies of five perennial weeds

Oecologia ◽  
1978 ◽  
Vol 36 (1) ◽  
pp. 113-126 ◽  
Author(s):  
S. J. Bostock
Keyword(s):  
Seed Germination ◽  
Perennial Weeds

Effect of Moonlight on Winter Activity of Showshoe Hares

1991 ◽  
Vol 23 (1) ◽  
pp. 61 ◽  
Author(s):  
B. Scott Gilbert ◽  
Stan Boutin
Keyword(s):  
Winter Activity

THE DISTRIBUTION OF DERMACENTOR TICKS IN CANADA IN RELATION TO BIOCLIMATIC ZONES

1967 ◽  
Vol 45 (4) ◽  
pp. 517-537 ◽  
Author(s):  
P. R. Wilkinson
Keyword(s):  
British Columbia ◽  
Deciduous Forest ◽  
Strong Association ◽  
Eastern Deciduous Forest ◽  
Egg Development ◽  
The North ◽  
Winter Activity ◽  
Bioclimatic Zone ◽  
Soil Temperatures ◽  
Time Of Year

Dermacentor andersoni has been collected north of Jasper, Alberta, close to 54° N. and near 53° N. in British Columbia. Spread to the north and northwest is probably limited by low summer soil temperatures, which would act principally by slowing egg development, thus disrupting the seasonal cycle of the tick. To the southwest, mild winters may fail to release diapause at the correct time of year. Aspect and slope are important factors. Altitude spread of records is from 1000–7000 ft. The most generally applicable description of its distribution is the ecotone between western grassland and moister regions, including clearings and rocky outcrops m the montane and Columbia forests, and shrubby areas of the prairies. In British Columbia, a series of randomly selected transects indicated a strong association between the tick's presence and several species of shrubs growing without tree shade.Each bioclimatic zone tends to have a characteristic group of rodents as main hosts of the immature stages. The prairie and montane regions differ in the indigenous hosts available to the adult tick.East of 105° D. andersoni is replaced by D. variabilis, which is adapted to the more humid summers of the eastern deciduous forest zones, and differs considerably from D. andersoni in its phenology. There are no reliable records of indigenous D. variabilis north of 52° latitude.D. albipictus occurs from the east to the west coast. Because of the winter activity of its larvae, allowing the whole summer for egg development, it is able to penetrate much farther north than the other two species. There are two records close to 60° latitude.

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