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.

Yield and Height of Cotton as Affected by Weed Density and Nitrogen Level

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 40-42 ◽  
Author(s):  
E. L. Robinson
Keyword(s):  
Gossypium Hirsutum ◽  
Nitrogen Level ◽  
Weed Density ◽  
Nitrogen Levels ◽  
Annual Weeds

Cotton (Gossypium hirsutumL. ‘Stoneville 7A’) grown for 3 yr in competition with various weed densities and nitrogen levels showed annual weeds could reduce cotton heights as much as 75% and cotton yields as much as 88%. Cotton yields were increased by 18 to 30% by adding nitrogen to plots with no weeds. In 1973, cotton supplied with 224 kg/ha of nitrogen could tolerate up to 50% weeds without loss of yield. Weeds left to grow and reseed with no control resulted in increasingly greater competition with each succeeding year.

Yield and Seed quality of barley (Hordeum vulgare L.) as affected by variety, nitrogen level and harvesting time

2014 ◽  
Vol 2 (2) ◽  
pp. 93-100
Author(s):  
Shahnaj Yesmina ◽  
Moushumi Akhtarb ◽  
Belal Hossain
Keyword(s):  
Grain Yield ◽  
Seed Weight ◽  
Seed Quality ◽  
Quality Parameters ◽  
Nitrogen Level ◽  
Yield Attributes ◽  
Harvesting Time ◽  
Nitrogen Levels ◽  
Vigour Index

The experiment was conducted to find out the effect of variety, nitrogen level and harvesting time on yield and seed quality of barley. The treatments used in the experiment consisted of two varieties viz. BARI Barley 4 and BARI Barley 5, three harvesting time viz. 35, 40 and 45 Days after Anthesis (DAA) and nitrogen levels viz. 0, 70, 85 and 100 kg N ha-1 . The experiment was laid out in a spilt- spilt-plot design with three replications assigning the variety to the main plot, harvesting time to the sub-plots and nitrogen level to the sub-sub plots. Variety had significant effects on the all yield attributes except fertile seeds spike-1 . Seed quality parameters viz. normal seeds spike-1 , deformed seeds spike-1 , germination (%) and vigour index were statistically significant. The variety BARI Barley 5 produced higher grain yield and seed quality than BARI Barley 4. Grain yield from BARI Barley 5 and BARI Barley 4 were 4.59 t ha-1 and 4.24 t ha-1 , respectively. Significantly, the highest 1000-seed weight (46.90 g) was produced by BARI Barley 5 than (37.90 g) BARI Barley 4. The result revealed that harvesting time had significant effect on yield and yield attributes and seed quality parameters. Seed yield was highest (4.65 t ha-1 ) when the crop harvested at 40 DAA and it was increased linearly from 35 DAA. Maximum quality seed and 1000-seed weight (43.20 g) was obtained when the crop harvested at 40 DAA. All the yields, yield attributes and seed quality parameters were significantly influenced by nitrogen levels. The highest grain yield (5.14 t ha-1 ) was obtained when BARI Barley 5 variety was fertilized by 100 kg N ha-1 and the lowest (3.14 t ha-1 ) was obtained from control treatments. Normal seeds spike-1 , vigour index, germination (%) were better at 85 kg N ha-1 in variety of BARI Barley 5 than BARI Barley 4. So it can be concluded that BARI Barley 5 showed better result when fertilized with 100 kg N ha-1 and harvested at 40 DAA for getting maximum yield and 85 kg N ha-1 and harvested at 40 DAA for getting better quality seed.

INORGANIC NITROGEN LEVELS AND NITRIFICATION POTENTIAL IN LOWBUSH BLUEBERRY SOILS

1988 ◽  
Vol 68 (1) ◽  
pp. 63-75 ◽  
Author(s):  
LEONARD J. EATON ◽  
DAVID G. PATRIQUIN
Keyword(s):  
Ammonium Nitrate ◽  
Ammonium Sulfate ◽  
Soil Nitrogen ◽  
Plant Uptake ◽  
Inorganic Nitrogen ◽  
Garden Soil ◽  
Laboratory Studies ◽  
Vaccinium Angustifolium ◽  
Nitrogen Levels ◽  
Lowbush Blueberry

Soil ammonium and nitrate in the top 15 cm of soil were monitored after application of ammonium nitrate and ammonium sulfate to plots at 14 PF (previously fertilized) and 12 NF (never fertilized) lowbush blueberry (Vaccinium angustifolium Ait.) stands representing a range of soil types and management histories. Overall, nitrate values in unfertilized and ammonium sulfate plots were higher at PF than at NF sites, suggesting greater nitrification at PF sites. In laboratory incubation studies, nitrification proceeded immediately in soil from a PF site, but only after a 4-wk lag in that from an adjacent NF site. Nitrification rates were low compared to that in a garden soil (pH 6.6). N-Serve inhibited nitrification in both soils. In ammonium nitrate plots, "excess" N values (N values in fertilized plots minus values in unfertilized plots) were higher for PF than for NF sites, suggesting greater immobilization, plant uptake or loss of N at NF sites. There was no evidence, in laboratory studies, of immobilization of added N by soil from either type of site. Rhizome N concentration increased significantly in response to fertilization at an NF site, but not at a PF site. Key words: Blueberry (lowbush), fertilizer and soil nitrogen

INFLUENCE OF FOLIAR NITROGEN LEVELS ON SURVIVAL, DEVELOPMENT, AND REPRODUCTION OF WESTERN SPRUCE BUDWORM, CHORISTONEURA OCCIDENTALS (LEPIDOPTERA: TORTRICIDAE)

1985 ◽  
Vol 117 (1) ◽  
pp. 23-32 ◽  
Author(s):  
J. Wayne Brewer ◽  
John L. Capinera ◽  
Robert E. Deshon ◽  
Mary L. Walmsley
Keyword(s):  
Larval Mortality ◽  
Spruce Budworm ◽  
Dry Weight ◽  
Douglas Fir ◽  
Nitrogen Level ◽  
Pupal Weight ◽  
Western Spruce Budworm ◽  
Foliar Nitrogen ◽  
Nitrogen Levels ◽  
White Fir

AbstractThe influence of nitrogen levels in foliage of white-fir, Abies concolor, and Douglas-fir, Pseudotsuga menziesii, seedlings on various biological characteristics of the western spruce budworm, Choristoneura occidentalis Freeman, was studied. Seedlings were grown under greenhouse conditions and provided with nutrient solutions to maintain five foliar nitrogen levels ranging from 1.29 to 4.42% dry weight for white fir and 1.43 to 3.94% for Douglas fir. Larvae confined to treated seedlings were monitored through the next generation. Larval mortality was higher, and development time longer, at both upper and lower extremes of foliar nitrogen than at mid-level. Mean pupal weight was significantly greater for larvae reared on white fir with the mid-range foliar-nitrogen level. Mean number, and weight, of eggs laid were highest when larvae fed on foliage from the mid-range nitrogen level. Total number of larvae produced was lowest at the high and low extremes of foliar nitrogen levels.

scholarly journals Decade-long soil nitrogen constraint on the CO2 fertilization of plant biomass

2012 ◽  
Vol 3 (3) ◽  
pp. 278-282 ◽  
Author(s):  
Peter B. Reich ◽  
Sarah E. Hobbie
Keyword(s):  
Soil Nitrogen ◽  
Plant Biomass ◽  
Co2 Fertilization

Influence of Winter Annual Weed Removal Timings on Soybean Cyst Nematode Population Density and Plant Biomass

Weed Science ◽  
2010 ◽  
Vol 58 (4) ◽  
pp. 381-386 ◽  
Author(s):  
Valerie A. Mock ◽  
J. Earl Creech ◽  
Virginia R. Ferris ◽  
Steven G. Hallett ◽  
William G. Johnson
Keyword(s):  
Soybean Cyst Nematode ◽  
Plant Biomass ◽  
Cyst Nematode ◽  
Population Increase ◽  
Population Densities ◽  
Soybean Production ◽  
Winter Annual ◽  
Winter Annual Weeds ◽  
Annual Weeds ◽  
Weed Removal

Soybean cyst nematode (SCN) is one of the most yield limiting pathogens in U.S. soybean production. Henbit and purple deadnettle are winter annual weeds shown to facilitate SCN reproduction after crop harvest in the eastern Corn Belt. These weeds, along with volunteer soybean that germinates in autumn after harvest, are common to postharvest soybean production fields and provide an opportunity for SCN reproduction and population increase outside of the typical soybean production season. The objective of this experiment was to determine if autumn removal of these weeds and volunteer soybean can influence the winter weed seedbank, plant biomass, and SCN population densities. Microplots were established with or without Lamium spp. and volunteer soybean, and four winter weed removal timings (none, October, December, and May). Dry weights of autumn Lamium spp. were reduced 50% in October when grown in competition with volunteer soybean. SCN juveniles were found in henbit roots at higher densities in October (42 per gram of root) than December (5 per gram of root) and were also found in the roots of volunteer soybean (14 per gram of root) in October. SCN egg population densities were 50% lower in August after the summer fallow period. The results of this experiment suggest that autumn removal of winter annual weeds and volunteer soybean did not reduce SCN populations.

The effect of increased soil nitrogen associated with medic ley on the performance of a standard and a semi-dwarf wheat cultivar

1973 ◽  
Vol 13 (60) ◽  
pp. 63 ◽  
Author(s):  
CL Tuohey
Keyword(s):  
Grain Size ◽  
Soil Nitrogen ◽  
Harvest Index ◽  
Wheat Cultivar ◽  
The Other ◽  
Nitrogen Level ◽  
Plant Nitrogen ◽  
Dwarf Cultivar ◽  
Standard Cultivar ◽  
Better Than

Two cropping rotations of fallow-wheat and four years of barrel medic (Medicago truncatula) pasture were used to obtain two levels of soil total nitrogen on a grey clay at Longerenong College, Dooen, Victoria. A semi-dwarf cultivar, Mexico 120, and a standard cultivar, Olympic, were then compared at the two levels of soil nitrogen over four years from 1964 to 1967. Mexico 120 outyielded Olympic by 1490 kg ha-1 in 1964 at the higher soil nitrogen level; however, it did not yield any better than Olympic at low soil nitrogen in that year nor at either soil nitrogen level in the other years. Mexico 120 had higher tiller survival, larger grain size, and shorter straw than Olympic in all years. In 1965 and 1966 its harvest index and the percentage of plant nitrogen in the grain responded more to higher soil nitrogen than that of Olympic.

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