Effect of soil moisture regimes on the growth and fecundity of slender amaranth (Amaranthus viridis) and redroot pigweed (Amaranthus retroflexus)

Weed Science ◽  
2020 ◽  
pp. 1-6
Author(s):  
Asad M. Khan ◽  
Ahmadreza Mobli ◽  
Jeff A Werth ◽  
Bhagirath S. Chauhan
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Seed Production ◽  
Maximum Growth ◽  
Primary Objective ◽  
Amaranthus Retroflexus ◽  
Limiting Factor ◽  
Redroot Pigweed ◽  
Irrigation Interval ◽  
Moisture Regimes

Abstract Slender amaranth (Amaranthus viridis L.) and redroot pigweed (Amaranthus retroflexus L.) are increasingly problematic weeds of summer crops in Australia. Water is considered the most limiting factor in an agroecosystem, and water stress adversely impacts the growth and reproduction of plant species. The primary objective of this study was to determine the growth and fecundity of two Australian biotypes (Goondiwindi and Gatton) of A. viridis and A. retroflexus under water-stress conditions. Four water-stress treatments (100%, 75%, 50%, and 25% field capacity [FC]) at a 4-d irrigation interval were chosen. No difference was observed for growth and seed production between the two biotypes of both species when grown under varying soil moisture regimes. At 100% FC, A. viridis produced 44 g plant−1 aboveground biomass and 1,740 seeds plant−1. The maximum growth (46 g plant−1) and seed production (3,070 seeds plant−1) of A. retroflexus were observed at 100% FC. The growth and seed production of both species were reduced with increased water-stress levels. Both weeds responded to water stress by decreasing the shoot:root biomass ratio. However, A. viridis (290 seeds plant−1) and A. retroflexus (370 seeds plant−1) were able to produce a significant number of seeds per plant even at 25% FC. Results suggest that both weeds will produce seeds under water-limiting conditions. Therefore, management strategies are required to minimize the growth and survival of weeds in water-deficit conditions.

Interference of Redroot Pigweed (Amaranthus retroflexus) in Corn (Zea mays)

Weed Science ◽  
1994 ◽  
Vol 42 (4) ◽  
pp. 568-573 ◽  
Author(s):  
Stevan Z. Knezevic ◽  
Stephan F. Weise ◽  
Clarence J. Swanton
Keyword(s):  
Zea Mays ◽  
Grain Yield ◽  
Seed Production ◽  
Field Experiments ◽  
Amaranthus Retroflexus ◽  
Corn Yield ◽  
Leaf Stage ◽  
Redroot Pigweed ◽  
Emergence Date

Redroot pigweed is a major weed in corn throughout Ontario. Field experiments were conducted at two locations in 1991 and 1992 to determine the influence of selected densities and emergence times of redroot pigweed on corn growth and grain yield. Redroot pigweed densities of 0.5, 1, 2, 4 and 8 plants per m of row were established within 12.5 cm on either side of the corn row. In both years, redroot pigweed seeds were planted concurrently and with corn at the 3- to 5-leaf stage of corn growth. A density of 0.5 redroot pigweed per m of row from the first (earlier) emergence date of pigweed (in most cases, up to the 4-leaf stage of corn) or four redroot pigweed per m of row from the second (later) emergence date of pigweed (in most cases, between the 4- and 7-leaf stage of corn) reduced corn yield by 5%. Redroot pigweed emerging after the 7-leaf stage of corn growth did not reduce yield. Redroot pigweed seed production was dependent upon its density and time of emergence. The time of redroot pigweed emergence, relative to corn, may be more important than its density in assessing the need for postemergence control.

scholarly journals Amaranthus retroflexus L. (Redroot Pigweed): Effects of Elevated CO2 and Soil Moisture on Growth and Biomass and the Effect of Radiant Heat on Seed Germination

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 728
Author(s):  
Sandra Weller ◽  
Singarayer Florentine ◽  
Muhammad Mansoor Javaid ◽  
Amali Welgama ◽  
Aakansha Chadha ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Seed Germination ◽  
Elevated Co2 ◽  
Elevated Temperatures ◽  
Germination Rate ◽  
Biomass Productivity ◽  
Moisture Stress ◽  
Amaranthus Retroflexus ◽  
Future Climate Change ◽  
Redroot Pigweed

Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been investigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120 °C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed.

scholarly journals SUSCEPTIBILITY OF STRAWBERRY CULTIVARS TO DROUGHT CONDITIONS

2020 ◽  
Vol 8 (12) ◽  
pp. 171-178
Author(s):  
Abdullaev Ravshan Mavlyanovich ◽  
◽  
Abdullaeva Khilola Ravshanovna ◽  
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Relative Humidity ◽  
Water Content ◽  
Limiting Factor ◽  
Ecological Groups ◽  
Water Deficiency ◽  
Drought Conditions ◽  
Before And After ◽  
Strawberry Cultivars

The article reveals the data on the drought tolerance of strawberry cultivars, studied the water content and water stress in the leaves of strawberry cultivars belonging to different ecological groups. Currently, water deficiency and the amount of water available for irrigation are a limiting factor in expanding the area under crops and increasing productivity. In the experiments, the air temperature, relative humidity, water content in the leaves and the effect of soil moisture on water scarcity and the correlation between them were studied by taking samples from the leaves of strawberry cultivars before and after irrigation of the experimental fields.

Effects of 2,4-D and Dalapon on Weed Seed Production and Dormancy

Weed Science ◽  
1978 ◽  
Vol 26 (6) ◽  
pp. 543-547 ◽  
Author(s):  
R. S. Fawcett ◽  
F. W. Slife
Keyword(s):  
Seed Production ◽  
Chenopodium Album ◽  
Datura Stramonium ◽  
Amaranthus Retroflexus ◽  
Common Lambsquarters ◽  
Setaria Faberi ◽  
Redroot Pigweed ◽  
Giant Foxtail ◽  
Before And After ◽  
Annual Weeds

2,4-D [(2,4-dichlorophenoxy)acetie acid] and dalapon (2,2-dichloropropionic acid) were applied to a natural stand of annual weeds at a time near flowering to determine effects on seed production and the dormancy and viability of seeds produced. At rates of 0.6 and 1.1 kg/ha, 2,4-D reduced, respectively the seed production of common lambsquarters(Chenopodium albumL.) 99 and 99%, redroot pigweed(Amaranthus retroflexusL.) 77 and 84%, and jimsonweed(Datura stramoniumL.) 64 and 100%, while giant foxtail(Setaria faberiHerrm) seed production was increased to 307 and 381% of the control, respectively. Dalapon at rates of 2.2 and 4.5 kg/ha reduced respectively seed production of giant foxtail 100 and 100%, and jimsonweed 100 and 91%. Before and after overwinter burial in the soil, common lambsquarters seeds from plants treated with 4.5 kg/ha dalapon were less dormant than control seeds. After overwintering, redroot pigweed seeds from dalapon-treated plants were less dormant than controls, and more seeds survived the winter burial. Common lambsquarters and redroot pigweed seeds from plants treated with 1.1 kg/ha 2,4-D were more dormant than control seeds before overwintering,’ while giant foxtail seeds from 2,4-D treated plants were less dormant than controls after overwintering. Viability of seeds produced by herbicide-treated plants, as determined by germination in KCN, was not greatly different from control seeds. Treatment with 2,4-D or dalapon resulted in the production of common lambsquarters seeds which produced seedlings about half as vigorous as controls. Jimsonweed seedlings grown from seeds from 2,4-D-treated plants showed phenoxy herbicide injury symptoms.

Effect of varied soil moisture regimes on the growth and reproduction of two Australian biotypes of junglerice (Echinochloa colona)

Weed Science ◽  
2019 ◽  
Vol 67 (05) ◽  
pp. 552-559 ◽  
Author(s):  
Gulshan Mahajan ◽  
Navneet Kaur Mutti ◽  
Michael Walsh ◽  
Bhagirath S. Chauhan
Keyword(s):  
Soil Moisture ◽  
Seed Production ◽  
Environmental Conditions ◽  
Water Channel ◽  
Moisture Regimes ◽  
Unpredictable Environment ◽  
Biotype B ◽  
Moisture Conditions ◽  
Response To Water ◽  
Water Holding

AbstractJunglerice [Echinochloa colona (L.) Link] is a problematic weed in the northern grain region of Australia. Two pot experiments (Experiment 1 and Experiment 2) were conducted in a screen house to evaluate the growth and reproductive behavior of two biotypes (A, collected from a cotton (Gossypium hirsutum L.)–fallow; B, collected from a fence near a water channel) of E. colona in response to water stress (100%, 75%, 50%, and 25% water holding capacity [WHC]). Averaged across both biotypes, the plant height, biomass, and seed production of E. colona were reduced at 25% WHC compared with 100% WHC. However, E. colona still produced a considerable amount of seeds at 25% WHC (at least 365 seeds plant−1). Biotype A produced more seeds in the second experiment, while biotype B produced more seeds in the first experiment. In Experiment 2, at 100% WHC, biotype A produced more seeds (17,618 seeds plant−1) than biotype B (4,378 seeds plant−1), and similar observations were noticed for root biomass. Growth and seed production of E. colona at all moisture levels and environmental conditions ensure survival in an unpredictable environment and contribute to the weedy nature of this species. Results indicate that biotype A is more invasive than biotype B under favorable environmental conditions (100% WHC). This study suggests an enhanced competitive ability of some biotypes of E. colona in response to a range of environmental and soil moisture conditions in Australia. Under favorable environmental conditions, biotype A could be more problematic, as it has higher seed production than biotype B. Therefore, it is important to implement sustainable weed control methods for such biotypes in the early stages of crop growth to prevent loss of stored moisture.

Competition between Barnyardgrass (Echinochloa crus-galli) and Redroot Pigweed (Amaranthus retroflexus)

Weed Science ◽  
1984 ◽  
Vol 32 (2) ◽  
pp. 218-222 ◽  
Author(s):  
Gamini D. Siriwardana ◽  
Robert L. Zimdahl
Keyword(s):  
Soil Moisture ◽  
Interspecific Competition ◽  
Intraspecific Competition ◽  
Competitive Ability ◽  
Field Capacity ◽  
Amaranthus Retroflexus ◽  
Planting Depth ◽  
Seed Burial ◽  
Redroot Pigweed

Growth and competition of barnyardgrass [Echinochloa crus-galli(L.) Beauv. ♯ ECHCG] and redroot pigweed (Amaranthus retroflexusL. ♯ AMARE) were studied at different seed proportions, seed burial depths, and soil moisture levels. After 7 days, emergence from 1-, 2-, 4-, and 8-cm depths was 96, 90, 83, and 27% for barnyardgrass and 84, 73, 62, and 0% for redroot pigweed, respectively. Barnyardgrass was more competitive than redroot pigweed. Intraspecific competition of barnyardgrass was greater than interspecific competition from redroot pigweed. Increasing planting depth from 1 to 4 cm and increasing soil moisture from 30 to 50% (low) to 100% (high) of field capacity reduced the competitive ability of redroot pigweed.

scholarly journals The influence of water table depth on evapotranspiration in the Amazon arc of deforestation

2019 ◽  
Author(s):  
John O'Connor ◽  
Maria J. Santos ◽  
Karin T. Rebel ◽  
Stefan C. Dekker
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Growing Season ◽  
Dry Season ◽  
Rooting Depth ◽  
Limiting Factor ◽  
Recycling System ◽  
Moisture Recycling ◽  
Growing Season Length ◽  
Arc Of Deforestation

Abstract. The Amazon rainforest evapotranspiration (ET) flux provides climate regulating and moisture provisioning ecosystem services through a moisture recycling system. The dense complex canopy and deep root system creates an optimum structure to provide large ET fluxes to the atmosphere forming the source for precipitation. Extensive land use and land cover change (LULCC) from forest to agriculture in the arc of deforestation breaks this moisture recycling system. Crops such as soybean are planted in large homogeneous monocultures and the maximum rooting depth of these crops is far shallower than forest. This difference in rooting depth is key as forests can access deep soil moisture and show no signs of water stress during the dry season while in contrast crops are highly seasonal with a growing season dependant on rainfall. As access to soil moisture is a limiting factor in vegetation growth, we hypothesised that if crops could access soil moisture they would undergo less water stress and therefore would have higher evapotranspiration rates than crops which could not access soil moisture. We combined remote sensing data with modelled groundwater table depth (WTD) to assess whether vegetation in areas with a shallow WTD had higher ET than vegetation in deep WTD areas. We randomly selected areas of forest, savanna and crop with deep and shallow WTD and examined whether they differ on MODIS Evapotranspiration (ET), Land Surface Temperature (LST) and Enhanced Vegetation Index (EVI), from 2001 to 2012, annually and during transition periods between the wet and dry season. As expected, we found no differences in ET, LST, and EVI for forest vegetation between deep and shallow WTD, which because of their deep roots could access water and maintain evapotranspiration for moisture recycling during the entire year. We found significantly higher ET and lower LST in shallow WTD crop areas than in deep WTD during the dry season transition, suggesting that crops in deep WTD undergo higher water stress than crops in shallow WTD areas. The differences found between crop in deep and shallow WTD, however, are of low significance with regards the moisture recycling system as the difference resulting from conversion of forest to crop has an overwhelming influence (ET in forest is ≈ 2 mm day−1 higher than that in crops) and has the strongest impact on energy balance and ET. However, access to water during the transition between wet and dry seasons may positively influence growing season length in crop areas.

Influence of emergence time and density on redroot pigweed(Amaranthus retroflexus)

Weed Science ◽  
1998 ◽  
Vol 46 (6) ◽  
pp. 665-672 ◽  
Author(s):  
Stevan Z. Knezevic ◽  
Michael J. Horak
Keyword(s):  
Seed Production ◽  
Dry Matter ◽  
Plant Density ◽  
No Reduction ◽  
Field Studies ◽  
Amaranthus Retroflexus ◽  
Lateral Growth ◽  
Seed Number ◽  
Emergence Time ◽  
Redroot Pigweed

Field studies were conducted at two locations near Manhattan, KS, in 1994 and 1995 to determine the influence of density (0.5, 1, 2, 4, and 12 plants m−1row) and time of emergence on redroot pigweed growth in monoculture or with sorghum. Redroot pigweed was seeded at sorghum planting and at the three- to four-leaf stage of sorghum in plots with sorghum or alone. When redroot pigweed grew with sorghum, dry matter and seed production were reduced with later times of emergence. In monoculture, there was no reduction in dry matter or seed number between the emergence dates studied. Redroot pigweed dry matter and seed production per plant were reduced as plant density increased for plants grown in monoculture. The same trend was observed for redroot pigweed grown with sorghum that did not emerge early relative to sorghum. Plants grown at low density exhibited more lateral growth than when grown at higher densities because of intraspecific competition.

Effect of Emergence Time on Growth and Fecundity of Redroot Pigweed (Amaranthus retroflexus) and Slender Amaranth (Amaranthus viridis): Emerging Problem Weeds in Australian Summer Crops

Weed Science ◽  
2021 ◽  
pp. 1-26
Author(s):  
Asad M. Khan ◽  
Ahmadreza Mobli ◽  
Jeff A Werth ◽  
Bhagirath S. Chauhan
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Management Practice ◽  
Growth Period ◽  
Amaranthus Retroflexus ◽  
Planting Date ◽  
Late Spring ◽  
Planting Dates ◽  
Planting Time ◽  
Redroot Pigweed

Abstract Redroot pigweed (Amaranthus retroflexus L.) and Slender amaranth (Amaranthus viridis L.) are considered emerging problematic weeds in summer crops in Australia. An outdoor pot experiment was conducted to examine the effects of planting time of two populations of A. retroflexus and A. viridis at the research farm of the University of Queensland, Australia. Both species were planted every month from October to January (2017-18 and 2018-19), and their growth and seed production was recorded. Although both weeds matured at a similar number of growing degree days (GDDs), these weeds required a different number of days to complete their life cycle within each planting date. The growth period was reduced, and flowering occurred sooner as both species experienced cooler temperatures and shorter daylight hours. Compared to other planting times, both species exhibited increased height, biomass, and seed production for the October-sown plants, and these parameters were reduced by delaying the planting time. The shoot and root biomass of A. retroflexus and A. viridis (averaged over both populations) was reduced by more than 70% and 65%, respectively, when planted in January, in comparison to planting in October. When planted in October, A. retroflexus and A. viridis produced 11,350 and 5,780 seeds per plant, but these were reduced to 770 and 365 seeds per plant in planting date January, respectively. Although the growth and fecundity of these species were dependent on planting time, these weeds could emerge throughout the late spring to summer growing season (October to March) in southeast Australia and produce a significant number of seeds. The results showed that when these species emerged in the late spring (October), they grew vigorously and produced more biomass, in comparison with the other planting dates. Therefore, any early weed management practice for these species could be beneficial for minimizing the subsequent cost and inputs towards their control.

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