Response of paraquat-resistant and -susceptible horseweed (Conyza canadensis) to diquat, linuron, and oxyfluorfen

Weed Science ◽  
2004 ◽  
Vol 52 (4) ◽  
pp. 549-553 ◽  
Author(s):  
Susan Weaver ◽  
Michael Downs ◽  
Brandi Neufeld
Keyword(s):  
Dry Weight ◽  
Conyza Canadensis ◽  
Modes Of Action ◽  
Shoot Dry Weight ◽  
Age Dependent ◽  
Winter Annual ◽  
Susceptible Populations

Horseweed is a winter annual weed that has evolved resistance to multiple herbicide modes of action in 11 countries worldwide. A paraquat-resistant horseweed population in an Ontario orchard that was being managed by a rotation of herbicides began to show increased tolerance to the herbicide linuron. Experiments were conducted in the greenhouse to compare the response of this population and several paraquat-susceptible populations to linuron, diquat, and oxyfluorfen. Plants were sprayed with a range of doses of each herbicide when they were from 5 to 10 wk old, and the ED50, or dose at which shoot dry weight was reduced by 50%, was estimated. There was a sevenfold difference in the ED50values of the paraquat-resistant and -susceptible populations in response to diquat and a threefold difference in response to linuron. The response to oxyfluorfen was age dependent. The ratio of resistance to susceptible ED50values was estimated as 57 for 5-wk-old plants and 11 for 8-wk-old plants in response to oxyfluorfen. Ten-week-old plants from both populations showed no response to oxyfluorfen at rates up to 4.8 kg ai ha−1.

Paraquat resistance in horseweed (Conyza canadensis) and Virginia pepperweed (Lepidium virginicum) from Essex County, Ontario

Weed Science ◽  
1998 ◽  
Vol 46 (2) ◽  
pp. 200-204 ◽  
Author(s):  
Alida Smisek ◽  
Colleen Doucet ◽  
Martha Jones ◽  
Susan Weaver
Keyword(s):  
Dose Response ◽  
Dry Weight ◽  
Repeated Exposure ◽  
Conyza Canadensis ◽  
Essex County ◽  
Shoot Dry Weight ◽  
Paraquat Resistance ◽  
Resistant Population ◽  
Susceptible Populations ◽  
Fruit Orchards

Populations of horseweed and Virginia pepperweed resistant to the herbicide paraquat were found in several fruit orchards in Essex County, Ontario, Canada, where paraquat had been applied four to five times per year for at least 10 yr. Dose–response experiments were conducted in the greenhouse for each species, using 2-to 4-mo-old plants from populations that had received repeated exposure to paraquat and those that had not. The paraquat dose that reduced shoot dry weight by 50% (ED50) was estimated for each population. Resistant populations of horseweed had ED50 values 25 to 35 times higher than susceptible populations. A resistant population of Virginia pepperweed had an ED50 10 times higher than susceptible populations.

Cell Size and Pretransplant Nutritional Conditioning Influences Early Vine Growth and Yield of Transplanted Watermelon

HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 594e-594
Author(s):  
Charles J. Graham
Keyword(s):  
Cell Volume ◽  
Significant Influence ◽  
Field Performance ◽  
Dry Weight ◽  
Soluble Solids ◽  
Growth And Yield ◽  
Average Weight ◽  
Shoot Dry Weight ◽  
Solids Concentration ◽  
Soluble Solids Concentration

Research is needed to better understand the influence of cell volume and fertility on watermelon transplant size and field performance in order to determine the most economic production practices. `Jubilee' watermelon transplants were grown using a 4 x 4 factorial experimental design consisting of 4 cell volumes (30.7, 65.5, 147.5, and 349.6 cm3) and 4 fertility rates (0, 1/4, 1/2, and full-strength Hoagland's solution). Transplant shoot dry weight significantly increased as cell volume and fertility increased. Increasing cell volume linearly increased watermelon number/ha and tons/ha for early and total harvest in 1995. The average weight per watermelon significantly increased for early-harvested fruit but not for total harvest as cell volume increased in 1995. Soluble solids concentration linearly increased with increasing cell volume for early and total harvests in 1995. Cell volume had no significant influence on the harvest parameters measured in 1997. In 1995, increasing fertility linearly increased watermelon number/ha and tons/ha for early harvests. Increasing fertility increased the soluble solids concentration linearly for early-harvested watermelons in 1997 but not in 1995. Fertility rate had no significant influence on any of the other harvest parameters measured in 1995 and 1997. The growing conditions and disease pressure in 1997 reduced melons/ha, yield, and soluble solids content when compared to 1995 values. The half-strength Hoagland's solution produced the greatest number of watermelons/ha, tons/ha, and the highest soluble solids concentration in 1995 and 1997. Pretransplant nutritional conditioning had no significant effect on total `Jubilee' watermelon production in Louisiana for 1995 and 1997.

Effects of an Autoregulatory Senescence-inhibitor Gene Construct on Nicotiana alata Link and Otto.

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 519d-519 ◽  
Author(s):  
Kenneth R. Schroeder ◽  
Dennis P. Stimart
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Plant Height ◽  
Dry Weight ◽  
Nicotiana Alata ◽  
Wild Type ◽  
Gene Encoding ◽  
Delayed Senescence ◽  
Gene Construct ◽  
Shoot Dry Weight ◽  
Inhibitor System

Nicotiana alata Link and Otto. was transformed via Agrobacterium tumefaciens encoding a senescence-specific promoter SAG12 cloned from Arabidopsis thaliana fused to a Agrobacterium tumefaciens gene encoding isopentenyl transferase (IPT) that catalyzes cytokinin synthesis. This was considered an autoregulatory senescence-inhibitor system. In 1996, we reported delayed senescence of intact flowers by 2 to 6 d and delayed leaf senescence of transgenic vs. wild-type N. alata. Further evaluations in 1997 revealed several other interesting effects of the SAG12-IPT gene construct. Measurement of chlorophyll content of mature leaves showed higher levels of both chlorophyll a and b in transgenic material under normal fertilization and truncated fertilization regimes. At 4 to 5 months of age transgenic plants expressed differences in plant height, branching, and dry weight. Plant height was reduced by 3 to 13 cm; branch counts increased 2 to 3 fold; and shoot dry weight increased up to 11 g over wild-type N. alata. These observations indicate the system is not tightly autoregulated and may prove useful to the floriculture industry for producing compact and more floriferous plants.

scholarly journals EFFECT OF MINERAL DEFICIENCY ON MORPHOLOGICAL AND PHYSIOLOGICAL PARAMETERS AND ON SHOOT AND ROOT MINERAL PARTITIONING IN THREE SUNFLOWER VARIETIES / EFECTO DE LA FALTA DE ELEMENTOS MINERALAS SOBRE LOS PARAMENTROS MORFOLOGICOS Y FISIOLOGICOS Y REPARTICION DE ELEMENTOS MINERALES DE LA PARTE SOBRE EL SUELO Y DE LA RAIZ EN TRES VARIEDADES / INFLUENCE DE LA CARENCE D’ÉLÉMENTS MINÉRAUX SUR LES PARAMÈTRES MORPHOLOGIQUES ET PHYSIOLOGIQUES ET SUR LA DISTRIBUTION DES ÉLÉMENTS MINÉRAUX ENTRE LA PARTIE AÉRIENNE ET LA RACINE POUR TROIS SORTES DE TOURNESOL

Helia ◽  
2001 ◽  
Vol 24 (35) ◽  
pp. 135-148
Author(s):  
Mohammed El Midaoui ◽  
Ahmed Talouizte ◽  
Benbella Mohamed ◽  
Serieys Hervé ◽  
Ait Houssa Abdelhadi ◽  
...  
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Growth Parameters ◽  
Dry Weight ◽  
Mineral Deficiency ◽  
P Deficiency ◽  
Plant Parts ◽  
Shoot Dry Weight ◽  
K Deficiency ◽  
Matter Effect

SUMMARYAn experiment has been carried out in order to study the behaviour under mineral deficiency of three sunflower genotypes, a population variety (Oro 9) and two hybrids (Mirasol and Albena). Sunflower seedlings were submitted to five treatments: N deficiency (N0), P deficiency (P0), K deficiency (K0), N and K deficiency (N0K0) and a control. Plants were harvested when they reached 3-4 true pairs of leaves. Growth parameters measured (height, total leaf area, root length, root and shoot dry mater) were all significantly reduced by mineral deficiency. Leaf area was most reduced by N0 (-61%) and P0 (-56%). Total dry matter was most affected by N0 (-63%) and by N0K0 (-66%). Genotype comparisons showed that Oro 9 had the highest shoot dry matter while Albena had the lowest root dry matter. Effect of mineral deficiency on content and partitioning of N, P, K, Ca and Na was significant and varied according to treatments and among plant parts. Shoot dry weight was significantly correlated with root N content (r2=0.81) and root K content (r2=-0.61) for N0 and K0.

scholarly journals Applications of plant growth promoting bacteria and Trichoderma spp. for controlling Orobanche crenata in faba bean

2020 ◽  
Vol 44 (1) ◽  
Author(s):  
Mahmoud Ahmed Touny El-Dabaa ◽  
Hassan Abd-El-Khair
Keyword(s):  
Plant Growth ◽  
Faba Bean ◽  
Growth Parameters ◽  
Dry Weight ◽  
Research Centre ◽  
Plant Growth Promoting Bacteria ◽  
Fresh Weight ◽  
Orobanche Crenata ◽  
Trichoderma Spp ◽  
Shoot Dry Weight

Abstract Background Orobanche crenata is an obligate root parasite belonging to Orbanchaceae. Broomrape causes great damage to the faba bean. Several attempts were applied for controlling parasitic weeds. So, the aim of this work is to study the application of Trichoderma spp. as well as three rhizobacteria species in comparison to herbicidal effect of Glyphosate (Glialka 48% WSC) for controlling broomrape infesting faba bean (Vicia faba). Materials and methods Three pot experiments were carried out in the greenhouse of the National Research Centre, Dokki, Giza, Egypt during two successive winter seasons. Trichoderma inocula were adjusted to 3.6 × 108 propagules/ml and the bacterium inocula were adjusted at 107–109 colony-forming unit (CFU)/ml. All treatments were applied, before 1 week of sowing, at rate of 50 ml per pot in experiments I and II, while 100 ml per pot in experiment III. Results Trichoderma spp. (T. harzianum, T. viride and T. vierns) as well as three rhizobacteria species (Pseudomonas fluorescens, Bacillus subtilis and Bacillus pumilus) enhanced the growth parameters in faba bean plants, i.e. shoot length, shoot fresh weight, shoot dry weight and leaf number in the first experiment when applied without O. crenata infection. In the second experiment, all bio-control could protect plants against O. crenata infection, where it had better juvenile number reduction, than glyphosate after 2 months of application. Both B. subtilis and B. pumilus had the highest reduction to juvenile fresh weight, while their effect was equal to herbicide for juvenile dry weight, respectively. The bio-control agents had high effects until the 4th month, but it was less than that of the herbicide. In experiment III, the bio-control agents could highly reduce the juvenile parameters after 2 months, as well as juvenile fresh weight and juvenile dry weight after 4 months, than the herbicide, respectively. The bio-control agents were effective until 6 months, but less than the herbicide effect. All bio-control treatments highly increased the plant growth parameters, than the herbicide. Conclusion The application of Trichoderma spp. as well as rhizobacteria species could play an important role in controlling broomrape in faba bean as a natural bioherbicide.

scholarly journals Environmental cues affecting horseweed (Conyza canadensis) growth type and their sensitivity to glyphosate

Weed Science ◽  
2021 ◽  
pp. 1-35
Author(s):  
John A. Schramski ◽  
Christy L. Sprague ◽  
Eric L. Patterson
Keyword(s):  
Soil Moisture ◽  
Glyphosate Resistance ◽  
Single Parent ◽  
Environmental Cues ◽  
Conyza Canadensis ◽  
Growth Type ◽  
Susceptible Population ◽  
Water Imbibition ◽  
Growth Types ◽  
Winter Annual

Abstract Horseweed [Conyza canadensis (L.) Cronquist] is a facultative winter annual weed that can emerge from March to November in Michigan. Fall emerging C. canadensis overwinters as a rosette, while spring emerging C. canadensis skips the rosette stage and immediately grows upright upon emergence. In Michigan, primary emergence recently shifted from fall to spring/summer and therefore from a rosette to an upright growth type. Growth chamber experiments were conducted to determine 1) whether both C. canadensis growth types could originate from a single parent and 2) if common environmental cues can influence growth type. Variations in temperature, photoperiod, competition, shading, and soil moisture only resulted in the rosette growth type in four C. canadensis populations originating from seed collected from a single parent of the upright growth type. However, a vernalization period of four weeks following water imbibition, but prior to germination, resulted in the upright growth type. Dose-response experiments were conducted to determine whether glyphosate sensitivity differed between C. canadensis growth types generated from a single parent of the upright growth type. Upright type C. canadensis from known glyphosate-resistant populations ISB-18 and MSU-18 were four and three-fold less sensitive to glyphosate than their rosette siblings, respectively. Interestingly, differences in glyphosate sensitivity was not observed between growth types from the susceptible population. These results suggest that while C. canadensis populations shift from winter to summer annual lifecycles, concurrent increases in glyphosate resistance could occur.

scholarly journals Testing the potential of LEDs to enhance growth and quality characteristics of Salvia fruticosa

2019 ◽  
Vol 46 (No. 2) ◽  
pp. 98-106 ◽  
Author(s):  
Filippos Bantis ◽  
Kalliopi Radoglou
Keyword(s):  
Root Biomass ◽  
Weight Ratio ◽  
Dry Weight ◽  
Total Phenolic ◽  
Root Weight ◽  
Light Emitting ◽  
Shoot Dry Weight ◽  
Radiation Spectra ◽  
Salvia Fruticosa ◽  
Developmental Characteristics

The effect of light-emitting diodes (LED) with broad radiation spectra on developmental, physiological, and phytochemical characteristics of Greek sage (Salvia fruticosa L.) seedlings was assessed. Fluorescent (FL – control) tubes and four LED lights [AP67 (moderate blue, red and far-red), L20AP67 (moderate blue, red and far-red, high green), AP673L (moderate blue, high red) and NS1 (high blue and green, low red, high red : far-red, 1% ultraviolet)] were used in a growth chamber. Seedlings grown under FL, L20AP67 and AP673L exhibited the best morphological and developmental characteristics. FL led to inferior root biomass formation compared to all LEDs. AP67 promoted greater root-to-shoot dry weight ratio and dry-to-fresh overground and root weight ratios, but induced the least morphological and developmental characteristics. NS1 performed well regarding the root biomass production. Total phenolic content and the root growth capacity were not significantly affected. The present study demonstrates that L20AP67 and AP673L LEDs performed equally to FL light regarding the developmental characteristics. AP67 and NS1 may have the potential to be used for compact seedling production.

Acetyl salicylic acid alleviates chilling-induced damage in muskmelon seedlings

2007 ◽  
Vol 87 (3) ◽  
pp. 581-585 ◽  
Author(s):  
Ahmet Korkmaz ◽  
Murat Uzunlu ◽  
Ali Riza Demirkiran
Keyword(s):  
Salicylic Acid ◽  
Cucumis Melo ◽  
Chilling Stress ◽  
Foliar Spray ◽  
Dry Weight ◽  
Acetyl Salicylic Acid ◽  
Signal Molecule ◽  
Stress Indicator ◽  
Shoot Dry Weight ◽  
Significant Difference

Salicylic acid (SA) is a common plant-produced signal molecule that is responsible for inducing tolerance to a number of biotic and abiotic stresses. An experiment was, therefore, conducted to test whether acetyl salicylic acid (ASA) application at various concentrations through seed immersion or foliar spray would protect muskmelon [Cucumis melo L. (Reticulatus Group)] seedlings subjected to chilling stress. Twenty-one-day-old plants pre-treated with ASA (0, 0.1, 0.25, 0.50 or 1.0 mM) were subjected to chilling stress for 72 h at 3 ± 0.5°C. ASA, applied either through seed immersion or foliar spray, was effective within the range of 0.1 to 1 mM in inducing tolerance to chilling stress in muskmelon seedlings; however, there was no significant difference between application methods. ASA significantly and curvilinearly affected all seedling growth and stress indicator variables tested except shoot dry weight. The best protection was obtained from seedlings pre-treated with 0.5 mM ASA. The highest ASA concentration used was slightly less effective in providing chilling stress protection. Even though both methods provided similar means of protection, due to its simplicity and practicality, immersion of muskmelon seeds prior to sowing in 0.5 mM ASA would be a more desirable method to induce tolerance to chilling stress. Key words: Cucumis melo, aspirin, chilling stress tolerance, gas exchange, electrolyte leakage

scholarly journals Foliar applications of bio-fabricated selenium nanoparticles to improve the growth of wheat plants under drought stress

2020 ◽  
Vol 9 (1) ◽  
pp. 706-714
Author(s):  
Muhammad Ikram ◽  
Naveed Iqbal Raja ◽  
Bilal Javed ◽  
Zia-ur-Rehman Mashwani ◽  
Mubashir Hussain ◽  
...  
Keyword(s):  
Drought Stress ◽  
Field Capacity ◽  
Dry Weight ◽  
Positive Control ◽  
Morphological Characterization ◽  
Leaf Length ◽  
Selenium Nanoparticles ◽  
Fresh Weight ◽  
Wheat Varieties ◽  
Shoot Dry Weight

AbstractThe present study was aimed to biosynthesize selenium nanoparticles (SeNPs) and assess their foliar applications to improve the growth of wheat plants under controlled irrigation and drought stress. Bud aqueous extract of Allium sativum L. was used as a reducing and stabilizing agent of SeNPs followed by their optical and morphological characterization by using ultraviolet-visible spectroscopy, scanning electron microscopy, Fourier-transform infrared, and energy dispersive X-ray analysis. Various concentrations of SeNPs (10, 20, 30, and 40 mg/L) were applied exogenously to drought-tolerant (V1) and drought-susceptible (V2) wheat varieties at the trifoliate stage. Under the positive control conditions, plants were irrigated with 450 mL of water/pot (100% field capacity); and under water-deficit environment, plants were irrigated with 160 mL of water/pot (35% field capacity). Remarkable increase in plant height, shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, leaf area, leaf number, and leaf length has been observed when 30 mg/L concentration of SeNPs was used. However, the plant morphological parameters decreased gradually at higher concentrations (40 mg/L) in both selected wheat varieties. Therefore, 30 mg/L concentration of SeNPs was found most preferable to enhance the growth of selected wheat varieties under normal and water-deficient conditions.

The relationship between multiple leaders and mechanical and frost damage to the apical meristem of Scots pine seedlings

1990 ◽  
Vol 20 (3) ◽  
pp. 280-284 ◽  
Author(s):  
Jarmo K. Holopainen
Keyword(s):  
Scots Pine ◽  
Apical Meristem ◽  
Dry Weight ◽  
Frost Damage ◽  
Night Temperature ◽  
Shoot Dry Weight ◽  
Frost Injury ◽  
Pine Seedlings ◽  
Before And After ◽  
Multiple Leaders

The responses of young Scots pine seedlings to mechanical apical meristem damage before and after 4 nights exposure to minimum night temperatures of −2.2 and −6.7 °C in controlled environment growth chambers were compared with control seedlings that were subjected or not to apical meristem damage and exposed to a minimum night temperature of 12 °C. The feeding damage caused by Lygus bugs was simulated by piercing the apical meristem of young pine seedlings with a hypodermic syringe needle and injecting a small drop of distilled water into the wound. At −6.7 °C increased numbers of dead seedlings were found. The proportion of seedlings with multiple leaders greatly increased after piercing, and about half of the seedlings subjected to the apical meristem damage had multiple leaders. The proportion of seedlings with multiple leaders and the number of leader shoots per seedling did not differ among seedlings subjected to apical meristem damage before or after the frost exposure. Short and twisted primary needles occurred in the basal parts of the new shoots in the seedlings with multiple leaders. Seedlings with necrotic needles were most often found after exposure to the night temperature of −6.7 °C. Shoot dry weight and length were significantly lower in seedlings subjected to apical meristem damage after frost exposure than in seedlings subjected to apical meristem damage before frost exposure or to no frost exposure. The results suggest that an increased reduction in growth is to be expected if Lygus bug attacks occur on pine seedlings that already suffer from frost injury.

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