Phytotoxic action of glyphosate and amitrole on corn seedlings

1978 ◽  
Vol 56 (18) ◽  
pp. 2196-2202 ◽  
Author(s):  
A. Ali ◽  
R. A. Fletcher
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Root Respiration ◽  
Primary Site ◽  
Purple Colour ◽  
Rapid Effect ◽  
Site Of Action

The phytotoxic actions of two herbicides, glyphosate and amitrole, were compared using corn seedlings. Six days after treatment with amitrole at 1.68 kg/ha, plant heights, leaf lengths, and shoot fresh weights were reduced 20, 20, and 25% respectively, whereas with glyphosate applied at 1.12 kg/ha the inhibition was 62, 60, and 84% respectively. The lowest concentration of glyphosate (0.28 kg/ha) inhibited plant growth more than the inhibition caused by the highest concentration of amitrole (3.36 kg/ha). A purple colour appeared on the whole shoot of plants treated with glyphosate, and with amitrole, only the new growth of shoots was white. Both treatments reduced chlorophyll levels and the amitrole treatment reduced the carotenoid levels more than the chlorophyll levels. The root growth of plants treated with 1.12 kg/ha glyphosate was inhibited more than 80%, whereas with amitrole at 1.68 kg/ha, the inhibition was 40%. Within 6 h glyphosate severely reduced the rate of root respiration and 12 h after treatment respiration was reduced more than 70%. This rapid effect on root respiration was not observed with amitrole, and even 48 h after treatment, the decrease in respiration was less than 30%. We conclude that the primary site of action of glyphosate in corn seedlings is in the roots whereas the effect of amitrole is in the shoot.

Sink strength of citrus rootstocks under water deficit

2021 ◽  
Author(s):  
Simone F da Silva ◽  
Marcela T Miranda ◽  
Vladimir E Costa ◽  
Eduardo C Machado ◽  
Rafael V Ribeiro
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Water Deficit ◽  
Carbon Allocation ◽  
Sink Strength ◽  
Rangpur Lime ◽  
Carbon Supply ◽  
Valencia Orange ◽  
Source Sink ◽  
Orange Trees

Abstract Carbon allocation between source and sink organs determines plant growth and is influenced by environmental conditions. Under water deficit, plant growth is inhibited before photosynthesis and shoot growth tends to be more sensitive than root growth. However, the modulation of source-sink relationship by rootstocks remain unsolved in citrus trees under water deficit. Citrus plants grafted on Rangpur lime are drought tolerant, which may be related to a fine coordination of the source-sink relationship for maintaining root growth. Here, we followed 13C allocation and evaluated physiological responses and growth of Valencia orange trees grafted on three citrus rootstocks (Rangpur lime, Swingle citrumelo and Sunki mandarin) under water deficit. As compared to plants on Swingle and Sunki rootstocks, ones grafted on Rangpur lime showed higher stomatal sensitivity to the initial variation of water availability and less accumulation of non-structural carbohydrates in roots under water deficit. High 13C allocation found in Rangpur lime roots indicates this rootstock has high sink demand associated with high root growth under water deficit. Our data suggest that Rangpur lime rootstock used photoassimilates as sources of energy and carbon skeletons for growing under drought, which is likely related to increases in root respiration. Taken together, our data revealed that carbon supply by leaves and delivery to roots are critical for maintaining root growth and improving drought tolerance, with citrus rootstocks showing differential sink strength under water deficit.

scholarly journals Sewage sludge application enhances soil properties and rice growth in a salt-affected mudflat soil

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuhua Shan ◽  
Min Lv ◽  
Wengang Zuo ◽  
Zehui Tang ◽  
Cheng Ding ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Organic Carbon ◽  
Plant Growth ◽  
Root Growth ◽  
Soil Fertility ◽  
Soil Properties ◽  
Soluble Sugar ◽  
Soil Reclamation ◽  
Rice Growth ◽  
Promote Plant Growth

AbstractThe most important measures for salt-affected mudflat soil reclamation are to reduce salinity and to increase soil organic carbon (OC) content and thus soil fertility. Salinity reduction is often accomplished through costly freshwater irrigation by special engineering measures. Whether fertility enhancement only through one-off application of a great amount of OC can improve soil properties and promote plant growth in salt-affected mudflat soil remains unclear. Therefore, the objective of our indoor pot experiment was to study the effects of OC amendment at 0, 0.5%, 1.0%, 1.5%, and 2.5%, calculated from carbon content, by one-off application of sewage sludge on soil properties, rice yield, and root growth in salt-affected mudflat soil under waterlogged conditions. The results showed that the application of sewage sludge promoted soil fertility by reducing soil pH and increasing content of OC, nitrogen and phosphorus in salt-affected mudflat soil, while soil electric conductivity (EC) increased with increasing sewage sludge (SS) application rates under waterlogged conditions. In this study, the rice growth was not inhibited by the highest EC of 4.43 dS m−1 even at high doses of SS application. The SS application increased yield of rice, promoted root growth, enhanced root activity and root flux activity, and increased the soluble sugar and amino acid content in the bleeding sap of rice plants at the tillering, jointing, and maturity stages. In conclusion, fertility enhancement through organic carbon amendment can “offset” the adverse effects of increased salinity and promote plant growth in salt-affected mudflat soil under waterlogged conditions.

THE EFFECT OF ULTRAVIOLET RADIATION UPON ENZYMATIC ACTIVITY AND VIABILITY OF THE YEAST CELL

1952 ◽  
Vol 30 (6) ◽  
pp. 561-570
Author(s):  
J. G. Aldous ◽  
D. K. R. Stewart
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ultraviolet Radiation ◽  
Lactic Dehydrogenase ◽  
Population Viability ◽  
Primary Site ◽  
Hexokinase Activity ◽  
Viable Cells ◽  
Site Of Action ◽  
Survival Level ◽  
Nuclear Damage

Suspensions of the cells of baker’s yeast were irradiated with ultraviolet light for sufficient times to produce populations of 75, 50, 30, and 5% viable cells. After washing and drying, various enzyme solutions were prepared from these cells. Enzymatic activities, on a nitrogen basis, were compared to those of solutions prepared from a nonirradiated population. At the 50% survival level, hexokinase, carboxylase, and zymase were inhibited to a degree roughly proportional to the viability. Carboxylase, and to a certain extent, hexokinase activity varied directly as the population viability. Catalase, alcohol dehydrogenase, and lactic dehydrogenase showed no diminution in activity even at the 5% survival level. These results suggest that although ultraviolet radiation may produce nuclear damage, the primary site of action may be certain enzymes of the cytoplasm.

scholarly journals Imaging local soil kinematics during the first days of maize root growth in sand

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Floriana Anselmucci ◽  
Edward Andò ◽  
Gioacchino Viggiani ◽  
Nicolas Lenoir ◽  
Chloé Arson ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Shear Strain ◽  
Root System ◽  
Capillary Rise ◽  
Image Correlation ◽  
Root Tip ◽  
Soil System ◽  
Local Soil ◽  
Initial Soil

AbstractMaize seedlings are grown in Hostun sand with two different gradings and two different densities. The root-soil system is imaged daily for the first 8 days of plant growth with X-ray computed tomography. Segmentation, skeletonisation and digital image correlation techniques are used to analyse the evolution of the root system architecture, the displacement fields and the local strain fields due to plant growth in the soil. It is found that root thickness and root length density do not depend on the initial soil configuration. However, the depth of the root tip is strongly influenced by the initial soil density, and the number of laterals is impacted by grain size, which controls pore size, capillary rise and thus root access to water. Consequently, shorter root axes are observed in denser sand and fewer second order roots are observed in coarser sands. In all soil configurations tested, root growth induces shear strain in the soil around the root system, and locally, in the vicinity of the first order roots axis. Root-induced shear is accompanied by dilative volumetric strain close to the root body. Further away, the soil experiences dilation in denser sand and compaction in looser sand. These results suggest that the increase of porosity close to the roots can be caused by a mix of shear strain and steric exclusion.

scholarly journals Effects of an azasterol inhibitor of sterol 24-transmethylation on sterol biosynthesis and growth of Leishmania donovani promastigotes

1995 ◽  
Vol 308 (1) ◽  
pp. 31-38 ◽  
Author(s):  
P A Haughan ◽  
M L Chance ◽  
L J Goad
Keyword(s):  
Cell Proliferation ◽  
Leishmania Donovani ◽  
Primary Site ◽  
Sterol Biosynthesis ◽  
Proliferation Inhibition ◽  
Complete Replacement ◽  
Inhibition Of Growth ◽  
Absolute Requirement ◽  
Cell Proliferation Inhibition ◽  
Site Of Action

Leishmania donovani promastigotes were cultured in the presence of an azasterol (20-piperidin-2-yl-5 alpha-pregnane-3 beta,20-diol) to determine the effects on sterol biosynthesis and cell proliferation. Inhibition of growth increased gradually with azasterol concentrations up to 5 micrograms/ml; concentrations of azasterol exceeding 5 micrograms/ml were lethal. Sterol biosynthesis was affected by the azasterol when administered at concentrations as low as 100 pg/ml. The primary site of action was the alkylation at C-24 of a delta 24-sterol precursor. The 24-alkylated sterols [ergosta-5,7,24(24(1))-trien-3 beta-ol and ergosta-5,7,22-trien-3 beta-ol] of the protozoan were replaced by delta 24-cholesta-type sterols which then accumulated in the cells. Administration of the azasterol together with a bis-triazole inhibitor of the 14 alpha-methylsterol 14-demethylase reaction, which operates in sterol biosynthesis, resulted in depletion of 24-alkylsterols and their replacement with predominantly 14 alpha-methylsterols lacking a 24-alkyl group. Continuous subculture of promastigotes in the presence of the azasterol resulted in gradual depletion of 24-alkylsterols and their complete replacement by delta 24-cholesta-type sterols. Transfer of the azasterol-treated cells to medium lacking azasterol resulted in a gradual restoration, after several subcultures, of the normal 24-alkylsterol pattern. The results indicate that, although 24-alkylsterols are normally produced by the protozoan, it can nevertheless survive with sterols possessing only the cholestane skeleton. Thus there is no absolute requirement for 24-alkylsterols to fulfil some essential ‘sparking’ role associated with cell growth in promastigotes.

A Technique to Assay Herbicide Translocation and Effect on Root Growth

Weed Science ◽  
1970 ◽  
Vol 18 (6) ◽  
pp. 715-716 ◽  
Author(s):  
W. A. Gentner
Keyword(s):  
Phaseolus Vulgaris ◽  
Plant Growth ◽  
Root Growth ◽  
Growth And Development ◽  
Plant Tissues ◽  
Rapid Evaluation ◽  
Plant Growth And Development ◽  
Red Kidney Bean ◽  
Soil Level ◽  
Nutrient Solutions

A split-stem technique was devised for the rapid evaluation of herbicide effect on root growth and herbicide translocation. Four rows of adventitious root initials were prominent on the stem of red kidney bean [Phaseolus vulgaris L.] seedlings. They were excised at the soil level above the vascular plate. Excised stems were longitudinally split for a distance of 75 to 90 mm leaving two rows of root initials on each stem portion. Split-stem halves were immersed in herbicide-nutrient and nutrient solutions, respectively, contained in paired 25 by 150-mm test tubes. Subsequent plant growth and development of treated plants reflected effects of the herbicide on root growth. Herbicide translocation often was indicated by abnormalities of growth of plant tissues remote from the herbicide solution.

Enhanced tomato plant growth in soil under reduced P supply through microbial inoculants and microbiome shifts

2019 ◽  
Vol 95 (9) ◽  
Author(s):  
Namis Eltlbany ◽  
Mohamed Baklawa ◽  
Guo-Chun Ding ◽  
Dinah Nassal ◽  
Nino Weber ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Growth Promotion ◽  
Bacterial Community Composition ◽  
Soil Microbial Communities ◽  
Rrna Gene ◽  
Pseudomonas Sp ◽  
Tomato Plants ◽  
Soil P ◽  
Bacterial Inoculants

ABSTRACT Soil microbial communities interact with roots, affecting plant growth and nutrient acquisition. In the present study, we aimed to decipher the effects of the inoculants Trichoderma harzianum T-22, Pseudomonas sp. DSMZ 13134, Bacillus amyloliquefaciens FZB42 or Pseudomonas sp. RU47 on the rhizosphere microbial community and their beneficial effects on tomato plants grown in moderately low phosphorous soil under greenhouse conditions. We analyzed the plant mass, inoculant colony forming units and rhizosphere communities on 15, 22, 29 and 43 days after sowing. Selective plating showed that the bacterial inoculants had a good rhizocompetence and accelerated shoot and root growth and nutrient accumulation. 16S rRNA gene fingerprints indicated changes in the rhizosphere bacterial community composition. Amplicon sequencing revealed that rhizosphere bacterial communities from plants treated with bacterial inoculants were more similar to each other and distinct from those of the control and the Trichoderma inoculated plants at harvest time, and numerous dynamic taxa were identified. In conclusion, likely both, inoculants and the rhizosphere microbiome shifts, stimulated early plant growth mainly by improved spatial acquisition of available nutrients via root growth promotion. At harvest, all tomato plants were P-deficient, suggesting a limited contribution of inoculants and the microbiome shifts to the solubilization of sparingly soluble soil P.

scholarly journals Root Microbiome Modulates Plant Growth Promotion Induced by Low Doses of Glyphosate

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Dario X. Ramirez-Villacis ◽  
Omri M. Finkel ◽  
Isai Salas-González ◽  
Connor R. Fitzpatrick ◽  
Jeffery L. Dangl ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Growth Inhibition ◽  
Growth Promotion ◽  
Action Spectrum ◽  
Dry Weight ◽  
Agricultural Fields ◽  
Low Doses ◽  
Shoot Dry Weight ◽  
Root Microbiome

ABSTRACT Glyphosate is a commonly used herbicide with a broad action spectrum. However, at sublethal doses, glyphosate can induce plant growth, a phenomenon known as hormesis. Most glyphosate hormesis studies have been performed under microbe-free or reduced-microbial-diversity conditions; only a few were performed in open systems or agricultural fields, which include a higher diversity of soil microorganisms. Here, we investigated how microbes affect the hormesis induced by low doses of glyphosate. To this end, we used Arabidopsis thaliana and a well-characterized synthetic bacterial community of 185 strains (SynCom) that mimics the root-associated microbiome of Arabidopsis. We found that a dose of 3.6 × 10−6 g acid equivalent/liter (low dose of glyphosate, or LDG) produced an ∼14% increase in the shoot dry weight (i.e., hormesis) of uninoculated plants. Unexpectedly, in plants inoculated with the SynCom, LDG reduced shoot dry weight by ∼17%. We found that LDG enriched two Firmicutes and two Burkholderia strains in the roots. These specific strains are known to act as root growth inhibitors (RGI) in monoassociation assays. We tested the link between RGI and shoot dry weight reduction in LDG by assembling a new synthetic community lacking RGI strains. Dropping RGI strains out of the community restored growth induction by LDG. Finally, we showed that individual RGI strains from a few specific phyla were sufficient to switch the response to LDG from growth promotion to growth inhibition. Our results indicate that glyphosate hormesis was completely dependent on the root microbiome composition, specifically on the presence of root growth inhibitor strains. IMPORTANCE Since the introduction of glyphosate-resistant crops, glyphosate has become the most common and widely used herbicide around the world. Due to its intensive use and ability to bind to soil particles, it can be found at low concentrations in the environment. The effect of these remnants of glyphosate in plants has not been broadly studied; however, glyphosate 1,000 to 100,000 times less concentrated than the recommended field dose promoted growth in several species in laboratory and greenhouse experiments. However, this effect is rarely observed in agricultural fields, where complex communities of microbes have a central role in the way plants respond to external cues. Our study reveals how root-associated bacteria modulate the responses of Arabidopsis to low doses of glyphosate, shifting between growth promotion and growth inhibition.

Carbonic anhydrase distribution in rodent embryos and its relationship to acetazolamide teratogenesis.

1981 ◽  
Vol 29 (10) ◽  
pp. 1213-1218 ◽  
Author(s):  
C M Schreiner ◽  
K S Hirsch ◽  
W J Scott
Keyword(s):  
Enzyme Activity ◽  
Carbonic Anhydrase ◽  
Staining Pattern ◽  
Carbonic Anhydrase Activity ◽  
Primary Site ◽  
Mouse Embryos ◽  
Histochemical Method ◽  
Site Of Action ◽  
Activity Form ◽  
Low Activity

The carbonic anhydrase inhibitor, acetazolamide, leads to a unique distal postaxial right forelimb deformity in rats and CBA/J mice, but SWV mice are completely resistant. Using Hansson's histochemical method, the distribution of carbonic anhydrase and its inhibition by acetazolamide in rat, CBA/J mouse, and SWV mouse embryos were compared. Carbonic anhydrase activity was demonstrable in many tissues of sensitive rat and CBA/J mouse embryos and in resistant SWV mouse embryos. The forelimb buds of resistant and sensitive embryos possess carbonic anhydrase activity in the area between the ectoderm and adjacent mesenchyma with no localization of enzyme activity corresponding to the malformation seen in acetazolamide teratogenesis. This suggests that carbonic anhydrase in the forelimbs is not the primary site of action for acetazolamide. A distinctive staining pattern of nucleated erythrocytes in resistant embryos indicated the presence of a low activity form of carbonic anhydrase in nearly half of the erythrocytes. A five-to tenfold greater amount of acetazolamide was needed to completely inhibit carbonic anhydrase activity in nucleated erythrocytes from resistant embryos than in those from sensitive embryos. The existence of a low activity form of carbonic anhydrase in SWV embryo erythrocytes may be the basis of resistance to acetazolamide teratogenesis.

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