Effects of lodine in Various Formulations on the Growth of Barley and Pea Plants in Nutrient Solution Culture

The forms of iodine added to cultures of barley were potassiumiodide, potassium iodate, potassium periodate, and iodoaceticacid at iodine concentrations of 1.0 ppm and 10.0 ppm. Withpea, only iodide and iodate at 1.0 ppm iodine concentrationwere used. For both species, comparisons were made with culturesto which no iodine was added. In barley, growth was increased by 1.0 ppm iodine, the relativeeffectiveness of the different formulations being in the order:iodoacetic acid > iodide > iodate > periodate. With10.0 ppm, iodide and iodoacetic acid treatments gave reducedgrowth, iodate was without effect, and periodate enhanced growth. In pea, 1.0 ppm iodine was inhibitory, iodide being more toxicthan iodate. Analysis of dry matter showed iodine content according to treatmentto be in the order: iodide > iodoacetic acid > iodate> periodate     

Manganese toxicity in standard culture solutions

Summary Atlas barley plants grown in standard Hoagland culture solutions developed dark brown necrotic spots on the older leaves. The symptoms varied from small freckle-like spots to large blotchy areas and were found to be associated with the concentrations of Mn and B in the culture solutions. An increase in the concentration of Mn or B in the solutions increased the intensity of the spotting. A decrease in the Mn- and B-concentrations to 0.025 ppm, or one-twentieth of the normal Hoagland value, caused the spots to almost completely disappear. Mn- and B-concentrations of 0.025 ppm are optimum only under a particular set of conditions. In deciding what concentration of Mn and B to use the number of plants, volume of solution, macro-salt concentration, and season must be taken into consideration. The recommended Hoagland concentrations of Mn and B were only slightly toxic to lettuce and non-toxic to tomato plants. Barley plants grown in the winter were able to tolerate much higher concentrations of Mn and B before showing toxicity symptoms. Mn- and B-toxicity symptoms on lettuce and barley are compared in photographs.     

Effect of nicotine on in vitro maturation of bovine oocytes

The putative effect of nicotine on maturation and the chromosomal complement of bovine oocytes were investigated in the present study. Cumulus-enclosed oocytes were incubated in maturation medium with 0, 0.5, 1.0, 2.5, 5.0, and 10.0 mmol concentrations of nicotine. The results indicated that: (1) nicotine affected cumulus cell expansion in a dose-dependent manner and the perivitelline space failed to form when concentrations were equal to or greater than 5.0 mmol; (2) oocytes treated with 0.5 and 1.0 mmol nicotine concentrations resulted in maturation rates (83.3% and 85.9%, respectively) which was similar to the control (86.2%), whereas treatment with 2.5 and 5.0 mmol concentrations significantly decreased maturation rates to 70.2% and 26.7%, respectively; (3) nicotine at or over 2.5 mmol caused extremely irregular meiotic spindles and interrupted microfilament organization; (4) chromosomal analyses of oocytes with PB1 showed that oocytes derived from 0.5 and 1.0 mmol nicotine groups had haploid complements similar to the control (87-90%), but when the concentrations were increased to 2.5 and 5.0 mmol the haploid state was significantly reduced to around 70%; (5) oocytes at GVBD (germinal vesicle breakdown) and metaphase I stages were less affected by nicotine at 5.0 and 10.0 mmol concentrations than GV-stage oocytes; (6) maturation rates of the short-term nicotine-treated oocytes could be improved when subsequently incubated in normal maturation medium. Prolonged culture of nicotine-pretreated oocytes resulted in self-activation and some oocytes formed 1 or 2 pronuclei. In conclusion, nicotine affects bovine oocyte cumulus cell expansion, maturation rate, and chromosomal complement in a dose-dependent and an oocyte-stage-dependent manner.     

Toxicological aspects of pendimethalin induced activities of certain oxidising and hydrolytic enzymes in the germinating seedlings of maize (Zea mays L.)

Maize (Zea mays L.) variety NAC-6002 grains were exposed to a range of field relevant concentrations (0.5, 1.0, 2.5, 5.0 and 10.0 ppm) of formulated grade of pendimethalin. The seedlings were maintained in Hogaland and Arnon's nutrient media for up to 15 days to study the toxicity of pendimethalin on germination and activities of certain oxidizing and hydrolytic enzymes using embryonic axis and endosperms of 4, 6, 8, 10 and 15-day-old germinating maize seedlings. The percent germination, length of radicle and plumule decreased significantly with increasing pendimethalin concentrations. The α-amylase activity in the treated seedlings decreased with increasing concentration of pendimethalin in both endosperm and embryonic axis of maize seedling, when compared with control in all the days of observations. The catalase, peroxidase and polyphenoloxidase activity was high in both cotyledons and embryonic axis of treated sets at all time intervals of seedling during early growth over the period of 15 day when compared to control. However, catalase and peroxidase activity was decreased and polyphenoloxidase activity was higher in treated seedlings at higher pendimethalin concentrations. The present study therefore indicates that herbicidical stress brings constraints in the physiological events of seed germination and enzyme activity.     

Temperature effects on the response to sulphur of barley,peas and rape

Summary The effects of temperature and sulphur nutrition on the growth, yield and mineral composition (N, NO₃-N, S and SO₄-S) ofHordeum vulgare L. cv Olli,Pisum sativum L. cv Dark Skin Perfection, andBrassica campestris L. cv Arlo, were investigated in controlled environments. When barley and rape plants were grown at O ppm S, deficiency symptoms developed in about two weeks, whereas peas at the same level developed deficiency symptoms in about three weeks. The location of the deficiency symptoms varied between species. Plant weight increased with increasing S levels, but the shoot had a greater growth response than did the root. Optimum day/night growing temperature regimes for barley and peas were found to be near 24/16 at four weeks from seeding and near 18/10°C at the mature stage as evident from weights, maximum fruit set and mineral uptake. Optimum temperature for rape plants was near 29/21°C at both stages of growth. Mineral concentration was higher at four weeks after seeding than at the mature stage in pea and rape plants, while in barley the mineral concentration was similar at both stages of growth. With increase in S supply there was an increase in concentration of both total S and SO₄-S. Concentrations also increased with increasing temperatures. S deficient plants had increased total N and NO₃-N concentrations in all three species. NO₃-N concentration also increased with an increase in temperature while total N concentration was not appreciably influenced. These experiments indicated that the effects of S nutrition on growth, development and mineral composition of plants depends on the species, temperature regime and growth stage     

The Effects of Growth Substances on the Growth of Tapinanthus bangwensis (Loranthaceae) in vitro

The growth response of Tapinanthus bangwensis (Engler and K.Krause) Danser to exogenous growth substances, indole-3yl-aceticacid (IAA), kinetin, and gibberellic acid (GA₃), not only varieswith the concentrations of each of these substances in the mediumbut follows a similar trend in each case. Kinetin, IAA, andGA₃ were found to enhance growth but not by very appreciableamounts, kinetin being the most effective growth promoter. Highconcentrations of these substances (5.0 and 10.0 ppm) exceptGA₃ were toxic to the parasite. Gibberellic acid induced theproduction of accessory leaves at all the concentrations used.Kinetin was also effective in inducing accessory leaves butonly at a concentration of 1.0 ppm. Some of the lower concentrationsof the growth substances affected significantly some aspectsof the parasite's growth and development. Nevertheless, thegrowth in vitro was still slower than that in vivo.     

Penetration of the eastern subterranean termite into soil treated at various thicknesses and concentrations of Dursban TC and Premise 75

The ability of eastern subterranean termites, Reticulitermes flavipes (Kollar), to penetrate various concentrations and treatment thicknesses ranging from 1.0 to 50.0 mm of Dursban TC and Premise 75 was evaluated in a laboratory bioassay. Termites penetrated only a few millimeters into 500 ppm Dursban TC-treated soil at all thicknesses. As concentration decreased, termite penetration into Dursban TC-treated soil increased with termites generally penetrating completely through 5.0- and 0.5-ppm treatments. Termites penetrated at least 30% into 10-, 25-, and 50-mm thicknesses of 100 ppm Premise 75. Termites generally completely penetrated all concentrations < or = 100 ppm and thicknesses < or = 5 mm. At 7 d, termite mortality was 100% at all treatment thicknesses of Dursban TC at 500 and 50 ppm. At 5.0 and 0.5 ppm Dursban TC, termite mortality ranged from approximately 45 to 98% across all treatment thicknesses. At 100- and 10-ppm concentrations of Premise 75-treated soil, termites suffered > or = 75% mortality. Premise 75 at 1.0 and 0.1 ppm generally killed < or = 50% of the assayed termites at all treatment thicknesses.     

Effects of ethylene on root extension and nodulation of pea (Pisum sativum L.) and white clover (Trifolium repens L.)

Summary Low concentrations of ethylene, comparable with those known to occur in anaerobic soil, inhibited extension of pea roots to a similar extent to that previously reported for barley. Thus pea appeared to be less sensitive to ethylene than some non-leguminous dicotyledons. Perfusion of 10ppm of ethylene through the soil around the roots of pea and white clover resulted in reduced shoot dry weight. Nodulation, and the nitrogenase activity of those nodules which did form, was also greatly reduced. The ecological consequences of the sensitivity of nodulation and nitrogen fixation to ethylene, and the possible significance for quantitative studies involving the acetylene-reduction assay, are discussed.     

Exogenous treatment with salicylic acid attenuates cadmium toxicity in pea seedlings

The present study investigated the possible mediatory role of salicylic acid (SA) in protecting plants from cadmium (Cd) toxicity. The exposure of pea plants to increasing Cd concentrations (0.5, 1.0, 2.0 and 5.0 μM) during early stages of their establishment, caused a gradual decrease in shoot and root fresh weight accumulation, the rate of CO₂ fixation and the activity of ribulose-1,5-bisphosphate carboxylase (RuBPC, E.C. 4.1.1.39), the effect being most expressed at higher Cd concentrations. In vivo the excess of Cd-induced alterations in the redox cycling of oxygen-evolving centers and the assimilatory capacity of the pea leaves as revealed by changes in thermoluminescence emission after flash illumination. The levels of some important parameters associated with oxidative stress, namely lipid peroxidation, electrolyte leakage and proline production were increased. Seed pretreatment with SA alleviated the negative effect of Cd on growth, photosynthesis, carboxylation reactions, thermoluminescence characteristics and chlorophyll content, and led to decrease in oxidative injuries caused by Cd. The data suggest that the beneficial effect of SA during an earlier growth period could be related to avoidance of cumulative damage upon exposure to cadmium thus reducing the negative consequences of oxidative stress caused by heavy metal toxicity. In addition, the observed high endogenous levels of SA after treatment with Cd suggests that SA may act directly as an antioxidant to scavenge the reactive oxygen species and/or indirectly modulate redox balance through activation of antioxidant responses.Taken together these evidences could explain at some extend the protective role of SA on photochemical activity of chloroplast membranes and photosynthetic carboxylation reactions in Cd-stressed pea plants.     

Significance of digging behavior to mortality of red imported fire ant workers, Solenopsis invicta, in fipronil-treated sand

The effect of fipronil-treated sand on digging behavior and mortality of red imported fire ant, Solenopsis invicta Buren, workers was examined in the laboratory. No-choice digging bioassays where fipronil-treated sand was the only available digging substrate were conducted on two colonies at fipronil concentrations of 0.00, 0.05, 0.10, 0.50, 1.00, 1.50, and 2.00 ppm. Workers dug into the fipronil-treated sand in all cases, even at 2.0 ppm level, which caused 100% mortality in acute toxicity tests for both colonies. At 1.5 and 2.0 ppm, workers from the less sensitive colony had significantly higher mortality than those from the more sensitive colony, which might be explained by the significantly higher digging activity of the less sensitive colony. In two-choice digging bioassays where untreated sand was also available, workers dug into the fipronil-treated sand in 29 of 30 cases, even at 10.0 ppm level. At 1.0 and 10.0 ppm, mortality was positively correlated to digging effort in treated sand; however, such correlation was significant only at 1.0 ppm level. This indicates that digging did affect mortality; however, such effect is concentration dependent.     

Effect of Ampicillin on E. Coli of Swine Origin

The in vitro susceptibility of 103 cultures of E. coli isolated from scouring and nonscouring pigs, and four cultures of Salmonella isolated from a case of necrotic enteritis was tested against Ampicillin contained in nutrient broth at concentrations of 0, 0.1, 1.0 and 5.0 uG per ml. of the medium. All but three cultures of E. coli were found to be susceptible to 5.0 uG/ml., all Salmonella isolates were also susceptible to this concentration of the antibiotic. Susceptibility of E. coli was also tested by plating dilutions of fecal samples obtained from either a scouring or a nonscouring pig, with E.M.B. agar containing 0, 0.1, 1.0, 2.5, 5.0 and 10.0 uG Ampicillin per ml. of the medium. No difference in the growth of E. coli was observed at 0, 0.1 and 1.0 uG concentrations. The three higher concentrations of the antibiotic inhibited the growth of E. coli proportional to the amount of Ampicillin in each concentration.Ampicillin proved very effective in alleviating the symptoms of hemorrhagic enteritis in a 11-week old pig. The disappearance of scours was associated with the replacement of the previously existing sero-biotypes of fecal E. coliwith another aberrant type of E.coli which produced H(2)S. No Ampicillin resistant strains of E. coli emerged following treatment of the animal with this antibiotic.     

Growth and Phosphate Transport in Barley and Tomato Plants During the Development of, and Recovery from, Phosphate-stress

Barley and tomato plants were cultured in nutrient solutionsincluding 0.15 mol m^–3 H²PO^–₄. The phosphate supplywas discontinued and the subsequent effects on growth, internalphosphorus concentrations, phosphate absorption and translocationwere measured at frequent intervals. Growth rates were at firstunchanged and the internal phosphorus concentration decreased.During this phase the rate of phosphate transport by the rootssometimes increased significantly. Growth slowed more in shootsthan in roots during a second phase of stress development andvisual symptoms of deficiency appeared in tomato but not inbarley. During this phase, enhancement of phosphate uptake capacityreached a maximum in both species. The subsequent decline inuptake capacity was associated with visible symptoms of deficiencydeveloping in barley and intensifying in tomato. When stressedplants were returned to a solution containing 0.15 mol m^–3H₂PO^–₄ rapid absorption continued for several days afterthe internal phosphorus concentration had returned to the levelof the controls. Phosphate toxicity may have been the causeof leaf lesions and necrosis during the ‘recovery’phase. Stomatal conductance in tomato was decreased at an early stageof stress development. Foliar-applied phosphate was absorbedmore rapidly by P-stressed barley leaves than by their controlsand much larger amounts were translocated from the leaves tothe roots.     

Interrelationship between phosphorus toxicity and sugar metabolism in Verticordia plumosa L

Phosphorus, an essential plant nutrient, may become toxic when accumulated by plants to high concentrations. Certain plant species such as Verticordia plumosa L. suffer from P toxicity at solution concentrations far lower than most other plant species. In this study, exposure of V. plumosa plants to a solution containing as low as 3 mg l^–1 P resulted in significant growth inhibition and typical symptoms of P toxicity. In a wide range of P levels studied, micronutrient concentrations in V. plumosa leaves were within the range considered adequate for optimal growth. Notably, tomato plants with high hexokinase activity due to overexpression of Arabidopsis hexokinase (AtHXK1) exhibited senescence symptoms similar to those of P toxic V. plumosa. The resemblance in senescence symptoms between P-toxic tomato plants and those with high hexokinase activity suggested that increased sugar metabolism could play a role in P toxicity in plants. To test this hypothesis, we determined the amount of hexose phosphate, the product of hexokinase, in V. plumosa leaves grown at various P levels in the nutrient solution. Positive correlations were found between concentration in the medium, P concentration in the plant, hexose phosphate concentration in leaves and P toxicity symptoms. Foliar Zn application suppressed P toxicity symptoms and reduced the level of hexose phosphate in leaves. Furthermore, Zn also inhibited hexokinase activity in vitro. Based on these results we suggest that P toxicity involves sugar metabolism via increased activity of hexokinase that accelerates senescence     

Some physical properties of pot-plant composts and their effect on plant growth

Summary The effect of peat and grit on the physical properties of composts made from soils of different structural properties has been examined. Peat was beneficial in giving improved physical properties to the composts, better vegetative growth of tomato and Antirrhinum and also earlier flowering with tomato. It had, however, no significant effect on the total yield of tomato fruit. Peat also eliminated a sterilizing toxicity in a chalky boulder clay.Measurement of macro-pore volume gave the best physical assessment of the mixtures with respect to vegetative growth, but the extent to which the improved growth was dependent on the physical property or to some inherent property of the peat has not been determined.Grit was not such a good physical conditioner from either a plant growth or physical point of view as peat. The size of the grit over the range 0.5–1.0 to 3.0–5.0 mm did not cause any significant change in the physical properties of mixtures when used in the proportions 60 soil, 25 well-granulated peat, 15 grit.     

Calcium requirements of cardiac myofibril ATPase activity following exhaustive exercise

Myocardial contractility is reduced in rats following strenuous activity. Thus, the purpose of this study was to determine some of the cellular mechanisms that may contribute to the depressed contractile function. Myofibril ATPase activity was determined with varying free calcium and monomeric vanadate (Vi) concentrations. The Mg2+ stimulated myofibril ATPase activities were significantly reduced in the activity group (E). Myofibril ATPase activity from control animals increased from 0.056 +/- 0.021 to 0.216 +/- 0.030 mumol X Pi X mg-1 X min-1 with 0.1-10.0 microM Ca2+. The addition of 15.0 microM Vi resulted in a 37% decrease in ATPase activity of C animals. With regard to the experimental group, the myofibril ATPase activity at 0.1 and 1.0 microM Ca2+ were depressed (P less than 0.05) with the values at 5.0 and 10.0 microM Ca2+ being similar to the control group (P greater than 0.05). Incubations with Vi resulted in an enhanced myofibril ATPase activity for E compared to C animals. The ATPase activities were increased by 17, 10, 10 and 15% at 3.0, 5.0, 10.0 and 15.0 microM Vi. The results suggest that the exhaustive exercise raises the CA2+ requirement for half-maximal activation of cardiac myofibril ATPase activity and that the contracto-regulatory mechanism of cardiac muscle is similarly altered.     

Methanol as alternative carbon source for quicker efficient production of the microalgae Chlorella minutissima: Role of the concentration and frequence of administration

Autotrophic cultures of the marine microalgae Chlorella minutissima were performed at 13 000 lux continuous illumination in 1 l chambers fertilised with 0.25 g l⁻¹ F2 medium and different doses of methanol. This was administered in two ways during two parallel experimental series of 10 days: 0.05, 0.1, 0.5, 1.0 and 5.0% methanol (v/v) in one unique dose at the beginning of the culture and 1/10 of these (i.e. 0.005, 0.01, 0.05, 0.1 and 0.5% methanol (v/v)) in daily doses for the 10-day culture period. Low concentrations of methanol induced a faster increase of cell density and dry weight than control, while high concentrations induced symptoms of toxicity. The higher cell densities and quicker growth were observed in the experiments with daily administration of 0.005 and 0.1% (v/v) methanol, while those with one dose presented an initial boosted growth but a final cell density lower than control. The role of methanol as alternative carbon source for microalgae, as well as its possible impact on the quality of biomass production and on the environment, are discussed.     

Benomyl tolerance in Verticillium dahliae

In Verticillium dahliae isolates (‘wild type’) obtained prior to the advent of benzimidazole fungicides, growth of germ tubes and extension of mycelium were typically inhibited by benomyl at 0–3 ppm and 0.5-1.0 ppm respectively. Culture of such isolates in the presence of increasing concentrations of benomyl resulted in the selection of variants able to grow at 12.0 ppm. Conidia, and mycelium grown for 24 b, were each more sensitive to inhibition by benomyl than mycelium grown for 48 h. Mycelium of both wild-type and selected variants was still viable after treatment with 20 ppm benomyl in a nutrient medium for 112 days. Long-term treatments at 20 ppm caused the enlargement of mycelial cells and conidia, thickening of the cell walls and formation of large spherical inclusions apparently comprising or containing lipids.     

Effects of azadirachtin on the nutrition and development of the tobacco budworm,Heliothis virescens (Fabr.) (Noctuidae)

The plant chemical azadirachtin was administered, either in artificial diet or by oral injection, to fifth instar larvae of the tobacco budworm, Heliothis virescens (Fabr.). At a dietary concentration of 0.03125 ppm, azadirachtin significantly reduced the amount of diet consumed and the weight gained by the larvae. Higher dietary concentrations (0.25 and 0.5 ppm) were necessary to reduce the efficiency of larval conversion of digested and ingested food, respectively. However, the approximate digestibility increased at the dietary concentration of 0.25 ppm.Orally injected azadirachtin (0.25 and 0.5 μg) delayed moulting to the pupal stage, produced defective pupae or adults, and inhibited development to the adult stage. Higher doses (5.0 and 10.0 μg) reduced the pre-pupal weight loss normally associated with pupation, and completely inhibited pupation. At the critical dose of 1.0 μg (the minimal dose that disrupted development to the pupal stage), azadirachtin had less of an effect on older than on younger larvae. Larvae injected on the first day of the fifth instar failed to pupate, whereas approx 40% of those injected on subsequent days pupated.The results suggest that azadirachtin affects H. virescens in a manner similar to other tested species of insects. The significance of these results, especially regarding hormonal events in the insects, is discussed.     

Effects of aluminum,manganese, and lime on toxicity symptoms,nutrient composition,and yield of barley grown on a podzol soil

Summary Aluminum toxicity resulted in abnormal root development with many short thick roots and was found at pH 4.3 with or without added Al. The toxicity of Mn was found with no added Mn, and with 50 and 100 ppm added Mn at pH values ranging from 4.0 to 4.7 and appeared as dark spots on the leaves. At pH values ranging from 5.8 to 6.0, no toxicity symptoms were recorded in the absence of added Mn. Al was more detrimental to seedling development than was Mn.No kernels developed at 25 and 50 ppm added Al at pH4.1. Such toxicity was associated with Al contents of 9.6 to 28.5 g/ml of saturated extract of soil. The highest kernel yields were recorded at pH 5.8 to 6.0 and were associated with 116 to 296 ppm Mn in tissue and of less than 0.1 g/ml of Al in the saturated extract. Increased rates of Mn and Al resulted in increased concentrations of Ca, Mg, and K in the saturated extract of soil. The results indicated that Al toxicity can be eliminated by liming to soil pH values of greater than 5.5; however, Mn toxicity may occur at pH values as high as 5.8 in the presence of large quantities of Mn.Contribution no. 274, Research Branch, Research Station, P. O. Box 1210, Charlottetown, P. E. I.     

Cadmium-induced stimulation of stress-protein hsp70 in lichen photobiont Trebouxia erici

The expression of stress protein 70 (hsp70) was studied in lichen photobiont Trebouxia erici during short-term exposition to cadmium and copper (0.0, 1.0, 5.0 and 10.0 μM). We found two isoforms of hsp70 in the untreated as well as in heavy metal-treated cells due to the maintenance of protein homeostasis. Cu-treated cells had a relatively constant amount of hsp70 over all the tested concentrations. However, Cd caused an increase in hsp70 expression, especially at the lowest concentration (1.0 μM). Higher Cd concentrations were associated with acute toxicity and a reduced expression of hsp70 in the cells.