Mg In Plants Research Articles

Influence of acidity and other soil properties on metal concentrations in forest plants and animals

The influence of acidity and other soil properties on the concentrations of 22 elements in Fagus sylvatica, Oxalis acetosella, Carex pilulifera, Carabus hortensis/nemoralis, Clethrionomys glareolus, Apodemus flavicollis and Ficedula hypoleuca was investigated in 30 stands of European beech in southern Sweden. Soil pH and metal-ion saturation were positively correlated with Al, Ca, Fe and Mg in plants. They were negatively correlated with Rb in 10 of the 11 plant and animal materials and with Mn in all the plants but only in one animal material. Clay was positively correlated with Al and Ni in plants and negatively correlated with Rb in plants and animals. Soil organic matter showed weak correlations except for Rb in animals (positive). The strong relationship between soil acidity and biological accumulation of Rb was maintained over several trophic levels. Soil properties usually accounted for 55–85% of the variability in the concentrations of Al, Mn and Rb in the plants. Except for Rb, the concentrations in animals were less explicable, possibly due to homeostatic regulation. In plants, K was increasingly preferred to Rb with increasing soil pH and clay content. Concentrations in organs of Apodemus flavicollis were significantly correlated with those in Fagus sylvatica nuts (the dominating food item) only for Cu in the liver.

Growth and chemical composition ofCelmisia spedenii, an ultramafic endemic, andCelmisia markiion ultramafic soil and garden loam

Abstract Celmisia markii and the ultramafic endemic Celmisia spedenii were grown on ultramafic soil and garden loam for 5 years. C. markii grew poorly on ultramafic soil; 70% of the original plants died. C. spedenii showed better growth and seedling establishment on ultramafic soil. Concentrations of Ni, Cr, and Mg in plants on ultramafic soil were at least double those found in plants on garden loam; and both species showed similar uptake patterns for these elements on the two soils. Elements which had concentrations in both species on ultramafic soil at least 30 percent less than that found in plants on garden loam included Mo, Zn, Ca, P, Al, Sr, and K. For Ca and K, C. spedenii appeared to maintain higher concentrations than C. markii on both soils. Ultramafic tolerance in C. spedenii seems to involve greater nutrient uptake rather than exclusion of potentially toxic heavy metals, although the former may be a way of offsetting the effects of the latter.

OPTIMAL SOIL pH AND SUFFICIENCY CONCENTRATIONS OF N, P AND K FOR MAXIMUM ALFALFA AND ONION YIELDS ON ACID ORGANIC SOILS

The optimal soil pH and sufficiency concentrations of N in plants and P, K and Ca + Mg in plants and soils were determined for alfalfa (Medicago sativa L.) and onion (Allium cepa L.) grown on three acid organic soils in a growth chamber experiment. The heaviest (14 t/ha) liming rate reduced soil acidity from pH 3.4 to 5.1 (1 N KCl), pH 3.9–6.2, and pH 2.6–4.9 on soils 1, 2 and 3, respectively. Liming increased alfalfa yields on all soils, but onion yields on only two soils out of three. Yields were, however, not increased by liming soils above pH 4.5 for alfalfa and 4.0 for onion. At maximum yields, the concentration of Ca + Mg in alfalfa at pH 4.5 was about 145 meq/100 g tissue while the concentration in onion at pH 4.0 was about 86 meq, concentrations that are typical for these crops grown successfully on other soils. Alfalfa and onion yields were not increased by fertilizing these soils at higher levels than 200 kg N, 100 kg P and 400 kg K/ha. The average sufficiency concentrations of plant nutrients for obtaining maximum yields were: tissue, 2.0 and 2.1% N, 0.2 and 0.24% P, 1.2 and 1.9% K; soil, 90 and 100 ppm P (13 and 15 μg P/cm3), and 0.8 and 0.9 meq K/100 g (44 and 50 μg K/cm3) for alfalfa and onion, respectively.

Nitrogen Fixation (Acetylene Reduction) by Epiphytes of Freshwater Macrophytes

The involvement of epiphytic microorganisms in nitrogen fixation was investigated in a shallow freshwater pond near Ithaca, N.Y. The acetylene reduction technique was used to follow diel and seasonal cycles of nitrogen fixation by epiphytes of Myriophyllum spicatum. Acetylene-reducing activity was maximal between noon and 6 p.m., but substantial levels of activity relative to daytime rates continued through the night. Experiments with the seasonal course of activity showed a gradual decline during the autumn months and no activity in January or February. Activity commenced in May, with an abrupt increase to levels between 0.45 and 0.95 nmol of ethylene formed per mg (dry weight) of plant per h. Through most of the summer months, mean rates of acetylene reduction remained between 0.15 and 0.60 nmol/mg (dry weight) per h. It was calculated from diel and seasonal cycles that, in the pond areas studied, epiphytes were capable of adding from 7.5 to 12.5 mug of N per mg of plant per year to the pond. This amount is significant relative to the total amount of nitrogen incorporated into the plant. Blue-green algae (cyanobacteria), particularly Gloeotrichia, appeared to bear prime responsibility for nitrogen fixation, but photosynthetic bacteria of the genus Rhodopseudomonas were isolated from M. spicatum and shown to support high rates of acetylene reduction.

Improvements in calcined magnesite as a magnesium fertilizer

SummaryA laboratory and glasshouse study investigated whether it was possible to improve the availability of magnesium from calcined magnesite (MgO). Samples varying from largely unchanged magnesite (MgCO3) to overburnt MgO were made by calcining small quantities of magnesite ore for up to 6 h at several temperatures between 500 and 1000 °C in the laboratory. The effect of calcining conditions on weight loss on ignition, particle size distribution, total, water-soluble and NH4+ -exchangeable Mg was determined and results compared with the current commercial oxide and kieserite (MgSO4. H2O).The results indicated that an oxide could be produced containing nearly double the amount of readily-exchangeable Mg of the oxide used at present. The analysis showed that the most reactive oxide was produced either by burning for 3 h at 700 °C or about half-an-hour at 800 °C, i.e. the minimum time at each temperature for complete conversion of the carbonate to the oxide. Either of these two oxides increased the Mg in plants of the three crops grown in the glasshouse by 0·3% on average, whereas plants given the commercial oxide increased it by only 0·2%. The three crops removed about 70% of the applied Mg from the most reactive oxides but only 50% of the Mg from the commercial oxide. The results of an incubation experiment suggested that burning at 700 °C for 3 h gave a marginally more reactive oxide than the short burn at 800 °C. However, the most reactive oxide produced supplied magnesium at a slower rate than kieserite. This may not necessarily be a disadvantage since most of the soils where Mg deficiency of sugar beet and similar crops is a potential problem need a Mg fertilizer which maintains or gradually increases soil Mg. Thus the improved oxide may bo suitable and a comparison in field experiments of the effects of kieserite and oxides produced under different calcining conditions is needed.

β-Sitosterolemia and Xanthomatosis

Although the usual diet may contain 150-250 mg of plant sterols, chiefly beta-sitosterol, only trace amounts of these sterols have heretofore been found in human or animal blood and tissues. We now report elevated plant sterol levels in the blood and tissues of two sisters with extensive tendon xanthomas but normal plasma cholesterol levels. Besides beta-sitosterolemia and xanthomatosis, no other physical, mental, or biochemical abnormalities were detected.Repeatedly, the plasmas of the two sisters have contained 27.1 and 17.7 mg/100 ml of beta-sitosterol, 9.7 and 8.2 mg/100 ml of campesterol, and 0.5 and 0.5 mg/100 ml of stigmasterol, respectively. These plant sterols constituted 15.6 and 11.3% of the total plasma sterols. Some 60% of the plasma beta-sitosterol and campesterol was esterified; the measurable stigmasterol was entirely unesterified. The transport of the plasma beta-sitosterol and campesterol was largely in low density lipoproteins (76 and 83%, respectively). High density lipoproteins carried the remainder. Plant sterols were barely detectable in the very low density lipoprotein fraction. Only trace amounts of stigmasterol could be detected in the low density and high density lipoprotein fractions. The plant sterol content of the red blood cells averaged 12-13 mg/100 ml packed cells or about 13% of the total sterols. Two tendon xanthoma biopsies with the usual high concentration of cholesterol had 36.7 and 4.0 mg of plant sterols/g dry wt, of which 25.7 and 2.9 mg were beta-sitosterol, entirely in the free form. Plant sterols were also found in adipose tissue (0.2 mg/g wet wt) and in skin surface lipids (3.2 mg/g of lipid). The intestinal absorption of beta-sitosterol in both the patients, measured by two techniques, indicated greatly increased absorption of this sterol (about 24 and 28% in the patients L. H. and R. H., respectively, normal absorption being <5%). We suggest that increased absorption of beta-sitosterol must be considered as one cause of this disease. The reason for the extensive xanthomatosis in these two patients remains unknown. Perhaps in some way plant sterols initiated the development of xanthomas with otherwise normal plasma cholesterol levels. Clinical atherosclerosis has not yet occurred. The occurrence of beta-sitosterolemia in these two sisters with un-affected parents suggests an inherited recessive trait.

Nutrient Concentration Changes in Corn as Affected by Dry Matter Accumulation with Age and Response to Applied Nutrients1

AbstractHybrid corn (Zea mays L.) was sampled each week on field plots of soil testing adequate in P and K at Muscle Shoals, Alabama, in 1972, to relate plant analyses results to growth and maturity. Treatments of N compared were no N, 28 kg/ha at planting + 84 kg/ha topdressed at tasseling, 56 kg/ha at planting, and 112 kg/ha at planting. Plots of cumulative yields vs nutrient concentrations were used to evaluate the results.Corn yields increased markedly with amount of applied N, but single and split applications of N resulted in similar yields. Concentrations of N in the top leaves, ears, and entire topgrowth also increased at each harvest date with amount of applied N. Applied N also resulted in higher concentrations of P, Ca, and Mg, but lower K concentrations in the top leaves at most sampling dates. At each rate of applied N, concentrations of N in leaves, ears, and entire tops decreased with maturity. Concentrations of P remained about the same; Ca and Mg first decreased and then increased to maturity, whereas the opposite trends resulted for K concentrations. These opposite trends in results from this experiment and from other studies illustrate the strong reciprocal relationship between concentrations of K and Ca + Mg in plants. Nutrient concentration trends with increasing yields and age of plant are influenced in general by amounts of available nutrients and various growth‐limiting factors.