Symptoms Of Mg Deficiency Research Articles

Potassium-magnesium imbalance causes detrimental effects on growth, starch allocation and Rubisco activity in sugarcane plants

While there is abundant literature on the antagonistic interaction between potassium (K) and magnesium (Mg) during root uptake and transport, there is, however, little published data on the interaction between these nutrients within tissue, especially for sugarcane plants having high demand for K and Mg. This study aimed to investigate the effects of the interactions between K and Mg. Plants were grown in nutrient solution with increasing K application doses at low and adequate Mg treatments under controlled greenhouse conditions. Leaves, stalks and roots have been analyzed for growth, nutrient concentrations, starch partitioning, and activity of Rubisco. There were significant decreases in Mg concentration in all plant parts by increasing K supply, especially in roots. Leaf symptoms of Mg deficiency appeared not only in low Mg, but also in Mg adequate plants when plants treated with very high K. Magnesium adequate plants contained much higher amount of starch in roots, stalks and young leaves than the low Mg plants when K applications were at low levels. By contrast, there was a high accumulation of starch in the older leaves of the Mg deficient plants. Magnesium deficiency was also associated with significant decreases in Rubisco activity in leaves. Our results show clearly that high K doses interfere significantly with the positive effects of Mg on plant growth, Rubisco activity and starch accumulation in sink organs such as roots and stalks. It is obvious that the imbalance between K and Mg nutrition in sugarcane results in adverse consequences in sugar yield capacity.

Potassium–calcium antagonistic interaction under tomato magnesium deficiency and magnesium fertiliser regulation in solar greenhouse

This study sought to clarify the antagonistic interactions of potassium (K) and calcium (Ca) to magnesium (Mg) under a deficiency of Mg in tomato. Tomato leaves and soil samples that had differing levels of Mg deficiency were collected to study the relationship between symptoms of Mg deficiency and contents of soil K and Ca. Four different Mg fertiliser treatments were conducted to analyse the regulation of Mg for soil K, Ca and Mg. The results showed the following: (1) The yield of tomatoes decreased significantly with an increase in Mg deficiency, and the yield of tomatoes with moderate (MD) and severe (SD) Mg deficiency decreased by 38.02% and 59.53%, respectively, compared with treatments without Mg deficiency (ND). (2) The cation saturation ratio of K+ (CSRK+) was significantly higher with MD and SD compared with ND, while the CSRMg2+ was lower. The soil K/Mg and Ca/Mg values were higher than the critical value of imbalance. (3) The soil exchangeable K, CSRK+, Ca/Mg and K/Mg under SD increased significantly when compared with that under ND. (4) The content of Mg in tomato leaves and its yield were significantly negatively correlated with soil exchangeable K, CSRK+ and K/Mg. (5) With the increase in application of Mg fertiliser, the soil exchangeable K content, K/Mg and CSRK+ decreased significantly, while the Ca/K increased. The soil exchangeable K content, K/Mg and CSRK+ with 90 kg/ha MgSO4 and 234 kg/ha K2O applied (M2K1 treatment) were the lowest among all treatments. (6) The yields of tomatoes and uptake of Ca and Mg increased as supply of Mg increased. (7). Reducing the application of K was a much more efficient way to decrease soil K/Mg and restore cation imbalance than providing Mg fertiliser in calcareous soil.

Effects of magnesium remobilization and allocation on banana plant growth

ABSTRACTMagnesium (Mg) is known as one of the mobile elements and can move from the lower to upper leaf blade when the plants suffer from Mg deficiency. It is generally recognized that symptoms of Mg deficiency appear on lower leaves. This study was conducted to reveal the effect of Mg deficiency stress on remobilization of Mg and nitrogen in banana plant and to collect the typical symptoms of Mg deficiency. Quartz sand cultures were used to study the effect of Mg deficiency on banana growth and its mobilization and allocation in the plants. Results showed that chlorosis, a typical symptom of Mg deficiency, occurs in the second leaf from top of banana plant after 35 days of Mg deficiency. Necrosis of the whole leaf in the middle part of banana and a significant reduction of leaf area from the top to middle leaves are detected. However, older leaves remain green, and their area is not affected. Mg is more stable in the banana plant and cannot be remobilized and transported from the old to young leaves under Mg deficiency. After 195 days of Mg deficiency, the growth and Mg nutrition of Mg-deficient plant can be normalized by the restoration of Mg nutrient after 49 days of deficiency. Therefore, Mg in banana leaves is not mobile and reusable from older to younger leaves.

Magnesium nutrition of apple trees I. Preliminary studies

Symptoms of Mg deficiency on apple trees in the Warsaw district, Central Poland are described and illustrated. Results of soil and leaf analyses of deficient and healthy trees and factors affecting Mg deficiency in apples are discussed. Mg deficiency was found mainly in young trees grown on light, sandy or sandy loamy grey-brown podsolic soils; an old trees it was very rare, because of deep root penetration and utilization of Mg from illuvial horizons rich in Mg. Severe Mg deficiency symptoms appeared on old trees, vigorously growing after topworking with Bancroft scions. Low soil and leaf of Mg content a high available potassium to magnesium ratio in the soil and high ratio in the leaves are suggested to be important factors promoting Mg deficiency symptoms. A three years' experiment run on old Bancroft apple trees showed that 400 kg of MgO applied in epsomite to the soil were as effective as 4 sprays of 2% epsomite. Soil or foliar Mg fertilization did not have any significant effect on tree growth, yields, fruit drop and fruit quality.

The effect of soil and foliar applications of magnesium fertilisers on yields and quality of vine (Vitis vinifera, L.) grapes

A one-year field trial was established with the vine variety Ryzlink vlašský (Riesling italico) to evaluate the effect of spring soil applications and 5x repeated foliar application of magnesium fertilisers on yields and quality of grapes. On light soil of the experimental locality Žabčice (ca 25 km south of Brno) visual symptoms of Mg deficiency on vine leaves had been monitored in the past. The experiment involved 4 treatments: 1) unfertilised control; 2) spring soil application of Kieserite – 20 kg Mg.ha−1; 3) 5x foliar application of a 5% solution of Epso Combitop – Mg, S, Mn, Zn; 11.8 kg Mg.ha−1; 4) 5x foliar applications of a 5% solution of Epso Top – Mg, S; 14.8 kg Mg.ha−1.No significant differences among the treatments were detected in the contents of K (1.40–1.67%) and Ca (1.63–1.91%) in leaves sampled after the applications. After foliar applications the contents of Mg and S significantly increased in treatments 3–4 to 0.42–0.49% and 0.34–0.40 %, respectively compared to treatments 1–2 (0.29–0.30% and 0.22%, respectively). The content of Zn (173–380 mg.kg−1) and Mn (90–551 mg.kg−1) increased significantly in treatment 3 compared to the other treatments. The chlorophyll index did not differ among the treatments. Grape yields (t.ha−1) in treatments 1–4 were the following: 7.04–8.16–7.51–7.26 t.ha−1, respectively. Only the soil-applied treatment 2 differed significantly from the other treatments. The content of sugar (16.5–17.9 °NM), titratable acids (12.78–13.25 g.l−1) and the pH of must (3.02–3.11) did not differ among the treatments.

RELATIONSHIP OF IRON-MANGANESE TOXICITY DISORDER IN MARIGOLD TO MANGANESE AND MAGNESIUM NUTRITION

The iron-manganese (Fe-Mn) disorder in marigold (Tagetes erecta L.) is related to high Mn and low magnesium (Mg) in leaves. Three solution-culture experiments with marigold were conducted in a greenhouse. One investigated Mn and the disorder. Based on dry matter production, 4.5 mg Mn/L was the toxicity concentration and gave 880 mg Mn g−1 dry weight in new leaves and 1200 in old leaves. Manganese above 4.5 mg L−1 produced bronzed speckles on leaves. A second experiment investigated Mg and the disorder. Based on dry matter production, 10 mg Mg L−1 was the deficiency concentration and gave 1.5% Mg in the shoots. Symptoms of Mg deficiency did not resemble those of the disorder. A third experiment investigated Mn and Mg. Leaf chlorosis appeared at 2.5 mg Mn L−1 with the lowest supply of Mg. These experiments suggest that Mn supply is related to the disorder but increasing Mg does not alleviate the problem.

Low Magnesium with High Potassium Supply Changes Sugar Partitioning and Root Growth Pattern Prior to Visible Magnesium Deficiency in Leaves of Rice (<i>Oryza sativa</i> L.)

This research was conducted to investigate the effects of low magnesium (Mg) with high potassium (K) supply on the Mg concentration, sugar partitioning and root growth of rice (Oryza sativa L. cv. Wuyunjing 7) plants grown in hydroponics under greenhouse conditions, at Nanjing Agricultural University, China. The nutrient solution contained 0.01 and 1.0 mM Mg concentration, with K at 1.0 and 6.0 mM. Compared with the control (1mM Mg and K) treatment, the soluble sugar content at the treatment of low Mg (0.01 mM) with high K (6 mM) decreased by 35.7% in leaves, whereas increased 29.2% in roots at day 15 after treatment initiation. The shoot dry weight (DW) declined 12.9%, but root DW increased 12.1% leading to the significant increase in the root to shoot ratio at day 30. Furthermore, the total root length, total root surface area, root volume, average root diameter, total length of 0 - 0.5 mm and 0.5 - 1.0 mm diameter roots at day 30 significantly increased by 11.8%, 16.4%, 25.3%, 8.1%, 16.6% and 12.5%, respectively. Correlation analysis revealed the root to shoot ratio is closely related to the soluble sugar contents in roots and root morphological parameters of rice at day 15 and day 30. The typical visible symptoms of Mg deficiency in leaves of rice were obtained in the treatment of low Mg with high K at day 35. These findings indicated that low Mg with high K supply altered sugar partitioning and root morphological parameters, resulting in the increased root to shoot ratio prior to visible Mg deficiency symptoms in rice leaves. The increase in root to shoot ratio maybe an important adaptive mecha-nism for rice plants to respond to low-Mg stress during the early growth stage.

Deficiências de magnésio em solos e culturas do Norte de Portugal

Several studies carried out in Northern Portugal have drawn attention to the occurrence of magnesium deficiencies or deficient Mg nutrition in different crops. From July-August onwards symptoms of Mg deficiency can be observed in certain areas of this region in maize, fruit crops, fruit-trees and forest species. In the Tras-os-Montes and Alto Douro region and in the Entre-Douro and Minho region, Mg deficiencies in crops have been detected predominantly in soils located on schists of the Siluric and Ordovician, on schists of Precambrian and Cambrian of the Schist and Greywacke complex, and soils derived from two-mica alkaline granite. The following lithology is found in the schists and in the Schist and Greywacke complex: feldspar quartz-phyllites, phyllites, micaschists, graphytic slates, siltstones, ampelites, lydites, psamites, greywackes, phyllito-quartzites and quartzites. The soil units where low foliar Mg concentrations or visible Mg deficiencies in crops more often observed are: Dystric and Umbric Leptosols, Umbric Regosols, Dystric and Umbric Cambisols, Dystric and Umbric Fluvisols, Umbric and Aric Anthrosols and Cumulic Anthrosols. Some of the data presented here were gathered from studies where the main purpose was the confirmation of Mg deficiencies and surveys to assess the nutritional status of various crops. The majority of the studies used, as a diagnostic tool, both the foliar Mg concentrations and, in some cases, the nutrient ratios Mg/N and Mg/K. In some studies, the threshold values for the occurrence of Mg deficiencies were determined. Most studies showed correlations between foliar Mg concentrations and several soil chemical parameters, such as soil solution Mg2+, exchangeable Mg2+, ratios between exchangeable cations Mg2+/K+, Mg2+/Ca2+, Mg2+/Ca2+ + Mg2+, Mg2+/Ca2++ Mg2++K+, Mg2+/CTC, Mg2+/NH4+ and Mg2+/Al3++H+ or the combination of some of these ratios. Mg deficiency seems to be a classic problem in acid soils derived from parent material poor in Mg, but it can also be triggered by local factors or by inappropriate management practices.

Relations among Valencia orange yields with soil and leaf nutrients in Northwestern Paraná, Brazil

The Valencia orange orchards established on soils of low fertility in the Northwest region of Paraná State, Brazil, have showed symptoms of Mg deficiency and reduced fruit yields. The objective of this study was to verify the relationship between yield with soil and leaf nutrients during 1996/97 growing season. Two sites of low and high productivity were selected in seven orchards. Leaf and soil samples (fertilized rows and interrows) were collected in 1996. The results showed that the citrus yields were negatively related with soil Mg/K and Ca+Mg/K ratios in the fertilized rows, and fruit weight positively correlated with leaf Zn in the low productivity orchards. The fruit weight was positively related with leaf Ca and soil Ca in the fertilized rows of the high productivity orchards. The results suggested an adequate lime and K fertilization managements in the fertilized rows, as well as an adequate Zn supply.

難消化性糖質（フラクトオリゴ糖）のミネラル吸収促進作用

The importance of indigestible carbohydrates such as dietary fiber is well recognized. In recent years, the stimulatory effects of indigestible sugars such as fructooligosaccharides (FOS) on mineral absorption have been discovered and examined. This review provides an overview of current research work in this field. FOS are not digested by human enzymes. Dietary FOS are effective for increasing not only apparent but also true intestinal calcium (Ca) absorption in rats. Dietary FOS also stimulate magnesium (Mg) and iron (Fe) absorption. These effects show dose dependency and are long-lasting. FOS increase the absorption of Mg from natural foods such as cocoa and rice bran. The increase in Ca and Mg absorption is diminished by cecectomy. Ca and Mg disappear from the colorectal contents in the course of transit from the cecum to the anus. The absorption of cecally infused Ca and Mg is increased by dietary FOS. Moreover, dietary FOS increase large intestinal calbindin-D9k. These results suggest that the stimulatory action of FOS is exerted in the large intestine. FOS improve the bioavailability of these minerals in sever disease models rats. Dietary FOS prevent osteopenia in both ovariectomized rats and gastrectomized rats. In gastrectomized rats, FOS feeding also prevents anemia. Supplying a diet with a high Ca and high phosphorus content markedly decreases Mg absorption, and rats fed such a diet exhibit typical symptoms of Mg deficiency. However, these symptoms are suppressed by FOS feeding. The Ca absorption-promoting effect of FOS has been confirmed in humans by two different methods (balance study and double isotope method). Therefore, it is expected that many clinical applications of FOS will be established in the near future.

Histology of magnesium-deficient Norway spruce needles influenced by nitrogen source.

Effects of magnesium deficiency and variation in nitrate to ammonium ratio on needle histology and chlorophyll concentration were investigated in current-year and one-year-old needles of clonal Norway spruce trees (Picea abies (L.) Karst.). Six-year-old trees were grown for one year in sand culture with circulating nutrient solutions containing a sufficient (0.2 mM) or a limiting (0.04 mM) concentration of Mg. The nitrogen concentration was not varied (5 mM), but the NO(3) (-)/NH(4) (+)-ratio was adjusted to 0.76 in Mg-sufficient and to 1.86, 0.76 or 0.035 in Mg-limited plants. Visible symptoms of Mg deficiency occurred only in current-year needles, indicating adequate Mg nutrition before the experiment. Under conditions of Mg limitation, chlorophyll and Mg concentrations were lowest in needles of trees supplied with NH(4) (+) as the major nitrogen source and highest in needles of trees supplied with NO(3) (-) as the major nitrogen source. In current-year and one-year-old needles, starch accumulation induced by Mg deficiency was increased when NH(4) (+) was the major nitrogen source. The accumulation of tannin spherules in current-year needles, which occurred in response to Mg deficiency, also increased with decreasing NO(3) (-)/NH(4) (+)-ratios. Deficient Mg supply caused premature aging in tissues of the vascular bundle, as indicated by modifications of the cambium and increased amounts of collapsed sieve cells. The number of collapsed sieve cells was slightly lower in needles grown in a NH(4) (+)-dominated nutrient regime than in needles grown in a NO(3) (-)-dominated nutrient regime. We conclude that was not directly toxic to Norway spruce trees at the applied concentrations. However, effects of Mg deficiency were considerably greater in an NH(4) (+)-dominated nutrient regime than in a NO(3) (-)-dominated nutrient regime.

FIELD DIAGNOSTIC TOOLS FOR ESTIMATING NITROGEN NEEDS FOR FRESH-MARKET TOMATOES IN KENTUCKY

In Kentucky, fresh-market tomato production is a 3-million-dollar crop involving 405 to 486 ha. During the 1980s, on-farm demonstrations showed yields and grower returns increased when intensive production practices were followed. Fertigation recommendations were based on a 1 N: 2 K ratio with a total of 225 kg N/ha. Symptoms of Mg deficiency and blossom-end rot sometimes were seen, and we were concerned about potentially high fertilizer concentrations in the plant root zone. Farm fertility trials (1992 to 1994) showed no yield response to applied N rates between 101 and 393 kg·ha–1. In 1993, a presidedress N test (PSNT) (NO3 + NH4-N) indicated 131 kg N/ha was available in the top 31 cm of soil. At the final tomato harvest, 343, 529, and 647 kg NO3 + NH4-N was measured in the top 46 cm of soil for the three N rates tested (191, 298, and 391 kg N/ha). In 1994, the PSNT showed 86 kg NO3 + NH4-N/ha was present in the top 31 cm of soil. At final harvest 58, 124, and 157 kg NO3 + NH4-N/ha was measured in the top 91 cm of soil for the 140, 225, and 309 kg N/ha applied. Tomato phenology vs. petiole NO3-N concentration showed that all three N levels gave similar values, with no clear distinction between petiole NO3-N and the N rates tested. Future tests need to include a zero applied N rate to determine if a predictable relationship exists between a PSNT or petiole NO3-N levels and a yield response to fertilizer N.

Consider Magnesium Homeostasis: III: Cytochrome P450 Enzymes and Drug Toxicity*

The serum contains only 0.3% of the body's magnesium (sMg). More than half is in bone and nearly half is intracellular. The bone Mg is in equilibrium with sMg, whereas red blood cell Mg (rbcMg) reflects sMg concentration while each cell is maturing. The kidney controls the sMg by reabsorption up to a serum level of 3mg/dL, and the amount saved varies with the Mg balance. Normal humans retain less than 25% of an intravenous Mg load test. When the sMg is normal and the load test and/or rbcMg values are abnormal, normomagnesemia Mg deficiency (MgD), Type I, exists. The earliest stage is latent MgD, which has been defined as more than 25% but less than 50% retention of Mg in a load test. In those with more severe stages of MgD, the Mg retention is more than 50%. Occult MgD is when there is more than 50% retention. Whenever the rbcMg level is also decreased, subclinical MgD is present. Type II MgD is clearly understood by everyone, because of the presence of hypomagnesemia. There are multiple causes of minimal urinary Mg wasting, plus other causes of MgD, and there are many subtle symptoms of MgD. Over 300 enzyme systems require Mg to function optimally, including the cytochrome P450 enzymes (CYP450). In vitro evaluation of CYP450 metabolism of drugs require a NADPH-generating system, which contains MgCl2 and requires NADPH cytochrome P450 reductase. NADPH-CYP450-reductase also requires Mg. Drug toxicity might well be due, in part, to CYP450 enzymes not being in an adequate environment when MgD is present. Symptoms and signs of both noncardiac and cardiotoxic drug reactions to theophylline and some of the second-generation antihistamines are similar to those found in MgD. MgD is a known risk factor for torsades de pointes TdP, which has been treated with Mg sulfate. Moreover, many of the causes of MgD are present in patients with drug intolerance. A comprehensive evaluation of Mg status should be done in all patients with drug reactions when CYP450 enzymes are involved, before, during and after intervention. This should include a sMg, rbcMg, and a 24-hour urine Mg levels. A urine creatinine/Mg ratio should be calculated using 24-hour urine concentrations. The metabolism of these drugs need to be studied in a population of patients with known normomagnesemia MgD.

A HYDROPONICS NUTRIENT SOLUTION BASED ON COMMERCIAL FERTILIZER'

Many people want to use hydroponics in production of plants but often are hobbyists with limited access to the reagents necessary to formulate a nutrient solution. Several readily available commercial fertilizers and chemicals with tomato-(Lycopersicon esculentum Mill.) as the test plant were used to develop a nutrient solution. A 20-8.8-16.6 IN-P-K) general purpose fertilizer was added (1 g/liter) to deionized water to make a basic solution. This solution was fortified with slow-release fertilizer (approx. 17N-2.6P-8.5K with Ca, Hg, and minor elements) at 1 g/liter added directly to hydroponics vessels. Tomato developed severe foliar symptoms of Ca deficiency in this medium. Addition of CaSO4 or CaCO3 at 0.5 or 1 g/liter to give a solid phase of these chemicals in the vessels prevented development of symptoms of Ca deficiency; however, plants now showed symptoms of Mg deficiency. Addition of MgS0 at 0.25 g/liter to the basic solution prevented symptoms o Mg deficiency. Analyses confirmed that leaf N, P, K, Ca, and Mg were sufficient. This solution was as good as Hoagland's No. 1 solution for growth of tomato, marigold, and cucumber and was better than Hoagland's solution for growth of corn and wheat.

A novel interaction of magnesium translocation with the supply of phosphorus to roots of grapevine (Vitis vinifera L.)*

Abstract. The role of phosphorus (P) in leaf magnesium (Mg) concentrations and photosynthesis was investigated in field and glasshouse experiments with grapevine (Vitis vinifera L., cvs. Chenin blane. Chardonnay, and Carignane). In the field, leaves of vines growing on soil with low available P exhibited symptoms of Mg deficiency and had low P and Mg concentrations. The rate of photosynthesis for leaves of untreated control vines was approximately 0.7 nmol CO2 cm 2 s 1. When P fertilizer was applied to the soil, Mg deficiency symptoms were eliminated, and leaf P and Mg concentrations increased to above critical levels. When Mg was applied as a foliar spray, leaf Mg increased to above critical levels, but leaf P did not change significantly. In both experiments, the rate of photosynthesis increased to greater than 1.0 nmol CO2 cm 2 s 1 after nutrient applications. Thus, under low soil P conditions, leaf photosynthesis was limited by leaf Mg concentrations. In glasshouse experiments in which vines were grown with and without P for three seasons, Mg accumulated in large roots of ‐ P vines to approximately twice the concentration found in roots of + P vines. Analysis of the xylem exudate from detopped plants showed that Mg concentration in xylem sap of + P vines was twice as great as that in ‐ P vines. When P was supplied to ‐ P vines, the concentration of Mg increased to the concentration of + P vines within 2 days. The results show that the translocation of Mg from roots to shoots of grapevine is dependent upon P supply to the roots and suggest that Mg translocation is more sensitive than uptake to P supply.

Changes in the content and form of magnesium in the first trifoliate leaf of subterranean clover under altered or constant root supply

Little is known of the forms of magnesium (Mg) in leaf tissue and how these forms may differ with increasing and decreasing Mg concentration in the leaf. In the present study, plants of subterranean clover (Trifolium subterraneum L.) were grown in solution, with increasing, decreasing and stable root supply of Mg over the range 0-160 8m. Old leaf tissue was sampled in six harvests over 21 days. The chlorophyll was extracted from the leafwith dimethyl sulfoxide. This partitioned Mg into that in either the chlorophyll or residual fibre after extraction, and that Mg unaccounted for by these fractions ('other'). The forms of Mg in leaves could be related to the Mg concentration in the leaf and were not influenced by whether the concentration in the leaf was increasing or decreasing. Chlorophyll concentration was stable at about 1% when the concentration of Mg in the leaf was greater than 776 8g g-1. Below this Mg concentration, the concentration of chlorophyll declined rapidly. The proportion of total leaf Mg in the chlorophyll ranged from 6% at 5000 8g g-1 Mg in leaf to 35% at 700 8g g-1. Magnesium associated with the residual fibre was generally 80% of the total tissue Mg, although this appeared to be about 60% when Mg concentrations in leaves were < 1000 8g g-1. When the Mg concentration in the first trifoliate leaf was below 600 to 800 8g g-1, the leaf showed symptoms of Mg deficiency and became relatively heavier than non-deficient leaves.

Effect of magnesium fertilization on yield and leaf composition of tomato plants

Abstract Tomato plants were grown for 2 years at 4 different rates of Mg fertilization on a Princeton loamy sand at pH 4.8 with 29 kg exchangeable Mg/ha. Calcareous limestone was used to provide a pH treatment in the second year. Magnesium deficiency symptoms were observed on plants grown on plots having ≤ 38 kg/ha NH4OAC‐extractable Mg. Application of 56 kg Mg/ha corrected Mg deficiency and produced a significant increase in yield. Application of calcitic limestone also produced significant yield increases, but did not affect the development of Mg deficiency symptoms. Tomato yield was increased 27.9% by Mg application and 17.7% by lime application. Highest tomato yield was obtained with application of 112 kg Mg/ha. Symptoms of Mg deficiency were observed when the Mg concentration in recently mature leaf tissue was in the 0.30 to 0.32% range. Magnesium concentration in leaf tissue increased linearly with increasing Mg rate. Leaf Mg concentration at various growth stages of the tomato plant was variable de...

INTERRELATIONSHIPS OF DIETARY MAGNESIUM, POTASSIUM AND PROTEIN IN HYPOMAGNESEMIA OF RATS

The purpose of this study was to investigate the effects of dietary magnesium, nitrogen and potassium on the hypomagnesemic syndrom in rats. Two hundred seventy male SpraguDawley rats weighing 50-{)0 g at the beginning wcre used in a 3x3x3 factorial treatment design. The experiment thus included '27 treatments, with ten rats randamly allotted to each. The experimental animals were fed diets in which the concentrations of Mg, N (as protein) and K were varied. Mg levels covered the range from deficiency to dietary adequacy. The symptoms of Mg deficiency, including skin lesions and lowered Mg contents of blood, muscle and bone, occured more quikly or with greater severityon the Mg-deficient diet when the levels of dietary N, supplied as casein, were increased from '2.2 to 3.0 or 3.8 %. These observations indicate that the interferenee by N is quantitative rather than qualitative and that presence of nitrate or other nonprotein nitrogen is not essentialto the depression of Mg availability. Elevated dietary K levels did not appear to influence the depressed weight gains and feed conversions resulting from law-Mg high-)l' feeding, but they did aggravate the hypomagnesemia. it is suggested that dietary K influenees Mg metabolism separatcly, rather than as part of the Mg-N interaction. An increased serum calcium generally occurred coincident to hypomagnesemia in this experiment, indicating that cakium is involved in same way in the Mg-)l' interaction. Dietary K levcls did not influence serum cakium concentrations.