Effect of soil pH and N fertilization oh uptake and fractions of Ca and Mg in two barley cultivars

Abstract

A study has been made of the amounts of Ca and Mg removed from dry matter of young barley plants by sequential extraction with water, M NaCl, 0.4 M acetic acid and 0.6 M HCl. Two contrasting cultivars were examined and other factors included the effects of the soil pH in which the plants were grown and the form of N‐fertilizer used. The distribution of total Ca and Mg and the different fractions between young and old tissues was also examined.

Water and NaCl between them removed the bulk of the Ca and Mg (between 80 and 90%) and broadly, where uptake of total Ca or Mg increased with increase in soil pH, there was little change in the percentage of either cation appearing in the fractions, indicating a constant removal by the extractants, irrespective of content.

Only about a third of the total Ca was found in the upper half of the plants, against over 60% in the case of Mg and the same distribution was found for the percentages of the water‐soluble and the exchangeable fractions.

Small differences between cultivars and between N forms in respect of fractions and their distribution in the plant were found, but these did not affect the overall general pattern.     

Relationship between water soluble and exchangeable soil cations for estimating plant uptake and leaching potential

Abstract

The relationship between water soluble and exchangeable cations (Ca, Mg, Na, and K) was investigated for surface horizons of 195 soils including many taxonomic categories and a wide range in physical and chemical properties from around the world. This will provide information on exchangeable soil cation solubility for use in estimating plant uptake and leaching potential. Amounts of water soluble and exchangeable cations were not consistently related (r² of 0.50, 0.08, 0.77, and 0.49 for Ca, Mg, Na, and K). High correlations were biased by high water soluble and exchangeable cation levels of a few soils that had 3.8‐ and 2.5‐fold greater mean than median values. The ratio of exchangeable to water soluble cations was closely related to cation saturation (r² of 0.87, 0.95, 0.95, and 0.93 for Ca, Mg, Na, and K, respectively). As the degree of saturation of the exchange complex by a certain cation increased, solubility Increased. A change in saturation had less effect on K than on Na, Mg, and Ca solubility. Only exchangeable soil cations (NH₄OAc extractable) are routinely measured and reported in soil survey reports, thus, water soluble levels may be determined from cation saturation. This will allow estimation of the amounts of cation that can potentially move in solution through the soil or be taken up by plants. Use of cation saturation, in addition to exchangeable content, will better characterize soil cation availability by representing quantity, intensity, and buffer factors.     

An Improved Procedure for Determining Magnesium Fertilizer Dissolution in Field Soils

Abstract

The sequential extraction procedure currently used to measure magnesium (Mg) fertilizer dissolution in soils consists of removing dissolved Mg (step 1), and partially dissolved Mg (step 2), followed by an 18‐h extraction with 2 M HCl at room temperature to determine undissolved Mg (step 3). This procedure is satisfactory for soluble and moderately soluble Mg fertilizers but is not an accurate procedure for slightly soluble fertilizers, such as serpentine. When step 3 is replaced by a digestion procedure using 2 M HCl for 4 h at 90–95°C (improved step 3), the total serpentine Mg recovery (dissolved and undissolved Mg) from soil samples, either immediately after serpentine was added to soil or after a 21‐day incubation with moist soil, was about 100% compared to 40–50% by the original procedure. The improved procedure also increased the recovery of serpentine Mg applied to field soils. Therefore, this study recommends that the third step of the sequential extraction procedure be replaced by a 4 h digestion using 2 M HCl (90–95°C).     

Identification and fine mapping of a candidate gene for oil yellow leaf 2 conferring yellow leaf phenotype in maize

Leaf colour is an important agronomic trait for studying molecular mechanisms in chlorophyll biosynthesis and chloroplast development. Here, a novel mutant oil yellow leaf 2 (Oy2) with a typical yellow leaf phenotype at the seedling stage was identified from the mutant population derived from the maize inbred line RP125. Compared with wild type, Oy2 mutant displays decreased chlorophyll content, reduced photosynthetic capacity and impaired chloroplast structure, which is likely controlled by a single recessive gene. The Oy2 locus was then delimited into a 117 kb region on chromosome 5 harbouring four genes, amongst which the gene Zm00001d013013, encoding a magnesium chelatase subunit D, was identified as the only candidate gene associated with Oy2 mutant phenotype. Moreover, the expression levels of candidate gene Oy2 and genes associated with chlorophyll biosynthesis and photosynthesis were tested by RNA‐seq and qRT‐PCR, implying that the causal gene Oy2 playing a critical role in chlorophyll synthesis. Taken together, we propose that the causal gene Oy2 highly associated with the yellow leaf phenotype may be helpful in elucidating photosynthetic pigments biosynthesis and chloroplast development in maize.     

不同色泽石粉的质量分析评估

为了在饲料生产中更安全、科学地使用石粉,试验检测了河南省南阳地区不同色泽的石粉中钙、镁、铅、氟和砷等几种金属的含量,结果表明:白石粉中钙含量最高,红石粉中镁含量最高,灰石粉中铅含量超标。由于南阳石粉不论其色泽如何价格均相同,所以白石粉的性价比更高,更适合用作饲料原料来获得更高的经济效益。     

丙酸镁对西门塔尔牛氮平衡和能量平衡的影响

选用4头年龄3.5岁,体况良好,体重(500±20)kg的中国西门塔尔牛阉牛。采用4×4拉丁方设计,研究日粮添加丙酸镁(100 g/d)、丙酸(87 g/d)和氧化镁(24 g/d)对西门塔尔牛氮平衡和能量平衡的影响。结果表明:日粮中添加丙酸镁、丙酸和氧化镁后,各组采食氮、采食总能、粪能、尿能、气体能、产热量、消化能/采食能差异均不显著(P>0.05);丙酸镁组粪氮较对照和氧化镁组显著降低(P<0.05);处理组尿氮较对照组显著降低(P<0.05),处理组间差异不显著(P>0.05);丙酸镁和丙酸组可消化氮和沉积氮、代谢能和沉积能较对照和氧化镁组显著提高(P<0.05),氧化镁组沉积氮较对照组显著提高(P<0.05)。丙酸镁组消化能、沉积能/消化能和沉积能/采食能较对照和氧化镁组显著提高(P<0.05)。丙酸镁降低了粪氮和尿氮,提高了可消化氮、沉积氮、消化能、代谢能、沉积能、沉积能/消化能、沉积能/采食能,改善了氮平衡和能量平衡。     

A review of phosphorus homeostasis and the impact of different types and amounts of dietary phosphate on metabolism and renal health in cats

Elevated concentrations of serum phosphate are linked with progression and increased case fatality rate in animals and humans with chronic kidney disease. Elevated concentrations of serum phosphate can be a risk factor for development of renal and cardiovascular diseases or osteoporosis in previously healthy people. In rodents, an excess intake of dietary phosphorus combined with an inverse dietary calcium : phosphorus ratio (<1 : 1) contributes to renal calcification. Renal injury also has occured in cats fed experimental diets supplemented with highly soluble phosphate salts, especially in diets with inverse calcium : phosphorus ratios. However, not all phosphorus sources contribute similarly to this effect. This review, which focuses on cats, summarizes the published evidence regarding phosphorus metabolism and homeostasis, including the relative impact of different dietary phosphorus sources, and their impact on the kidneys. No data currently shows that commercial cat foods induce renal injury. However, some diets contain high amounts of phosphorus relative to recommendations and some have inverse Ca : P ratios and so could increase the risk for development of kidney disease. While limiting the use of highly soluble phosphates appears to be important, there are insufficient data to support a specific upper limit for phosphate intake. This review also proposes areas where additional research is needed in order to strengthen conclusions and recommendations regarding dietary phosphorus for cats.     

Potassium uptake characteristics of prunus rootstocks: Influence of solution Ca/Mg ratios and solution nickel

Abstract

Nutrient solution experiments were conducted in the growth chamber to study the influence of rootstock, solution Ca/Mg ratios and solution nickel on K uptake. The experimental plants were one‐year‐old prune trees: ‘French’ prune (Prunus domestica L.) scions grafted on Myrobalan 29C (P. cerasifera Ehrh.), Marianna 2624 (P. cerasifera x P. munsoniana?) or Nemaguard (P. persica x P. davidiana) rootstocks. Ion uptake parameters Imax, Km, and Cmin were calculated from ion depletion measurements over a 6 to 10‐hr period.

With K solution concentrations initially adjusted to 100 μM, K uptake rates of Prunus rootstocks were constant down to approximately 20–30 μM, then declined. Rootstocks were able to deplete solution K to concentrations less than 1 μM. There were no significant differences in K uptake parameters among the rootstocks tested.

Varying solution Ca/Mg ratio from 2.75/1 to 1/4 (Ca + Mg = 3.75 mM) had no effect on K uptake. Potassium uptake rates of Myrobalan 29C rootstocks in the presence of 100 μM nickel were not significantly different from those in the absence of nickel. Rates of nickel uptake were significantly lower than those of K. After eight days of pretreatment in solutions adjusted daily to 100 μM Ni(NO₃)₂, prune leaves began to show signs of interveinal chlorosis. Potassium uptake by nickel pretreated trees was not significantly different from that by control trees. Results are discussed in relation to field observations of K deficiency in prune orchards.     

Evaluation of Alternative Methods of Applying Sulfur Fertilizers to Chrysanthemums

ABSTRACT

Previous research has shown that supplying adequate sulfur (S) continuously in combination with reduced amounts of nitrogen (N) will produce a quality plant. However, not all commercially available fertilizers use the same source of S, contain the same or optimal concentration of it, or contain any S at all. Additionally, nutrient incompatibility can occur if all the macronutrients are combined in one solution or one dry fertilizer. Thus, the objective of this research was to determine the effect of different methods of application and different types of S fertilizers on chrysanthemum growth. Two experiments were conducted in which three S sources (H₂SO₄, MgSO₄, and K₂SO₄) were applied in combination with three N concentrations (50, 100, and 150 mg L^?1) as fertilizer treatments. Sulfur was applied at 10 mg L^?1, either continuously—by slightly acidulating the fertilizer solution with H₂SO₄—or in one, two, or three single, discrete applications as either K₂SO₄ or MgSO₄. Leaf N concentration was greatest when 100 or 150 mg N L^?1 was applied. As expected, S applied continuously by slightly acidulating the fertilizer solution with sulfuric acid resulted in higher leaf S concentration and larger flower diameter than under any of the other treatments. Together, plants fertilized with S continuously at 10 mg S L^?1 and N at 100 mg L^?1 were the largest, had the largest flower diameter, and contained the greatest leaf N and S concentrations. Sulfur concentration in the mix was highest and N concentration lowest when S was supplied continuously. Thus, if growers need to supply S and acidulate their water, sulfuric acid would be the best choice. If there are concerns about possible S contamination in landfills or in mix recycling, either potassium or magnesium S, applied multiple times as single applications in combination with 100 or 150 mg N L^?1, may be a better choice.     

Citrus leaf nutrient status: A critical evaluation of guidelines for optimal yield in Israel

Maintaining orchards with trees at optimal leaf nutrient concentrations is one of the key issues for maximizing yield. Experiments for evaluating and updating guidelines are very rare since they require several years of field experiments with mature fruit‐bearing trees. In the present paper, we first evaluated the Israeli guidelines for citrus by comparing them to the Israeli orchard leaf mineral status using a 10‐year leaf‐mineral database (results of 20 244 leaf analyses from commercial orchards all over Israel). Then, we created an updated guideline using a second database (the Israeli National Wastewater Effluent Irrigation Surveys database; INWEIS). This database summarizes yield and leaf mineral concentrations of commercial orchards from all over Israel. The data were collected from 122 orchards: 39 orchards of “Oroblanco” Pomelit (Citrus grandis), 33 orchards of “Michal” mandarin (C. reticulata), 30 orchards of “Star Ruby” grapefruit (C. paradise), and 20 orchards of “Shamouti” oranges (C. sinensis) over a 7‐year period. Based on the first database, there was a disagreement between recommendations and the leaf nutrient status (e.g., the Israeli Ministry of Agriculture recommendations were higher than orchard median values), which indicated that the growers and/or the recommendations need to be corrected. Based on the INWEIS database, a new guideline was set. It was found that the optimal leaf nutrient concentrations for grapefruit trees are 1.7% to 2.1% dry weight (DW) for N, 0.08% to 0.010% DW for P, 0.37% to 0.48% DW for K, and 0.33% to 0.45% DW for Mg. For orange trees, the optimal leaf nutrient concentrations are 1.9% to 2.3% DW for N, 0.11% to 0.14% DW for P, 0.80% to 1.00% DW for K, and 0.19% to 0.26% DW for Mg. For mandarin trees, the optimal leaf nutrient concentrations are 2.0% to 2.4% DW for N, 0.09% to 0.12% DW for P, 0.55% to 0.69% DW for K, and 0.19% to 0.26% DW for Mg. Maintaining leaf nutrient concentrations within these ranges will support maximal yields of 110 to 120 t ha^–1 for grapefruit, 65 to 70 t ha^–1 for orange, and 60 to 70 t ha^–1 for mandarin cultivars.