Influence of nano-iron oxide and zinc sulfate on physiological characteristics of peppermint

To evaluate the impact of nano-iron oxide and zinc sulfate fertilizers on peppermint in field conditions, a factorial split experiment with two micro-nutrient fertilizers [Zinc (Zn) and Iron (Fe)] in RCBD with three replicates was conducted at University of Tehran, during 2014 and 2015. Fe at four levels (0, 0.25, 0.5, and 0.75 g L-1) and Zn at three levels (0, 2.5, and 5 g L-1) were applied. Fe and Zn fertilizer application significantly improved photosynthetic pigments, mineral nutrient content, essential oil concentration, and dry matter yield in peppermint. The highest iron content (1578.00 mg kg^?1) was achieved when 5 g L^?1 of Zn was applied along with 0.75 g L^?1 Fe. According to our results, the application of 2.5 g L^?1 of Zn plus 0.5 g L^?1 Fe fertilizers could be recommended to achieve the highest plant dry matter and essential oil yield.     

Zinc fertilization of lentil for grain yield and grain zinc concentration in ten Saskatchewan soils

Fertilization of grain legumes with zinc (Zn) can affect both marketable yield and Zn content of the grain, which is important in addressing human nutritional deficiencies in certain regions of the world. A pot experiment was conducted to determine the response of three different market classes of lentil to Zn fertilization using ten surface soils from Saskatchewan (Canada). The distribution of Zn among labile and stable fractions chemically separated from the soil was also determined in the ten prairie soils and related to the lentil responses observed. The three market classes of lentils (large and small green, small red) were grown without Zn (control), and with 2.5 and 5 kg Zn ha^?1 added as zinc sulfate to each soil prior to planting. Zinc fertilizer application significantly influenced grain yield and was soil dependent. A significant increase in grain yield over the control was observed from application of Zn on some low organic matter, high pH Brown Chernozem soils whereas a decrease in grain yield over control was observed in other soils such as a Black Chernozem of high organic matter content and low (<7) pH. Lack of positive yield response to addition of Zn were related to measured high diethylene triamine pentaacetic acid (DTPA) extractable and plant root simulator (PRS) resin membrane probe Zn, and large amounts of native Zn in exchangeable and iron/manganese (Fe/Mn) oxide bound fractions. Application of Zn fertilizer generally increased the grain concentration of Zn. For example, an increase of ～20% in Zn concentration over control was observed when 5 kg Zn ha^?1 was added to a loamy textured low organic matter Brown Chernozem soil. Overall, small green lentil was more consistent in producing a positive response to Zn fertilizer application on soils with low plant available Zn compared to large green lentil and small red lentil.     

Nitrogen,Phosphorus, and Zinc Supply on Seed and Metal Accumulation in Canola Grain

Nutrient supply is important for yield and quality of canola (Brassica napus L.) crop production. A controlled study was conducted to determine the effects of nitrogen (N), phosphorus (P), and zinc (Zn) supply and their interactions on yield and accumulation of four microelements in canola grain. Results showed that seed yield increased 1.45 to 5 times by increasing N and up to 24.4% by increasing P supply, with significant N-by-P interactions. Nitrogen-by-Zn interaction also exhibited large effects on grain metal concentrations, with increased iron (Fe) and copper (Cu) as increasing N supply, and decreased Mn concentration at all N supply levels above 0 N. Zinc concentration was decreased at low N and increased at high N levels compared to 0 N. Increasing P supply reduced grain Fe and Zn accumulations, but had no effect on Mn and Cu. Overall, this study revealed that canola yield and micronutrient accumulations can be improved by appropriate nutrient supply.     

Triticum dicoccoides: An important genetic resource for increasing zinc and iron concentration in modern cultivated wheat

Abstract

One major strategy to increase the level of zinc (Zn) and iron (Fe) in cereal crops, is to exploit the natural genetic variation in seed concentration of these micronutrients. Genotypic variation for Zn and Fe concentration in seeds among cultivated wheat cultivars is relatively narrow and limits the options to breed wheat genotypes with high concentration and bioavailability of Zn and Fe in seed. Alternatively, wild wheat might be an important genetic resource for enhancing micronutrient concentrations in seeds of cultivated wheat. Wild wheat is widespread in diverse environments in Tarkey and other parts of the Fertile Crescent (e.g., Iran, Iraq, Lebanon, Syria, Israel, and Jordan). A large number of accessions of wild wheat and of its wild relatives were collected from the Fertile Crescent and screened for Fe and Zn concentrations as well as other mineral nutrients. Among wild wheat, the collections of wild emmer wheat, Triticum turgidum ssp. dicoccoides (825 accessions) showed impressive variation and the highest concentrations of micronutrients, significantly exceeding those of cultivated wheat. The concentrations of Zn and Fe among the dicoccoides accessions varied from 14 to 190 mg kg^?1 DW for Zn and from 15 to 109 mg kg^?1 DW for Fe. Also for total amount of Zn and Fe per seed, dicoccoides accessions contained very high amount of Zn (up to 7 μg per seed) and Fe (up to 3.7 μg per seed). Such high genotypic variation could not be found for phosphorus, magnesium, and sulfur. In the case of modern cultivated wheat, seed concentrations of Zn and Fe were lower and less variable when compared to wild wheat accessions. There was a highly significant positive correlation between seed concentrations of Fe and Zn. Screening different series of dicoccoides substitution lines revealed that the chromosome 6A, 611, and 5B of dicoccoides resulted in greater increase in Zn and Fe concentration when compared to their recipient parent and to other chromosome substitution lines. The results indicate that Triticum turgidum L. var. dicoccoides (wild emmer) is an important genetic resource for increasing concentration and content of Zn and Fe in modern cultivated wheat.     

Yield and Zinc,Copper, Manganese and Iron Concentration in Maize (Zea mays L.) Grown on Vertisol as Influenced by Zinc Application from Various Zinc Fertilizers

Zinc (Zn) deficiency in soils and field crops is widespread across the world, including India, resulting in severe reduction in yield. Hence, soil application of Zn fertilizers is recommended for ameliorating Zn deficiency in soil and for obtaining higher crop yield and better crop quality. Zinc sulfate is commonly used Zn fertilizer in India because of its solubility and less cost. However, good quality and adequate quantity of zinc sulfate is not available in the market round the year for farmers' use. Field experiments were therefore conducted during rainy season of 2010 and 2011 at research farm of Indian Institute of Soil Science, Bhopal, India to assess the influence of Zn application through zinc sulfate monohydrate (33% Zn), zinc polyphosphate (21% Zn) and Zn ethylenediaminetetraacetate (EDTA) (12% Zn) on yield and micronutrient concentration and uptake by maize (Zea mays L.). In both the years, grain and vegetative tissue (stover) yield of maize increased significantly with successive application of Zn up to 1 kg ha^?1 added through zinc sulfate monohydrate and zinc polyphosphate. Addition of 2.5 kg Zn ha^?1 did not increase yield further but resulted in highest stover Zn concentration. Zinc, copper (Cu), manganese (Mn), and iron (Fe) concentration in maize grain varied from 22.2 to 27.6, 1.6 to 2.5, 3.5 to 4.7 and 19.9 to 24.5 mg kg^?1 respectively in both the years. Maize stover had 25.9 to 36.2, 7.9 to 9.8, 36.7 to 44.9 and 174 to 212 mg kg^?1 Zn, Cu, Mn, and Fe, respectively. Zinc application did not influence Cu, Mn and Fe concentration in both grain and stover of maize. Transfer coefficients (TCs) of micronutrients varied from 0.72 to 0.95, 0.18 to 0.30, 0.08 to 0.13 and 0.10 to 0.15 for Zn, Cu, Mn, and Fe respectively. Total Zn uptake significantly increased with Zn application from 0.5 to 2.5 kg ha^?1 supplied through zinc sulfate monohydrate and zinc polyphosphate. Recovery efficiency of Zn declined with increased Zn rates.     

Effects of Zinc Application on Growth,Absorption and Distribution of Mineral Nutrients Under Salinity Stress in Soybean (Glycine Max L.)

The purpose of the present work was to evaluate effects of zinc application on growth and uptake and distribution of mineral nutrients under salinity stress [0, 33, 66, and 99 mM sodium chloride (NaCl)] in soybean plants. Results showed that, salinity levels caused a significant decrease in shoot dry and fresh weight in non-zinc application plants. Whereas, zinc application on plants exposed to salinity stress improved the shoot dry and fresh weight. Potassium (K) concentration, K/sodium (Na) and calcium (Ca)/Na ratios significantly decreased, while sodium (Na) concentration increased in root, shoot, and seed as soil salinity increased. Phosphorus (P) concentration significantly decreased in shoot under salinity stress. Moreover, calcium (Ca) significantly decreased in root, but increased in seed with increased salinization. Iron (Fe) concentration significantly decreased in all organs of plant (root, shoot, and seed) in response to salinity levels. Zinc (Zn) concentration of plant was not significantly affected by salinity stress. Copper (Cu) concentration significantly decreased by salinity in root. Nonetheless, manganese (Mn) concentration of root, shoot, and seed was not affected by experimental treatments. Zinc application increased Ca/Na (shoot and seed) ratio and K (shoot and seed), P (shoot), Ca (root and seed), Zn (root, shoot, and seed) and Fe (root and shoot) concentration in soybean plants under salinity stress. Zinc application decreased Na concentration in shoot tissue.     

Effect of Zn application on its uptake,distribution and concentration of Fe and Cu in finger millet [Eleusine coracana (L.) Gaertn.]

Zinc (Zn) malnutrition can be alleviated by increasing the dietary Zn intake through Zn biofortification of edible crops. Agronomic and genetic biofortification has been suggested as better option to increase the dietary Zn. In this study, we show considerable genetic variability for seed Zn concentration in six leading finger millet genotypes. External application of Zn resulted in improved Zn concentration in different plant parts; in particular there was significant increase in seed Zn concentration in all genotypes. Though genotypes GPU28 and INDAF5 showed differences in root and shoot Zn at vegetative stage but at reproductive stage there was no significant difference. Apart from that, Zn application increased the seed iron (Fe) concentration with no or minimal effect on copper (Cu) concentration.     

Soybean Micronutrient Content in Irrigated Plants Grown in the Midsouth

Concentrations and contents of iron (Fe), boron (B), zinc (Zn), manganese (Mn), and copper (Cu) were determined for two MG IV and one MG V irrigated soybean (Glycine max L. Merr.) cultivars grown on clay and sandy loam soils in 2011 and 2012. Plants were sampled at V3, R2, R4, R6, and R8, tissues separated, dried, weighed, and nutrient concentrations determined. Nutrient contents were calculated. No cultivar, site, or year differences in nutrient concentrations or contents were observed. Iron had the greatest concentration and content of all followed by B, Zn, Mn, and Cu. Maximum concentrations and contents in leaves occurred at R4 and later declined. Concentrations and contents in stems remained constant or increased while pods rapidly increased until (R8). A 3328 kg ha^?1 seed yield will remove 325.0 g Fe ha^?1, 153.9 g B ha^?1, 175.6 g Zn ha^?1, 100.0 g Mn ha^?1, and 52.5 g Cu ha^?1.     

Zinc delivery to plants through seed coating with nano-zinc oxide particles

In India, zinc (Zn) has been recognized as the fourth most important yield-limiting nutrient after nitrogen (N), phosphorus (P) and potassium (K). Supplementing the zinc (Zn) requirement of agricultural crops through water soluble zinc sulfate ZnSO₄ fertilizer is a costly management option whereas, utilization of ZnO (water insoluble and a cheaper material) as a source of Zn could be an alternative cost effective option to encourage farmers for wider adoption. In this present investigation, in order to supply the requisite amount of Zn to the plants, a protocol has been developed to coat the seeds of maize (Zea mays L.), soybean (Glycine max L.), pigeon pea (Cajanas cajan L.) and ladies finger (Abelmoschus esculentus L.) with microns scale (<3 µm) and nano-scale (<100 nm) ZnO powder at 25 mg Zn/g seed and at 50 mg Zn/g seed. Different Zn sources, ethyl alcohol, and crude pine oleoresin (POR) were used for coating of seeds. The germination test carried out with coated and uncoated seeds indicated better germination percentage (93–100%) due to ZnO coating as compared to uncoated seeds (80%). Pot culture experiment conducted with coated seeds also revealed that the crop growth with ZnO coated seeds were similar to that observed with soluble Zn treatment applied as zinc sulfate heptahydrate (ZnSO₄·7H₂O) (at 2.5 ppm Zn) which is evident from the periodic SPAD reading taken after 20, 25, 30 and 45 days after sowing. Application of Zn through different sources also enhanced the auxin indole-3-acetic acid (IAA) production in plant roots, which subsequently improved the overall growth. The most important advantage of seed coating with ZnO (both micron/nano-scale) is that it did not exert any osmotic potential at the time of germination of the seed, thus, the total requirement of Zn of the crop can be loaded with the seed effectively through nano-scale ZnO particle.     

Phytic acid,iron and zinc content in wheat ploidy levels and amphiploids: the impact of genotype and planting seasons

Micronutrient deficiency is one of the most common and widespread nutritional issues. Among the factors mitigating the bioavailability of Zn (zinc) and Fe (iron), phytic acid plays a key role; therefore, in order to scrutinize genetic alterations ?related to micronutrient and phytate contents, we examined the concentrations of zinc, iron, and phytic acid, as well as its mole ratio to ?zinc in various wheat species grown in two planting seasons. The concentrations of phytic acid and its mole ratio to zinc were 0.61?1.55 g kg^?1 dry weight and 1.88?4.17 for autumn, and 0.97?2.02 g kg^?1 dry weight and 2.10?4.05 for spring planting. There was a significant discrepancy among wheat species; tritipyrum had the highest concentration of iron, phytic acid and its mole ratio to zinc, and T. monococcum and T. aestivum recorded reasonable zinc bioavailability. Correlation studies between grain phytic acid concentrations and other measured traits revealed various relationships, denoting an irrefutable impact of planting season and wheat ploidy levels on modification of wheat genotypes. The characters contributing more positively with principal component (PC) 1 were Zn and Fe under spring planting and Fe under autumn planting. Spike number per square meter, biological yield and grain yield in spring cultivation, and grain zinc concentration in autumn cultivation were positively correlated to principal component (PC) 2. Given that the concentration of Fe and Zn in all the studied genotypes is relatively high and due to the existence of other desirable agronomic traits, this study believes that it could possibly enhance the applicability of some of these genotypes for breeding purposes.     

An agar nutrient solution technique as a screening tool for tolerance to zinc deficiency and iron toxicity in rice

Abstract

Studies examining iron (Fe) toxicity and zinc (Zn) deficiency in rice have shown that screening experiments in nutrient solutions are of limited use because the rankings of genotypes as tolerant or intolerant can be very different from the results obtained in field-screening experiments. A possible reason for such deviation is that crucial rhizosphere processes cannot be reproduced in nutrient solutions. The objective of the present study was to evaluate the suitability of low-concentration agar nutrient solutions (ANS) as an alternative screening tool. Agar was dissolved in boiling water and mixed with nutrient solution to achieve a final agar concentration of 0.1% (w/v). Zinc deficiency was induced by supplying Zn at a low concentration (0.1 × 10^?3 µmol L^?1), while Fe toxicity was induced by supplying excess Fe²⁺ (200 mg L^?1). Three-week-old seedlings were transplanted into this medium. Symptoms of Zn deficiency and Fe toxicity developed more rapidly in ANS compared with conventional nutrient solutions (CNS). For Zn deficiency this was probably because of the development of Zn depletion zones as a result of the reduced convection in the viscous agar medium. In the case of Fe toxicity we observed far less Fe precipitation in ANS compared with CNS. Genotypic comparisons showed that the tolerance rankings obtained in ANS were very similar to the field tolerance rankings, whereas this was not the case in CNS. This was particularly evident with regard to the considerable root growth inhibition detected in intolerant genotypes when stress treatments were imposed in ANS.     

Effect of Sources,Methods and Time of Application of Zinc on Productivity,Zinc Uptake and Use Efficiency of Oats (Avena Sativa L.) Under Zinc Defficient Condition

A field experiment conducted at the Indian Agricultural Research Institute, New Delhi, India showed that oats (Avena sativa L.) responded (grain yield increase) to zinc (Zn) fertilizer and coating of oat seeds with Zn sulfate or Zn oxide is the best practice. Zinc fertilizer applied to soil, deep placement (5 cm below the seed placement) was superior for growth and yield than soil surface (broadcast) application. Delaying Zn application to 25 days after sowing (first irrigation) was inferior to Zn application at sowing. Partial factor productivity (PFP) of applied Zn varied from 700–2,024 kg grain kg Zn^?1, agronomic efficiency (AE) varied from 62–428 kg grain increase kg^?1 Zn (applied) and physiological efficiency (PE) of Zn varied from 1,822–3,221 kg grain kg^?1 Zn (absorbed). The crop recovery efficiency (CRE) varied from 3.1–17.7%. Thus, adequate Zn fertilizer of oats can lead to higher grain yield and higher Zn concentration in grain (improved quality for human nutrition) under Zn deficient soil.     

Influence of potassium and magnesium fertilizer application on the yield and nutrient accumulation of maize genotypes under field conditions

The use of maize (Zea mays L.) genotypes that are able to utilize nutrients efficiently is an important strategy in the management of plant nutritional status; it is of particular importance with regard to potassium (K) and magnesium (Mg), due to their high requirement and influence on plant growth. The influence of K and Mg fertilizers on certain growth parameters of maize genotypes TM.815 and KL.72.AA, including length, seed in ear, seed weight growth, and nutrient concentration, was determined under field conditions over two successive years. The aim of the experiment was to study the effect of different rates of K and Mg fertilizers on maize genotype plant growth parameters, grain yield, and nutrient accumulation under field conditions.

A split plot design with three replicates was used and each block contained three treatments of 0, 100, and 200 kg ha^?1 of K₂O and 0, 10, and 20 kg ha^?1 of Mg; K₂SO₄ was used to supply K, and MgSO₄ was used for Mg.

Plants that responded to the K fertilizer had an increase in height, yield, and the concentration of K in the leaves and seeds. The addition of K fertilizer increased the concentration of nitrogen (N), iron (Fe), zinc (Zn), manganese (Mn), and K in the plant leaves and increased seed K concentration. Mg fertilizer increased the concentration of N, Fe, copper, and Mn in the leaves; however, it exerted no significant influence on K concentration. The KL.72.AA maize genotype had a higher mean plant height, number of seeds in ear, yield, and N, K, Fe, and Zn concentrations compared to the TM.815 maize genotype. In the experiment, the K fertilizer exerted a statistically significant effect on the leaf and seed K concentration; however, on a statistical basis, the Mg fertilizer did not affect the Mg concentration.     

Relation of Toxicity in Corn Seeds Treated with Zinc and Salicylic Acid

The beneficial effect of corn seed treatment with zinc (Zn) is directly related to the source used. The excess of this micronutrient causes seedling stress and reduces growth. Thus, assuming that the use of exogenous phytohormones can minimize such effects, we evaluated different doses and sources of Zn for the treatment of maize seeds with or without salicylic acid. The experiment took place in the laboratory, and two factorial experiments, 2 × 4 + 1, were performed in a randomized design. The seeds were treated with either ZnO or ZnSO₄ at doses of 0.5, 1, 2, and 3 g.kg^?1 seed with four replications, differing only by the addition of 4.14 mg L^?1 salicylic acid. Treating seeds with Zn and salicylic acid did not affect germination. ZnO led to a greater increase in dry mass in corn seedlings as compared with zinc sulfate, especially at higher doses (2 and 3 g kg^?1 seed). Seed treatment with sulfate reduces root and shoot length, and salicylic acid did not attenuate this toxic effect. Dry mass is not affected when oxide is used. Salicylic acid reduces the accumulation of zinc in the treatment of corn seeds, regardless of the source used.     

Optimal Level of Iron and Zinc in Relation to Its Influence on Herb Yield and Production of Essential Oil in Menthol Mint

Abstract

A pot experiment was conducted under glasshouse conditions during 2004 at the Central Institute of Medicinal and Aromatic Plants (CIMAP) in Lucknow. The study presented here was aimed at evaluating the response of Mentha arvensis (cv. Kushal), an essential oil–bearing plant, to different concentrations of zinc (Zn) and iron (Fe) supply with respect to their influence on biomass, oil yield, and oil quality. Suckers of Japanese mint were grown with four graded levels each of Fe and Zn (viz. 0, 5.0, 10.0, 25.0 mg Fe kg^?1 and 0, 2.5, 5.0, 15.0 mg Zn kg^?1) and a combination of both the elements. The results indicated that the fresh weight, oil content, and chlorophyll content increased significantly with increase in Fe supply; the optimum level was recorded as 10 mg Fe kg^?1. Iron uptake increased significantly with increases in its supply. Zinc, when applied singly, showed enhancement in growth parameters, but the effects were nonsignificant. The optimal levels of supply for Zn and Fe in M. arvensis was evaluated to be 5 mg Zn kg^?1 and 10 mg Fe kg^?1, respectively.     

Bioavailability of Nutrients in Seeds from Tropical and Subtropical Soybean Varieties

The selection of varieties or species of plants with higher nutrient uptake efficiency and nutrient concentration for biofortification of food crops is a key tool to reduce malnutrition. Soybean (Glycine max L. Merr) is one of the most important food crops, because it is consumed directly or indirectly, in the form of seeds, processed (milk and/or derivatives), or used as a protein component of animal feed worldwide. In order to select plants with higher nutrients concentration in seeds, 24 soybean varieties for tropical and subtropical conditions and different general features were assessed. There was great variability in photosynthesis rate, chlorophyll content, seed yield (SY), and concentration and uptake of nutrients by seeds between the varieties. Not genetically modified (NGM) crops showed higher nitrogen (N), cooper (Cu), and manganese (Mn) concentration and higher N, potassium (K), Cu, iron (Fe), Mn, and zinc (Zn) uptake, while for genetically modified (GM) crops only calcium (Ca) concentrations were higher. Varieties BRS 284 and BMX Magna RR showed the highest nutrients concentrations in the group with the highest nutrient efficiency. The genetic variability observed among the varieties regarding uptake and translocation of nutrients into seeds allows selecting more promising materials to be used in the biofortification of nutrients in soybean seeds.     

Genotypic Differences in Concentration and Bioavailability of Kernel‐Iron in Tropical Maize Varieties Grown Under Field Conditions

Abstract

Iron deficiency is estimated to affect over one‐half the world population. Improving the nutritional quality of staple food crops through breeding for high bioavailable iron represents a sustainable and cost effective approach to alleviating iron malnutrition. Forty‐nine late maturing tropical elite maize varieties were grown in a lattice design with two replications in three locations representing three agroecologies in West and Central Africa to identify varieties with high levels of kernel‐Fe. Bioavailable iron was assessed for some varieties selected for high Fe concentration in kernel and improved agronomic traits using an in vitro digestion/Caco‐2 cell model. Significant differences in kernel‐Fe and ‐zinc concentration were observed among varieties (P < 0.001). Kernel‐Fe levels ranged from 16.8 to 24.4 mg kg^?1, while kernel‐Zn levels ranged from 16.5 to 24.6 mg kg^?1. Environment did not have a significant effect on kernel‐iron and ‐zinc levels, but genotype by environment (G × E) interaction was highly significant. The genetic component accounted for 12% of the total variation in kernel‐Fe and 29% for kernel‐Zn levels. Kernel‐Fe was positively correlated with kernel‐Zn (R ² = 0.51, P < 0.0001). Significant differences in iron bioavailability were detected among selected Fe‐rich varieties grown at one location. Mean bioavailable Fe ranged between 30% below to 88% above the reference control variety. The results indicate that genetic differences exist in kernel‐Fe and ‐Zn concentrations and Fe bioavailability. These differences may be useful in biofortification intervention programs, but additional research is needed to determine the efficacy of iron‐rich maize varieties in alleviating iron deficiency in humans.     

RESPONSES OF COOL-SEASON GRAIN LEGUMES AND WHEAT TO SOIL-APPLIED ZINC

The yield and zinc (Zn) content response of faba bean (Vicia faba L.), chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik.) and wheat (Triticum aestivum L.) to applications of Zn fertilizer was compared in a glasshouse experiment using two alkaline soils from southwestern Australia. Comparative Zn requirements were determined from yields of 46-day-old dried shoots when no Zn fertilizer was applied, the amount of Zn required to produce the same percentage of the maximum (relative) yield of dried shoots, and the Zn content of dried shoots (Zn concentration multiplied by yield of dried shoots). The concentration of Zn in youngest tissue and in dried shoots was used to determine critical concentrations for Zn in tissue. Faba bean used indigenous soil Zn more effectively than chickpea, followed by wheat and then lentil. The Zn requirement was lowest for faba bean, and increased in the order faba bean < chickpea < wheat < lentil. Zinc concentration in dried youngest tissue and in dried shoots increased with an increase in the amount of added Zn. The critical Zn concentration in the youngest tissue, associated with 90% of the relative yield, was (mg Zn kg^?1): 25 for lentil, 18 for faba bean, 17 for chickpea and 12 for wheat; corresponding values for dried whole tops (mg Zn kg^?1) were: 30 for lentil, 19 for faba bean, 17 for chickpea, and 20 for wheat. Information on comparative responses of the grain legumes to Zn additions relative to wheat, and critical tissue test values, will aid in the fertilizer management of Zn in cool-season grain legumes in the southwestern Australian farming systems.     

Zinc,Copper, Boron and Iron Requirement of Upland Rice Grown on a Brazilian Oxisol

Deficiency of micronutrients increasing in field crops, including upland rice in recent years. The objective of this study was to determine requirement of zinc (Zn), copper (Cu) boron (B) and iron (Fe) for upland rice grown on a Brazilian Oxisol. The levels used were: Zn (0, 10, 20, 40, and 80 mg kg^?1), Cu (0, 5, 10, 20 and 40 mg kg^?1), B (0, 5, 10, 20 and 40 mg kg^?1) and Fe (0, 250, 500, 1000, and 2000 mg kg^?1). Plant height, straw yield, grain yield, panicle number and grain harvest index (GHI) were significantly improved with the addition of these micronutrients. Root growth was also improved with the application of micronutrients, except with the addition of B. Maximum grain yield was obtained with the addition of 51 mg Zn, 24 mg Cu, 5 mg B kg^?1, and 283 mg Fe kg^?1 soil. Similarly, maximum straw yield was obtained with the addition of 38 mg Zn, 17 mg Cu, 6 mg B kg^?1, and 1500 mg Fe kg^?1 soil. Maximum plant height was obtained with the addition of 54 mg Zn, 10 mg B kg^?1, and 1197 mg Fe kg^?1 soil. Copper did not affect plant height significantly. Maximum panicle number was obtained with the addition of 22 mg Cu kg^?1, 3 mg B kg^?1, and 1100 mg Fe kg^?1 soil. Zinc did not affect panicle number significantly. Maximum GHI was obtained with the addition of 61 mg Zn kg^?1, and 8 mg B kg^?1. Zinc was had a linear increase in GHI in the range of 0 to 80 mg kg^?1, and Fe showed a negative relationship with GHI.     

DETERMINING THE ZINC REQUIREMENT OF ONION BY SEED ANALYSIS

Our study analyzed the effect of foliar tissues and seed tissue for determining the micronutrient status of a crop. Zinc (Zn) requirements of onion (Allium cepa L.) leaves and seeds were estimated from yield response curves based on field experiment conducted on a Zn-deficient calcareous soil. Three onion cultivars, i.e., ‘Swat-1’, ‘Phulkara’, and ‘Sariab Red’ were grown by applying 0, 2, 4, 8, and 16 kg Zn ha^?1. Zinc application significantly increased seed yield of all the three cultivars of onion. The order of seed yield response to Zn fertilization was: ‘Swat-1’ < ‘Phulkara’ < ‘Sariab Red’. Fertilizer Zn requirement for near-maximum seed yield was 2 kg Zn ha^?1. Zinc concentration in mature onion seed also appeared to be a good indicator of soil Zn availability status. Critical Zn concentration in seed was 18 mg Zn kg^?1, and in matured leaves was 21 mg kg^?1.