APPLICATION OF INCREASING LEVELS OF ZINC TO SOIL REDUCED ACCUMULATION OF CADMIUM IN LUPIN GRAIN

Yellow lupin (Lupinus luteus L.) and narrow-leafed lupin (L. angustifolius L.) are grown as grain legumes in rotation with spring wheat (Triticum aestivum L.) on acidic sandy soils of south-western Australia. Yellow lupin can accumulate significantly larger cadmium (Cd) concentrations in grain than narrow-leafed lupin. A glasshouse experiment was undertaken to test whether adding increasing zinc (Zn) levels to soil increased Zn uptake by yellow lupin reducing accumulation of Cd in yellow lupin grain. Two cultivars of yellow lupin (cv. ‘Motiv’ and ‘Teo’) and 1 cultivar of narrow-leafed lupin (cv. ‘Gungurru’) were used. The soil was Zn deficient for grain production of both yellow and narrow-leafed lupin, but had low levels of native soil Cd (total Cd <0.05 mg kg^?1) so 1.6 mg Cd pot^?1, as a solution of cadmium chloride (CdCl₂·H₂O), was added and mixed through the soil. Eight Zn levels (0–3.2 mg Zn pot^?1), as solutions of zinc sulfate (ZnSO₄·7H₂O), were added and evenly mixed through the soil. Yellow lupin accumulated 0.16 mg Cd kg^?1 in grain when no Zn was applied, which decreased as increasing Zn levels were applied to soil, with ～0.06 mg Cd kg^?1 in grain when the largest level of Zn (3.2 mg Zn pot^?1) was applied. Low Cd concentrations (<0.016 mg Cd kg^?1) were measured in narrow-leafed lupin grain regardless of the Zn treatment. When no Zn was applied, yellow lupin produced ～2.3 times more grain than narrow-leafed lupin, indicating yellow lupin was better at acquiring and using indigenous Zn from soil for grain production. Yellow lupin required about half as much applied Zn as narrow-leafed lupin to produce 90% of the maximum grain yield, ～0.8 mg pot^?1 Zn compared with ～1.5 mg Zn pot^?1. Zn concentration in whole shoots of young plants (eight leaf growth stage) related to 90% of the maximum grain yield (critical prognostic concentration) was (mg Zn kg^?1) 25 for both yellow lupin cultivars and 19 for the narrow-leafed lupin cultivar. Critical Zn concentration in grain related to 90% of maximum grain yield was (mg Zn kg^?1) 24 for both yellow lupin cultivars compared with 20 for the narrow-leafed lupin cultivar.     

Type and placement of zinc fertilizer impacts cadmium content of harvested durum wheat grain

Due to potential international marketing concerns, North Dakota durum wheat (Triticum turgidum L. Desf.) producers require strategies that limit cadmium (Cd) in harvested grain. These trials were conducted in order to determine the impact of type and placement of zinc (Zn) fertilizer on harvested grain seed Cd levels and to determine the best timing of foliar Zn-ethylenediaminetetraacetic acid (EDTA). Foliar Zn-EDTA applied at Feekes 10 growth stage had the lowest grain Cd of 0.97 mg kg^?1 when evaluating different fertilizer sources and application timings. Application of 22.4 kg ha^?1 potassium chloride with the seed at planting resulted in the highest grain Cd of 0.151 mg kg^?1 and might be a concern when environmental conditions are conducive for Cd uptake from soil. Stepwise linear regression determined that soil pH and chloride explained 96% of the variability of grain Cd. Applying 1.1 kg Zn ha^?1 as foliar Zn-EDTA in combination with 33 kg nitrogen ha^?1 at Feekes 10.54 growth stage resulted in significantly lower grain Cd, and significantly higher grain Zn, iron, and protein content. Treatments that significantly lowered grain Cd did not decrease grain yield, test weight, or protein content. The treatments that most reduced grain Cd resulted in the most benefits from a production, marketing, and nutritional standpoint and represents an agronomic approach to biofortification of durum wheat.     

Zinc Deficiency in Rainfed Wheat in Pakistan: Magnitude,Spatial Variability,Management, and Plant Analysis Diagnostic Norms

Abstract

Zinc (Zn) deficiency is a widespread micronutrient disorder in crops grown in calcareous soils; therefore, we conducted a nutrient indexing of farmer‐grown rainfed wheat (Triticum aestivum, cv. Pak‐81) in 1.82 Mha Potohar plateau of Pakistan by sampling up to 30 cm tall whole shoots and associated soils. The crop was Zn deficient in more than 80% of the sampled fields, and a good agreement existed between plant Zn concentration and surface soil AB‐DTPA Zn content (r=0.52; p≤0.01). Contour maps of the sampled areas, prepared by geostatistical analysis techniques and computer graphics, delineated areas of Zn deficiency and, thus, would help focus future research and development. In two field experiments on rainfed wheat grown in alkaline Zn‐deficient Typic Haplustalfs (AB‐DTPA Zn, 0.49–0.52 mg kg^?1), soil‐applied Zn increased grain yield up to 12% over control. Fertilizer requirement for near‐maximum wheat grain yield was 2.0 kg Zn ha^?1, with a VCR of 4∶1. Zinc content in mature grain was a good indicator of soil Zn availability status, and plant tissue critical Zn concentration ranges appear to be 16–20 mg kg^?1 in young whole shoots, 12–16 mg kg^?1 in flag leaves, and 20–24 mg Zn kg^?1 in mature grains.     

土壤中Cd、P、Zn含量对水稻产量和植株中矿物浓度的影响

在温室中进行了剖析添加的Cd、P、Zn对稻谷产量、植株和稻草中的矿物含量以及糙米中Cd的浓度的研究。P增加了稻谷和植株产量,而Cd、Zn和P-Zn的交互作用使其降低。稻谷和植株产量有类似的线性回归方程式,其稻谷的线性回归方程为: Y=17.24+0.0466(P)-0.1850(Cd)-0.1115(Zn)-0.0005(P-Zn) 其R²=0.97^**,式中Y为稻谷产量(克/株);P为添加的P浓度(毫克/公斤);(Cd)为添加的Cd浓度(毫克/公斤);(Zn)为添加的Zn浓度(毫克/公斤);(P-Zn)为P和Zn的交互作用。所有处理均明显地影响着稻草中矿物元素的含量。粕米中的Cd浓度随着添加的Cd、P、Zn浓度的增加而增加;但多元回归分析表明只有Cd的影响是显著的。粕米中Cd的浓度与收获时用0.05M HCI所提取的风干土中的Cd浓度有极显著相关性(Y=0.75^**).对糙米中Cd浓度的评价进行了简要的讨论。     

GENOTYPIC VARIATION FOR PRODUCTIVITY,ZINC UTILIZATION EFFICIENCIES,AND KERNEL QUALITY IN AROMATIC RICES UNDER LOW AVAILABLE ZINC CONDITIONS

Zinc (Zn) has emerged as the plant nutrient limiting rice growth in several parts of the world. About 50% of world soils are deficient in Zn and this is also true for India. An analysis of 0.233 million samples taken from different states showed that 47% of Indian soils are deficient in Zn. In India, Zn deficiency is widespread, especially in the rice–wheat cropping system belt of North India, which has high pH calcareous soils. Zinc is also now recognized as the fifth leading health risk factor is developing Asian countries, where rice is the staple food and Zn nutrition of humans and animals has recently received considerable attention. However, no reports are available on the effect of Zn fertilization on kernel quality of aromatic rices. The present study was therefore undertaken to study the effect of Zn fertilization on yield attributes, grain, and straw yield, Zn concentrations in grain and straw, Zn uptake, Zn use indices and kernel qualities of the aromatic rices. A field study at the Indian Agricultural Research Institute, New Delhi, India showed that Pusa Sugandh 4 (‘PS 4’) is a better than the earlier developed aromatic rice variety Pusa Basmati 1 (‘PB 1’) in terms of grain yield (4.08 tonnes ha^?1), kernel quality, zinc (Zn) concentrations in grain and Zn uptake (1,396.9 g ha^?1), recovery efficiency (5.2%), agronomic efficiency (122.7 kg grain increase kg^?1 Zn applied), partial factor productivity (1,064.7 kg grain kg^?1 Zn applied) and physiological efficiency (39,625 kg grain kg^?1 Zn uptake) of applied Zn. From the grain yield (4.64 tonnes ha^?1) viewpoint an application of 5 kg Zn ha^?1 was found sufficient for the aromatic rices grown on ustochrepts of north Indian rice-wheat cropping system belt. Application of 7.5 kg Zn ha^?1 increased Zn concentrations in the grain (37.0 mg kg^?1 DM) and straw (117.3 mg kg^?1 DM) of aromatic rices studied and this is important from the human and animal nutrition viewpoint under Indian conditions.     

Heavy Metal Uptake and Extraction Potential of Two Bechmeria nivea (L.) Gaud. (Ramie) Varieties Associated with Chemical Reagents

Two varieties of Bechmeria nivea (L.) Gaud. (Ramie), namely, triploid Tri-2 and diploid Xiangzhu-3, were potted with soils from Guangdong for 15 weeks and treated with 10 mmol kg^?1 EDTA or EGTA before harvest at 17th week. Lead, Zn, and Cd in plant and soil materials were analyzed, and their potential ecological risk in soils was simultaneously evaluated. These three metals in soils was found to be above 14.4, 3.0, and 29.9 times higher than the national (China) background value, 10.9, 6.19, and 96.7 times higher than the local (Guangdong) background value, and 1.25, 1.20, and 9.67 times higher than the maximum permissible concentration for soils, respectively. An ecological risk analysis of metals using Häkanson's method indicated an extremely high contamination and a significantly high potential ecological risk by these three metals in soils. The both ramie varieties contained respective concentration exceeding the concentration of <10, <80, and <0.27 mg kg^?1, respectively, for Pb, Zn, and Cd in normal plants, suggesting they were multimetal tolerant. Tri-2 generally contained higher Pb, Zn, and Cd than Xiangzhu-3. Treatment with EDTA or EGTA applied at 10 mmol kg^?1 generally promoted Pb or Cd concentration in both plants while the uptake of Zn was depressed. The ramie variety of Tri-2 and Xiangzhu-3 could extract 0.161 and 0.147 t?ha^?1 of Cd, respectively, equaling to the 0.17 t Cd per hectare by Cd-hyperaccumulating species Viola baoshanensis. Therefore, two ramie varieties in this study had a higher extracting potential for removal of Cd from contaminated soils.     

Assessment of ZN Interaction with Nutrient Cations in Alkaline Soil and its Effect on Plant Growth

An experiment was conducted to assess the zinc (Zn) availability to wheat in alkaline soils during Rabi 2009–2010. Wheat seedlings in pots having 2 kg alkaline sandy soil per pot were treated with 5, 10 and 15 kg Zn ha^?1 as soil and with 0.5 and 1.0% zinc sulfate (ZnSO₄) as foliar application. Results showed that Zn increasing levels in soil helped in phosphorus uptake up to boot stage but its conversion to grain portion lacked in Zn treated plants. Potassium (K) uptake also increased up to 6.24% in boot stage with treatment of 10 kg Zn ha^?1 + 1.0% ZnSO₄ foliar spray. Zinc (Zn) concentration increased in plant tissues with the increasing level of Zn application but this disturbed the phosphorus (P)-Zn interaction and, thus, both of the nutrients were found in lesser quantities in grains compared to the control. Despite of the apparent sufficient Zn level in soil (1.95 mg kg^?1), improvement in growth and yield parameters with Zn application indicate that the soil was Zn deplete in terms of plant available Zn. The above findings suggest that the figure Zn sufficiency in alkaline soil (1.0 mg kg^?1) should be revised in accordance to the nature and type of soils. Furthermore, foliar application of Zn up to 1.0% progressively increased yield but not significantly; and it was recommended that higher concentrations might be used to confirm foliar application of Zn as a successful strategy for increasing plant zinc levels.     

Phosphorus-induced zinc deficiency in wheat pot-grown on noncalcareous and calcareous soils of different properties

High levels of phosphorus (P) often induce zinc (Zn) deficiency in plants grown on Zn-poor soils. We investigated P-induced Zn deficiency in durum wheat (Triticum durum L. ‘Carpio’) grown on 16 noncalcareous and 31 calcareous soils differing in levels of available (Olsen) P and available (diethylenetriaminepentaacetic acid (DTPA)-extractable) Zn using micropots. A completely randomized factorial design with two levels of P (0 and 40 mg P kg^?1 soil) and Zn (0 and 3 mg Zn kg^?1 soil), i.e. four treatments (‘control’, + P, + Zn, and + PZn), were used. Grain yield of control plants depended mainly on the Olsen P level. Phosphorus had a negative effect on yield in 6 soils with Olsen P/Zn_DTPA > 25, and Zn a positive one in 5 soils with Olsen P/Zn_DTPA > 50; and the + PZn treatment generally resulted in the highest yield. Grain Zn concentration of control plants was negatively correlated with growth and Olsen P. Calcareous soils were less sensitive to P-induced Zn deficiency than noncalcareous soils because phosphate is sorbed by calcite rather than being co-adsorbed with Zn on the Fe oxides. Co-application of P and Zn to soil at low and application of Zn at high Olsen P ensured both maximum yield and grain Zn bioavailability.     

Soil affects on the cadmium and zinc contents of Chinese cabbage in Yunnan Province,China

Chinese cabbage and surface soil samples (0–20 cm) from a periurban market garden in Yunnan Province (P.R. China) were collected to determine variations of cadmium (Cd) and zinc (Zn) contents in Chinese cabbage and the influence of soil factors. Mean Cd content was 0.49 mg kg^?1 dry materials (DM) in Chinese cabbage, ranging between 0.23 and 1.34 mg kg^?1 DM (n = 21 samples). Mean Zn content was 51.2 mg kg^?1 DM, ranging from 34.9 to 157.5 mg kg^?1 DM (n = 21 samples). The soil factors best predicting Chinese cabbage Cd and Zn contents were total and available Cd and Zn contents and cation exchange capacity (CEC). Soil samples and corresponding Chinese cabbage samples were divided into two groups: soils with low pH (<6.5, n = 10) and soils with high pH (>6.5, n = 11). Positive correlation between CEC with pH > 6.5 and Cd and Zn contents in Chinese cabbage were observed. Available trace element contents and CEC explained 77% and 69% of variation of Cd and Zn contents in Chinese cabbage, respectively. AEC (enrichment coefficient related to trace element availability) and BCF (bioaccumulation factors) could be used to understand Cd and Zn accumulation in Chinese cabbage.     

Arsenic and heavy metal accumulation by Athyrium yokoscense from contaminated soils

Abstract

Athyrium yokoscense, a type of fern that grows vigorously in mining areas in Japan, is well known as a Cd hyperaccumulator as well as a Cu, Pb and Zn tolerant plant. However, no information is available on As accumulation of A. yokoscense, although it often grows on soils containing high levels of both heavy metals and As. In this study, young ferns collected from a mine area were grown in media containing As-spiked soils or mine soil in a greenhouse for 21 weeks. Athyrium yokosense was highly tolerant to arsenate and survived in soils containing up to 500 mg As (V) kg^?1. The addition of 100 mg As (V) kg^?1 resulted in the highest fern biomass (1.95 g plant^?1) among As-spiked soils. Although the As concentration of the fern was lower than other As hyperaccumulators, such as Pteris vittata, A. yokoscense could hyperaccumulate As in mature and old fronds. Arsenic was accumulated most efficiently in old fronds (922 mg kg^?1) in the media containing 5 mg As (III) kg^?1. Moreover, higher As accumulation was found in the roots of the ferns, with a range from 506 to 2,192 mg kg^?1. In addition, in the mine soil with elevated concentrations of As and heavy metals, A. yokoscense not only hyperaccumulated As (242 mg As kg^?1 in old fronds), but also accumulated Cd, Pb, Cu and Zn at concentrations much higher than those reported for other terrestrial plants. Athyrium yokoscense accumulated Cd mostly in fronds in high concentrations, up to 1095 mg kg^?1, while it accumulated Cu, Zn and Pb mainly in the roots and the concentrations were 375, 2040 and 1165 mg kg^?1, respectively.     

CUMULATIVE AND RESIDUAL EFFECTS OF ZINC SULFATE ON GRAIN YIELD,ZINC, IRON,AND COPPER CONCENTRATION IN CORN AND WHEAT

Re-application of zinc (Zn) sulfate for corn (Zea mays L.) production in rotation of wheat-corn has varied effects on yield of crops grown in Zn deficient soils. Therefore, this study was done as split plots in a complete randomized block design (CRBD) where the main plots were control with and without Zn application in wheat (Triticum aestivum L.) production. Sub-plots were of control, without Zn fertilizer, base application of 75 kg per hectare (kg Zn ha^?1), 25% and 50% less than base application and as foliar spray in combination with the 4 soil Zn treatments for corn production. Effect of previous Zn application on grain Zn concentration of corn was significant (P < 0.01). Zinc concentrations in treatments of without previous Zn (nil Zn) application and with Zn application were 28.1 and 31.8 mg kg^?1, respectively. Soil application of 75 kg ha^?1 and foliar application of Zn sulfate gave the highest yield (8853 kg ha^?1) showed an increase of 25 percent in compared with nil-Zn. Although re-application of Zn has small effect on yield, but resulted in was the highest grain concentration.     

RELATIONSHIP OF SOIL EXTRACTABLE AND FERTILIZER BORON TO SOME SOIL PROPERTIES,CROP YIELDS,AND TOTAL BORON IN COTTON AND WHEAT PLANTS ON SELECTED SOILS OF PUNJAB,PAKISTAN

Boron (B) is an essential microelement, which is necessary for reproductive organs including pollen tube formation in wheat (Triticum aestivum L.), and flowering and boll formation in cotton (Gossypium hirsutum L.) The study was associated with wheat-cotton rotation in 80 farm fields, belonging to different soil series, in four districts of cotton belt of Punjab, Pakistan to assess concentrations of extractable B in soils [0.05 M hydrochloric acid (HCl) extractable B], and added fertilizer B and their relationship to some soil physico-chemical properties [pH, organic matter (OM), calcium carbonate (CaCO₃) and clay content], yields and total B concentrations in wheat and cotton plants. All soils had alkaline pH (7.45 to 8.55), high CaCO₃ content (2.14 to 8.65%), less than 1.0% OM (0.33 to 0.99%), low plant available-P (Olsen P less than 8 mg kg^?1 soil) and medium ammonium acetate extractable potassium (K) (< 200 mg K kg^?1 soil). Of the 80 soil samples, 65 samples (81%) were low in available B (<0.45 mg B kg^?1, ranging from 0.11 to 0.43 mg B kg^?1) Of the corresponding 80 plant samples, leaves B concentrations were below critical levels (<10 mg B kg^?1 for wheat; <30 mg B kg^?1 for cotton) for all the tested samples for wheat and cotton. The regression analysis between plant total B concentrations and soil extractable B concentrations showed strong linear positive relationships for both wheat (R² = 0.509***, significant at P <0.001) and cotton (R² = 0.525***, significant at P <0.001). Further regression analysis between extractable soil B and wheat grain yield as well as between wheat leaves total B and wheat grain yield also depicted strong linear relationships (R² = 0.76 and 0.42, respectively). Boron fertilizer demonstration plots laid out at farmers’ fields low in extractable B, in each district not only enhanced grain yields of wheat crop but also contributed a significant increase towards seed cotton yield of succeeding cotton crop through residual B effect. In conclusion, the findings suggest that many soils in the cotton belt of Punjab may be low in extractable B for wheat and cotton, especially when these crops are grown on low OM soils with high CaCO₃ content.     

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.     

EFFICACY OF GYPSUM AND MAGNESIUM SULFATE AS SOURCES OF SULFUR TO RAPESEED IN LATERITIC SOILS

A field experiment conducted on rapeseed (Brassica juncea L.) during 2005–2006 in a typical lateritic soil (Alfisol) of West Bengal, India revealed that sources of sulfur viz. gypsum and magnesium sulfate and levels of sulfur (0, 20, 40, 60 kg S ha^?1) have significant influence on grain yield, total biological yield, sulfur concentration in grain and stover, total sulfur uptake, oil content and oil yield and chlorophyll content. The maximum grain yield (18.28 q ha^?1) and oil yield (8.59 q ha^?1) was obtained with magnesium sulfate followed by gypsum yielded the grain yield of 17.99 q ha^?1 and oil yield of 8.22 q ha^?1 at 40 kg S ha^?1. Overall, the best performance was recorded when sulfur was applied at 40 kg S ha^?1 either as magnesium sulfate or gypsum. Results revealed that magnesium sulfate may be considered as the better source of sulfur than gypsum to raise the mustard crop in sulfur deficient acidic red and lateritic soils of West Bengal and if farmers apply either magnesium sulfate or gypsum to soils, the possible deficiency of sulfur and magnesium/calcium in soils and plants can be avoided.     

Accumulation of Cadmium by Lupin Species as Affected by Cd Application to Acidic Yellow Sand

Cadmium (Cd) accumulation in the aboveground parts of grain crops, and cultivar variation in uptake are of significant concern in the food supply chain. A glasshouse experiment on an acidic yellow sand was conducted to determine the effect of applied cadmium (0, 0.83, 1.67, 2.5, 3.35 mg Cd kg^?1 soil) on the grain yield of Lupinus angustifolius L. (narrow-leafed lupin; cv. Gungurru) and Lupinus luteus L. (yellow lupin) cultivars, and the concentration and uptake (content) of cadmium by stems and grain. The addition of Cd decreased the grain yield of all varieties of yellow lupin, except Teo-105. However, the grain yield of narrow-leafed lupin was not significantly (p = 0.05) reduced by the addition of Cd to the soil. The grain yield of yellow lupin varieties of P283553 and 94017-3 decreased by 50–60% by the addition of Cd compared to other varieties (Wodjil, 94DO19-1) where grain yield decreased by about 10% with Cd application. Cadmium concentration in plant stems and grain and the content of Cd in lupin plants increased markedly with increasing levels of Cd in the soil. The increase in Cd concentration in stems and grain with the addition of Cd was always higher in yellow lupin than for narrow-leafed lupin. The Cd concentration in the grain of narrow-leafed lupin was about 40% of that of yellow lupin. The concentration of Cd in the stem at maturity was always higher than the Cd concentration in the grain for both Lupinus species. Yellow lupin, except 94DO19-1 had higher concentration of Cd in grain where no Cd was applied to the soil. However, compared to narrow-leafed lupin, all yellow lupin varieties had higher concentration of Cd in grain where Cd was applied to the soil.     

Zinc fertilization approaches for agronomic biofortification and estimated human bioavailability of zinc in maize grain

Maize (Zea mays L.) is generally low in bioavailable zinc (Zn); however, agronomic biofortification can cure human Zn deficiency. In the present experiment, Zn was applied in pots as ZnSO₄ · 7H₂O to maize cultivar DK-6142 as foliar spray (0.5% w/v Zn sprayed 25 days after sowing and 0.25% w/v at tasseling), surface broadcasting (16 kg Zn ha^?1), subsurface banding (16 kg Zn ha^?1 at the depth of 15 cm), surface broadcasting + foliar and subsurface banding + foliar in comparison to an unfertilized control. As compared to control, all treatments significantly (P ≤ 0.05) increased growth, yield and nutritional attributes in maize. Grain Zn and protein concentrations were correlated and ranged from 22.3 to 41.9 mg kg^?1 and 9 to 12 %, respectively. Zinc fertilization also significantly reduced grain phytate and increased grain Zn concentration. Zinc fertilization, especially broadcasting and subsurface banding combined with foliar spray decreased grain [phytate]:[Zn] ratio to 28 and 21 and increased Zn bioavailability by trivariate model of Zn absorption to 2.04 to 2.40, respectively. Conclusively, broadcasting and subsurface banding combined with foliar spray is suitable for optimal maize yield and agronomic Zn biofortification of maize grain. This would also be helpful to optimize Zn and protein concentration in maize grain.     

Bioavailability of zinc and lead from a contaminated soil amended with pine bark-goat manure compost

The distribution in soil and plant uptake of zinc (Zn) and lead (Pb) as influenced by pine bark-goat manure (PBG) compost additions were investigated from the soils artificially contaminated with Zn or Pb ions using maize (Zea mays L.) as a test crop. Soils were amended with four rates of pine bark-goat manure compost (0, 50, 100, and 200 tons ha^?1) and four rates (0, 300, 600 and 1200 mg kg^?1) of Zn or Pb. Maize was planted and grown for 42 days. At harvest, plants samples were analyzed for Zn and Pb concentration. Soils samples were analyzed for pH, extractable and diethylene triamine pentaacetic acid (DTPA) extractable Zn and Pb. Extractable Zn and Pb was lower in PBG compost amended soils than in unamended soils and steadily declined with increasing amount of compost applied. The extractable fraction for Zn dropped by 62.2, 65.0 and 44.6% for 300, 600 and 1200 mg Zn kg^?1, respectively when 200 t ha^?1 of PBG compost was applied. Metal uptake by maize plants were directly related to the rate of applied heavy metal ions with greater concentrations of metals ions found where metal ions were added to non-amended soils.     

Effects of Soil Amendments on Growth and Metal Uptake by Ocimum gratissimum Grown in Cd/Zn-Contaminated Soil

Hydroponic and pot experiments were conducted to assess the uptake of heavy metals (Cd and Zn) by a common crop plant, African basil, Ocimum gratissimum. In addition, the effects of soil amendments, hydroxyapatite (HA) and cow manure on plant growth and metal accumulations were compared. In the hydroponic study, plants were exposed to various concentrations of Cd (2.5 and 5 mg L^?1) and Zn (10 and 20 mg L^?1) for 15 days. O. gratissimum was shown to be a Cd accumulator more than a Zn accumulator. Cadmium concentration in its shoots exceeded 100 mg kg^?1. In the pot experiments, soils from a heavily Cd-contaminated site (Cd 67.9 mg kg^?1 and Zn 2,886.8 mg kg^?1) were treated with cow manure and HA at the rates of 10% and 20% (w/w), and 0.75 and 1.5% (w/w), respectively. Plants were grown in the greenhouse for 3 months. The addition of cow manure resulted in the highest biomass production and the lowest accumulations of Cd in plant parts, while HA was more efficient than cow manure in reducing Zn uptake. Leaves of African basil showed a decreased Cd concentration from 1.5 to 0.3 mg kg^?1 (cow manure) and decreased Zn concentration from 69.3 to 34 mg kg^?1 (HA). This clearly demonstrates the efficiency of HA and cow manure in reducing metal content in leaves of plants grown on high metal-contaminated soil to acceptable or close to acceptable values (0.2 mg kg^?1 for Cd, 99.4 mg kg^?1 for Zn).     

Accumulations of Cadmium,Zinc, and Copper by Rice Plants Grown on Soils Amended with Composted Pig Manure

A pot experiment, in which composted pig manure was applied to soils at rates of 0%, 0.5%, 1.5%, 3.0%, and 5.0% (W/W) to simulate additions of different amounts of cadmium (Cd), copper (Cu), and zinc (Zn) to soil, was conducted to assess accumulation of metals by rice (Oryza sativa L.) plants from soils treated with manure. Results indicated that Cd concentrations in rice grains were more than the limit of 0.2 mg kg^?1 when 0.14 mg kg^?1 or more Cd was loaded to Ferralsols by manure application, but it was not more than the limit in Calcaric Cambisols. Zinc contents in polished rice grains did not exceed the permissible limit of 50 mg kg^?1 in two soils. Copper concentrations in rice grain were slightly more than the limit of 10 mg kg^?1 in Ferralsols but not in Calcaric Cambisols. Results suggested greater risk of heavy‐metal contamination from manure to paddy rice in Ferralsols than in Calcaric Cambisols.     

RESPONSES OF TOMATO VAR. TINY TOM TO APPLICATION OF COPPER AND ZINC FERTILIZERS IN THREE LIMED TROPICAL PEAT SOILS OF SARAWAK

We assessed the response of the tomato variety “Tiny Tom” to the application of copper (Cu) and zinc (Zn) fertilizers in three tropical peat soils of Sarawak: mixed swamp forest, Alan forest and Padang Alan forest. Limed soils were used because peat soils in their natural condition are unsuitable to sustain healthy growth of most crops. Yield responses were correlated with added Cu and Zn using Mitscherlich model. Adequate levels of applied Cu and Zn were calculated as those which resulted in 90% of the maximum obtainable shoot dry weight. Application of Cu and Zn significantly (P ≤ 0.05) increased the shoot dry weight and the shoot Cu and Zn concentrations of tomato. Application of the equivalent of 8.3 kg Cu and 5.2 kg Zn per ha was required to achieve 90% of the maximum shoot dry weight. In tomato shoots, the critical concentration for Cu was 18 mg/kg and for Zn, 92 mg/kg. The corresponding concentrations for diethylenetriaminepentaaceticacid (DTPA) extractable Cu and Zn in the soils were 2.3 mg Cu kg ^?1 and 3.6 mg Zn kg ^?1 . However, the addition of Cu fertilizer also increased Zn uptake by tomato plant, probably by displacing native Zn that was weakly sorbed to the soil solid phase.