Zn Content In Grains Research Articles

Effect of variability of zinc on enhancement of zinc density in basmati rice grain grown in three different soils in India

Initially, a preliminary study was conducted to assess the variation of grain zinc (Zn) and iron (Fe) content of 10 basmati rice cultivars. Thereafter, comprehensive study was conducted to enhance the Zn density in grain using three cultivars (CSR 30, Pusa Basmati-6 and PusaSugandh 5) selected from the preliminary study, using three diverse soil types ((Inceptisols of IARI, New Delhi; Inceptisols of farmer’s field, Karnal; and Alfisols of CRIDA, Hyderabad) and six zinc nutrient management treatments including control. The results in the preliminary study indicated that the Zn content in rice grain (after hulling) varied from 13.3 to 22.5 mg kg−1 with mean of 18.8 mg kg−1, while Fe content varied from 8.3 to 14.3 mg kg−1 with mean of 10.7 mg kg−1. In the comprehensive study, the highest Zn content in grain (21.2 mg kg−1) and straw (33.2 mg kg−1) was observed in CSR-30 Cultivar. Among the soil types, Alfisols of CRIDA, Hyderabad maintained significantly highest Zn content in grains and straw. Among the Zn containing nutrient management treatments, application of 5 mg Zn kg−1 (basal) + foliar spray of 0.5% ZnSO4 (bi-weekly) maintained significantly highest Zn content in grain (21.9 mg kg−1) and straw (41.3 mg kg−1). Further, based on the assumption that when an individual consumes rice @ 200 g day−1, his daily dietary intake of Zn would be 3.53 mg day−1 in control (without Zn application) as compared to 4.38 mg day−1 with the rice grown with soil and foliage application of Zn.

Evaluation of Different Methods of Zinc Application on Growth, Yield and Biofortification of Zinc in Rice (Oryza sativa L.)

Zinc (Zn) fertilization, not only gives better yield of cereals but also provides better nutrition to the population. This study evaluated the effect of different Zn application methods on growth, yield and biofortification of Zn in rice. Zinc treatments included were: soil application (5 kg Zn ha−1) (SA), root dipping (2% ZnO slurry) (RD), foliar spray (0.5% ZnSO4.7H2O + 0.25% lime) at tillering and milking stage (FS) and combinations of these treatments. Significantly higher grain yield was obtained in SA + RD + FS and RD + FS (27.2 and 22.6% increase over RDF, respectively). Zinc content in grains had a significant positive correlation with grain yield (r = 0.395, p< 0.05). Efficiencies of applied Zn decreased with increasing Zn application rates, except crop recovery efficiency. Maximum Zn content in grains and bioavailability of the fortified Zn was recorded in SA + FS treatment. However, less than 1% of the fortified grain Zn was bioavailable. Zinc enrichment had a negative (p< 0.01) impact on Fe content in both grain (r =-0.538) and straw (r =-0.603), but showed a positive (p< 0.01) correlation in respect of Mn content in grain (r = 0.556).

Assessing the impact of wastewater irrigation on some toxic heavy metals concentration in grains of Sorghum bicolor

The impact of waste irrigation on the concentrations of the metals Cu, Fe, Ni, and Zn contents in grains of Sorghum bicolor was investigated through analyzing (for three seasons 2008-2010) four different-irrigation sorghum grains samples grown on four different-irrigation soil areas according to the experimental design. The two original soils: Soil, historically and experimentally, irrigated with Wastewater (SHEwastewater), and Soil, historically and experimentally, irrigated with wells water (SHEwells water), were analyzed in the 1st season. Wastewater and wells water samples were analyzed in the 1st and 2nd seasons. According to the procedures used in the literature, Samples were collected, pretreated, preserved, digested according to the microwave assisted acids digestion procedures, and analyzed for metals by ICP-AES. Quality control was performed and %R(s) we got were in the acceptable ranges for real samples analysis. Fe contents of the two types of soil samples were not significantly different. Cu and Ni contents of SHEwastewater were higher than that of SHEwells water whereas Zn content of SHEwastewater was lower than that of SHEwells water. In addition, not all metal levels of the two types of soil samples have exceeded the upper EU standards except nickel in SHEwastewater. The average means (of 1st and 2nd seasons) levels of Cu, Fe, Ni of wastewater was higher than that of wells water, but for Zn, the case is reversed. In addition, the average means of all metal ions of both wastewater and wells water was lower than Yemeni standard for irrigation water. Sorghum grains analysis results, for at least two of the three seasons, indicated that: wastewater irrigation resulted in an increase of nickel content of grains of Sorghum bicolor. Wells water irrigation resulted in an increase in zinc content. In addition, there is no significant difference between the effect of wastewater and wells water irrigation on copper and iron contents of grains of Sorghum bicolor.

English

Biofortification is a process in which plant species are improved in order to raise the nutritional content of the product consumed. The following are some of the main techniques that can be introduced in plant breeding programs in order to improve the nutritional quality of the food to be produced. The rice breeding for higher Fe and Zn content in grain, rice breeding for higher &beta;-carotene content in the grain, rice breeding for higher folate content in the grain, techniques used for plant transformation, transformation via protoplasts, transformation via bioballistics (or biolistic), transformation via Agrobacterium tumefaciens, identification and in vitro selection of transformed tissues, concepts of gene expression and regulation, protein expression, proteomics, mutant study, patch-clamp, were studied. It is necessary to verify the occurrence of variability among the rice genotypes for the Fe, Zn and B complex vitamins; therefore, it will be possible to select these materials within breeding programs. The simple selection of these superior genotypes in relation to nutritional quality, even though by means of conventional breeding techniques, can bring benefits to rice consumption by the human population. Key words: Cultivated rice (Oryza sativa), agriculture, plant breeding, genetics, transformation, selection, gene expression, micronutrient. &nbsp

Agronomic biofortification in rice varieties through zinc fertilization under aerobic condition

A field experiment on agronomic biofortification in rice varieties through zinc fertilization under aerobic condition was carried out at Assam Agricultural University, Jorhat during autumn season of 2014. Among the Varities, Inglongkiri recorded significantly higher grain yield (21.09 q/ha) followed by Banglami (19.88 q/ha) under aerobic condition. Application of ZnSO4 @ 25 kg/ha + foliar spray @ 0.5% at 3 stages recorded the highest grain yield (21.46 q/ha) followed by application of ZnSO4 @ 25 kg/ha + seed priming with ZnSO4 (2%) (20.72 q/ha). The lowest grain yield was recorded in control treatment (16.47 q/ha). Highest grain Zn content (32.03 mg/kg) and Zn content of brown rice(without polish) (26.81 mg/kg) was noticed in Inglongkiri. Application of ZnSO4 @ 25 kg/ha as basal + foliar spray @ 0.5 % at three stages reveals significantly highest Zn content in grain (35.09 mg/kg) and brown rice (28.31mg/kg).

Effect of foliar application of Cu, Zn, and Mn on yield and quality indicators of winter wheat grain

Micronutrients are part of many crucial physiological plant processes. The combined application of N and micronutrients helps in obtaining grain yield with beneficial technological and consumer properties. The main micronutrients needed by cereals include Cu, Mn, and Zn. The subject of this study was to determine yield, quality indicators (protein content and composition, gluten content, grain bulk density, Zeleny sedimentation index, and grain hardness), as well as mineral content (Cu, Zn, Mn, Fe) in winter wheat grain (Triticum aestivum L.) fertilized by foliar micronutrient application. A field experiment was carried out at the Educational and Experimental Station in Tomaszkowo, Poland. The application of mineral fertilizers (NPK) supplemented with Cu increased Cu content (13.0%) and ω, α/β, and γ (18.7%, 4.9%, and 3.4%, respectively) gliadins in wheat grain. Foliar Zn fertilization combined with NPK increased Cu content (14.9%) as well as high (HMW) and low molecular weight (LMW) glutenins (38.8% and 6.7%, respectively). Zinc fertilization significantly reduced monomeric gliadin content and increased polymeric glutenin content in grain, which contributed in reducing the gliadin:glutenin ratio (0.77). Mineral fertilizers supplemented with Mn increased Fe content in wheat grain (14.3%). It also significantly increased protein (3.8%) and gluten (4.4%) content, Zeleny sedimentation index (12.4%), and grain hardness (18.5%). Foliar Mn fertilization increased the content of ω, α/β, and γ gliadin fractions (19.9%, 9.5%, and 2.1%, respectively), as well as HMW and LMW glutenins (18.9% and 4.5%, respectively). Mineral NPK fertilization, combined with micronutrients (Cu + Zn + Mn), increased Cu and Zn content in grain (22.6% and 17.7%, respectively). The content of ω, α/β, and γ gliadins increased (20.3%, 10.5%, and 12.1%, respectively) as well as HMW glutenins (7.9%).

Effect of spacing on P and Zn uptake of local T. Aman rice varieties in Khulna area

A field experiment was conducted at the Agronomy field of Khulna University, Khulna during T. Aman season to evaluate the effects of spacing on nutrient content and total uptake of phosphorus and zinc by grain and straw of traditional rice of Khulna region. The experiment was laid out in split-plot design with three replications assigning three varieties viz., Jotai, Bashfulbalam, Ranisalute and three spacings viz., 30 cm x 30 cm, 40 cm x 40 cm and 50 cm x 50 cm. The variety was assigned in main plot and spacing in sub plot. The plot was fertilized with 40-50-35-5 kg of Urea-TSP-MOP and ZnS04 ha-1 respectively. The results indicated that the single effect of variety and spacing on P and Zn content in grain and straw varied significantly while the straw P content was found insignificant. The interaction effect of variety and spacing on P and Zn content was found significant in all the treatments. The highest P and Zn content of grain was found from the variety Ranisalute at 50 cm x 50 cm (V3S1) but in straw from Ranisalute x 40 cm×40 cm (V3S2) and Bashfulbalam x 30 cm × 30cm (V2S1), respectively. The total uptake of P and Zn was found the highest from Jotai variety at 30 cm x 30 cm spacing. From the interaction it showed that the highest P and Zn uptake was found from Jotai x 30 cm × 30 cm (V1S1) and the lowest from Ranisalute x 50 cm x 50 cm (V3S3). The study indicated that though wider spacings of 40 cm x 40 cm and 50 cm x 50 cm increased the number of tillers hill-1 and nutrient uptake but it cannot increase the nutrient uptake and grain yield ha-1. So, 30 cm x 30 cm spacing showed positive relationship on nutrient uptake than 40 cm x 40 cm and 50 cm x 50 cm spacing.Bangladesh Agron. J. 2014, 17(1): 81-88

Effects of soil zinc availability, nitrogen fertilizer rate and zinc fertilizer application method on zinc biofortification of rice

SUMMARYRice (Oryza sativa L.) is one of the most important cereal crops in the world and a potentially important source of zinc (Zn) in the diet. The improvement of Zn content of rice is a global challenge with implications for both rice production and human health. The objective of the present study was to identify the effects of nitrogen (N) fertilizer rates and Zn application methods on Zn content of rice by evaluating rice production on native soils with different Zn availabilities in 2010/11. The results indicated that Zn application increased rice grain yield and Zn content in grains compared with the control; however, this effect was also affected by the native soil Zn availability, N fertilizer rate and Zn fertilizer application method. The native soil Zn status was the dominant factor influencing grain yield and grain Zn content in response to Zn fertilizer application. Grain Zn content ranged from 19·74 to 26·93 mg/kg under the different Zn statuses. The results also indicated that Zn application method has a significant influence on grain yield. Application of Zn fertilizer to the soil was more effective than the foliar spray on rice grain yield; however, the foliar spray resulted in a greater increase in grain Zn content when compared with soil application. Grain Zn content was affected by application method and displayed the following general trend: soil application + foliar spray &gt; foliar spray &gt; soil application. The experiments investigating the effect of N fertilizer rate combined with Zn application method showed a clear increase in both grain yield and Zn content as the N fertilizer level increased from 200 to 300 kg/ha. In addition, the results also indicated that N content and accumulation increased in all plant tissues, which suggests that Zn application might influence the uptake and translocation of N in rice plants. These results suggest that soil application in addition to a foliar spray of Zn should be considered as an important strategy to increase grain yield and grain Zn content of rice grown in soils with low background levels of Zn-associated diethylene triamine pentaacetate acid. Moreover, this process could be further strengthened by a high N application rate. In conclusion, these results demonstrate the potential of optimizing nutrient management using Zn fertilizer to obtain higher grain yields and higher grain Zn content in fields with low native Zn status.

Zinc enrichment in wheat genotypes under various methods of zinc application

Around half of the cereal growing soil in the world are zinc (Zn)-deficient and it severally affects the health of plants, animals and humans. In order to investigate the enrichment of Zn in cereals a pot experiment was conducted in two contrasting wheat genotypes viz., UP2628 (Zn efficient) and UP262 (Zn inefficient) under different meth ods of Zn application such as control (0 Zn), soil application (5 mg Zn/kg soil tagged with 3.7 MBq of 65 Zn/pot), foliar spray of 0.5% ZnSO 4 at 30, 60 and 90 days (tagged with 925 KBq of 65 Zn/pot), soil application (5 mg Zn/kg soil tagged with 3.7 MBq of 65 Zn/pot) + foliar spray of 0.5% ZnSO 4 at 30, 60 and 90 days (tagged with 925 KBq of 65 Zn/pot). Cultivars showed marked difference in 65 Zn accumulation and grain Zn content. In both contrasting genotypes the highest Zn content in grains was recorded under soil application + foliar spray of Zn fertilizers. Both UP262 and UP2628 showed similar accumulation of 65 Zn in leaves however, UP2628 exhibited better translocation efficiency and accumulated higher 65 Zn in stem and grains than UP262.

Screening of Rice Cultivars for their Zinc Biofortification Potential in Inceptisols

Twenty six rice cultivars were evaluated in field experiment for their native zinc (Zn) contents as well as response to Zn applied through soil (20 kg Zn ha−1) with or without foliar spraying (0.5% ZnSO4.7H2O solution). Results revealed that increased harvest index (HI) of rice also corroborated with higher Zn content in grains upon its basal application as well as foliar spraying. The concentration of native Zn in rice grains was higher in aromatics (27.8 mg kg−1) followed by locals (26.3 mg kg−1), HYVs (23.0 mg kg−1) and hybrids (22.0 mg kg−1). Foliar application of Zn was effective than soil application regarding Znbiofortification of rice. Two foliar spraying of Zn along with basal application increased the grain and straw Zn concentration up to two to three folds. Transfer coefficient of Zn from shoot to grains, on the other hand, recorded an increase with Zn application in hybrids and locals but decreased in HYVs and aromatic cultivars. Zinc efficiency was higher in aromatic cultivars followed by HYVs, hybrids and locals. Transfer coefficient of Zn within the rice cultivars might be related to their physiological activities, which possibly reduced the translocation of Zn from shoot to grains in HYVs and aromatic cultivars. Increased Zn efficiency of aromatic cultivar might be related to its adaptive mechanisms to tolerate Zn deficiency stress.

Residual Effect of Zinc Application Doses and Methods on Nutrition and Productivity of Corn

Zinc is the micronutrient that presents the greatest response in corn grain production. However, the mode of application and the dose used are decisive factors with respect to fertilizer efficiency in the crop. Thus, the objective of the present study was to evaluate the residual effect of zinc application methods and rates on corn nutrition and productivity. The experiment was conducted in the experimental area of the Teaching, Research and Production Farm of the FCAV/UNESP. Soil in the area is classified as dystrophic Dark-Red Latosol (dRL). The experimental setup consisted of a randomized complete block design with four replications. Treatments included three localized Zn doses applied to the soil (planting row); three Zn doses incorporated into the soil at depth of 0 - 20 cm; foliar application, seed application and treatment without addition of Zn. Two evaluations of growth during cultivation were performed. Grain productivity of the crop and the zinc content in soil, leaves and seeds were evaluated. Foliar spraying with Zn simultaneously promoted increased leaf Zn content and basal diameter of the plant. The Zn contents in grains and in the soil, as well as grain yield, were not affected by the Zn application methods or the applied doses. The residual effect of incorporated Zn doses was observed only in the basal diameter and number of leaves at 60 days after emergence.

Enrichment of &lt;sup&gt;65&lt;/sup&gt;Zn in two contrasting rice genotypes under varying methods of zinc application

Zinc (Zn) is an essential micronutrient for growth and development of almost all organisms and its deficiency severely affects the health of plants, animals and humans. In order to investigate the enrichment of Zn in cereals a pot experiment was performed in two contrasting rice varieties viz., PD16 (zinc efficient) and NDR359 (zinc inefficient) under different levels of zinc regimes such as control (0 Zn), soil application (5 mg Zn/kg soil tagged with 3.7 MBq of &lt;sup&gt;65&lt;/sup&gt;Zn/pot), foliar spray of 0.5% ZnSO&lt;sub&gt;4&lt;/sub&gt; at 30, 60 and 90 days (925 KBq of &lt;sup&gt;65&lt;/sup&gt;Zn/pot), soil application (5 mg Zn/kg soil tagged with 3.7 MBq of &lt;sup&gt;65&lt;/sup&gt;Zn/pot) + foliar spray of 0.5% ZnSO&lt;sub&gt;4&lt;/sub&gt; at 30, 60 and 90 days (925 KBq of &lt;sup&gt;65&lt;/sup&gt;Zn/pot). Both varieties markedly differ in &lt;sup&gt;65&lt;/sup&gt;Zn accumulation and grain Zn content. NDR359 showed poor translocation efficiency and accumulated relatively less &lt;sup&gt;65&lt;/sup&gt;Zn in all the plant parts. In both rice varieties, highest concentration of Zn in dehusked grains could be obtained with soil application of Zn + foliar spray of zinc sulphate. Though NDR359, a zinc inefficient variety exhibited poor zinc translocation efficiency yet, it contained more Zn content in grains with husk and dehusked grains than PD16.

Maize local landraces as sources for improved mineral elements availability from grain

The aim of this study was to investigate thirteen maize local landraces from Maize Research Institute (MRIZP) Gene Bank drought tolerant mini-core collection in respect to Fe, Mn and Zn content in grain. In addition, phytate (Phy) and β-carotene contents were determined. According to the results obtained, the highest Fe content was found in grain of LL3, whereas LL1and LL13 were the genotypes with the highest Mn, i.e. Zn content, respectively. However, due to the lowest level of Pphy, along with relatively higher level of Fe, Mn and Zn contents in grain, LL2 could be considered as valuable source in further breeding programs for improved mineral nutrient contents, particularly for Fe. Possible availability of investigated mineral elements was determined according to molar ratio between phytate as inhibiting factor and β-carotene as promoting factor for their absorption. Accordingly, genotype LL2, being with the lowest Pphy content, and genotype LL3, being with the highest β-carotene content (25.63 μg g-1) and the lowest phytate/β-carotene ratio, could be considered as potential sources of favorable genes for further breeding programs for improved nutritional quality, such as enhanced availability of investigated mineral elements.

Enhancement of Wheat Growth and Zn Content in Grains by Zinc Solubilizing Bacteria

Two bacterial isolates (B1 and B2), recovered from the rice rhizosphere produced siderophore and indole acetic acid and solubilized insoluble phosphate, ZnO and ZnSO4.7H2O. Based on routine biochemical tests, both the isolates were characterized as species of Pseudomonas. A shift in pH from 7 to 5 was observed in minimal medium supplemented with Zn compounds after 15 days of bacterial growth. Isolate B1 solubilized maximum amount of ZnO (1.348ppm) after 15 days of incubation. In a pot experiment on wheat (PBW 373), application of bacterial isolates and their consortium with ZnSO4.7H2O @ 5mM significantly enhanced plant height, chlorophyll, grain number per plant over control after 90 days of sowing. Consortium (B1B2) treated wheat plants showed 31% increase in grain Zn over control. HPLC analysis of the root extract of bacterized wheat plants showed the dominance of oxalic, maleic, á-ketoglutaric and fumaric acid. Presence of higher amount of valine and leucine, sugar, protein and phenolic compounds was observed in the root extracts of consortium treated wheat plants than control.

Effect of split application of zinc on yield of rice (Oryza sativa L.) in an inceptisol

Rice is mostly transplanted under puddled low land soil conditions in India, where Zinc (Zn) deficiency is a common problem. The objective of this study was to find out the efficacy of split application of Zn on growth and yield of rice in an inceptisol. The split application of Zn as ZnSO4 · 7H2O performed better than its single basal application, while the split application of Zn-EDTA did not show any significant difference on yield and yield components of rice over its single basal application. Zn-EDTA was found to be better for growth and yield of rice among the two sources of Zn. The soil application of Zn at 1.0 kg ha−1 as Zn-EDTA (T7) recorded highest grain yield of 5.42 t ha−1, filled grain percentage of 90.2%, 1000-grain weight of 25.41 g and number of panicles m−2 of 452. The Zn content of grain and straw were found to be maximum in the treatment T7 i.e. 38.19 and 18.27 mg kg−1, respectively. Linear regression studies indicated that grain yield of rice is significantly influenced by Zn content of grain, Zn content of straw and DTPA extractable Zn content of soil at the level of 95.96, 96.74 and 95.57%, respectively.

Performance of chickpea (Cicer arietinum) as influenced by moisture management and zinc fortification in pearlmillet (Pennisetum glaucum) chickpea cropping system under limited moisture conditions

A field experiment was conducted during the winter (rabi) season of 201213 and 201314 at research farm of Indian Agricultural Research Institute, New Delhi, to determine the effect of moisture management and direct as well as residual effect of zinc fortification on performance of chickpea (Cicer arietinum L.) in pearlmillet [Pennisetum glaucum (L.) R. Br.]chickpea cropping system under limited moisture conditions. Different moisture- management practices resulted in significantly higher plant height, dry-matter accumulation, number and weight of root nodules, number of branches, pods/plant, grains/pod and 1,000-grain weight compared to flat planting. How- ever, flat bed planting recorded significantly higher values of root parameters than crop residue-applied treat- ments. Significantly higher grain (2.48 t/ha) and stover (5.98 t/ha) yields with water productivity of 116.9 kg/m3 were observed under flat bed with 5.0 t/ha crop residue over flat bed without residue and flat bed with 2.5 t/ha crop residue. Narrow bed and furrow with 2.5 t/ha crop residue cover fetched significantly higher production efficiency, whereas, flat bed with 5.0 t/ha crop residue recorded significantly higher Zn content in grain and stover of chickpea than rest of the moisture-management practices. Under direct-applied zinc fortification treatments in- creasing levels of zinc up to 5.0 kg/ha significantly enhanced the growth parameters, yield attributes, yield, water productivity, production efficiency and Zn content in both grain and stover of chickpea. Under residual effect of zinc fortification, plant height, number and dry weight of root nodules, root parameters, number of secondary branches, pods/plant, test weight, stover yield, water productivity and production efficiency of chickpea were in- creased significantly only up to 2.5 kg Zn/ha. However, application 5.0 kg Zn/ha to pearlmillet recorded signifi- cantly higher dry-matter accumulation, number of primary branches, grain yield (2.32 t/ha) and content of Zn in grain as well as in stover than lower levels.

Impact of zinc application methods on zinc concentration and zinc-use efficiency of popularly grown rice (Oryza sativa) cultivars

In the present investigation, 26 rice (Oryza sativa L.) cultivars viz., some locals, aromatics, high yielding variet- ies (HYVs) and hybrids were evaluated for yield efficiency, Zn content in grains and also Zn recovery efficiency in a strip plot design during the rainy (kharif) season for the consecutive 2 years (2009 and 2010) under varied Zn application practices. Rice cultivars differed significantly in their yield and native Zn contents as well as recovery of applied Zn allocation in grains, straw and roots. Grain and straw yields as well as harvest index of different cul- tivars showed wide variations both with and without Zn applications. On an average, grain yields of different rice cultivars increased by 29 and 22% with soil + foliar and only soil application of Zn, respectively. HYVs showed highest yield efficiency followed by hybrid, aromatic and local cultivars, irrespective of methods of Zn fertilization. The content of native Zn in whole rice grain was the highest in aromatics (27.8 mg/kg) followed by locals (26.3 mg/ kg), HYVs (23.0 mg/kg) and hybrids (22.0 mg/kg). Zinc content in whole grains increased significantly in all the cultivars with Zn-application and the magnitude of increase was higher when Zn was applied as soil + foliar appli- cation (118%) than soil application only (30%). Zinc concentration in milled grains increased to the extent of 29.5 and 119.5% upon soil application and soil + foliar application of Zn fertilizers. In rice bran and husk Zn concentra- tion increased to the extent of 21 and 155% and 41 and 373% through soil and soil + foliar application, respec- tively. Zinc-use efficiency varied from 0.53 to 2.83% with a mean value of 0.90% upon soil application of 20 kg Zn as ZnSO .7H O and 1.89 to 4.80% with a mean value of 2.74% upon application of 20 kg Zn as ZnSO .7H O with 4 2 4 2 two foliar spray @ 0.5% ZnSO .7H O solution i.e. soil + foliar applied Zn increased the Zn-use efficiency, on an 4 2 average, three fold than with only soil applied Zn. Thus, soil + foliar application of Zn offers a useful means for en- riching rice grain Zn concentrations irrespective of the cultivars tested and contributed towards enhanced Zn-use efficiency by rice.

Direct and residual effects of pulp and paper mill sludge on crop yield and soil mineral N

Abstract. Paper sludge composted or stored in static piles for six months was compared to raw and lime‐stabilized sludge in a three‐year pot experiment (loam) and a four‐year field experiment (silt loam) at rates of up to 40 t DM ha‐l. The original sludge contained equal amounts of fibre sludge and biological sludge, mixed with bark in 1:1 ratio to improve the structure. The N content in composted sludge (1.30%) was markedly lower than that of the uncomposted piles (1.98%), indicating significant loss during composting. The yield results were generally inversely proportionate to the C:N ratios of the sludges applied. Sludge from the uncomposted piles gave significant grain yield increases in the year following sludge application, while the other sludge types gave variable results. In the residual years there was, generally, a small but positive effect on yield from all the sludge types. The N and P content in grain generally increased with sludge application, but only the higher rates gave statistically significant increases. Sludge application also increased the Zn content in grain, while Mn, B and Cu was less affected. The increase in Cd content was very small. The 40 t ha‐l sludge rate tended to increase the residual mineral N in soil at the field site and thus the risk of nitrate leaching.

Potential for increasing the content and bioavailability of Fe, Zn and Ca in plants for human nutrition

This paper reviews the possibility and limits for increasing the content and bioavailability of iron (Fe), zinc (Zn) and calcium (Ca) in edible parts of staple crops, such as cereals, pulses, roots and tubers as a way to combat mineral deficiencies in human populations. Theoretically, this could be achieved by increasing the total level of Fe, Zn and Ca in the plant foods, while at the same time increasing the concentration of compounds which promote their uptake (ascorbic acid), and/or by decreasing the concentration of compounds which inhibit their absorption (phytic acid or phenolic compounds). The content of Zn and Ca in grains and fruits can in some cases be increased through soil and/or foliar applications of Zn and Ca fertilisers. Plant breeding and genetic engineering techniques, however, have the greatest potential to increase Fe and Zn content in grains, roots and tubers. The possibility of enhancing Ca and ascorbic acid content in plant foods by plant breeding and genetic engineering remained to be explored. The critical factor is to ensure that the extra minerals have an adequate bioavailability for man. Given the important role of phytic acid and polyphenols in plant physiology, reducing the levels of these compounds in the edible parts of plants does not appear to be wise although introduction of phytases which are active during digestion is an exciting possibility.

Micronutrient deficiencies in rainfed calcareous soils of Pakistan. IV. Zinc nutrition of sorghum

Zinc (Zn) deficiency in crops is a major micronutrient disorder particularly in alkaline‐calcareous soils like those of the rainfed Potohar plateau in Pakistan. A nutrient indexing of sorghum (cv. Potohar 4–8) by sampling <30 cm tall whole shoots and associated soils from 255 random field locations revealed that the crop was deficient in Zn in 54% fields in Jehlum district and 64% in Chakwal. In a greenhouse experiment using a Zn‐deficient calcareous Typic Ustorthents, maximum increase in grain yield with Zn fertilizer was 177% over control in improved sorghum variety (cv. PARC‐SS‐1) and only 10% in local sorghum (cv. Potohar 4–8). Although biomass production of cv. PARC‐SS‐1 was much greater compared with cv. Potohar 4–8, fertilizer Zn requirement for the two cultivars was not much different, 8.3 mg Zn/kg soil for improved sorghum variety and 7.3 mg Zn/kg for local sorghum variety. Contrary to its higher sensitivity to Zn deficiency, the improved sorghum variety was more efficient in utilizing fertilizer Zn. Despite low Zn availability in the Potohar fields, local sorghum is not expected to respond to fertilizer Zn. However, adequate Zn fertility must be assured for cultivating improved sorghum in these soils. Zinc content in mature grains of sorghum proved a good index of soil Zn fertility status. Internal Zn requirement in foliar plant parts of cv. PARC‐SS‐1 (whole shoots, 33 mg/kg; leaves, 22 mg/kg) was greater than in cv. Potohar 4–8 (whole shoots, 27 mg/kg; leaves, 20 mg/kg). In contrast, critical Zn content in grains of the improved sorghum variety (10 mg/kg) was lower than of local variety (14 mg/kg). Three soil tests were equally effective in determining soil Zn fertility. Critical soil Zn levels for cv. PARC‐SS‐1 were: DTPA, 3.4 mg/kg; AB‐DTPA, 3.7 mg/kg; and Mehlich 3, 8.0 mg/dm3. Similar to internal Zn requirement in foliar plant parts, soil test critical Zn levels were lower for cv. Potohar 4–8, i.e., DTPA, 3.1 mg/kg; AB‐DTPA, 3.5 mg/kg; and Mehlich 3, 7.2 mg/dm3. Because of their better efficiency, ‘universal’ soil tests appear superior to the DTPA test for routine Zn analysis.