Protein biofortified sorghum: effect of processing into traditional african foods on their protein quality

Protein biofortification into crops is a means to combat childhood protein-energy malnutrition (PEM) in developing countries, by increasing the bioavailability of protein in staple plant foods and ensuring sustainability of the crop. Protein biofortification of sorghum has been achieved by both chemically induced mutation and genetic engineering. For this biofortification to be effective, the improved protein quality in the grain must be retained when it is processed into staple African foods. Suppression of kafirin synthesis by genetic engineering appeared to be superior to improved protein digestibility by chemical mutagenesis, because both the lysine content and protein digestibility were substantially improved and maintained in a range of African foods. For the genetically engineered sorghums, the protein digestibility corrected amino acid score was almost twice that of their null controls and considerably higher than the high protein digestibility sorghum type. Such protein biofortified sorghum has considerable potential to alleviate PEM.     

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.     

Effect of Intensive Agriculture-Nutrition Education and Extension Program Adoption and Diffusion of Biofortified Crops

Biofortification of staple crops to combat micronutrient deficiencies is gaining global recognition. Projects promoting biofortified food crops use intensive agriculture-nutrition education and extension activities to increase adoption of such crops. This study examines the effect of such programs on the adoption and diffusion of orange-fleshed sweetpotato (OFSP). It finds that intensive agriculture-nutrition education and extension programs adopted by some of the biofortification projects increases the adoption and diffusion of OFSP. Specifically, participation in mother-to-mother nutrition support clubs and nutrition-focused health talks affect its adoption and diffusion, but with varying degrees of importance. The paper discusses the implications of these findings.     

High potential for selenium biofortification of lentils ( Lens culinaris L.)

Beneficial forms of selenium (Se) and their impact on human health are a global topic of interest in public health. We are studying the genetic potential for Se biofortification of pulse crops to improve human nutrition. Lentils ( Lens culinaris L.) are an important protein and carbohydrate food and are a valuable source of essential dietary components and trace elements. We analyzed the total Se concentration of 19 lentil genotypes grown at eight locations for two years in Saskatchewan, Canada. We observed significant genotypic and environmental variation in total Se concentration in lentils and that total Se concentration in lentils ranged between 425 and 673 microg kg(-1), providing 77-122% of the recommended daily intake in 100 g of dry lentils. Over 70% of the Se was present as selenomethionine (SeMet) with a smaller fraction (<20%) as inorganic Se and very small amounts as selenocysteine (SeCys). We found that soils from the locations where the lentils were grown were rich in Se (37-301 microg kg(-1)) and that lentils grown in Saskatchewan have the potential to provide an excellent natural source of this essential element. Our analyses gave us a preliminary understanding of the genetic basis of Se uptake in lentil and indicated that any potential strategy for micronutrient biofortification in lentil will require choice of field locations that minimize the spatial variability of soil Se content.     

植物源铁生物有效性及评价方法研究进展

缺铁是个世界性的营养失衡问题,给人类健康和经济发展带来严重的负面影响。主要膳食中的铁缺乏或低生物有效性被认为是造成铁缺乏的主要原因。通过植物育种措施,尤其是提高植物源铁富集育种被认为是解决铁营养失衡最经济且有效的途径。然而,近年的研究表明,人体铁吸收与植物源有效铁量密切相关,而与铁积累总量没有相关性。快速、准确的评价植物源铁生物有效性对高有效性富铁作物育种意义重大。本文阐述了植物源铁富集和生物有效性的基因型差异及影响因素, 并分析了铁生物有效性评价方法的优缺点,为植物源铁生物有效性育种及评价提供参考。     

Lead Toxicity in Cereals and Its Management Strategies: a Critical Review

Cereal grains such as wheat, rice, and maize are widely consumed as a staple food worldwide. Lead (Pb) is one of the non-essential trace elements and its toxicity in crops especially cereals is a widespread problem. The present review highlighted Pb toxicity in cereal and management strategies to reduce its uptake in plants. Lead toxicity reduced the cereal growth, photosynthesis, nutritional value, yield, and grain quality. The response of cereals to excess varies with plant species, levels of Pb in soil, and growth conditions. Reducing Pb bioavailability in the soil is a viable approach due to its non-degradability either by microbes, chemicals, or other means. Cultivation of low Pb-accumulating cultivars may reduce the risk of Pb toxicity in plants and humans via the food chain. Use of plant growth regulators, microbes, organic, and inorganic amendments might be promising techniques for further decreasing Pb contents in shoot and grains. Soil amendments along with selecting low Pb-accumulating cultivars might be a feasible approach to get cereal grains with low Pb concentrations. Furthermore, most of the studies have been conducted under controlled conditions either in hydroponic or pots and less is known about the effects of Pb management approaches under ambient field conditions.     

Screening of iron bioavailability patterns in eight bean (Phaseolus vulgaris L.) genotypes using the Caco-2 cell in vitro model

The common bean ( Phaseolus vulgaris) is an important staple plant food in the diets of people of Latin America, East Africa,and other regions of the developing world. It is also a major source of dietary iron. The primary goal of this research was to use an in vitro digestion/Caco-2 model to study iron bioavailability in eight genotypes (three Mesoamerican and five Andean) that represent the diversity of grain types in this crop. Complementing this goal, we measured the distribution of both iron and phytate in different bean grain tissues (cotyledon, seed coats, and embryos). Seed coats were confirmed to be the exclusive tissue containing polyphenols. The removal of the seed coat and associated polyphenols improved Caco-2 iron bioavailability, and significant differences were observed between genotypes. The addition of ascorbate enhanced iron bioavailability and exposed additional differences in Fe availability among the genotypes. These results indicate that iron accumulation and in vitro iron bioavailability vary among bean genotypes and that polyphenols had greater inhibitory effects on Caco-2 iron bioavailability as compared to phytate.     

Effects of ZnSO4 and Zn‐EDTA applied by broadcasting or by banding on soil Zn fractions and Zn uptake by wheat (Triticum aestivum L.) under greenhouse conditions

Zinc biofortification of staple food crops is essential for alleviating worldwide human malnutrition. Agronomic interventions to promote this should include fertilizer selection and management. A chelated Zn source, Zn‐EDTA, and an inorganic Zn source, ZnSO₄ × 7 H₂O, were applied either by banding or by broadcasting in soil, and Zn fractions in soil and Zn uptake by wheat were determined in a pot experiment. Compared to ZnSO₄ × 7 H₂O, Zn‐EDTA produced higher Zn concentration in grain regardless of application method and even at a lower application rate. Residual Zn fraction was the largest Zn fraction with both ZnSO₄ and Zn‐EDTA amendment. ZnSO₄ banded in soil caused Zn fractions to be restricted to the Zn‐amended soil band and resulted in lower grain Zn concentrations than did broadcast ZnSO₄. Planting wheat slowed Zn fixation by promoting the maintenance of a high concentration of Zn fraction loosely bound to organic matter (LOM‐Zn) in soil. Zn‐EDTA was a better Zn source for Zn biofortification of wheat than was ZnSO₄.     

Identification of introgression lines of Oryza glaberrima Steud. with high mineral content in grains

Mineral concentrations in cereals are crucial for human health, especially for people who consume cereals as a subsistence diet. Although rice (Oryza sativa L.) is one of most important staple crops in the world, starch constitutes a large portion of its grains, and mineral concentrations are lower than in other staple crops. One solution is the improvement of mineral concentrations in rice grains through biofortification, and this approach requires investigation of genetic resources that confer high mineral concentrations to rice grains. In the present study, we performed 2 years of field experiments, in 2012 and 2013, and determined sodium (Na), magnesium (Mg), phosphorus (P), potassium (K), calcium (Ca), boron (B), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn) and molybdenum (Mo) concentrations in the rice grains of 40 introgression lines derived from a cross between a japonica cultivar, Taichung 65 (T65), and African rice, Oryza glaberrima Steud. Substantial variation in mineral concentrations was observed among the 40 introgression lines. We selected several elite lines that had significantly higher concentrations of minerals, including Fe, Cu, Zn, Mo, Mg, P and Ca than the cultivated rice T65. These lines could be novel potential materials for breeding programs for biofortification and provide us with positional information for the candidate loci in the O. glaberrima genome responsible for high mineral concentrations in rice grains.     

Genetic modification of low phytic acid 1-1 maize to enhance iron content and bioavailability

High phytate content in staple food crops is a major barrier to successful iron biofortification. We have exploited the low phytic acid 1-1 (lpa1-1) mutant of maize to generate transgenic plants with up-to 70 μg/g seed iron through the endosperm-specific overexpression of soybean ferritin, resulting in more than 2-fold improvement in iron bioavailability. The levels of bioavailable seed iron achieved in this study greatly exceed any achieved thus far and closely approach values estimated to have a nutritional impact on target populations. Gene expression studies reveal a large induction of the YS1 transporter in leaves and severe repression of an iron acquisition gene DMAS1 in roots, suggesting significant alterations in the iron homeostatic mechanisms in transgenic lpa1-1. Furthermore, preliminary tests show that the high-iron lpa1-1 seeds have higher germination rates and seedling vigor when compared to those of the nontransgenic seeds, which may help improve their value to plant breeders.     

Resource flows,crops and soil fertility management in smallholder farming systems in semi‐arid Zimbabwe

Poor soil fertility and erratic rains are major constraints to crop production in semi‐arid environments. In the smallholder farming systems of sub‐Saharan Africa, these constraints are manifested in frequent crop failures and endemic food insecurity. We characterized a semi‐arid smallholder farming system in south‐western Zimbabwe to assess crop production, nutrient use and factors that constrain productivity. The farming system was studied using resource flow mapping, farmer interviews and calculations of crop production over three cropping seasons (2002/2003, 2003/2004 and 2004/2005) to capture variability between years. Farmers were categorized into three groups: better resourced, medium resourced and poorly resourced. Better resourced farmers produced adequate grain for basic household consumption, except in the drought year (2002/2003). Poorly resourced farmers had large grain deficits, whereas the medium resourced class had smaller deficits. Better resourced and medium resourced farmers produced adequate amounts of staple cereal in two of the seasons, while poorly resourced farmers produced inadequate amounts of food in all three seasons. All farmers produced less than 300 kg/ha of legumes per season. Lack of seed was cited as the main reason for poor legume production. Better resourced farmers used animal manure (2000–5000 kg per season) and some fertilizer on their cereal crops, while the medium resourced group used less manure (1000 kg or less) and no fertilizer. The use of manure varied strongly across the years. Poorly resourced farmers used no nutrient inputs on any of their crops. All groups had negative nitrogen balances during the three cropping seasons, although the values varied strongly between seasons. Investigation of the potential strategies for developing sustainable production systems are required to address the problems of food security in the semi‐arid parts of the country and the region.     

Zinc–nitrogen interaction effect on wheat biofortification and nutrient use efficiency

Background : The enhancement of zinc (Zn) concentration in cereal crops without compromising yield is a global challenge with crucial health and food security implications. Aims : To achieve Zn biofortification in wheat through the appropriate management of fertilization with both Zn and nitrogen (N), due to the synergistic effect between them, using natural organic sources of Zn. Methods : We carried out a field experiment using a rainfed winter wheat (Triticum aestivum L.) crop fertilized with four Zn sources (Zn‐sulphate, Zn‐lignosulphonate, Zn‐amino acids and Zn‐gluconate) and three N application rates under semi‐arid conditions. Results : The strategy of increasing the N rate by 50% with respect to the recommended N rate (i.e., 120 kg N ha^?1) did not improve either wheat yield or grain Zn‐N concentration. The combined effect of applying natural organic Zn complexes and the recommended N rate tended to increase grain Zn concentrations (by an average of 14%), although this increase was significantly higher when Zn‐sulphate was applied (63%) due to its higher recommended Zn application rate. Natural organic Zn fertilizers achieved the highest grain yields, probably due to the enhancement of N uptake. The natural organic Zn fertilizers resulted in higher Zn utilization efficiency compared with the Zn‐sulphate fertilizer. Conclusions : In calcareous Zn‐deficient soils, our results suggest that Zn–N co‐fertilization involving Zn‐sulphate combined with the recommended N application rate would be advisable for obtaining grain Zn biofortification, while the highest yields can be obtained with the application of natural organic Zn fertilizers.     

The Influence of Organic and Integrated Production on Nutritional,Sensory and Agricultural Aspects of Vegetable Raw Materials for Food Production

In a six-year crop rotation trial organically and integrated grown vegetables were produced according to current good agricultural practices, taking quality and quantity aspects into consideration. The raw materials assessed focussed on materials used for industrial food production. Nutritional, sensory and agricultural aspects were evaluated. Carrot, cabbage, onion, pea and potato are possible to grow organically for industrial purposes. Depending on crop, the yield was lower (65-90%) for organically grown compared to integrated grown. Cultivation of organic spinach and dill turned out to be difficult due to problems with weed and discoloration. The chemical analyses included pesticide residues, nitrate, glycoalkaloid, dry matter, vitamin C and 25 different minerals and trace elements. Overall, the organically grown crops had higher dry matter content than the integrated grown. However, when examining the data for the different crops contradictory results were noted. No significant differences due to growing system were noticed for vitamin C and the other nutrients except for 4 of the trace elements. The growing system did not influence the sensory properties.     

The effect of preceding crop on wheat grain zinc concentration and its relationship to total amino acids and dissolved organic carbon in rhizosphere soil solution

The role of cropping systems practices in agronomic biofortification programs with the aim of increasing micronutrient density in food plants has to be clarified. In these field experiments, the effect of four preceding crops, i.e., sunflower (Heliantus annus L. cv. Allstar), Sudan grass (Sorghum bicolor L. cv. Speed Feed), clover (Trifolium pratense L.), and safflower (Carthamus tinctorius L. cv. Koseh-e-Isfahan), on the total amino acids (AA) and dissolved organic carbon (DOC) concentration in rhizosphere soil solution and grain Zn content of successive wheat (Triticum aestivum cvs. Back Cross and Kavir) was investigated during 2009–2010 and 2010–2011 growing seasons. A fallow treatment was also considered as the control. In both growing seasons, preceding crops increased the concentrations of AA and DOC in the soil solution in comparison with the fallow control treatment; although the magnitude of this increase varied upon the preceding crop type and wheat cultivar. In general, clover and sunflower had greater effect on increasing soil solution DOC probably due to higher decomposability of their litter residues in soil. Preceding crops increased the total AA concentration, on average, by 45.9 % for the first year and 10.8 % for the second year. The preceding sorghum and clover had the highest and lowest influence on the concentration of AA in wheat rhizosphere soil solution, respectively. The preceding crops increased grain wheat Zn concentration and content over the fallow control treatment, although this effect was dependent on the crop type. For “Back Cross”, a positive and significant correlation was found between grain Zn concentration and soil solution DOC concentration (r?=?0.60, P?<?0.05) and particularly AA (r?=?0.76, P?<?0.001), while no such correlation was found for “Kavir”. At the second growing season, the concentration of AA in the rhizosphere of Back Cross was greater than that of Kavir, probably due to higher release of these compounds from the roots. According to the results, the preceding crop significantly affect grain Zn density of the successive wheat, that is, at least in part, by releasing soluble organic ligands into soil solution.     

A Meta-Analysis on Phenotypic Variation in Cadmium Accumulation of Rice and Wheat: Implications for Food Cadmium Risk Control

In some densely-populated countries, farmland has been widely cadmium (Cd) contaminated, and the utilization of the contaminated farmland for crop production is currently unavoidable. This necessitates the use of low-Cd crops (i.e., pollution-safe cultivars, the crop varieties with the ability to accumulate a low level of Cd in their edible parts when grown on polluted soil) in these areas and highlights the importance of knowledge on phenotypic variation in crop Cd accumulation for food Cd risk control. Studies on phenotypic variation in heavy metal accumulation started decades ago for a wide range of crops, and synthesis of the scattered experimental results in the literature is in need. We built a Low-Cd Crops Database based on literature research, and relevant meta-analysis was performed to quantitatively explore the phenotypic variation in Cd uptake and translocation of rice and wheat. Considerable variability existed among rice (median grain Cd bioconcentration factor (BCF) of 0.10) and wheat (median grain Cd BCF of 0.21) phenotypes in grain Cd accumulation, and this variability was labile to soil pH and the level of Cd stress. Wheat statistically had a higher root-to-shoot Cd-translocating ability than rice, highlighting potential food Cd risks and the importance of growing low-Cd wheat in slightly Cd-contaminated regions. Meanwhile, no correlations were detected among soil-to-root, root-to-shoot, and shoot-to-grain translocation factors, implying that Cd uptake and internal translocation in crops were probably controlled by different underlying genetic mechanisms. Root-to-shoot Cd transport could be a favorable target trait for selecting and breeding low-Cd rice and wheat. In all, this review provides a comprehensive low-Cd crop list for remediation practice and a systematic meta-analysis inferring food Cd risks based on plant capacity for Cd accumulation and desired traits for low-Cd crop breeding.     

国内外主要粮食作物对施用锌肥响应的研究进展

【目的】 锌 (Zn) 对于人体健康至关重要，缺Zn会影响人体正常发育，并易受致病菌的入侵，降低人体耐受氧化胁迫的能力。人体主要通过摄食的方式补Zn，占全球50%的用于种植粮食作物的耕地缺Zn，主要粮食作物中可食部分的Zn含量普遍偏低，世界上50%的人口健康受到了影响。本文通过探讨国内外主要粮食作物对Zn肥施用的响应，旨在为以后相关的作物富Zn研究提供理论依据。 主要进展 施用Zn肥可以有效改善主要粮食作物籽粒部分的缺Zn状况，土施与叶面喷施均可提高主要粮食作物小麦、水稻和玉米可食部分的Zn含量，并能够增加产量。但由于受到土壤pH、有机质含量等的影响，土施Zn肥有效性偏低，施用的量较大，Zn肥的表观利用率低于叶喷Zn肥，叶喷Zn肥的增产效果显著低于土施Zn肥；锌肥的效果还受营养元素之间交互作用的影响，Zn与P和Fe存在拮抗作用，与Cu存在协同作用；Zn元素在籽粒的不同组份中为不均匀分配，在麦麸、小麦籽粒、白面粉中的含量依次递减，在水稻籽粒、糙米、精米中的含量也依次下降，Zn元素在主要食用的白面和精米中的分配较低；小麦籽粒部分的Zn来自于根的吸收以及茎和叶的再分配，水稻籽粒部分的Zn主要来自于根的吸收。 问题与展望 目前有关Zn在肥–土–作物系统中的迁移分配规律尚不清楚，施用Zn肥的成本较高，肥料中各营养元素的最佳投入量与最佳配比还不确定。因此，Zn肥施用可在以下六个方面进行深入研究:1) Zn元素在肥–土–作物系统中的吸收分配机制，清楚掌握Zn元素在肥–土–作物系统中的富集与分配规律，建立全国主要农田土壤的Zn数据库，构建产量、富Zn量与Zn肥之间的响应模型；2) 研发肥料施用技术及新型廉价肥料，降低补施Zn肥的成本；3) 继续研究Zn与其它营养元素之间的协同和拮抗作用，找到最佳投入量与最佳配比，整体提升粮食作物的营养价值；4) 改善土壤理化性质，提高Zn肥对于农作物的有效性及其肥效的持久性；5) 加强高富Zn品种的筛选，获得对Zn肥高产量与高富Zn量响应的品种类型；6) 研究主要粮食作物富Zn的分子生物学机制，进行品种的改良。      

Zinc biofortification in rice: leveraging agriculture to moderate hidden hunger in developing countries

A restricted dietary range and a deficit of essential minerals such as zinc (Zn) characterize the diets of under-nourished people. Zn deficiency is a global nutritional problem and intensity of the issue is even severe in developing countries. Cereal grains are key to fulfill a person’s daily energy requirements, but they have very low grain Zn concentrations, especially when grown in Zn-deficient soils. Zinc deficiency can be addressed in several ways viz., nutritional diversification, food enrichment and biofortification. Several limitations regarding nutritional diversification and food enrichment favored Zn biofortification as a perpetual solution of malnutrition. Among the potential biofortification options to rectify Zn deficiency, plant breeding approaches and agronomic biofortification offers major advantage. Current review appraised the possible role of Zn in plants, its uptake, translocation and partitioning efficiencies in cereal grains that is driven by various agronomic, breeding and biotechnological approaches. Moreover, review also discussed Zn application methods, Zn-phosphate hostility and indicators of Zn bioavailability which may improve Zn-use efficiency in rice. There is a genuine need to integrate Zn in rice production systems by using agronomic and conventional breeding tools. Likewise, agronomic biofortification is economically sustainable and practically adoptable solution to overcome the Zn deficiency issue in rice.     

Genetic diversity of thiamin and folate in primitive cultivated and wild potato (Solanum) species

Biofortification of staple crops like potato via breeding is an attractive strategy to reduce human micronutrient deficiencies. A prerequisite is metabolic phenotyping of genetically diverse material which can potentially be used as parents in breeding programs. Thus, the natural genetic diversity of thiamin and folate contents was investigated in indigenous cultivated potatoes (Solanum tuberosum group Andigenum) and wild potato species (Solanum section Petota). Significant differences were found among clones and species. For about 50% of the clones there were variations in thiamin and folate contents between years. Genotypes which contained over 2-fold the thiamin and 4-fold the folate content compared to the modern variety Russet Burbank were identified and should be useful material to integrate in breeding programs which aim to enhance the nutritional value of potato. Primitive cultivars and wild species with widely different amounts of thiamin and folate will also be valuable tools to explore their respective metabolic regulation.     

气候变化和大气CO2上升条件下土壤有机碳的动力学研究

Considering that even contaminated soils are a potential resource for agricultural production, it is essential to develop a set of cropping systems to allow a safe and sustainable agriculture on contaminated lands while avoiding any transfer of toxic trace elements to the food chain. In this review, three main strategies, i.e., phytoexclusion, phytostabilization, and phytoextraction, are proposed to establish cropping systems for production of edible and non-edible plants, and for extraction of elements for industrial use. For safe production of food crops, the selection of low-accumulating plants/cultivars and the application of soil amendments are of vital importance. Phytostabilization using non-food energy and fiber plants can provide additional renewable energy sources and economic benefit with minimum cost of agricultural measures. Phytoextracting trace elements (e.g., As, Cd, Ni, and Zn) using hyperaccumulator species is more suitable for slightly and moderately polluted sites, and phytomining of Ni from serpentine soils has shown a great potential to extract Ni-containing bio-ores of economic interests. We conclude that appropriate combinations of soil types, plant species/cultivars, and agronomic practices can restrict trace metal transfer to the food chain and/or extract energy and metals of industrial use and allow safe agricultural activities.     

Zinc bioavailability response curvature in wheat grains under incremental zinc applications

Zinc application is generally recommended to enrich wheat grains with Zn; however, its influence on Zn bioavailability to humans has not received appreciable attention from scientists. In this pot experiment, seven Zn rates (from 0 to 18 mg kg^?1 soil) were applied to two wheat cultivars (Shafaq-2006 and Auqab-2000). Application of Zn significantly increased grain yield, grain Zn concentration and estimated Zn bioavailability, and significantly decreased grain phytate concentration and [phytate]:[Zn] ratio in wheat grains. The response of grain yield to Zn application was quadratic, whereas maximum grain yield was estimated to be achieved at 10.8 mg Zn kg^?1 soil for Shafaq-2006 and 7.4 mg Zn kg^?1 soil for Auqab-2000. These estimated Zn rates were suitable for increasing grain Zn concentration and Zn bioavailability (>2.9 mg Zn in 300 g grains) to optimum levels required for better human nutrition. Conclusively, Zn fertilization for Zn biofortification may be practiced on the bases of response curve studies aimed at maximizing grain yield and optimum Zn bioavailability. Moreover, additive Zn application progressively reduced the grain Fe concentration and increased the grain [phytate]:[Fe] ratio. However, a medium Zn application rate increased grain Ca concentration and decreased the grain [phytate]:[Ca] ratio. Hence, rate of Zn application for mineral biofortification needs to be carefully selected.