Effect of Soil Application of Zinc on Growth, Yield and Zinc Concentration in Rice Varieties

Zinc (Zn) deficiency is widespread nutrient disorder in lowland rice growing areas in Asia, especially in Bangladesh. Intensive cropping with modern varieties causes depletion of inherent nutrient reserves in soils. The application of Zn fertilizers results in higher crop productivity and increases Zn concentration in crops. A field experiment was conducted to evaluate the effect of Zn application on growth, yield, and grain-Zn concentration in eight varieties of rice. The experiment was laid out in a split plot design with a distribution of Zn rates (0 kg ha-1 and 3 kg ha-1 from ZnO) to the main plots and rice varieties (BRRI dhan49, BRRI dhan52, BRRI dhan56, BRRI dhan57, Kalizira, Biroin, Gainja and Khirshapath) to the sub-plots. Zinc application improved effective tillers hill-1, grains panicle-1 and 1000-grain weight which impacted the grain yield of rice. Among the eight rice varieties, a significant increase of grain yield was recorded in BRRI dhan49, BRRI dhan52, BRRI dhan56 and BRRI dhan57 due to application of Zn. Zinc concentration of grain significantly increased in all rice varieties except Biroin. The highest grain-Zn concentration (19.1 mg kg-1) was noted in BRRI dhan57 with 3 kg ha-1 Zn and the lowest value (11.3 mg kg-1) was observed in BRRI dhan52 without Zn application. The highest percent increase of grain Zn concentration over control was obtained in high yielding rice variety BRRI dhan49 and the lowest Zn concentration was found in local rice variety Biroin.

Good soil management can reduce dietary zinc deficiency in Zimbabwe

Background Dietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of surveys and field experiments. Methods An ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios. Results A baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg−1 and an estimated dietary Zn intake of 9.3 mg capita−1 day−1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and woodland leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg−1. This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2238 DALYs year−1. Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg−1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9119 DALYs year−1. Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods. Conclusion Farmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

Wheat Rhizosphere Metagenome Reveals Newfound Potential Soil Zn-Mobilizing Bacteria Contributing to Cultivars’ Variation in Grain Zn Concentration

An effective solution to global human zinc (Zn) deficiency is Zn biofortification of staple food crops, which has been hindered by the low available Zn in calcareous soils worldwide. Many culturable soil microbes have been reported to increase Zn availability in the laboratory, while the status of these microbes in fields and whether there are unculturable Zn-mobilizing microbes remain unexplored. Here, we use the culture-independent metagenomic sequencing to investigate the rhizosphere microbiome of three high-Zn (HZn) and three low-Zn (LZn) wheat cultivars in a field experiment with calcareous soils. The average grain Zn concentration of HZn was higher than the Zn biofortification target 40 mg kg–1, while that of LZn was lower than 40 mg kg–1. Metagenomic sequencing and analysis showed large microbiome difference between wheat rhizosphere and bulk soil but small difference between HZn and LZn. Most of the rhizosphere-enriched microbes in HZn and LZn were in common, including many of the previously reported soil Zn-mobilizing microbes. Notably, 30 of the 32 rhizosphere-enriched species exhibiting different abundances between HZn and LZn possess the functional genes involved in soil Zn mobilization, especially the synthesis and exudation of organic acids and siderophores. Most of the abundant potential Zn-mobilizing species were positively correlated with grain Zn concentration and formed a module with strong interspecies relations in the co-occurrence network of abundant rhizosphere-enriched microbes. The potential Zn-mobilizing species, especially Massilia and Pseudomonas, may contribute to the cultivars’ variation in grain Zn concentration, and they deserve further investigation in future studies on Zn biofortification.

Seed priming with zinc improves field performance of maize hybrids grown on calcareous chernozem

Highlights Seed priming with Zn resulted in an average increase of maize grain yield by about 18% compared to control, and by about 8.4 % compared to water priming. Zn-priming promoted plant growth and increased final plant height of three maize hybrids. Overall experiment plant growth parameters were correlated with grain yield components and grain yield Overall effect of seed priming on grain Zn concentration was significant, but it was increased by Zn-priming in two hybrids. Using the seeds with elevated Zn content can improve overall field performance of maize grown on calcareous chernozem. Abstract Delivery of micronutrients to plants through seed priming improves seedling vigour and increase crops yields. Two-year filed trial was conducted in Pančevo, Serbia, with aim to study the effect of seed priming with zinc (Zn) on field performance of three maize hybrids on calcareous chernozem deficient in plant available Zn. Seed priming treatments were: control (without priming), water priming and priming with 4 mM zinc sulphate water solution . Seed priming had significant effect on early plant growth, plant height, yield components, grain yield and grain Zn concentration. Zn-priming promoted plant growth and increased final plant height. Across two growing seasons with contrasting precipitation and three tested maize hybrids, Zn-priming resulted in an average increase of grain yield by about 18% compared to control, and by about 8.4 % compared to water priming. A significant relationship between plant growth parameters, grain yield components and grain yield was detected. Grain Zn concentration was increased by Zn-priming in two hybrids in the season with less precipitation and in one hybrid in the second season.. The results imply that using the seeds with elevated Zn content can improve overall field performance of maize grown on calcareous chernozem.

Good soil management can reduce dietary zinc deficiency in Zimbabwe.

Dietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of survey and field experiments. An ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios. A baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg-1 and an estimated dietary Zn intake of 9.3 mg capita-1 day-1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg-1. This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2,238 DALYs year-1. Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg-1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9,119 DALYs year-1. Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods. Farmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

Novel Sources of Variation in Grain Yield, Components and Mineral Traits Identified in Wheat Amphidiploids Derived from Thinopyrum bessarabicum (Savul. & Rayss) Á. Löve (Poaceae) under Saline Soils in India

Salt-affected soils constrain wheat production globally. A wild wheat species, Thinopyrum bessarabicum (Savul. & Rayss) Á. Löve (Poaceae), and its derivatives are tolerant of high external NaCl concentrations but have not been tested yet in field conditions. The aim of this study was to study the performance of amphidiploids derived from T. bessarabicum for grain yield (GYD), yield components and grain mineral composition traits under normal and saline soil conditions. Field experiments were conducted at Karnal (pH(water) = 7.3) and Hisar (pH(water) = 8.3) sites in 2014–2015 and 2015–2016 in India. Grain samples were analysed using inductively coupled plasma–mass spectrometry (ICP-MS). Yield and yield component traits of amphidiploids were typically greater at Karnal than Hisar. The GYD was greater at Karnal (1.6 t ha−1) than Hisar (1.2 t ha−1) in 2014–2015. However, GYD was greater at Hisar (1.7 t ha−1) than Karnal (1.1 t ha−1) in 2015–2016. Mean grain zinc (Zn) concentration of eight amphidiploids, averaged across sites and years, varied from 36 to 43 mg kg−1. Some amphidiploids derived from T. bessarabicum showed greater GYD and grain Zn concentration under saline soils (Hisar) than normal soils (Karnal). These might be potential new sources for the development of salt-tolerant wheat varieties with increased grain Zn concentration under salt-affected soils.

Improvement of Nutrient Concentration in Rice Grain by Zinc Biofortification

The experiment was conducted in the research farm at Bangladesh Agricultural University (BAU) to investigate the nutrient biofortification ability of rice grain at different doses of zinc fertilization. In this experiment two rice varieties (BRRI dhan28 and Binadhan-16) and five doses (0, 1.5, 3.0, 4.5 and 6.0 kg ha-1) of zinc fertilization were used following split -plot design with three replications. The concentrations of N, Zn and Fe were significantly and positively influenced by the Zn treatments. The crop varieties did not differ significantly in respect of N and Fe concentrations, but the grain Zn concentration was considerably higher in BINA dhan16 than in BRRI dhan28. The grain N content as well as grain protein content increased with the rates of Zn application. Application of Zn increased the protein concentration in rice grain showing that zinc had helped protein synthesis. The grain Zn concentration increased with Zn application rates in a quadratic line which indicates that Zn concentration in rice grain was increased by Zn fertilization, but it attained a maximum value up to Zn6.0 treatment which was 12.2% increase over control.

Quantify the Requirements to Achieve Grain Zn Biofortification of High-yield Wheat on Calcareous Soils

The solution to address global human Zn deficiency is Zn biofortification of staple food crops, aimed at high grain Zn concentration as well as high yield. However, the desired high grain Zn concentration above 40 mg kg-1 is rarely observed for high-yield wheat on worldwide calcareous soils, due to inadequate Zn uptake or Zn distribution to grain. The present study aims to investigate how much Zn uptake or distribution is adequate to achieve the Zn.t of high-yield wheat on calcareous soils with low available Zn (∼ 0.5 mg kg-1). Of the 123 cultivars tested in a three-year field experiment, 19 high-yield cultivars were identified with similar yields around 7.0 t ha-1 and various grain Zn concentrations from 9.3 to 26.7 mg kg-1. The adequate Zn distribution to grain was defined from the view of Zn biofortification, as the situation where the Zn distribution to grain (Zn harvest index) increased to the observed maximum of ∼ 91.0% and the Zn concentration of vegetative parts (straw Zn concentration) decreased to the observed minimum of ∼ 1.5 mg kg-1 (Zn.m). Under the assumed condition of adequate Zn distribution to grain (∼ 91.0%), all the extra Zn above Zn.m was remobilized from straw to grain and the grain Zn concentration would be increased to its highest attainable level, which was 14.5 ∼ 31.3 mg kg-1 for the 19 high-yield cultivars but still lower than 40 mg kg-1. Thus, even with the adequate Zn distribution to grain, the current Zn uptake is still not adequate and needs to be increased to 308 g ha-1 or higher to achieve Zn.t for high-yield wheat (7.0 t ha-1) on low-Zn calcareous soils. Besides, the established method here can also provide the priority measures and quantitative guidelines to achieve Zn biofortification in other wheat production regions.

Foliar application of nano-Zn and mycorrhizal inoculation enhanced Zn in grain and yield of two barley (Hordeum vulgare) cultivars under field conditions

Zinc (Zn) deficiency is a global micronutrient problem in agricultural systems. The main target of this experiment was to investigate the effectiveness of foliar application of Zn under field conditions. Grain yield and Zn concentration in seed were assessed with three replicate plots per treatment in a factorial (2 x 3 x 2) experiment for two barley cultivars (Yusuf and Julgeh), three foliar ZnO applications (nano, ordinary and nano+ordinary ZnO) and two commercial inocula of arbuscular mycorrhizal (AM) fungi (F. mosseae and R. irregularis). Among all Zn foliar applications, Zn applied in both nano and nano+ordinary forms were labile and resulted in the highest Zn concentration in grain of both barley cultivars. Cultivar Julgeh had higher grain Zn concentrations than did cultivar Yusuf in the same treatments. Nano ZnO was more effective than the ordinary form of ZnO and had the highest potential to improve physiological traits, plant growth and yield parameters in both cultivars. There was also a positive impact of the nano form of ZnO on phytase activity and carbonic anhydrase concentration in both barley cultivars. Inoculation with commercial inocula of AM fungi also enhanced grain Zn concentration, with Julgeh more responsive to inoculation with F. mosseae, and Yusuf more responsive to inoculation with R. irregularis. Generally, the combined application of Zn and inoculation with AM fungi improved physiological traits, grain yield and Zn availability to these two barley cultivars grown under field conditions. Accordingly, the nano form of Zn positively enhanced shoot morphological parameters, physiological parameters and grain Zn concentration. Application of the nano form ZnO in combination with inoculation with AM fungi had the most beneficial effects on grain Zn concentration, so this combined practice may have potential to reduce the requirement for application of synthetic Zn chemical fertilizers.