Agronomic biofortification is possible through foliar zinc fertilisation around the earing and early milk stage of wheat. Farmers can be encouraged to apply foliar zinc fertilisation if there is yield enhancement or if it is compatible with other pesticides which are used during these stages to control aphid and stripe rust. To investigate the effectiveness of tank-mix applications of fertiliser and pesticide for enriching grain zinc and controlling the spread of aphid and stripe rust, studies were conducted at Punjab Agricultural Univeristy, Ludhiana, India for 4 years (2017–18 to 2020–21). We tested tank-mixing of zinc (0.5% ZnSO₄.7H₂O) + thiamethoxam 25 WG (50 g/ha), zinc + propiconazole (500 mL/ha) and zinc + thiamethoxam + propiconazole with one foliar application at the milk stage and two foliar applications at the flag leaf and milk stages. We did not find any adverse effect of tank-mix application of zinc sulfate, thiamethoxam and propiconazole on zinc enrichment in grains, nor in aphid and stripe rust control. The grain zinc enhancement was 99.8–114.9, 100.2–112.1 and 98.0–115.5% with application of foliar Zn, foliar Zn + thiamethoxam and foliar Zn + thiamethoxam and propiconazole respectively. We also found 5.74% increased grain yield with foliar Zn + thiamethoxam and 7.24% increased grain yield in foliar Zn + thiamethoxam + propiconazole. Better net returns in combining Zn + thiamethoxam + propiconazole were also recorded. The results advocate for the tank-mix application of Zinc + thiamethoxam + propiconazole for pest management and Zn biofortification.

Seed priming with zinc (Zn) and potassium (K) has been suggested to improve plant growth and productivity; however, the same effects have not yet been established when a simultaneous Zn+K solution is applied. This study aimed to determine the effects of priming seed and foliar application with Zn and K solution on seedling growth, yield, and grain Zn concentration in three rice varieties (SPT1, BL and KDK). The study consisted of three independent experiments. In Experiment 1, seed germination and seedling vigour were evaluated after priming rice seeds with a solution of 0.5% ZnSO₄, in combination with various concentrations (1–4%) of K, compared with a control of no Zn and K. In Experiment 2, the selected concentrations of K solution combined with Zn (Zn0K0, Zn+K0, Zn0K+ and Zn+K+) were applied for each rice variety to evaluate seedling growth and development at 7 and 21 days. In Experiment 3, foliar application with the same solution as in Experiment 2 was used to evaluate its effect on yield and grain Zn accumulation. Seed priming with Zn combined with K at concentrations of 1%, 3% and 2% resulted in the maximum seedling growth traits in SPT1, BL and KDK respectively. Seed priming with a combination of Zn and K (Zn+K+) markedly increased the dry weight of 7-day-old seedlings, for about 14–15% in SPT1 and BL varieties compared with the unprimed seeds. Moreover, foliar application with Zn+K0 and Zn+K+ increased grain yield by 16–29% in the BL variety, whereas it increased grain Zn concentration in all rice varieties by 18–27% from the control treatment. This study concluded that priming rice seed with a combination of Zn and K can be used to improve seed germination and seedling growth, whereas increasing grain yield and grain Zn concentration requires an additional foliar Zn application.

Zinc deficiency impedes wheat productivity and is major cause of malnutrition in humans consuming wheat products low in Zn, especially in developing countries, which experience low rates of soil and foliar Zn application owing to high cost of chemical Zn fertilisers. This pot study was conducted to evaluate the potential of seed priming with Zn for improving performance and grain biofortification of bread wheat (Triticum aestivum L.). Seeds of wheat cultivars Faisalabad-2008 and Lasani-2008 received one of four Zn treatments involving soaking in aerated solutions of ZnCl₂ (0.05 or 0.1 M Zn) or ZnSO₄ (0.1 or 0.5 M Zn); untreated seeds were taken as a control. All Zn seed priming treatments improved wheat performance. Seed priming with 0.1 M ZnCl₂ advanced seedling emergence, whereas seed priming with 0.5 M ZnSO₄ improved leaf elongation/expansion, chlorophyll content, shoot Zn concentration and plant photosynthetic traits. Seed priming with 0.1 and 0.5 M ZnSO₄ improved plant water relations. Moreover, seed priming with 0.5 M ZnSO₄ improved grain yield (63.1%), and grain Zn concentration (43.1%) and content (93.1%), with low [phytate]:[Zn] compared with non-primed seeds. Faisalabad-2008 performed better than Lasani-2008. In conclusion, seeds of bread wheat may be primed with 0.5 M ZnSO₄ as a Zn source for improving plant physiology, yield and grain biofortification.

Phytic acid (PA) is the most prevalent storage form of grain phosphorus (P) and acts as an anti-nutrient by lowering mineral bioavailability. Genotypic variation of grain PA and its relation to mineral bioavailability, and their nutritional fortification potential with zinc (Zn) supply has not been fully investigated in pigmented rice. Here, we compared the differences in grain PA concentration and mineral bioavailability among 13 pigmented rice (red, yellow, and green rice) and six non-pigmented rice cultivars (three common white rice and their corresponding low-PA (lpa) mutant). Pigmented rice was enriched with micronutrients, especially Zn and Fe, on an average of 39.1 and 44.8 mg kg^-1 as compared with 31.9 and 33.1 mg kg^-1 in non-pigmented rice respectively. The lpa cultivars showed the highest bioavailability for most of the minerals. However, no significant difference was observed for mineral bioavailability between pigmented and common white rice, owing to higher anti-nutritional PA in pigmented rice (9.25 g kg^-1) than in common white rice (8.29 g kg^-1). However, a large difference in grain PA was found among green rice (11.19 g kg^-1), yellow rice (9.82 g kg^-1) and red rice (8.56 g kg^-1) cultivars. Therefore, foliar Zn was used to investigate PA concentration and Zn bioavailability. Foliar Zn application increased grain Zn but decreased grain PA concentration, which ultimately increased grain Zn bioavailability. Zn application had a remarkable effect on Zn bioavailability for red rice (an average of 82%) as compared with common white rice (48%). These findings could provide helpful knowledge for pigmented rice fortification.

Livestock is a major component of agriculture, and a continuous supply of nutritious forage/fodder is necessary for sustainable livestock production. Zinc (Zn) deficiency is a global concern for human as well as animal health, but Zn fertilisation for productivity and biofortification of forages is not well understood. Therefore, a 2-year field study was conducted to investigate the influence of soil-applied ZnSO₄ on morphological traits, yield, nutritional quality and Zn biofortification in four forages. The grass forages (oat, barley, annual ryegrass and triticale) were factorially combined with four levels of soil-applied ZnSO₄ (0, 5, 10 and 15 kg ha^-1) and two harvesting stages (booting and 50% heading). The treatments were arranged in a triplicate randomised complete block design with a split–split plot arrangement where grass forage species were kept in main plots, ZnSO₄ application in subplots and harvest stage in subsub plots. ZnSO₄ fertilisation significantly improved morphological traits, dry-matter yield, crude protein, acid detergent fibre (ADF) and shoot Zn concentration in all grass forages at both harvesting stages. Best performance for yield, quality traits, and Zn contents across all crops was observed where ZnSO₄ was applied at 15 kg ha^-1 and harvested at 50% heading stage. The highest economic returns were provided by triticale and annual ryegrass with 15 kg ZnSO₄ ha^-1 harvested at 50% heading. In conclusion, for a profitable forage production with good nutritional quality and Zn biofortification, triticale and annual ryegrass may be recommended with a 15 kg ZnSO₄ ha^-1 fertilisation.

The present study aimed to demonstrate the use of two strains of Streptomyces albus (CAI-24 and KAI-27) and one strain of S. griseus (MMA-32) for plant growth-promotion (PGP) and improving pearl millet yield and nutrient content under greenhouse and field conditions. Two hybrids, a low-Fe (PA-9444; non-biofortified hybrid) and high-Fe (ICMH-1201; biofortified hybrid), treated with selected Streptomyces strains, significantly enhanced a range of traits including grain yield in the glasshouse (13–23%) and field (9–12%) over the control. In the greenhouse experiments an enhanced stover and grain nutrient concentrations were observed in ICMH-1201 (Fe 53% and 40%; Zn 15% and 10%; Ca 11% and 29%) over the control, while such nutrition augmentations were not found in PA-9444. The field harvested stover and grain nutrient concentrations were also increased over the control in both hybrids. A higher stover nutrient concentration was found in ICMH-1201 while PA-9444 had an increase in grain nutrient concentration indicating the significance of these Streptomyces strains' PGP role in the non-biofortified hybrid. Based on this study, strains KAI-27 and MMA-32 significantly improved shoot weight, root weight and grain yield while CAI-24 and MMA-32 improved nutrient concentrations including Fe contents (up to 49%) in grain as well as in stover. Further, the stover samples of pearl millet contained a higher Fe concentration (150–200%) compared to grain samples. This study confirms that the selected Streptomyces strains have the potential for enhancing PGP and stover and grain nutrient concentrations in pearl millet and can complement the existing conventional biofortification strategies.

Context. The production of chickpea (Cicer arietinum L.) is negatively affected by boron (B) deficiency. In Pakistan, the crop grown under B deficiency produces grains with low B concentration. Application of B-tolerant bacteria (BTB) is a promising option to improve B supply to plants grown under B deficiency.

Aims. This study was focused on determining the appropriate concentration of B for seed priming, and its effects with BTB inoculation on growth, productivity and grain B concentration of chickpea.

Methods. Chickpea seeds were primed in aerated solutions of B concentrations in the range 0.01–0.5% (w/v), with hydroprimed and dry seeds as controls. Concentrations >0.1% proved toxic and seeds failed to germinate. Hence, B was further diluted to concentrations in the range 0.0001–0.1%. Pots containing chickpea seeds were divided into two sets having all B treatments. One set was inoculated with BTB (5 mL per pot of pure Bacillus sp. MN54 culture at 10 9 cfu mL^-1); the other set was not inoculated.

Key results. Seed priming with B along with BTB inoculation improved stand establishment, growth, nodulation, yield and grain B concentration of chickpea. Seed priming treatments with B at 0.001% and 0.0001% along with BTB inoculation were most effective for improving stand establishment, seedling growth and grain yield, whereas 0.1% B was more effective for improving grain B concentration.

Conclusions. Seed priming with 0.001% B along with inoculation of Bacillus sp. MN54 improved seed germination, nodulation, yield and grain B concentration of chickpea under B-deficiency conditions.

Implications. Seed inoculation with BTB i.e., Bacillus sp. MN54 coupled with seed priming in 0.001% B solution is a viable option to improve yield and grain B concentration of chickpea grown on B-deficient soils.

Biofertiliser is considered a promising biofortification intervention that can integrate with plant breeding as well as agronomic measures to overcome malnutrition in regions where the staple diet is cereal. This study was conducted to improve maize (Zea mays L.) productivity and biofortification with zinc (Zn) through the application of Zn-solubilising biofertilisers. Four pre-isolated, promising Zn-solubilising Bacillus strains, Bacillus sp. ZM20, B. aryabhattai ZM31, B. aryabhattai S10 and B. subtilis ZM63, were coated on maize seeds by forming slurry-based sole- and co-inoculated biofertilisers. The treated maize seeds were grown in a spring season (Trial I) and the experiment was repeated the following year on the same field (Trial II). The seed-applied co-inoculated Bacillus biofertiliser formulations significantly promoted antioxidant enzyme activities (ascorbate peroxidase, peroxidase and superoxide dismutase), growth and yield attributes, and nutrient accumulation in maize grains during both field trials compared with sole-inoculated biofertiliser formulations. Application of ZM31–ZM63 biofertiliser formulation showed a greater increase in these attributes than other biofertiliser formulations, as well as an increase in grain iron (Fe) concentration (up to 1.69-fold in Trial I and 1.77-fold in Trial II) and Zn concentration (up to 1.50-fold in Trial I and 1.41-fold in Trial II) relative to the uninoculated control. Fe and Zn concentrations in maize grains resulting from the application of seed-based Bacillus biofertiliser formulations could fulfill the minimum required level of these nutrients for daily intake. From the study, recommendation can be made to apply Zn-solubilising bioinoculants for the biofortification of maize grains to overcome malnutrition issues in regions with cereal-based staple diets.

Kazakhstan–Siberian Network on Spring Wheat Improvement unites 18 spring wheat (Triticum aestivum L.) research and breeding programs and presents opportunities to study genotype × environment interactions. Trial data from six locations in Kazakhstan and Russia in 2017–18 were used for grain ionomics analysis to evaluate the relative contributions of environment and genotype to variation in elemental composition and to formulate a methodology to enhance concentrations of important minerals in grain. The effect of year was least important to variation. For several elements (P, S, Cu, Mn and Mo), the effect of site was 2–3 times higher than the effect of genotype. The effects of genotype and site were similar for Ca, Mg, Fe, Cd and Sr concentration. Average broad-sense heritability across six sites in both years was: (for macroelements) Mg 0.59 > Ca 0.50 > K 0.44 > P 0.30 > S 0.20; and (for microelements) Zn 0.44 > Mn 0.41 > Cu 0.40 > Fe 0.38. Biplot analysis grouped the traits into five clusters: (1) concentrations of Co, Cu, Mo and Sr; (2) concentrations of Mg, P and Zn; (3) concentrations of K and Ni; (4) protein content, concentrations of Cd, Fe, Mn and S; and (5) grain yield, concentrations of Ca and Rb. These associations reflect regional soil and environment variation independent of genotype. Protein content had positive and significant genotypic correlations with Mg (0.57), P (0.60), S (0.68), Fe (0.64), Cu (0.50), Mn (0.50) and Zn (0.53). A combination of high grain yield, relatively high protein content, and high concentrations of P, S, Mn, Cu and Zn (singly or combined) was identified in the genotypes Element-22 (check cultivar), Lutescens-3-04-21-11, and Silach. The study contributes to research and cultivar development to improve the nutritional profile of grain for consumers.

Cereal crop Zn biofortification is an effective solution to global human Zn deficiency and is achieved by increasing grain Zn concentration concurrently with yield. However, the desired grain Zn concentration (>40 mg kg^-1) is rarely observed for high-yielding wheat on calcareous soils, owing to inadequate Zn uptake or Zn distribution to grain. This study was designed to determine how much Zn uptake or distribution is adequate for Zn biofortification, by considering 123 bread wheat (Triticum aestivum L.) cultivars grown on calcareous soils with low available Zn (=0.5 mg kg^-1) in the field on the southern Loess Plateau, China. Nineteen high-yielding cultivars were identified with similar yields (∼7.0 t ha^-1) and various grain Zn concentrations from 9.3 to 26.7 mg kg^-1. Adequate Zn distribution to grain was defined as the situation where the Zn harvest index at maturity increased to its maximum of ∼91.0% and straw Zn concentration at maturity decreased to its minimum of ∼1.5 mg kg^-1. For each cultivar, the extra Zn in straw above the minimum could be again remobilised to grain and raise grain Zn concentration to its highest attainable level, which was 14.5–31.3 mg kg^-1 for the 19 high-yielding cultivars but still =40 mg kg^-1. Thus, the current Zn uptake needs to be increased to ≥308 g ha^-1 to achieve Zn biofortification on low-Zn calcareous soils. For other wheat production regions, the method established here can also provide the priority measures and quantitative guidelines for Zn biofortification.

Biofortification of zinc (Zn), iron (Fe) and selenium (Se) in crops could be affected by environmental factors such as soil salinity and phosphorus supply levels, as well as by the genotypic effect. Two pot experiments were conducted with one examined the effects of P supply and salinity on plant growth and Zn, Fe and Se uptake in wheat, and the other examined genotypic differences in Zn, Fe and Se accumulation among 20 wheat genotypes. The results of the first pot study showed significant interactive effects between P supply and salinity on Zn, Fe and Se accumulation. Increasing salinity at the same P supply level increased shoot Zn concentrations, but significantly decreased total shoot Zn amount owing to decreased aboveground biomass. An increased accumulation of total shoot Fe and Se in P-added treatments, relative to the no-P treatments, was mainly due to increased aboveground biomass. The results of the second pot study showed substantial genotypic variations in Zn, Fe and Se accumulation; principal component analysis (PCA) suggested that agronomic traits and nutrient accumulation were controlled by independent genetic mechanisms. These results indicated that the amount of P supply is a key factor regulating biomass and accumulation of Zn, Fe and Se in certain saline soils; the sizable genotypic difference in Zn, Fe and Se accumulation observed in salinised conditions has provided potential scope for genetic improvement by breeding strategies.

Context. Soil salinity is a serious environmental issue that is drastically reducing crop productivity via limiting the uptake of important micronutrients including iron (Fe) and zinc (Zn).

Aims. To identify the wheat genotypes with better Fe and Zn uptake potential under saline conditions.

Methods. The seedlings of eight wheat genotypes (SARC-1, SARC-2, SARC-3, SARC-4, SARC-5, SARC-6, SARC-7 and SARC-8) were exposed to salinity (100 mM NaCl), deficiency of Fe and Zn (one-fourth of the control) and their combination of salinity and deficiency of Fe and Zn, created usingHoagland's nutrient solution for 28 days.

Key Results. It was noticed that root and shoot growth of all the genotypes decreased due to salinity and nutrient (Fe and Zn) deficiency, and even higher in their combined treatment. The concentration of Na increased while K decreased under both salinity alone and it's combination with nutrient deficiency. The concentrations and uptake of Fe and Zn greatly decreased in the combinedapplication of salinity and nutrient deficiency followed by nutrient deficiency and saline treatments. Multivariate analysis showed that Na uptake was the major reason for the limited growth and nutrient uptake by wheat genotypes.

Conclusions. SARC-5 was the most sensitive genotype against salinity and nutrient deficiency. In contrast, SARC-1 was the most tolerant genotype against salinity, whichaccumulated the highest contents of both Fe and Zn. Among the eight genotypes used in the present study, SARC-1 is the most suitable genotype for cultivation on Zn and Fe deficient saline soils.

Implications. The obtained results would be very helpful for ensuring food security and quality in salt affected areas.

Context. Soil salinity mitigation with nanoparticles enriched biochar (Bc) can be a better strategy to resolve the uprising threat against food security.

Aim. The present study was designed to prepare silicon nanoparticles enriched biochar (Si-En-Bc) and zinc nanoparticles enriched biochar (Zn-En-Bc), which may not only reduced the toxic effects of NaCl stress on initial growth of radish crop but also improved its physiology and defensive mechanism.

Method. Seeds were germinated in pots with six treatments under normal and NaCl stress, (100 mM NaCl), Zn-En-Bc (1% w/w), and Si-En-Bc (1% w/w). Twenty days old seedlings were harvested and their fresh weight and various germination and biochemical parameters were tested.

Key results. A significant reduction in malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents was observed with Si-En-Bc + NaCl relative to NaCl stress. It might be due to the significant increase in the antioxidants such as superoxide dismutase (SOD) (42%), ascorbate peroxidase (APX) (38.7%), catalase (CAT) (30.9%) and shoot phenolics (59%) with Si-En-Bc + NaCl over NaCl stress. Application of Zn-En-Bc also caused a maximum increase in root and shoot Zn concentration (76.8 and 54.9%, respectively) under NaCl stress.

Conclusions. Hence, Si-En-Bc proved to be the best treatment for the radish plant to complete its early growth stage under NaCl stress while Zn-En-Bc not only compensated NaCl stress but also enhanced Zn availability.

Implications. This study implies that Si-En-Bc or Zn-En-Bc should be applied to the salt affected soil before the crop sowing so seedling can grow under the ameliorative effects of applied amendments. Also, Si-En-Bc or Zn-En-Bc should be tested on a degraded soils at larage scale such as field level.

Plants varyingly serve as control agents for heavy metal loads in environmental compartments, including soils, by accumulating and partitioning most heavy metals in their organs. However, by doing this wonderful job, the plant health and productivity get affected because of the elevated cellular heavy metals. Therefore, exploration of approaches for strengthening plant's tolerance to cellular heavy metals is very imperative. As an indispensable macronutrient in plants, sulfur (S) is widely known to assist numerous plant functions and is also argued as vital element for various plant metabolic processes both in normal and stressed conditions. However, the discussion on the heavy metal-specific roles of S-containing compounds in plants have been considered least. In this paper, the aspects discussed included the following: (1) heavy metals and their relation with plants; and nutrient-management and S in control of metal stress-impacts in plants are introduced; (2) major insights into S-assimilation and -assimilatory products are overviewed; (3) important roles of assimilatory products in plant tolerance to common heavy metals are highlighted, and (4) metal-specific influence on assimilatory products in plants are discussed.

Antimony (Sb) pollution is causing serious concerns in some regions globally, such as around the XiKuangShan mine in China, which is the largest Sb mine in the world. However, remediation measures are scarce. In this study, we assessed the effects of two fertilisers, sodium dihydrogen phosphate (NaH₂PO₄ at 200, 500 and 2000 mg kg^-1) and calcium chloride (CaCl₂ at 20, 80 and 200 mg kg^-1), on uptake by rice (Oryza sativa L.) of Sb, cadmium (Cd) and arsenic (As) from contaminated soil under flooded conditions. Despite a very low soil As concentration (10.89 mg kg^-1), the results showed that flooded conditions will result in excess accumulation of As in rice grains. NaH₂PO₄ generally enhanced the release of As and Sb by increasing pH and competitive adsorption in the soil, which resulted in their accumulation in many tissues of the rice plants. NaH₂PO₄ (200 mg kg^-1) significantly reduced soil available Cd concentration by increasing soil pH, which resulted in a decrease in Cd concentration in the roots and husks. CaCl₂ at 200 mg kg^-1 decreased soil pH, and CaCl₂ treatments increased the available Sb concentration, although not as much as NaH₂PO₄. Both NaH₂PO₄ and CaCl₂ enhanced the formation of root iron plaques, and in many cases increased the concentrations of As, Cd and Sb in the root plaques, suggesting a storage role rather than a barrier of root iron plaques for plant uptake of As, Cd and Sb. CaCl₂ at 200 mg kg^-1 was the most effective treatment for reducing As, Sb and Cd concentrations in rice grains. We conclude that utilisation of fertilisers containing P on a soil co-contaminated by Sb and Cd poses a risk of Sb and As accumulation under continuous flooded conditions, whereas addition of CaCl₂ at 200 mg kg^-1 may control As, Sb and Cd accumulation in grains of rice plants under these conditions.

Context. Anthropogenic activities are increasing Cd concentration in soil and environment that limits seed germination capacity and causes poor seedling establishment.

Aims. The effect of different Cd concentrations on seed germination and seedling growth of two maize cultivars (C-20 and EV-1098) was tested in this study.

Methods. Maize seeds were sown in Petri dishes lined with double filter paper. The seedlings were grown in a growth chamber, applied with different Cd concentrations (0, 2, 4, 6, 8 and 10 μM), and harvested 12 days after germination.

Key results. Seeds applied with higher levels of Cd showed a significant decrease in seed germination percentage (GP), seed emergence index (EI) and germination energy (GE). A significant delay in seed germination was observed at the highest Cd treatment in terms of increased mean emergence time (MET), days to 50% germination (T₅₀) and coefficient of uniformity of emergence (CUE). A marked decline in leaf K, Ca, Na, and P was observed, whereas root K, Ca and P increased with an increase in external Cd concentration. The roots and leaves of maize C-20 showed greater activities of superoxide dismutase (SOD) than did those of EV-1098. In contrast, peroxidase (POD) activity was reasonably high in roots and leaves, whereas catalase (CAT) was high only in roots of EV-1098. Non-enzymatic antioxidants such as phenolics and ascorbicacid (AsA) also significantly increased, accompanied with substantially lowermalondialdehyde (MDA) contents in the roots and leaves of EV-1098 than of C-20.

Conclusions. The differential modulation of the activities of enzymatic and non-enzymaticanti-oxidative defense system in roots and leaves played a critical role intolerance of both cultivars to Cd stress.

Implications. The findings of this study are helpful in improving seed germination capacity and seedling growth of maize in Cd contaminated soils.