Summary• This study focussed on the effect of increasing nitrogen (N) supply on root uptake and root-to-shoot translocation of zinc (Zn) as well as retranslocation of foliar-applied Zn in durum wheat (Triticum durum).• Nutrient solution experiments were conducted to examine the root uptake and root-to-shoot translocation of 65 Zn in seedlings precultured with different N supplies. In additional experiments, the effect of varied N nutrition on retranslocation of foliar-applied 65 Zn was tested at both the vegetative and generative stages.• When N supply was increased, the 65 Zn uptake by roots was enhanced by up to threefold and the 65 Zn translocation from roots to shoots increased by up to eightfold, while plant growth was affected to a much smaller degree. Retranslocation of 65 Zn from old into young leaves and from flag leaves to grains also showed marked positive responses to increasing N supply.• The results demonstrate that the N-nutritional status of wheat affects major steps in the route of Zn from the growth medium to the grain, including its uptake, xylem transport and remobilization via phloem. Thus, N is a critical player in the uptake and accumulation of Zn in plants, which deserves special attention in biofortification of food crops with Zn.

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Sorghum is one of the water-and nutrient-use efficient crops raised in dry regions worldwide. A 3 × 3 split-plot experiment in randomized complete block design was conducted to study the effects of petroleum refinery waste aqueous ammonia (NH 3 ) on irrigated fodder sorghum for two consecutive growing seasons. The main plots consisted of 0 (control), 40, and 80 kg N ha −1 , respectively, and the injection depths (surface 15 cm, and 20 cm depth) were assigned to sub-plots. A significant effect of NH 3 on both fresh and dry biomass production was observed where the highest yield was recorded from the 80 kg N ha −1 than the control and 40 kg N ha −1 , respectively. Sorghum biomass yield increased most when NH 3 was injected at 20 cm depth as compared to other depths. Biomass nutrient content and nitrogen-use efficiency were increased when 80 kg N ha −1 was applied as compared to the control. The critical limit of K:(Ca+Mg), above which the tetany risk increases, did not exceed in sorghum biomass by NH 3 fertilization. Results suggested that industrial waste NH 3 equivalent to 80 kg N ha −1 injected at 20 cm depth can be a sustainable approach to fertilize irrigated sorghum growing as a forage crop.

The present study aimed to test the contribution of the iron (Fe) deficiency‐induced uptake system to zinc (Zn) and copper (Cu) uptake by using bread wheat (Triticum aestivum cv. Bezostaja). For this purpose, two different uptake experiments, long‐term and short‐term, were set up in a nutrient solution culture under controlled growth chamber conditions. For the long‐term experiment, wheat cv. plants were grown with different concentrations of Fe or Zn. Results show that there was an uptake system induced under Fe‐limiting conditions which also contributed to Zn and Cu uptake. However, the Zn deficiency‐induced uptake mechanism affected neither Fe nor Cu uptake by wheat. Short‐term uptake experiments indicate that Fe deficiency‐induced Zn2+ uptake was more enhanced than the absorption of Zn‐phytosiderophore (PS) complexes. In addition, the Fe‐deficient plants absorbed more Zn in comparison to those plants supplied with sufficient Fe. Similar tendencies in Zn uptake under Fe deficiency in both short‐ and long‐term experiments suggest that there may be a specific Fe uptake system induced under Fe‐limiting conditions for non‐chelated metals in bread wheat. Moreover, this system also contributes to the transport of inorganic forms of some other metals, such as Zn and Cu. Although evidence is still needed involving the use of molecular biological techniques, it is hypothesized that IRT‐like proteins are responsible for this uptake system. Moreover, the release of Fe deficiency‐induced phytosiderophores and uptake of Fe(III)‐phytosiderophore complexes may not be the only mechanisms involved in the adaptation of wheat to Fe‐limiting conditions.

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