Phosphorus Application Decreased Copper Concentration but Not Iron in Maize Grain

Abstract

Copper (Cu) and iron (Fe) are essential micronutrients for plants and animals. How phosphorus (P) application affects Cu and Fe concentrations in maize grain still remains unclear. Two-year field studies were conducted in a long-term experiment with six P levels (0, 12.5, 25, 50, 100, and 200 kg∙ha−1 P) on calcareous soil. Phosphorus application significantly decreased the average grain Cu concentration by 12.6% compared to no P treatment, but had no effect on grain Fe concentration. The copper content increased as the P application rate increased from 0 to 25 or 50 kg·ha−1, but then decreased, while Fe content kept increasing. As the P application rate increased, the specific Cu uptake by the roots decreased, but not for Fe. The root length density in response to P application had a positive relationship with shoot Cu and Fe content. The shoot Cu content and grain Cu concentration decreased with the reduction in the arbuscular mycorrhizal fungi (AMF) colonization of roots due to increasing P application. The reduction in grain Cu concentration with increasing P rates could be partly explained by the decreasing uptake efficiency.

In addition to foliar manganese concentration, both iron and zinc provide proxies for rhizosheath carboxylates in chickpea under low phosphorus supply

“…We have no explanation for the mechanism of chickpea selectively maintaining substantial Mn and Fe uptake under KP50, but note that similar results have been reported for other species (Huang et al 2017;Zhang et al 2020). Third, antagonistic interactions between micronutrients may also contribute to a decrease in leaf [Zn] and…”

“…[Zn] and [Cu] may be related to the interactions between P and micronutrients (Tsai and Schmidt 2017). A high soil P supply inhibited plant Zn and Cu uptake, as have been well documented (Touchton et al 1980;Haldar and Mandal 1981;Zhang et al 2017Zhang et al , 2020.…”

The Assessment of Soil Availability and Wheat Grain Status of Managnese and Iron in Calcareous Soils and Implication for Human Safety in Iraqi Kurdistan

“…Also, the regression analysis showed a high positive correlation (r 2 =0.39, p≤ 0.001) between Mn and Ca concentrations in wheat grains. In contrast, Zhang et al (2020) resulted in P application to calcareous soil not affected by decreasing the wheat grain Fe concentration. Singh et al (2018) studied N fertilization on the concentration of Fe in the wheat grain and found that split application of 160 kg ha -1 is an effective agriculture practice to improve Fe content of grain.…”

“…The grain content of Fe is not increased by soil application of Fe fertilizer in the calcareous soils (Prasad et al, 2014), this is due to the presence of a high amount of CaCO3 which causes decreasing the availability of Fe in this type of soil (Alam and Ansari, 2001). Thus, foliar fertilization of Fe could raise the concentration of Fe in the wheat grain to about 35%, due to the limitation of transporting of Fe to the endosperm (Zhang et al, 2020). Pahlavan-Rad and Pessarakli (2009) found that foliar application of 1% of FeSO4 increased about 21% of Fe concentration in the wheat grain.…”

“…On the other hand, in calcareous soils, the deficiency of P is very common (Boukhalfa-Deraoui et al, 2015). Thus, phosphorus fertilizer application in wheat grown fields is common this is to increase in the wheat grain yield Zhang et al, 2020), while it could affect micronutrients concentration in the wheat grain. In this survey, regression analysis showed a significant correlation (r 2 = 0.143, p≤ 0.001) between Mn and P concentrations in the wheat grain.…”