Internal Zn allocation influences Zn deficiency tolerance and grain Zn loading in rice (Oryza sativa L.)

One of the important factors that influences Zn deficiency tolerance and grain Zn loading in crops is the within-plant allocation of Zn. Three independent experiments were carried out to understand the internal Zn distribution patterns in rice genotypes grown in Zn-sufficient and Zn-deficient agar nutrient solution (ANS). In one of the experiments, two rice genotypes (IR55179 and KP) contrasting in Zn deficiency tolerance were leaf-labeled with 65Zn. In the other two experiments, two Zn biofortification breeding lines (IR69428 and SWHOO) were either root- or leaf-labeled with 65Zn. Rice genotype IR55179 showed significantly higher Zn deficiency tolerance than KP at 21 and 42 days after planting. When KP was Zn-deficient, it failed to translocate 65Zn from the labeled leaf to newly emerging leaves. Similarly, the root-to-shoot translocation of unlabeled Zn was lower in KP than in IR55179. These results suggest that some Zn-efficient rice genotypes have greater ability to translocate Zn from older to actively growing tissues than genotypes sensitive to Zn deficiency. Among the two Zn biofortication breeding lines that were leaf-labeled with 65Zn at 10 days before panicle initiation stage, 65Zn distribution in the grains at maturity was similar between both genotypes in Zn-sufficient conditions. However, under Zn-deficient conditions, SWHOO accumulated significantly higher 65Zn in grains than IR69428, indicating that SWHOO is a better remobilizer than IR69428. When the roots of these two Zn biofortication breeding lines were exposed to 65Zn solution at 10 days after flowering, IR69428 showed higher root uptake of 65Zn than SWHOO in Zn-sufficient conditions, but 65Zn allocation in the aerial parts of the plant was similar between both genotypes.ISSN:1664-462

Ein- und mehrjährige Nützlingsstreifen im Ackerland

Das Merkblatt hat zum Ziel, Beratungskräfte, Landwirtinnen und Landwirte sowie weitere landwirtschaftliche Akteure bei der Auswahl der Samenmischung, der Standortwahl, Anlage, Pflege und Aufhebung von ein- und mehrjährigen Nützlingsstreifen auf offener Ackerfläche zu unterstützen. Ebenfalls wird der Nutzen der Nützlingsstreifen für die Kulturen aufgezeigt

Bandes annuelles et pluriannuelles pour organismes utiles sur terres ouvertes

La fiche technique a pour but d‘aider les conseillers-ères, les agriculteurs-trices et les autres acteurs agricoles à choisir le mélange de semences, l‘emplacement, l‘installation, l‘entretien et la suppression des bandes pour organismes utiles annuelles et pluriannuelles sur les terres ouvertes. La fiche traite également de l‘utilité de ces bandes pour les culture

Availability of Zinc and the Ligands Citrate and Histidine to Wheat: Does Uptake of Entire Complexes Play a Role?

Organic ligands in soils affect the availability of trace metals such as Zn to plants. This study investigated the effects of two of these ligands, citrate and histidine, on Zn uptake by wheat under hydroponic conditions. Uptake of ⁶⁵Zn in the presence of these ligands was compared to uptake in the presence of EDTA at the same free Zn concentration (Zn²⁺ ∼ 50 nM). In the presence of citrate Zn root uptake was enhanced ∼3.5 times and in the presence of histidine, by a factor of ∼9, compared to the EDTA treatments. Citrate uptake was slightly reduced in the treatment containing ligands and Zn compared to the treatment containing the same ligand concentration but no Zn. In addition, a higher uptake of Zn than of citrate was observed. This suggests that the enhanced Zn uptake was primarily due to increased supply of Zn²⁺ by diffusion and dissociation of Zn–citrate complexes at the root surface. Histidine uptake was much higher than citrate uptake and not influenced by the presence of Zn. As histidine forms stronger complexes with Zn than citrate, the results suggest that the enhancement of Zn uptake in the presence of histidine was in part due to the uptake of undissociated Zn–histidine complexes