Uptake and distribution of soil applied zinc by citrus trees-addressing fertilizer use efficiency with 68Zn labeling.
The zinc (Zn) supply increases the fruit yield of Citrus trees that are grown, especially in the highly weathered soils of the tropics due to the inherently low nutrient availability in the soil solution. Leaf sprays containing micronutrients are commonly applied to orchards, even though the nutrient supply via soil could be of practical value. This study aimed to evaluate the effect of Zn fertilizers that are applied to the soil surface on absorption and partitioning of the nutrient by citrus trees. A greenhouse experiment was conducted with one-year-old sweet orange trees. The plants were grown in soils with different textures (18.1 or 64.4% clay) that received 1.8 g Zn per plant, in the form of either ZnO or ZnSO4 enriched with the stable isotope 68Zn. Zinc fertilization increased the availability of the nutrient in the soil and the content in the orange trees. Greater responses were obtained when ZnSO4 was applied to the sandy loam soil due to its lower specific metal adsorption compared to that of the clay soil. The trunk and branches accumulated the most fertilizer-derived Zn (Zndff) and thus represent the major reserve organ for this nutrient in the plant. The trees recovered up to 4% of the applied Zndff. Despite this relative low recovery, the Zn requirement of the trees was met with the selected treatment based on the total leaf nutrient content and increased Cu/Zn-SOD activity in the leaves. We conclude that the efficiency of Zn fertilizers depends on the fertilizer source and the soil texture, which must be taken into account by guidelines for fruit crop fertilization via soil, in substitution or complementation of traditional foliar sprays.
Centro de Citricultura Sylvio Moreira, Instituto Agronômico (IAC), Cordeirópolis, São Paulo, Brazil.
Franz Walter Rieger
FW
Hippler
Centro de Citricultura Sylvio Moreira, Instituto Agronômico (IAC), Cordeirópolis, São Paulo, Brazil.
Rodrigo Marcelli
RM
Boaretto
Centro de Solos e Recursos Ambientais, Instituto Agronômico (IAC), Campinas, São Paulo, Brazil.
José Antônio
JA
Quaggio
Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, São Paulo, Brazil.
Antonio Enedi
AE
Boaretto
Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, São Paulo, Brazil.
Cassio Hamilton
CH
Abreu-Junior
Centro de Citricultura Sylvio Moreira, Instituto Agronômico (IAC), Cordeirópolis, São Paulo, Brazil.
Dirceu
D
Mattos
D002957:Citrus / Q000254:growth & development* / Q000378:metabolism; D005308:Fertilizers / Q000032:analysis*; D005638:Fruit / Q000737:chemistry / Q000254:growth & development; D018515:Plant Leaves / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D015032:Zinc / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D015033:Zinc Isotopes / Q000737:chemistry
D005308:Fertilizers; D012987:Soil; D015033:Zinc Isotopes; D015032:Zinc