Native mycorrhizal fungi and phosphate doses in the development of peanut RUNNER IAC 886

Objetivou-se avaliar a interação entre fungos micorrízicos arbusculares nativos (FMA) com plantas de amendoim (Arachis hypogea) cultivar RUNNER IAC 886, em diferentes doses de fósforo (P). O experimento foi conduzido em casa de vegetação em delineamento inteiramente casualizado, em esquema fatorial (2 x 5), sendo com e sem a inoculação dos endófitos e cinco doses de P (0; 20; 40; 60 e 180 mg kg-1 na forma de KH2PO4), com quatro repetições. Avaliaram-se massa seca de: raiz, parte aérea, total, taxa de colonização radicular (CR), dependência micorrízica (DM) e eficiência micorrízica (EM). Concluiu-se que as doses crescentes de adubação fosfatada promoveram aumento no desenvolvimento das plantas de amendoim. Os FMA promoveram a produção máxima de massa seca total do amendoim na dose estimada de 114,0 mg kg-1 de P. A maior colonização radicular e eficiência micorrízica foram verificadas na dose 60 mg kg-1 de P.The objective was to evaluate the interaction between native arbuscular mycorrhizal fungi (AMF) with peanut plants (Arachis hypogea) RUNNER cultivar IAC 886, at different levels of phosphorus (P). The experiment was conducted in a greenhouse in a randomized design in factorial (2 x 5), with and without inoculation of AMF and five P levels (0; 20; 40; 60 and 180 mg kg-1 in the form of KH2PO4) in four replications. Shoot, root and total dry mass, root colonization, mycorrhizal dependency and mycorrhizal efficiency were evaluated. It was concluded that increasing levels of phosphorus caused an increase in the development of peanut plants. The AMF promoted maximum production of total dry mass of the peanut in estimated dose of 114.0 mg kg-1 of P. The highest root colonization and mycorrhizal efficiency were observed at 60 mg kg-1 of P.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Efficiency of foliar application of sparingly soluble sources of boron and zinc in citrus

This study evaluated leaf supply of zinc (Zn) and boron (B) using either soluble or sparingly soluble fertilizers in young sweet orange trees. Three experiments were set up in a greenhouse to compare two sources and four doses (control, low, adequate and high) of fertilizers as follows: (i) Experiment I (B): boric acid and calcium borate; (ii) Experiment II (Zn): Zn sulfate and Zn oxide; and (iii) Experiment III (B + Zn): boric acid + Zn Sulfate and Zn Borate. The sparingly soluble sources were effective in increasing the Zn and B leaf concentration. Dry matter of the aerial part increased 18 % with B applications in adequate concentration independent of the B fertilizer sources. In contrast, trees did not grow well with applications of adequate concentration of Zn as Zn Sulfate or high Zn concentration as Zn borate. Superoxide dismutase activity in leaves increased with applications of low concentration of Zn as Zn oxide and decreased with high concentration of Zn from either source. Polyphenol oxidase activity increased with application of adequate concentration of B as boric acid and high concentration of B as calcium borate. Furthermore, the upper concentrations of Zn were toxic in orange trees when the source was Zn sulfate. Increases in plant growth without damage to leaf tissue and positive responses of key enzymes of orange trees in a range of nutrient concentration applications demonstrated the practical use of sparingly soluble fertilizers to supplying B and Zn foliarily to plants

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

Copper supply and fruit yield of young Citrus trees: fertiliser sources and application methods

<div><p>ABSTRACT This study aimed to evaluate the fertiliser sources and application methods of copper (Cu) in citrus trees during the first years of fruit production. Two experiments were set up in an orchard with 3-year-old sweet orange trees, which were applied with three sources of Cu (nitrate, sulfate or EDTA) either via fertigation (Experiment 1) or via foliar sprays (Experiment 2). Regardless of the fertiliser source, Cu application via fertigation was not efficacious to increase the micronutrient concentration in leaves and, consequently, did not affect fruit yield. Conversely, foliar application of Cu, either as nitrate or sulfate, increased this nutrient level in leaves but when applied as copper nitrate, visual phytotoxicity symptoms were verified in leaves due to salt accumulation in the plant canopy, which reduced the fruit yield. Considering the plant growth and intensified phytosanitary management of the orchard with the application of copperbased products after the third year of the experiment, the effects of Cu treatments on fruit yield are expected to be negligible as the trees age.</p></div

Copper supply and fruit yield of young Citrus trees: fertiliser sources and application methods

<div><p>ABSTRACT This study aimed to evaluate the fertiliser sources and application methods of copper (Cu) in citrus trees during the first years of fruit production. Two experiments were set up in an orchard with 3-year-old sweet orange trees, which were applied with three sources of Cu (nitrate, sulfate or EDTA) either via fertigation (Experiment 1) or via foliar sprays (Experiment 2). Regardless of the fertiliser source, Cu application via fertigation was not efficacious to increase the micronutrient concentration in leaves and, consequently, did not affect fruit yield. Conversely, foliar application of Cu, either as nitrate or sulfate, increased this nutrient level in leaves but when applied as copper nitrate, visual phytotoxicity symptoms were verified in leaves due to salt accumulation in the plant canopy, which reduced the fruit yield. Considering the plant growth and intensified phytosanitary management of the orchard with the application of copperbased products after the third year of the experiment, the effects of Cu treatments on fruit yield are expected to be negligible as the trees age.</p></div

Superoxide dismutase (SOD) activity in the leaves of young orange trees 150 days after Zn application (enriched on ⁶⁸Zn) in different soils.

<p>Legend: Bovine SOD standard (S), ZnSO₄ (S1), and ZnO (O1) in the sandy loam soil; ZnSO₄ (S2) and ZnO (O2) in the clay soil.</p

Zinc derived from fertilizer (Zn_dff) in young orange trees 150 days after ⁶⁸Zn application in soils with sandy loam or clay texture.

<p>Soil type: the means (n = 3 or 6) followed by different uppercase letters within the columns are significantly different by the Tukey test (<i>p</i><0.05). Zn sources: the means (n = 3 or 6) followed by different lowercase letters across paired columns are significantly different by the Tukey test (<i>p</i><0.05).</p><p>^aF test in the ANOVA of Soil vs. Source for each evaluated parameter. ns: not significant (<i>p</i>>0.05);</p><p>*<i>p</i><0.05;</p><p>**<i>p</i><0.01.</p><p>^bYoung fruits: 3–5 cm in diameter.</p><p>Zinc derived from fertilizer (Zn_dff) in young orange trees 150 days after ⁶⁸Zn application in soils with sandy loam or clay texture.</p