Search

Background and Aims: Phosphate (Pi) is one of the most limiting nutrients for agricultural production in Brazilian soils due to low soil Pi concentrations and rapid fixation of fertilizer Pi by adsorption to oxidic minerals and/or precipitation by iron and aluminum ions. The objectives of this study were to quantify phosphorus (P) uptake and use efficiency in cultivars of the species Coffea arabica L. and Coffea canephora L., and group them in terms of efficiency and response to Pi availability. Methods: Plants of 21 cultivars of C. arabica and four cultivars of C. canephora were grown under contrasting soil Pi availabilities. Biomass accumulation, tissue P concentration and accumulation and efficiency indices for P use were measured. Key Results: Coffee plant growth was significantly reduced under low Pi availability, and P concentration was higher in cultivars of C. canephora. The young leaves accumulated more P than any other tissue. The cultivars of C. canephora had a higher root/shoot ratio and were significantly more efficient in P uptake, while the cultivars of C. arabica were more efficient in P utilization. Agronomic P use efficiency varied among coffee cultivars and E16 Shoa, E22 Sidamo, Iêmen and Acaiá cultivars were classified as the most efficient and responsive to Pi supply. A positive correlation between P uptake efficiency and root to shoot ratio was observed across all cultivars at low Pi supply. These data identify Coffea genotypes better adapted to low soil Pi availabilities, and the traits that contribute to improved P uptake and use efficiency. These data could be used to select current genotypes with improved P uptake or utilization efficiencies for use on soils with low Pi availability and also provide potential breeding material and targets for breeding new cultivars better adapted to the low Pi status of Brazilian soils. This could ultimately reduce the use of Pi fertilizers in tropical soils, and contribute to more sustainable coffee production. [ABSTRACT FROM AUTHOR]

Abstract: Sewage sludge has been used to fertilize coffee, increasing the risk of metal contamination in this crop. The aim of this work was to study the effects of Cd, Zn and Ni in adult coffee plants growing under field conditions. Seven-year-old coffee plants growing in the field received one of three doses of Cd, Zn or Ni: 15, 45 and 90gCdplant−1; 35, 105 and 210gNiplant−1; and 100, 300 and 600gZnplant−1, with all three metals in the form of sulphate salts. After three months, we noticed good penetration of the three metals into the soil, especially in the first 50cm, which is the region where most coffee plant roots are concentrated. Leaf concentrations of K, Ca, Mg, S, B, Cu, Fe and Mn were not affected. N levels did not change with the application of Ni or Zn but were reduced with either 45 or 90gCdplant−1. Foliar P concentrations decreased with the addition of 45 and 90gCdplant−1 and 600gZnplant−1. Zn levels in leaves were not affected by the application of Cd or Ni. The highest concentrations of Zn were found in branches (30–230mgkg−1), leaves (7–35mgkg−1) and bean (4–6.5mgkg−1); Ni was found in leaves (4–45mgkg−1), branches (3–18mgkg−1) and beans (1–5mgkg−1); and Cd was found in branches (0–6.2mgkg−1) and beans (0–1.5mgkg−1) but was absent in leaves. The mean yield of two harvests was not affected by Ni, but it decreased at the highest dose of Zn (600gplant−1) and the two higher doses of Cd (45 and 90gplant−1). Plants died when treated with the highest dose of Cd and showed symptoms of toxicity with the highest dose of Zn. Nevertheless, based on the amounts of metal used and the results obtained, we conclude that coffee plants are highly tolerant to the three metals tested. Moreover, even at high doses, there was very little transport to the beans, which is the part consumed by humans. [Copyright &y& Elsevier]

High-technology coffee cultivation systems involving fertigation commonly apply high rates of nitrogen (N). However, there is little information on the plants' uptake of N under these conditions. The objective of this study was to evaluate the changes in the nutritional status of coffee plants during a phenological cycle in response to N applied by fertigation. The study was conducted with 7-year-old trees of Coffea arabica L., under pivot irrigation and fertigation, with five N rates (0, 200, 400, 600, and 800 kg ha−1) applied on the plants. The changes in nutritional status were monitored during the phenological cycle, and the yield was measured at the end of the cycle. The N concentration increased with the N rates and varied with the phenological period, with the greatest concentration occurring during anthesis, the same as for the sulfur level. However, N rate did not affect the concentrations of other nutrients. The greatest concentrations of phosphorus, calcium, and magnesium were obtained in the final fructification phases and for potassium in the initial phases. Micronutrient concentrations were greater in the vegetative phases and anthesis but were reduced in the fruit- formation phase and increased again when the berries started to mature. The maximum yield, considering a relative production of 90%, was obtained with application of 415 kg ha−1 of N. Leaf concentrations of N were directly related to the N rates, showing that the nutritional status of coffee plants can be evaluated in the ripening phase to adjust the fertilization parameters for the next year. [ABSTRACT FROM AUTHOR]

Nutritional and physiological significance of micronutrients in coffee plants, especially with regard to nickel (Ni) is still unknown. The dynamics of nitrogen (N), phosphorus (P), potassium (K) and Ni accumulation in coffee fruits, as well as their relationships with total soluble protein, amino acids, reducing sugars, and starch content during coffee fruit development (green, ripe, and dry fruits), were investigated. Coffee trees received three N fertilizer rates (0, 150, and 300 kg of N ha−1) as ammonium sulfate split into three applications per year. Nitrogen fertilization increased reducing sugars and starch concentrations in ripe fruits. In contrast, green fruits showed the highest amino acid and Ni concentrations. Fruit Ni concentration decreased in both green and ripe fruits as N rates increased; thus, indicating the possibility of either a N-associated dilution effect on Ni concentration or that Ni uptake by roots and/or transport to developing fruit was limiting. Plant nutritional status and fruit development stage influenced the coffee grain chemical composition. Furthermore, the variation in reducing sugars and starch content was more closely linked to the stage of fruit development than to N supply. A supposed relationship among the decreased of caffeine, starch, amino acids, and proteins with Ni content during green fruit development suggests a fundamental role for Ni in coffee fruit ripening. The interaction between N and Ni metabolism during fruit ripening might influence the chemical parameters involved in the coffee grain quality. This is the first report documenting changes in Ni concentrations of coffee fruit as a function of N fertilization rates and the development stage, but further research is needed to better understand the significance of N-Ni interaction in developing coffee fruit. [ABSTRACT FROM AUTHOR]