Estudos sôbre a alimentação mineral do cafeeiro: XX. efeito da variação de pH no desenvolvimento e composição química do cafeeiro (Coffea arabica L., var. Mundo Nôvo) cultivado em solução nutritiva

Amorim, Henrique Vianna de; Scoton, Luiz Carlos; Haag, H.P.; Malavolta, E.

doi:10.1590/s0071-12761968000100011

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“…Table 3. Leaf concentration (mg g -l dry weight) of several elements, in conditions of Ca deficiency, adequate and excess to coffee plants (data from Amorim et al, 1968;Carvajal, 1984;Malavolta, 1963and Matiello, 1985.…”

Section: Nutrient Analysismentioning

confidence: 99%

Effects of calcium deficiency on Coffea arabica. Nutrient changes and correlation of calcium levels with some photosynthetic parameters

et al. 1995

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A b s t r a c tCalcium deficiency was induced in hydroponically grown 1.5-years-old coffee plants with 12-14 pairs of leaves. Calcium was given in the form of Ca(NO3)2: 5, 2.5, 0.1, 0.01 and 0 mM. After 71 days of Ca-treatment root and shoot as well as total biomass were decreased by severe Ca-deficiency. However, a stronger decrease was observed for shoot growth as revealed by the increase in the root/shoot ratio. New leaves were affected showing decreases in the total leaf area and in Leaf Area Duration (LAD). After 91 days of deficiency, leaf protein concentration decreased (by about 45%) in the top leaves while nitrate reductase activity (NRA) and NO3 content showed no significant changes. Total nitrogen and mineral concentrations (P, K, Ca, Mg and Na) were also determined in leaves and roots. With the decrease in calcium concentration in Ca-deficiency conditions, we observed concomitant increases in the concentrations of K +, Mg 2+ and Na + in leaves (maximal changes of 32% for K +, 96% for Mg 2+ and 438% for Na +) and in roots (108% for K +, 86% for Mg 2+ and 38% for Na+). Accordingly, the ratio between elements changed, including the ratio N/P, showing a non-equilibrium in the balance of nutrients. Significant correlations were obtained between Ca 2+ concentration and some photosynthetic parameters. Ca-deficiency conditions would increase the loss of energy as expressed by the rise in qE and decrease the photochemical efficiency, which confirms the importance of this element in the stabilization of chlorophyll and in the maintenance of good photochemical efficiency at PS II level.Abbreviations: Chl -Chlorophyll, Fv/Fm -ratio of variable to maximal fluorescence, LAD -leaf area duration, LHC II -light harvesting complex of PS II, NRA -nitrate reductase activity, PC -photosynthetic capacity, PS II -photosystem II, P680 -reaction center of PS II, qN -non-photochemical quenching, qE --high-energy dependent quenching, qp -photochemical quenching, SLA -specific leaf area.

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Section: Nutrient Analysismentioning

confidence: 99%