Acúmulo de nutrientes em frutos de cafeeiro em quatro altitudes de cultivo: cálcio, magnésio e enxofre
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2007-11
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Revista Brasileira de Ciência do Solo
Resumo
As curvas de acúmulo de nutrientes em frutos permitem estimar sua exportação, bem como as épocas de maior demanda. Estudou-se o acúmulo de MS, Ca, Mg e S em frutos de Coffea arabica (L.) da antese à maturação em quatro altitudes, bem como a variação na concentração dos elementos em folhas dos ramos produtivos. O experimento foi constituído da variedade de cafeeiro Catuaí IAC 44 cultivada a 720, 800, 880 e 950 m de altitude, no município de Martins Soares-MG. O delineamento experimental foi inteiramente ao acaso, com três repetições, usando-se um esquema de parcela subdividida no tempo. O aumento da altitude influenciou o ciclo reprodutivo do cafeeiro, pois houve demanda de maior tempo para formação dos frutos. No estádio de expansão rápida, a percentagem de acúmulo de MS, Ca, Mg e S foi maior na altitude de 720 m, comparada, principalmente, à de 950 m. A TMAD (taxa máxima de acúmulo diário) no estádio de granação-maturação apresentou tendência de ser mais tardia com a elevação da altitude. O consumo de nutrientes pelos frutos, assim como o enchimento de grãos, é mais crítico em condições de menor altitude, já que a planta necessita completar esses processos em menor espaço de tempo. De modo geral, na altitude de 720 m ocorreu maior competição fruto/folha pela partição de Ca, Mg e S.
Crurves of fruit nutrient accumulation are tools for estimating the peaks of nutrient demand and the nutrient export form the soil. The accumulation of dry matter (DM), Ca, Mg and S was studied in fruits of Coffea arabica (L.) in the period between anthesis and maturation at four altitudes of cultivation, as well as the variation in the leaf content of the elements in productive branches. The experiment consisted of the coffee variety Catuaí IAC 44 cultivated at 720, 800, 880 and 950 m above sea level (asl), in Martins Soares-MG. The experimental design was entirely randomized with tree replications using a split-plot in time scheme. The height asl of the crop influenced the coffee reproduction cycle, particularly the time required for fruit formation. In the fast expansion stage the percentages of DM and Ca, Mg and S accumulation were higher in trees grown at 720 m than at 950 m. The DMAR (daily maximum accumulation rate) in the grain filling stage tended to be delayed at higher altitudes. Nutrient accumulation in the fruits as well as grain filling are more critical at lower altitudes since these processes have to occur in a shorter time. In general, the fruit/leaf competition for the partitioning of Ca, Mg and S was higher at 720 m.
Crurves of fruit nutrient accumulation are tools for estimating the peaks of nutrient demand and the nutrient export form the soil. The accumulation of dry matter (DM), Ca, Mg and S was studied in fruits of Coffea arabica (L.) in the period between anthesis and maturation at four altitudes of cultivation, as well as the variation in the leaf content of the elements in productive branches. The experiment consisted of the coffee variety Catuaí IAC 44 cultivated at 720, 800, 880 and 950 m above sea level (asl), in Martins Soares-MG. The experimental design was entirely randomized with tree replications using a split-plot in time scheme. The height asl of the crop influenced the coffee reproduction cycle, particularly the time required for fruit formation. In the fast expansion stage the percentages of DM and Ca, Mg and S accumulation were higher in trees grown at 720 m than at 950 m. The DMAR (daily maximum accumulation rate) in the grain filling stage tended to be delayed at higher altitudes. Nutrient accumulation in the fruits as well as grain filling are more critical at lower altitudes since these processes have to occur in a shorter time. In general, the fruit/leaf competition for the partitioning of Ca, Mg and S was higher at 720 m.
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Palavras-chave
Fisiologia vegetal, Nutrição mineral, Temperatura