No presente trabalho são relatados os efeitos determinados; por diferentes combinações copa-cavalo, na composição mineral das fôlhas de citros. O material para o presente estudo foi retirado de dois ensaios de cavalos para laranja pêra e laranja baianinha (Citrus sinensis Osbeck) instalados na Estação Experimental de Limeira, do Instituto Agronômico. Amostras de fôlhas foram colhidas em diferentes estágios de crescimento e correspondentes o dois ciclos vegetativos, e a composição estudada separadamente para árvores de mesma idade. Os resultados obtidos permitiram concluir que além dos efeitos na composição das folhas devidos à variedade e ao porta-enxêrto, outros fatôres como longevidade e moléstias de vírus devem ser considerados pora o julgamento dos efeitos da adubação pela análise foliar.

The influence of five different combinations scion-rootstock for two scion varieties on the percentage of nitrogen, phosphorus, potassium, calcium, and magnesium in citrus leaves is reported. Leaves from fruiting shoots of two spring flushes were taken from Baianinha and Pêra oranges trees (Citrus sinensis Osbeck) on two experimental orchards located in the Experiment Station of Limeira, State of Sao Paulo. The rootstocks On which they are budded and used for this study were: Pêra orange, and sweet orange (C. sinensis Osb.), Rangour lime (C. reticulata Blanco X C- aurantifolia Swing (?)), rough lemon (C. limon Burm. f. X (?)), and Cleopatra mandarin (C. reticulata Blanco). In the spring of 1957 when the leaf sampling was started the trees on sweet orange, Rangpur lime and rough lemon rootstocks were 21 years old and those an Pêra and mandarin rootstocks 7 years old, but only plants of the same age were compared. Fertilization was uniform in all plots and the soil apparently very uniform. Confidence limits for the mean results of inorganic composition of leaves 3 to 6 months old of two flushes are presented. Seasonal changes in nutrient composition of leaves ore olso shown. The leaves of both scion varieties differed in their principal mineral constituents. The major difference was found in the potassium content. Leaves of Baianinha orange trees contained relatively more potassium than Pêra orange leaves. The composition of leaves changed according to the rootstock species. Differences in potassium, calcium, and magnesium levels in leaves of the some scion variety were found to be significant when Pêra orange and Cleopatra mandarin were the rootstocks. Variations in the composition of scion leaves in the older combinations could be associated with virus disease tolerance and longevity of species. In view of the results obtained, other factors such as virus diseases, longevity, etc. besides varietal effects and selectivity of rootstocks to absorb nutrients, must be taken into account in attempting to associate the results of foliar analysis with fertilizer utilization by citrus trees.

O presente trabalho representa a primeira contribuição ao estudo da diagnose foliar dos citros, para as nossas condições. São estudadas as variações nos teores de nitrogênio, fósforo, potássio, cálcio e magnésio nas fôlhas de laranjeira baianinha enxertada sôbre cavalo de laranja caipira (Citrus sinensis, Osbeck), de um experimento de adubação iniciado em 1947 na Estação Experimental de Limeira, do Instituto Agronômico, e apresentadas as tendências das curvas de concentração para êsses elementos. Além disso, o estudo em aprêço teve por objetivo verificar os efeitos da adubação nítrogenada, fosfatada e potássica sôbre o nível daqueles constituintes, nas fôlhas. Os resultados obtidos mostraram que a composição química das fôlhas foi sensivelmente modificada com a idade das mesmas e pela adubação.

The results reported herein represent the first step in diagnosing the nutrient status of citrus trees by means of foliar analysis, for the average conditions of the State of São Paulo. A study was made concerning the seasonal variation in nitrogen, phosphorus, potassium, calcium and magnesium levels of spring-cycle Baianinha orange leaves. The trees were budded on sweet orange rootstock (Citrus sinensis Osbeck) in a foctorial fertilizer experiment started in 1947. The mineral composition changed with the age of leaves. Generally the N, P, K, and Mg contents decreased, while Ca increased fast in the young leaves and remained without great variation until the end of the cycle. Leaves 3 to 6 and 10 months old are suitable for sampling if referred to respective standards. Nitrogen and phosphorus levels in leaves increased linearly with fertilizer application, while potassium increases were due only to o single dosis. Application of fertilizer containing nitrogen shows o tendency to reduce the levels of P and K, and to increase Mg in the leaves. The simple superphosphate applied decreased the levels of N and K, and increased Ca in the leoves. There was a decline in Ca and Mg contents of leaves with potassium fertilizer application. The following negative correlations between leaf nutrients were found to be significant: 1) nitrogen and phosphorus; 2) nitrogen and calcium; 3) potassium and calcium; 4) potassium and magnesium.