Deficiências de kacronutrientes e de boro em seringueira (Hevea brasiliensis L.)

In order to obtain: a) a clear picture of the deficiencies symptoms of N, P, K, Ca, Mg, S and B; b) the lack of the elements on the dry matter production; c) concentration of the macro and micronutrients on the leaves, stems and roots. Young rubber plants (Hevea brasiliensis L.), were cultivated in nutrients solutions, in which one the following elements were omitted at once: N, P, K, Ca, Mg, S and B. Clear out symptoms were obtained for all macronutrients and boron. The growth rate of the rubber plants were drastically affected by lack of N, K followed by other nutrients. The omission of P from the nutrient solution did not affected the growth of the plants. The levels detected by chemical analysis of the leaves from with symptoms of deficiency and without symptoms of deficiency plants were: N% = 1.94 and 3.40: P% =0.14 and 0.25; K% = 0.79 and 2.22; Ca% = 0.59 and 1.28; Mg% = 0.26 and 0.50; S% = 0.10 and 0.10; B ppm = 31-3 and 171.8.Plantas de seringueira (Hevea brasiliensis L.) foram cultivadas em casa de vegetação, em quartzo moído, irrigado com soluções nutritivas, e submetidas aos seguintes tratamentos: completo, omissão de N, omissão de P, omissão de Ca, omissão de Mg, omissão de S e omissão de B, com o objetivo de: (a) obter sintomas de deficiências de macronutrientes e de boro; (b) analisar o crescimento das plantas através da produção de matéria seca; (c) determinar a concentração de macro e micronutrientes nas folhas, caule e raízes das plantas cultivadas nos diversos tratamentos. Os sintomas visuais de deficiência foram identificados e descritos. As plantas foram coletadas e separadas em raiz, caule e folhas, e determinaram-se os teores de macro e micronutrientes . Os resultados mostraram: - foram identificados sintomas de deficiências para todos os tratamentos com omissão de nutrientes (N, P, K, Ca, Mg, S e B); - a omissão de N, K, Mg ou B da solução nutritiva diminuiu o crescimento das plantas; - as concentrações dos elementos nas folhas de plantas com sintomas e sem sintomas de deficiência foram, respectivamente: N% = 1,94 e 3,40; P% = 0,14 e 0,25; K% = 0,79 e 2,22; Ca% = 0,59e 1,28; Mg% = 0,26 e 0,50; S% = 0,10 e 0,10; Bppm = 31 ,3 e 171,8

Assessment of rubber tree panels under crowns resistant to South American leaf blight

The objective of this work was to assess the performance of panel clones under crowns resistant to South American leaf blight (Microcyclus ulei). The experiment was carried out with 18 panel clones crown-budded with Hevea pauciflora x H. guianensis, in a Xanthic Ferralsol (Oxisol) in Manaus, AM, Brazil. The following parameters were evaluated: dry rubber yield, plant nutritional status, and anatomical and physiological characteristics of the latex vessels. In the first three years of evaluation, the panel clones IAN 2878, IAN 2903, CNS AM 7905, CNS AM 7905 P1, and PB 28/59 showed the highest dry rubber yield potential, while the clones IAN 6158, IAN 6590, and IAN 6515 should not be recommended for crown budding. Higher potassium and copper foliar content in panel clones were associated to an increase in dry rubber yield. The simultaneous evaluation of anatomical and physiological characteristics of latex is fundamental for the selection of panel clones in the Amazon region. Crown budding is an efficient technology for South American leaf blight management in endemic regions