FAIXAS CRÃTICAS DE TEORES FOLIARES DE MACRO E MICRONUTRIENTES EM MUDAS DE CAFEEIRO(Coffea arabica L.). / Critical ranges of macro and micronutrient leaf levels in coffee seedlings (Coffea arabica L.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The presente research aimed to quantify the macro and micronutrient leaf levels in coffee seedlings, aiming the identification of deficiency and excess for the setting of threshold range, and verify the best developmental stage to harvest leaves for analysis. The experiment was conducted in nursey house located in coffee research area at Agronomy Department of the Federal University of Lavras, from may 2002 to January 2003. It was used a block design, in factorial 6 x 4, with 4 replicates, with nine plants per plot. The treatments (fertilization levels) used were: level 1 (25% of standard substrate); level 2 (50% of standard fertilization substrate); level 3 (75% of standard substrate); level 4 (100%, standard substrate); level 5 (125% of standard substrate); level 6 (150% of standard substrate). The evaluations were realized when the seedlings had, 3, 4, 5 and 6 pairs of true leaves, time 1, 2, 3 and 4 respectively. There were evaluated the following characteristics: plant height (cm), stem diameter (mm), leaf area (cm2), root dry weight (g), stem dry weight (g), leaf dry weight (g), total dry weight (g), and leaf analysis to quantify the levels of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn. Using regression analysis the maximum point for growth characteristics evaluated, in order to determine the ideal range considering 90% of this. Using the resolutive Bhaskara equation, the range from fertilization levels from soil composition substrate, that cause this growth. These values were used in regression equation to obtain the macro and micronutrient leaf levels in each sampling time to find the lower and higher levels. The objective to find these lower and higher levels were to find critical ranges for all characteristics evaluated. There were identified critical ranges for micro and macronutrients for coffee seedlings: nitrogen (2,57 to 2,78 dag/kg), phosphorus (0,33 to 0,38 dag/kg), potassium (2,58 to 2,70 dag/kg), calcium (0,70 to 0,77 dag/kg), magnesium (0,11 to 0,12 dag/kg), sulfur (0,22 to 0,26 dag/kg), boron (39,74 to 39,94 mg/kg), copper (6,94 to 9,29 mg/kg), iron (209,01 to 213,88 mg/kg), manganese (33,05 to 37,21 mg/kg), zinc (3,68 to 4,08 mg/kg). It was verified that the four true leaves pair stage were the ideal for leaf sampling aiming to identify the macro and micronutrient levels.

ASSUNTO(S)

fitotecnia macronutriente muda seedling macronutriente coffee cafÃ

ACESSO AO ARTIGO

Documentos Relacionados