Acumulação de matéria seca e macronutrientes por dois cultivares de mandioca Dry matter and macronutrients accumulation by two cassava cultivars

• Main Authors: José Osmar Lorenzi, José Romano Gallo, E. Malavolta
• Format: Article
• Language: English
• Published: Instituto Agronômico de Campinas 1981-01-01
• Series: Bragantia
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051981000100014

Com a finalidade de determinar a acumulação de matéria seca, extração e exportação de macronutrientes por dois cultivares de mandioca, foi conduzido um experimento de campo no Centro Experimental de Campinas, Instituto Agronômico, em solo do grande grupo Latossolo Roxo (Typic Euthrorthox). As amostragens foram feitas em seis épocas do desenvolvimento das plantas, a intervalos regulares de 60 dias. As plantas amostradas foram divididas em raízes tuberosas, hastes e folhas e analisadas para N, P, K, Ca, Mg e S. Os resultados mostraram que: a) O período de maior acumulação de matéria seca ocorreu dos 120 aos 180 dias após a brotação, com a taxa média de 105,0kg/ha/dia; b) Os cultivares extraíram quantidades diferentes de fósforo e exportaram quantidades diferentes de potássio e enxofre; c) A extração dos elementos, em quilogramas/hectare e quilo-gramas necessários para produção de uma tonelada de raízes foi de 113,3 e 6,21, 11,0 e 0,62, 78,6 e 4,24, 62,0 e 3,37, 18,5 e 1,00, 8,3 e 0,46 de N, P, K, Ca, Mg e S respectivamente; d) A exportação de nutrientes, em quilogramas/hectare e quilogramas/tonelada de raízes foi de 39,1 e 2,12, 3,9 e 0,22, 32,5 e 1,71, 12,1 e 0,66, 6,7 e 0,36, 1,7 e 0,09 de N, P, K, Ca, Mg e S respectivamente.<br>Material collected in a field trial conducted in Dark Red Latosol (Typic Euthror-thox) was used to study dry matter and macronutrients accumulation in two cassava cultivars (Branca-de-santa-catarina and IAC-Mantiqueira). Plants received a uniform fertilization of N, P(2)0(5) and K2O of 40, 80 and 60 kg/ha, respectively as ammonium sulfate, simples superphosphate, and muriate of potash; N was top dressed 60 days after the sprouting. Samples were taken at six occasions during the growing season, with an interval of sixty days between each sampling. The plants were divided into roots, leaves and stems and each part was analysed for N, P, K, Ca, Mg and S. The results showed that: a) The period of greatest dry matter accumulation was between 120 and 180 days after the sprouting of the plants, with the average of 105.0 kg.ha-¹.day-¹; b) Extraction of macronutrients was the same in the two cultivars, with the exception of P; export was different only in the case of K and S; c) The extraction, in kg/ha and kilograms needed for the production of one metric ton of roots were respectively 113.3 and 6.21 for N, 11.0 and 0.62 for P, 78.6 and 4.24 for K, 62.0 and 3.37 for Ca, 18.5 and 1.00 for Mg and 8.3 and 0.46 for S; d) The export, in kg/ha and kg/ton of roots were respectively 39.1 and 2.12 for N, 3.9 and 0.22 for P, 32.5 and 1.71 for K, 12.1 and 0.66 for Ca. 6.7 and 0.36 for Mg and 1.7 and 0.09 for S.