Demanda de nutrientes e diagnose do estado nutricional da cultura do alho

• Autor(a) principal: Cunha, Mário Lúcio Pereira
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2035
• topic: Composição nutricional; CND; DRIS; Nutritional composition; CND; DRIS; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA

Among the factors influencing the garlic crop productivity, fertilization promotes the most significant changes. However, the main methods employed to garlic fertilization management are still fertilizer recommendation tables and the ranges of sufficiency for foliar diagnosis. Such methods are outdated because the first one is based on political limits rather than on regional edaphoclimatic conditions; and the second one is subjected to dilution effects and nutrient accumulation in tissues. For preparation of the recommendation systems of fertilizers and correctives, some information with most scientific basis are needed, highlighting the demand for nutrients. In foliar diagnosis, the univariate methods must be replaced, such as the ranges of sufficiency, using bivariate or multivariate methods, with emphasis on the DRIS (Diagnosis and Recommendation Integrated System) and CND (Compositional Nutrient Diagnosis), respectively. Thus, models were constructed that could explain the garlic's nutrients demand according to the bulb yield, as well as to develop standards for foliar diagnosis using DRIS and CND methods, aiming to foster the creation of more modern systems for the recommendation and adjustment of fertilization programs. This study was carried out in the region of Alto Paranaíba, Minas Gerais State, Brazil, during the harvests of 2012 and 2013. Samples of leaves and bulbs were collected from 142 commercial plots of garlic. All plots were cultivated with the garlic variety "Ito" and mostly of them were established in Oxisols Red Yellow clayey or strong clay. The sampled crops productivity ranged from 9.1 to 24.2 t ha-1 with an average of 17.3 t ha-1. The harvest index and average dry matter content were 72.1 and 38.2%, respectively. Linear models or decreasing increments were adjusted for all correlations between bulb yield and the nutrient total accumulation or nutrient accumulation in the bulbs. The first type of model explains the behavior of those nutrients that were in deficiency area, while the second type explains the behavior of those nutrients that were in transition between the deficiency and appropriate area. It was not possible to set significant models for the accumulation of Cu and Fe in the bulbs and the total accumulation of Cu, Fe, Mn, and Zn. For these cases, accumulation of these nutrients was analyzed in five productivity classes. Average nutrient accumulation by the crop was 206.5 kg N ha -1 ; 29.4 P; 123.0 K; 59.8 viiCa; 10.4 Mg; 45.4 S; 179.4 g B ha -1; 134.7 Cu; 1442.1 Fe; 85.0 B; 118.7 Mn; 308.5 Zn. The average harvest indices for nutrient accumulation followed the order: P (75.9%)>S(72.0%)>N(71.4%)>Zn(69.0%)>K(56, 0%)>B (47.5%)>Ca (44.4%)>Fe (43.1%)>Mn (41.9%)>Mg (41.4%)>Cu (26.1%). Cu and K were the nutrients with greater number of plots diagnosed as limiting by fault (LF) and limiting by excess (LE), respectively. The DRIS method showed greater tendency to LF diagnostic, while the CND method tended to LE diagnostic. The ranges of sufficiency produced by both methods showed narrower intervals than those ones suggested by literature. Additionally, all ranges produced by CND method yielded narrower intervals than their respective ranges by DRIS method. The CND method showed better performance than the DRIS method to distinguish crops in relation to productivity belonging to different diagnoses. Regarding evaluation criteria, nutritional status has considerably greater ability than the ranges of sufficiency to distinguish their diagnoses related to productivity.