Uso do DRIS na avaliação do estado nutricional de plantas cítricas afetadas pela clorose variegada dos citros. / Use of DRIS to evaluate nutritional status of citric plants affected by citrus variegated chlorosis.

AUTOR(ES)

Juliano Gullo de Salvo

DATA DE PUBLICAÇÃO

2002

RESUMO

Among all factors which affect the yield and fruit quality from citric plants, pests and diseases are of outstanding importance. There are several pests and diseases wich affect the citrus crop. The citrus variegated chlorosis (CVC) is one of the most severe and destructive diseases affecting both yield and quality. Because this disease is caused by a xylem bacteria, the water and nutrients dinamics is affected resulting in a series of visual simptons of different intensities. There objective of this work was to evaluate the nutritional status os citrus plants without visual simptons of CVC and, with different levels of simptons of this disease. The Sufficiency Range Criteria, traditionally used in the state of São Paulo and the Diagnosis and Recommendation Integrated System (DRIS) were the methods used for leaf analysis interpretation. The study was carried out in commercial orchards of Pêra sweet orange budded on Cravo lemom, seven years old, in the region of Araraquara – SP. Plants with three levels of CVC and plants without visual simptons were selected from two plots. Concentrations of macronutrients (N, P, K, Ca, Mg, S) and micronutrients (B, Cu, Fe, Mn, Zn) were determined on leaves of fruit branches. Fruit production from each plant was measured. The analysis through the DRIS method involved the utilization of a software developed specially for the citrus crop by the Instituto Agronômico de Campinas – IAC, where the method proposed by Jones (1981) was used. The results showed that the DRIS was efficient in ranking the nutrients and indicating the nutritional defficiency for some nutrients considered adequate or excessive by the Sufficiency Range Criteria. Regardless the presence of CVC simptons, all plants show low foliar concentrations of Ca, wich resulted in a diagnose of defficiency by the two criteria of interpretation. There was a foliar concentration reduction of N and P, in plants with more severe simptoms. With respect to the foliar concentration of the other nutrients there was not observed a standard decrease or increase due to CVC. The local DRIS-Citros IAC software norms utilized should be adjusted according to the work conditions and objectives to a improve yield correlation with plant nutrition.

ASSUNTO(S)

citrus variegated chlorosis citrus crop diagnose foliar nutrição vegetal citricultura clorose-variegada-dos-citros plant diseases doenças de plantas leaf diagnosis plant nutrition

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