EFFECT OF MICRONUTRIENTS AND LIME IN RICE IN CERRADO SOILS

Abstract

Since the growing season of 1966-67, there have been abnormalities appearing in the rice plants cultivated in the "cerrado” in various regions of the State of Goiás. One of the abnormalities is brown coloring on the leaf blades which worsens as the life cycle progresses, eventually leaving green pigmentation only along the edges and the principal vein of the leaf. Generally, this symptom appears more intensely in spotty areas where the plants are stunted and can die, causing an appreciable loss in production. When the plants don’t die, their life cycle is retarded. It has been observed that these characteristic frequently appear in rice fields that have been with lime. In the present research project, the cause of these symptoms has been studied, by observing the effect of lime and micronutrients which were added to the soil. The research design was composed of random plots with four replications. The experiment was instatted near Goiânia in red latosol in an area of natural vegetation typical of the “campo-cerrado”. The variety of rice used was I. A. C. 12/46, after it had been disinfected with dry neantina at 0.3%. Dry brush country with stunted vegetation. The treatments were as follows: T1 - Basic fertilizer; T2 - Basic fertilizer + Ca B Zn; T3 - Basic fertilizer + Ca B Cu; T4 - Basic fertilizer + B Cu Zn; T5 - Basic fertilizer + Ca Cu Zn; T6 - Basic fertilizar + Ca B Zn. The doses were as follows: a) basic fertilizer: 100 kg of P2O5 and 50 kg K2O per hectare. Simple superphosphate ( 20% of P2O5) and potassium chloride (60% of K2O) were used; b) lime: 3.0 t/ha; c) zinc sulphate: 20 kg/ha; d) copper sulphate: 20 kg/ha; e) Sodium tetraborate: 20 kg/ha. The fertilizers, with the exception of the lime, which was sprin-kled over the plots, were placed in the planted furrows. Grain yield and the intensity of leaf symptoms were the data computed. The plots that received zinc were statistically superior to the others. The analysis of variance showed a significant difference among the treatments at the 5% level. The Duncan test indicated that, in rela-tion to grain yield, the treatments fell into two categories. The T1 and T3 treatments gave low yields, and the T2, T4, T5 and T6, produ-ced higher yields. With regard to the intensity of leaf symptoms, the treatments fell into two groups. In the T1 and T3 treatments, the manifestations ware more intense than in the T2, T4 , T5, and T6 treatments. Though there was no significant difference, lime seems to ag-gravate the intensity of the leaf symptom. In the plots that received lime and did not receive zinc, grain yield was significantly lower.