Doses de Zinco em dois genótipos de milho em gleissolo háplico no município de Iranduba-AM

Abstract

The objective of this study was to evaluate five doses of Zn in maize genotypes grown in the Haplic Gleysol at municipal district of Iranduba-AM, in the agricultural crop period of 2010/2011. The soil was tillaged mechanically with a plowing and two soft disking and fertilizing was done according to technical recommendations for culture. The experimental design was a randomized complete block split plot with four replications. The plots were defined by using two genotypes of maize, being a hybrid (AG 1051) and a variety (BRS Saracura) and the subplots consisted of five doses of Zn (0; 1; 2,5; 5 and 10 kg ha-1). Variables were evaluated in to agronomic parameters and production (plant height, stem diameter, root and stalk lodging, length and ear diameter, ear weight without straw, weight of 100 grains, stand and yield), and leaf analysis performed to verify the levels of nutrients (N, P, K, Ca, Mg) and micronutrients (Fe, Zn, Cu, Mn). The data were subjected to analysis of variance and treatment means compared by Tukey test at 5% significance for qualitative parameters and regression analysis for the quantitative parameters (doses of Zn). Growth variables plant height, stem diameter, number of broken plants and stand showed significant differences between genotypes in the F-test analysis of variance but only stem diameter showed significance in the test medium, and the hybrid AG 1051 showed greater diameter (2,01 cm) from the range than Saracura (1,77 cm). The doses of Zn promoted changes in length and weight of ears without straw, number of kernels per row, 100 grain weight and yield. With respect to leaf analysis between genotypes was significant for the variables P, Ca and Zn, and Zn only showed significant differences in dose and dose x genotype interaction. For the variables N, K, Mg, Cu, Fe and Mn were not significant differences among the treatments. The variety Saracura presented higher concentrations of P (3,36 g kg-1) and Ca (3,28 g kg-1) when compared to 2,86 g kg-1 of P and 2,73 g kg-1 Ca absorbed by the hybrid AG 1051. However, the hybrid AG 1051 showed higher leaf contents of Zn (24,92 mg kg-1) compared to that presented by the variety Saracura (20,21 mg kg-1). In relation to the productive performance of the plants was significant for the diameter of the spikes and number of kernels per row. For the dose of Zn, the variables that were significantly different length and weight of ears without straw, number of kernels per row, 100 grain weight and yield. Regarding the interaction between genotype and dose, the only variable that showed significant differences was the number of grains per row, and the hybrid AG 1051 obtained more value. For variable rate spike was not significant for genotype, dose and not to interaction between them. Although plants respond to fertilization with Zn sulfate the levels in the soil were sufficient to the vegetative and reproductive production since zinc is with suitable levels and fit available in Gleysol with high base saturation and high phosphorus rates.