Precisão dos delineamentos tipo Lattice em milho

Abstract

O presente artigo estuda a eficiência do delineamento em lattice comparada à do delineamento em blocos ao acaso. Foram analisadas 51 experiências, das quais 32 foram instaladas na Estação Experimental Central de Campinas, 12, na Estação Experimental de Ribeirão Prêto e 7 na Estação Experimental de Pindorama. Êsse total de 51 experiências reúne as de competição de híbridos de milho nos anos de 1939/40 até 1950/51. O delineamento em lattice mostrou-se pouco eficiente em relação ao cm blocos ao acaso, dando um aumento de eficiência de 8,2% em Campinas, 9,6% em Ribeirão Prêto e apenas 1,7% em Pindorama. Pode-se atribuir esse fato à utilização de canteiros pequenos, de 5 ou 10 m² e também à acertada distribuição das repetições no terreno. Foi feito, também, um estudo do coeficiente de variação, que veio mostrar que as experiências instaladas em Campinas e Pindorama foram mais precisas do que as instaladas em Ribeirão Prêto.<br>Lattice design for testing hybrid corn is being used since 1939 at the Genetics Department of the Instituto Agronômico de Campinas. Preliminary observation from the comparative analysis of experiments carried out in 1950 and 1951 as lattice and randomized blocks indicated that only a small increase in efficiency was obtained by use of lattice analysis. Presented here are the results of a larger number of comparisons of both types of analysis for 32 lattice experiments carried out at the Central Station of Campinas, 12 from Ribeirão Preto Station and 7 from Pindorama Station of this Institute. Both the efficiency of the lattice design and the precision of the experiments were calculated and the results are presented in table 1. The results of these experiments analysed as a lattice in comparison with randomized blocks gave an average efficiency increase of only 8.2% for the experiments from Campinas, 9.6% for R. Preto and 1.7% for the Pindorama experiments. The average coefficient of variability indicated that the experiments from Campinas and Pindorama, were more precise than that from It. Preto where the stand of plants in the field was usually lower due to insect attack. It was concluded that the small increase in efficiency of the analysis as lattice in comparison with randomized blocks must be due to the small size of the plots and location of the replication in the field