Clayton Albuquerque Sousa

Avaliação de testes estatísticos de comparações múltiplas de médias

Evaluation of multiple mean comparison tests The objective was to verify the efficiency and uniformity of responses from different tests to compare means and the rate of occurrence of Type I error. Four different tests for multiple comparison of means were applied to 200 experiments and 10 variables created with random values, to assess the number of levels; agreement with the F test and rate of occurrence of type I error per variable and per experiment. The tests differed in their results for all variables. The greatest divergences in results were found when using the LSD test. For the level of significance, the greatest agreement was found by the Tukey test.

Evaluation methods used for phosphate-solubilizing bacteria

Phosphorus solubilizers naturally acidify rhizospheric soil and increase phosphorus availability; therefore, their evaluation may help to reduce phosphorus fertilizer use. This work aimed to evaluate the different selection methods and select inorganic phosphorus-solubilizing bacteria as potential plant-growth promoters. Bacterial isolates obtained from sugarcane roots and soil were tested using solid growth media containing bicalcium phosphate and Irece Apatite ground rock phosphate as phosphorus sources. Seven isolates with high (3), moderate (3) and low solubilization indices (1) and the Pseudomonas fluorescens R-243 strain were tested in two liquid growth media, followed by the pH and soluble P in the solution. The same isolates, in the absence of inoculation, were tested in Leonard jars with two high- and low-solubility sources using cowpea as a test species. Forty-four days after planting aboveground dry mass, the phosphorus content and total aboveground phosphorus and substratum phosphorus contents were evaluated. The growth media affected phosphorus solubilization by the bacteria. Evaluation of liquid media was the most reliable method for analyzing bicalcic phosphorus solubilization by the bacteria not linked to pH reduction. Isolates UAGC 17, 19 and 65 should be better studied because they were the best solubilizers in culture media; however, they did not demonstrate the same efficiency when inoculated on cowpea. Key words: Solubilization, phosphate, P-solubilizing-microorganisms.