RESUMO A cebola é a terceira hortaliça em importância econômica para o Brasil, sendo superada apenas pela batata e o tomate, e responde com aumento de produção ao uso de adubos orgânico e mineral. Objetivou-se com este trabalho avaliar o efeito de doses de esterco bovino e nitrogênio sobre o crescimento e rendimento da cebola. O delineamento experimental utilizado foi em blocos casualizados, em esquema fatorial 6 x 2 correspondente a seis doses de esterco bovino (0; 10; 20; 30; 40 e 50 t ha-1), na presença e ausência do nitrogênio, em quatro repetições. Foram avaliadas as variáveis: massa verde e seca da parte aérea, produtividades total e comercial de bulbos, percentagem de bulbos classificados e teor de N foliar. Houve efeito interativo (p ≤ 0,05) das doses de esterco bovino e nitrogênio sobre a massa verde e seca da parte aérea, produtividades total e comercial, para a classificação de bulbos de acordo com o diâmetro transversal e o teor de N em bulbos de cebola. A dose ótima para produtividade comercial de bulbos é de 27 t ha-1 de esterco bovino na presença de nitrogênio.

ABSTRACT Onion is the third vegetable crop in economic importance for Brazil, only behind potato and tomato, and responds with increased production to the use of organic and mineral fertilizers. The objective of this study was to evaluate the effect of doses of cattle manure and nitrogen (N) on onion growth and yield. The experimental design used was randomized blocks, in 6 x 2 factorial scheme, corresponding to six doses of cattle manure (0; 10; 20; 30; 40 and 50 t ha-1), in the presence and absence of N, with four repetitions. The variables studied were: shoot fresh and dry masses, total and marketable bulb yields, percentage of bulbs classified and leaf N content. There was an interactive effect (p ≤ 0.05) of cattle manure and N doses on shoot fresh and dry masses, total and marketable yields, classification of bulbs according to transverse diameter and N concentration in onion bulbs. The optimal dose for marketable yield of bulbs is 27 t ha-1 of cattle manure in the presence of N.

The morphology of Streptomyces olindensis (producer of retamycin, an antitumor antibiotic) grown in submerged culture was assessed by image analysis. The morphology was differentiated into four classes: pellets, clumps (or entangled filaments), branched and unbranched free filaments. Four morphological parameters were initially considered (area, convex area, perimeter, and convex perimeter) but only two parameters (perimeter and convex perimeter) were chosen to automatically classify the cells into the four morphological classes, using histogram analysis. Each morphological class was evaluated during growth carried out in liquid media in fermenter or shaker. It was found that pellets and clumps dominated in early growth stages in fermenter (due to the inoculum coming from a shaker cultivation) and that during cultivation, the breakage of pellets and clumps caused an increase in the percentage of free filaments. The criteria of morphological classification by image analysis proposed were useful to quantify the percentage of each morphological class during fermentations and may help to establish correlations between antibiotic production and microorganism morphology.