Produtividade e podridão parda em couve-flor de inverno influenciadas pelo nitrogênio e boro

The hollow stem disorder is a common problem in cauliflower, resulting in similar symptom to B deficiency. Its occurrence is associated, specially to nitrogen and boron rates. There is few information about this subject in Brazil. The experiment was carried out from March to June/2006 in a randomized complete block design with 4 replications. The objective was to evaluate rates of nitrogen (100, 150, 200 and 250 kg ha-1) and B aplication (0 and 3 kg ha-1) on yield and hollow stem disorder of the cauliflower ‘Julia’ cultivated in Kandiustalf at Tiete region, Sao Paulo State, Brazil. The curd diameter was not influenced by treatments and corresponding mean value was 17.74 cm. Nitrogen levels increased mean weight, yield and N content of curds. Fertilization increased boron contents in curds, commercial yield and reduced hollow stem disorder. There was a negative correlationship between B concentration at curds and hollow stem disorder incidence. Therefore, to reduce this physiological disorder the boron fertilization is required when cauliflower is grown even in soil with average B level.