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

Abstract

YIELD AND HOLLOW STEM DISORDER OF WINTER CAULIFLOWER INFLUENCED BY NITROGEN AND BORONThe 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 'Júlia' cultivated in Kandiustalf at Tietê region, São 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.

Effects of top-dressing nitrogen levels on the productivity of cauliflower

“…However, Camargo et al (2008) and Kano et al (2010) recorded a significant response to inflorescence mass with the increase in nitrogen levels, as also reported by this study. Inflorescence diameter can be influenced by plant spacing.…”

“…Regarding inflorescence diameter, Camargo et al (2008) found no significant differences with the increase in nitrogen levels (0-250 kg ha -1 ). The average diameter ranged between 17.46 and 18.03 cm.…”

“…The consequences of malnutrition are thus more marked at the reproductive stage, i.e., the commercial product (Camargo et al, 2008). Nitrogen levels recommended by the technical literature differ greatly.…”

“…Crop yield response related to nitrogen increase in cauliflowers can be characterized by linear functions (Camargo et al, 2008;van den Boogaard & Thorup--Kristensen, 1997). However, as the limits of a response function to fertilization are delimited by levels evaluated experimentally, so that productivity do not tend to infinity with the continue increase in nitrogen in the field, it becomes necessary to identify the maximum N levels that the crop may receive without decreasing productivity.…”

Nitrogênio e boro na produção e incidência de haste oca em couve-flor 'Sharon'

“…A massa fresca das inflorescências, produtividade total, produtividade comercial, teores de B e de N nas folhas e nas inflorescências da couveflor 'Sharon' também não foram afetadas pela aplicação isolada de B (Tabela 1 CAMARGO et al (2008) também observaram redução drástica no número de plantas com haste oca (4,06%) com a aplicação de 3 kg ha -1 de B em relação à testemunha, cujo valor verificado para essa anomalia foi de 46,87%. Esse resultado indica a necessidade de suprimento de B, mesmo em solo argiloso com teor elevado desse elemento, para a melhoria da qualidade da couve-flor 'Sharon', em função do comportamento deste micronutriente na planta, da época de cultivo e das características genéticas da cultivar.…”