Broccoli growth in response to increasing rates of pre-plant nitrogen. I. Yield and quality

Abstract

in response to increasing rates of pre-plant nitrogen. I Yield and quality. Can. J. Plant Sci. 89: 527Á537. Nitrogen management is critical to the production of broccoli (Brassica oleracea L. italica Plenck). Field trials were conducted in 2001 and 2002 to determine the rate of pre-plant nitrogen required to optimize broccoli yield and quality. Seven rates of nitrogen (0, 50, 100, 150, 200, 300, 400 kg N ha (1 ) as ammonium nitrate were broadcast and incorporated before transplanting two broccoli cultivars, Captain and Decathlon. Maturity of the heads was delayed by 5 d at 0 kg N ha(1 compared with the other rates of applied N. Marketable yield was maximized at 243 to 272 kg N ha(1 for yield expressed in t ha (1 and 171 to 187 kg N ha (1 for yield expressed as cases ha (1 . Averaged over cultivar and year the most economical rate of nitrogen (MERN) ranged from 298 to 309 kg ha(1 , 50 kg higher than estimates for the maximum marketable yield derived from quadratic plateau models. The incidence of misshapen heads decreased and floret color improved as nitrogen rate increased, but hollow stem and head rot also increased with high rates of nitrogen. Floret NO 3 ( -N concentration increased and vitamin C concentration decreased at high nitrogen rates. Applying the rates of nitrogen required to maximize yield may have negative economic and environmental consequences. However, restricting nitrogen also jeopardizes both yield and quality. Hence, the optimum amount of pre-plant nitrogen to apply to broccoli that balances yield, quality, economics and environmental concerns remains a complex issue. , les auteurs ont proce´de´a`des essais sur le terrain afin de de´terminer le taux de fertilisation azote´e requis avant la plantation pour optimiser le rendement et la qualite´de cette culture. Pour cela, ils ont e´pandu a`la vole´e puis incorpore´au sol de l'azote sous forme de nitrate d'ammonium a`sept taux (0, 50, 100, 150, 200, 300 et 400 kg de N par hectare), avant le repiquage des cultivars Captain et Decathlon. Comparativement aux autres taux, l'application de 0 kg de N par hectare retarde la maturation des pommes de cinq jours. Le rendement commercialisable atteint un maximum au taux de 243 a`272 kg de N par hectare quand on l'exprime en tonnes par hectare ou a`celui de 171 a`187 kg de N par hectare quand il est exprime´en cageots par hectare. Le taux d'application le plus e´conomique apre`s calcul de la moyenne par cultivar et par anne´e se situe entre 298 et 309 kg de N par hectare, soit 50 kg de plus que ce que les mode`les a`plateau quadratique estiment ne´cessaire pour parvenir au meilleur rendement commercialisable. L'incidence des pommes difformes diminue et la couleur des fleurons s'ame´liore avec la hausse du taux d'application, mais on note e´galement une hausse du nombre de tiges creuses et de pourriture de la pomme quand le taux d'application est e´leve´. La concentration de N-NO 3 ( dans les fleurons augmente tandis que celle de vitamine C diminue avec la hausse du taux d'application. L'application du ...

Broccoli growth in response to increasing rates of pre-plant nitrogen. II. Dry matter and nitrogen accumulation

“…Maximizing NUE is a common objective in nitrogen management studies. However, as the amount of N applied influences market quality as well as yields (Bakker et al 2009), NUE as a tool for nitrogen management in broccoli is limited. Measurements of NUE may be useful in screening for cultivars able to produce high yields with less nitrogen.…”

“…(1 applied nitrogen optimized yield of broccoli for the fresh market (Bakker et al 2009). However, the amount of estimated available soil nitrogen must also be included; thus, total nitrogen requirements were 180 kg ha…”

“…Key words: Brassica oleracea L. italica Plenck, nitrogen budget, nitrogen rates, nitrogen use efficiency, nutrient management Bakker, C. J., Swanton, C. J. et McKeown, A. W. 2009. Re´action du brocoli a`une hausse de la fertilisation azote´e avant les semis : II Accumulation de matie`re se`che et d'azote.…”

“…Bakker, C. J., Swanton, C. J. and McKeown, A. W. 2009. Broccoli growth in response to increasing rates of pre-plant nitrogen.…”

“…Average preplant soil NO 3 ( -N was 13 and 14 mg kg (1 in 2001 and 2002, respectively. Site preparation and crop management practices are described in detail in Bakker et al (2009).…”