Determination of the critical nitrogen concentration of white cabbage

作者：Ekbladh Goran^*; Witter Ernst

来源：European Journal of Agronomy, 2010, 33(4): 276-284.

DOI：10.1016/j.eja.2010.08.001

• Growth rate
• Leaf area ratio
• Nitrogen use efficiency
• Response function
• Brassica oleracea

A measure of a crop's nitrogen (N) status can be obtained by relating the actual N concentration of the crop to the critical plant nitrogen concentration (PNC(c)), the minimum N concentration required for maximum growth. In annual crops, PNC(c) declines as plant size increases. Describing this decline is one of the main challenges for the implementation of the PNC(c) concept in fertilizer management strategies. From two field experiments with repeated harvests of Dutch white cabbage and with N supply ranging from limitation to excess, the relation between PNC(c) and weight per unit ground area of plant dry matter exclusive of roots (W) was estimated as: PNC(c) = 5.1W(-0.33)% for the linear growth phase (W>1.5 t ha(-1); LAI > 1.4). From a third field experiment, a value of 4.5% N was estimated for PNC(c) for the pre-linear growth phase. Also a power function: LAR = 0.011W(-0.33) described the relationship between leaf area ratio and weight. The exponent of the power function determines the rate of the decline. Therefore, having the same value of the exponent: -0.33. LAR and PNC(c) declined at the same rates.

• 出版日期2010-11