). Nutrient-deficient plants often have lower growth rates and higher concentrations of carbon-based (nonnitrogen-containing) secondary compounds (CBSCs) than do plants with access to ample nutrients ( Bryant et al., 1983 ; Coley et al., 1985 ). This negative
) to perform a preliminary yield gap analysis regarding actual and attainable potato yield in different areas of Argentina. We tested the performance of a model based on studies of maximum rates of carbon dioxide assimilation for a C 3 crop as a
interaction, data not shown). Table 2. Mean effects of nitrogen concentration and grafting combination on final leaf area (LA), root-to-shoot ratio, SPAD index, and shoot nitrogen uptake of melon plants. The root-to-shoot ratio was
weighed. Dried leaves were then ground using a Wiley mill (Thomas Scientific, Swedesboro, NJ). Carbon isotope compositions were determined using an online carbon–nitrogen analyzer coupled with an isotope ratio mass spectrometer (Finnigan ConFlo II
significantly increased both chlorophyll a and b contents, total chlorophyll content, and the chlorophyll a:b ratio ( Fig. 3A–D ). Nitrogen deficiency greatly reduced chlorophyll a (by 52% and 56% under no-salt and salt stress, respectively) and chlorophyll b
degree of discrimination against 13 C is determined largely by intercellular CO 2 concentration, which is controlled by the ratio of A to g wv ( Farquhar et al., 1989 ). Stable carbon isotope discrimination may be used to estimate WUE during the
; Wright and Browder, 2005 ). In contrast to peat and PB, plant production in substrates composed of wood, or large portions of wood, have a tendency to become nitrogen (N) -deficient as a result of high rates of N immobilization ( Handreck, 1991 , 1993
et al., 1996 ). Water limitations are commonly thought to trigger an adaptive response in plants to avoid water stress by promoting greater relative carbon allocation to root growth, which ultimately would result in higher root-to-shoot ratio and
conventional soluble fertilizer was formulated from inorganic salts to result in a 4:1 NO 3 -N:NH 4 -N ratio. Constant levels of other nutrients were supplied, except in the control (0 N treatments) ( Table 1 ). The organic soluble fertilizer was fish
other amendments ( Table 1 ), and moreover the rye and ammonium nitrate separately ( Table 1 ). This was most likely attributable to the generally high carbon (C) to N ratio (C:N) of rye residue (although we did not determine the C and N of the rye