DIFFERENCES IN NITROGEN PARTITIONING AND ISOTOPE COMPOSITION OF SIXTEEN LETTUCE CULTIVARS
The influence of lettuce type and cultivar on the partitioning of biomass and nitrogen assimilation between shoot and root were studied by measuring the 15N natural abundance (δ15N). Sixteen cultivars of lettuce plants (Lactuca sativa L.) belonging to three different types (Romaine, Mini-romaine and Little Gem) were grown in a greenhouse in 5 L pots filled with unfertilized peat. Plants were irrigated with a nutrient solution containing (mM): 6 N, 7 K, 4 Ca, 1 Mg, 1 P, 1 S; and (µM): 2.24 Fe, 0.11 Mn, 0.27 B, 0.13 Zn, 0.032 Cu and 0.05 Mo. Differences in lettuce size between lettuce types were accompanied by differences in shoot/root (S/R) ratios, N net-uptake rates (calculated as plant total-N per root dry weight), plant N concentrations and plant δ15N values. Smaller lettuce cultivars showed a higher S/R ratio, higher N net-uptake per root mass and lower N efflux rate, as confirmed by lower whole-plant fractionation (higher δ15N values). In addition, these cultivars presented a lower proportion of N assimilation in the root (as seen by lower intra-plant fractionation) which was attributed to lower root growth.
Flores, P., López, A., Hellín , P. and Fenoll, J. (2012). DIFFERENCES IN NITROGEN PARTITIONING AND ISOTOPE COMPOSITION OF SIXTEEN LETTUCE CULTIVARS. Acta Hortic. 932, 421-425
15N, stable isotope, N partitioning, varietal differences, Lactuca sativa L.