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.

XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Plant Physiology from Cell to Fruit Production System

P. Flores, A. López, P. Hellín , J. Fenoll

¹⁵N, stable isotope, N partitioning, varietal differences, Lactuca sativa L.

https://doi.org/10.17660/ActaHortic.2012.932.61