Effect of Nitrogen Application on Growth and Photosynthetic Nitrogen use Efficiency in Two Ecotypes of Wild Strawberry, Fragaria chiloensis (L.) Duchn

The relationships between increasing nitrogen fertilization and growth, maximum CO2 assimilation and the initial slope of the CO2 response curve were studied in two ecotypes of wild strawberry, Fragaria chiloensis (L) Duchn. Nitrogen accumulation of CAll, an ecotype from a low -nutrient dune site, was greater at all nitrogen concentrations than that of RCP37, an ecotype from a highernutrient strand site. Maximum CO2 assimilation, total Rubisco activity, dry weight, and initiation of leaves and crowns were higher in CAll than RCP37 as nitrogen treatment was increased from 0 to 200 mg 14, whereas these parameters were lower in CAll when fertilized at 300 mg 1 "1, but not in RCP37. The mean leaf area of CAll was greater than RCP37 when grown with no supplemental nitrogen, but mean leaf area of the two lines was similar under nitrogen fertilization. Maximum CO2 assimilation and carboxylation efficiency increased with increasing leaf nitrogen in both clones. At equivalent concentrations of leaf nitrogen, RCP37 had higher CO2 assimilation and carboxylation efficiency than CAll and the difference between the 2 clones increased as leaf nitrogen increased. Thus, RCP37 had a higher photosynthetic nitrogen use efficiency than CAll. However, at a given applied nitrogen level, CAll allocated more nitrogen to a unit of leaf area so that photosynthetic rates were higher than RCP37, except at the highest application of 300 mg l''. The high nitrogen accumulation capacity and resource allocation to fruiting structures (crowns) in CAll lead us to suggest that this clone may possess genes that could increase fruit yield in cultivated strawberry.