ISHS Acta Horticulturae 475: VII International Symposium on Pear Growing
EVOLUTION OF NITROGEN AND AMINOACIDS IN PEAR BARK |
| Authors: | M.P. Bañados, M.S. Santiago |
| Keywords: | nitrogen reserves, chemical composition |
| Abstract:
Samples of 1-year old pear bark were collected monthly during 1995 from a commercial 12-year-old pear orchard cv. Packham's Triumph / French pear in Santiago, Chile (33°38'S). Samples were immediately frozen in liquid nitrogen to be analyzed. Total nitrogen (N) concentration (%), total amino acids (TA), free amino acids (FA) and proteic amino acids (PA) were analyzed on each sample. For total N samples were ground, stove dry at 65°C and analyzed using the Kjeldahl method. Samples for TA were ground in liquid N and hydrolyzed using HCL 6 N. For FA, samples were extracted with ethanol at 60°C. PA were obtained by difference between TA and FA. Extracted samples were derivatized and analyzed using HPLC. Total N, TA and PA showed a seasonal variation, with maximum values observed during winter and minimum in summer. Total N concentration ranged between 0.6 % in November and 1.1% in May-July. TA ranged between 95 mg/g fresh weight (FW) in April to 40 mg/g FW in September. FA varied from 4 mg/g FW in April to 15 mg/g FW in September. PA represented 85% to 95% of TA depending on month. Arginine was the most TA during summer and phenylalanine the most abundant in winter. | |
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