tailieunhanh - Báo cáo lâm nghiệp: "development of winter hardiness of pine and spruce seedlings in a simulated acid rain experimen"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài:development of winter hardiness of pine and spruce seedlings in a simulated acid rain experiment. | 621s Ann. Sci. For. 1989 46 suppl. 621s-623s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA The development of winter hardiness of pine and spruce seedlings in a simulated acid rain experiment J. Reinikainen and s. Huttunen Department of Botany University of Oulu SF-90570 Oulu Finland Introduction The effects of acidified rainwater on the hardiness level perceivable in the ultrastructure of needles of conifer seedlings were examined during autumn and winter 1986-87. Results The hardening of the seedlings had already begun in mid-August with decreasing numbers of starch grains and chloroplasts moving towards cell corners Fig. 1 . The needles of the northernmost provenances of spruce seedlings lost their starch grains Materials and Methods One and 2 yr old Scots pine Pinus sylvestris and Norway spruce Picea abies seedlings from several provenances had been irrigated with artificially acidified rain H2SO4 HNO3 2 1 for 7 wk during the hardening time in the previous autumn. In the experiment performed at the University of Oulu the seedlings investigated comprised samples treated with pH 3 pH 4 and clean pH about 7 water in addition to a dry control with samples of each group from 2 different provenances. The development of the hardiness level was followed by making light and electron microscope observations of the mesophyll tissue of the current year s needles. Sampling was done about once a month from August until April. The mm thick needle cuttings were fixed with glutaraldehyde and OsO4 in or M phosphate buffer and after fixation the needle sections were dehydrated in an alcohol series and embedded in Ladd s epon. Fig. 1. August a clean water-treated needle from a southern spruce provenance. Small starch grain ST indicates the beginning of the hardening period cw cell wall M mitochondria bar 1 pm. 622s Fig. 2. September a pH 3-treated needle from a southern spruce provenance. The cytoplasm membranes appear net-like and small lipid droplets L