tailieunhanh - Báo cáo lâm nghiệp: "of stem cuttings of Populus x euramericana under different water potentials"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: of stem cuttings of Populus x euramericana under different water potentials. | 127s Ann. Sci. For. 1989 46 suppl. 127s-129s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Rooting of stem cuttings of Populus X euramericana under different water potentials s. Puri1 and . Thompson2 1 Department of Forestry Haryana Agriculture University Hisar 125 004 India and 2 Oxford Forestry Institute South Parks Road Oxford 0X1 3RB . Introduction The rooting of stem cuttings is affected by many environmental factors Haissig 1974 Puri and Shamet 1988 . The maintenance of water balance is one of the important factors. The water balance of cuttings is affected by high transpirational water losses coupled with either low water absorption or slow water transport through the conducting tissues. However little is known about maintenance and control of plant water potential during the rooting of cuttings. The present studies were undertaken to examine rooting as influenced by initial plant water potential. Materials and Methods Variation in the initial plant water potential p of Populus X euramericana was obtained by 3 pretreatments viz. fresh soaked 5 d in water and dried 7 d old cuttings kept in the open . Initial Tị were - and MPa respectively. Cuttings were planted in a mixture of peat and grit sand 1 1 v v maintained at and MPa by weighing the pots daily and adding water to restore these soil moisture potentials. Tensiometers were also used as a check. The pots with cuttings were kept in a growth chamber at 25 c RH at 70 and illumination of 1000 foot candles for 16 h. The cuttings were assessed for shoot and root development moisture content water and osmotic potentials stomatai diffusion resistance relative conductivity and starch content. Water potentials of shoots f shoot were measured with a pressure chamber Scholan-der et al. 1964 and those of bark bark according to the Shardakov method. Osmotic potential V solute was measured with a Wes-cor C52 chamber hygrometer connected to a Wescor HR-33 T microvolt meter.