Eco-physiological studies on reforestation in barren lands

(1)研究了水分胁迫对烟草和罗汉桦幼苗生理驯化的影响。培养基缺水2个月可提高海棠幼苗的抗旱性。当水势降至-0.69 Mpa时，在-0.42 Mpa条件下培养的海棠幼苗的蒸腾速率迅速下降，而未处理的海藻幼苗的蒸腾速率不变。长期缺水不影响桦树幼苗的耐旱性。阿拉伯半岛干旱地区的旱生植物在长期缺水后没有表现出任何生理驯化，而中生植物金合欢则表现出胁迫驯化。(2)中国干旱地区旱生植物叶片的远轴和近轴面都有大量的气孔、毛发和角质蜡。日本中生植物叶片近轴面气孔稀少。(3)接种丹参的黑松幼苗生物量增量大于无菌苗。(4)干旱胁迫下，速生矮生品种(Chamaecyparis Obtusa)的插条表现出较强的耐旱性和较快的ABA产生能力。

(1) The effect of water stress on the physiological acclimation of pittosporum Tobira and Betula grossa seedlings was investigated. Water deficiency in a culture medium for 2 months raised the drought tolerance of the Pittosporum seedlings. The transpiration rate of the stress-preconditioned Pittosporum seedlings cultured in the -0.42 MPa medium rapidly decreased when the water potential of the medium was lowered to -0.69 MPa, whereas the transpiration rate of unconditioned plants did not. Prolonged water deficiency did not affect the drought tolerance of the Betula seedlings.Xerophytes living in the arid area of Arabian peninsula did not indicate any physiological acclimation after a long-period water deficiency, whereas Pseudoacacia, a mesophyte, indicated stress acclimation.(2) A large number of stomata, hairs, and cuticle wax were observed on both abaxial and adaxial sides of leaves of xerophytes living in arid areas of China. Very few stomata were observed on the adaxial side of leaves of Japanese mesophytes.(3) Biomass increment of Pinus Thunbergii seedlings inoculated with mychorrhiza was greater than that of aseptic seedlings. Removal of rhizomorph of mychorriza decreased photosynthetic activity of them.(4) Cuttings of fast-growing cultivars of Hinoki (Chamaecyparis obtusa) indicated high dehydration tolerance and rapid ABA production under drought stress.