4种针叶幼树的光合生理特性与大气湿度关系的研究

STUDY ON THE RELATIONSHIP BETWEEN THEPHOTOSYNTHETIC FEATURES OF FOURCONIFEROUS SPECIES SAPLINGS AND AIR HUMIDITY

应用２２５ＭＫ＿３ＩＲＧＡ（英ＡＤＣ公司）在室内控制的环境条件下测定研究了侧柏、樟子松、油松和白等４种针叶幼树的净光合速率、暗呼吸强度、光补偿点与大气湿度的关系，研究结果证明：各种幼树的净光合速率均随大气湿度的降低而减弱，二者之间的关系可用ｙ＝ａ＋ｂｌｎｚ方程表达。其变化速率（ｂ） 在树种间有明显差异，它可以反映出不同树种对大气干旱忍耐力即抗旱性的差异。“ｂ”值小的树种表明其抗旱性强。依此排列出的上述４种幼树的抗旱性强弱顺序与应用ＰＶ技术所测抗旱性水分生理指标所排顺序一致。大气湿度的下降亦能明显提高幼树的暗呼吸强度和光补偿点。

he relationship between the air humidity and the rate of the net photosynthesis,ten-dency of respiration and the compensation point of light quantum of saplings of four conifer-ous species. Namely . Platycladus orientaris , Pinus sylvestris var. mongolica , P. tabulaeformisand Picea meyeri were measured and studied by using 225MK,IRGA(ADC) under the con-trolled indoor conditions. The results show that all the rates of net photosynthesis in thefour species of salings declined with decreasing air humidity and their relation is expressed bya logistic equation Y=α+blnX , where in b is the rate of such a change ,having a widely inter-specific variation and reflecting the interspecific variation in the. resistance to atmosphericdrought ,i. e. ,drought hardiness. An order ranking for drought hardiness based on the b-values for the above 4 species of saplings was coincident with the order ranking for physiologi-cal index of moisture representing a drought hardiness determined by a PV technique. Thereduction in air humidity may obviously incrcase the tendence of dark respiration and com-pensation point of light quantum of saplings.