土壤干旱对2个沙棘品种叶片水势和光合特性的影响

Leaf water potential and photosynthetic characteristics of two Hippophae rhamnoides cultivars with soil drought

为了研究干旱胁迫对沙棘Hippophae rhamnoides生长的影响,通过模拟土壤自然干旱和复水过程,研究不同程度土壤干旱下中国沙棘H.rhamnoides subsp.sinensis品种‘丰宁’‘Fengning’和蒙古沙棘H.rhamnoides subsp.mongolia品种‘向阳’‘Xiangyang’2个品种叶片水势和光合特性。结果表明:蒙古沙棘‘向阳’在控水第22天(19.40%)左右出现叶片干缩,而中国沙棘‘丰宁’在第33天(11.66%)左右出现,说明‘丰宁’的抗旱性要高于‘向阳’。随着土壤体积含水量的降低,2个沙棘品种的叶片水势下降,增加了对水分的吸收能力,并且‘丰宁’下降幅度要大于‘向阳’。与光合生理相关的最大净光合速率、蒸腾速率、气孔导度、光饱和点、表观量子效率均随着干旱程度加深而下降,而叶绿素相对含量和光补偿点出现上升,水分利用效率先上升后下降,‘丰宁’试验组的暗呼吸速率出现先下降后恢复趋势,而‘向阳’试验组先不变后上升。复水后各生理指标出现不同程度的恢复。因此,在人工林的培育过程中出现极度干旱,沙棘叶片干缩,要及时灌溉,以免对沙棘生长造成不可恢复的伤害。‘丰宁’比‘向阳’更适合作为选育良种的亲本。

To study the effects of drought stress on the growth of Hippophae rhamnoides in a natural environment, plant water relations and photosynthetic characteristics of two cultivars： H. rhamnoides subsp. sinensis‘Fengning’ and H. rhamnoides subsp. mongolia ‘Xiangyang’ with different degrees of drought were studied by simulating natural soil drought conditions and water recovery processes. Results showed that leaves, experiencing drought treatment, initially shrunk at 22 nd（19.40%） for the exotic species ‘Xiangyang’ and 33 rd（11.66%） for the native species ‘Fengning’. Also, ‘Fengning’ had stronger drought resistance compared to‘Xiangyang’. In addition, with increasing drought stress, the leaf water potential of both species decreased（0.77 and 0.45） and the moisture absorption ability increased. The maximum net photosynthetic rate, net photosynthetic rate, transpiration rate, stomatal conductance, light saturation point, and apparent quantum yield decreased with increasing drought stress; whereas, the relative content of chlorophyll and the light compensation point increased. Also, water efficiency rose after falling. The dark respiration rate of ‘Fengning’ treatment group decreased first and then recovered, but ‘Xiangyang’ treatment group was unchanged and then increased. After rehydration, the physiological indexes appeared in different degrees of recovery. Therefore, when extreme drought occurred in the process of cultivating a plantation, the leaves shrunk and need timely irrigation to avoid unrecoverable damage with ‘Fengning’ being more suitable than ‘Xiangyang’ as a breeding parent.