CAJ | 학술논문

为了探讨红砂适应极端干旱的生理生态机制,对盆栽红砂停止浇水造成土壤持续干旱直到叶片完全脱落,然后复水.干旱和复水期间,对土壤、叶片和枝条的相对含水量、叶片和枝条中的叶绿素质量分数以及超微结构进行了测定和观察.结果表明:在干旱初期,叶片中叶绿素a和b质量分数上升,枝条中的下降并在随后的干旱过程中保持不变;复水后新叶片叶绿素a和b质量分数、枝条中叶绿素a质量分数低于对照.超微结构研究表明红砂嫩枝的亚细胞组织中含有叶绿体.正常条件下,无论是枝条还是叶片的亚细胞组织,叶绿体紧贴细胞壁,叶绿体中的类囊体排列整体有序.随着干旱的加剧,叶绿体脱离细胞壁,向细胞中央靠近.严重干旱造成了叶片叶肉细胞和叶绿体结构不可恢复性的破坏,而嫩枝的亚细胞组织和叶绿体都保持完整.因此,红砂通过叶片脱落减少光照面积来适应极端干旱对自身造成的伤害,通过保持枝条中叶绿体的完整性和一部分叶绿素,为在复水条件下光合作用的快速恢复提供了保证.
위료탐토홍사괄응겁단간한적생리생태궤제,대분재홍사정지요수조성토양지속간한직도협편완전탈락,연후복수.간한화복수기간,대토양、협편화지조적상대함수량、협편화지조중적협록소질량분수이급초미결구진행료측정화관찰.결과표명:재간한초기,협편중협록소a화b질량분수상승,지조중적하강병재수후적간한과정중보지불변;복수후신협편협록소a화b질량분수、지조중협록소a질량분수저우대조.초미결구연구표명홍사눈지적아세포조직중함유협록체.정상조건하,무론시지조환시협편적아세포조직,협록체긴첩세포벽,협록체중적류낭체배렬정체유서.수착간한적가극,협록체탈리세포벽,향세포중앙고근.엄중간한조성료협편협육세포화협록체결구불가회복성적파배,이눈지적아세포조직화협록체도보지완정.인차,홍사통과협편탈락감소광조면적래괄응겁단간한대자신조성적상해,통과보지지조중협록체적완정성화일부분협록소,위재복수조건하광합작용적쾌속회복제공료보증.
@@@@In order to study the eco-physiological mechanism of Reaumuria soogorica adapt under extreme drought stress, the soil, leaf and stem relative water content, contents of chlorophyll (Chl) a and b, and chloroplast ultrastructure in leaves and stems during progressive soil drought were investigated by the cessation of watering until all leaves had been shed and the hydration process was restarted. The results show that during early day’s dehydration, the contents of chlorophyll a and b in leaves increased, contents of chlorophyll a and b in stem decreased and then were kept constant in the following drought stress. After rehydration, the contents of chlorophyll a and b in new leaves and chlorophyll a in the stem were lower than those in the control plant. The results of an atomical study in Reaumuria soogorica indicated that in most cases, choroplasts appeared in subcellular organization and choroplasts clung to the cell wall. Chloroplasts were surrounded by a persistent envelope and presented an abundant and ordered thylakoid system. With the ongoing drought stress, chloroplasts broke away from the cell wall and appeared in the center of the cell. The mesophyll ultrastructure and chloroplasts configuration in leaves were disturbed beyond retrieval in the leaves under severe drought stress, with the inner and outer membranes having been destroyed, hylakoid dis-intergrated, starch grain lost and parts of cell tissue dismantled into debris. But in stems, the mesophyll ultrastructure and chloroplast configuration completely remained. The conclusion is that Reaumuria soogorica utilizes leaf abscission to reduce the surface area exposed to light to avoid the damage from extreme drought stress and retains chloroplast integrity and that a considerable amount of chlorophyll enables a rapid recovery of photosynthesis upon rehydration.