不同土壤含水量下沙棘叶片解剖结构研究

Study on seabuckthorn leaf anatomical structure under different soil moisture contents

【目的】研究不同土壤含水量下沙棘叶片解剖结构,为进一步深入研究沙棘抗旱耐涝机制提供依据。【方法】以一年生中国沙棘扦插苗为试验材料,设置干旱、水涝处理,以常规灌水为对照(CK),通过石蜡切片观察其幼叶及老叶解剖结构在不同土壤含水量下的变化情况。【结果】干旱条件下,沙棘幼叶的叶片、表皮及栅栏组织显著增厚(P<0.05);老叶的叶片、下表皮及栅栏组织厚度与CK相比无显著差异(P>0.05),上表皮及海绵组织显著增厚(P<0.05);幼叶栅海比及叶片组织结构紧密度(CTR)较CK升高,叶片组织结构疏松度(SR)降低,老叶与之相反;幼叶的叶脉、维管束及木质部最大导管直径与CK相比无显著差异(P>0.05),老叶显著增粗(P<0.05)。水涝条件下,沙棘幼叶变薄,老叶厚度与CK相比无显著差异(P>0.05);与CK相比,幼叶及老叶均表现出栅栏组织变薄、海绵组织增厚、栅海比和CTR降低、SR升高;幼叶主叶脉和木质部最大导管直径与CK相比无显著差异(P>0.05)、维管束直径显著减小(P<0.05),而老叶均显著增大(P<0.05)。【结论】靠近顶端生长点的沙棘幼叶通过调节叶肉结构适应不同水分条件,靠近茎基部的老叶通过调节叶脉维管组织适应不同水分条件。

【Objective】To study the anatomical leaf structure of seabuckthorn under different soil moisture contents and to provide basis for further research on drought and waterlogging tolerance mechanism of seabuckthorn.【Methods】Drought and waterlogging treatments were set up using one-year Chinese seabuckthorn cuttings as experimental materials,with conventional irrigation as control(CK).Under different soil moisture contents,the changes in the anatomical structure of young and old leaves were observed through paraffin sectioning.【Results】Under drought conditions,the leaf blade,epidermis and palisade tissue of seabuckthorn young leaves significantly thickened(P<0.05).The thickness of leaf blade,lower epidermis and palisade tissue of old leaves were not significantly different from that of CK(P>0.05),while the upper epidermis and spongy tissue significantly thickened(P<0.05).In comparison with CK,the young leaf palisade to spongy ratio and leaf cell tense ratio(CTR)increased,while the leaf spony ratio(SR)decreased,with old leaves showing the reverse trend.The young leaf vein,vascular bundle and xylem maximal vessel diameter were not significantly different from those of CK(P>0.05),while those of the old leaves significantly thickened(P<0.05).Under waterlogging conditions,seabuckthorn young leaves became thinner.There was no significant difference between the thickness of old leaves and CK(P>0.05).In comparison to the CK,both the young and old leaves had thinning palisade tissue,thickening spongy tissue,decreased palisade to spongy ratio and CTR,and increased SR.There was no significant difference in the main vein and xylem maximal vessel diameter between young leaves and CK(P>0.05),the vascular bundle diameter decreased significantly(P<0.05),while all of those in the old leaves increased significantly(P<0.05).【Conclusion】Seabuckthorn young leaves near the top growth point adapted to different water conditions by adjusting mesophyll structure,while old leaves near the stem base adapted to different water conditions by adjusting leaf vein vascular tissue.