紫花苜蓿组织解剖结构对NaHCO3盐碱胁迫的响应

为研究苜蓿组织结构对NaHCO₃胁迫的响应,本实验采用石蜡切片技术和光学显微技术,以甘农3号紫花苜蓿为研究试材,比较研究了0,100和150 mmol/L的NaHCO₃胁迫处理对甘农3号紫花苜蓿根、茎和叶内部结构的影响。最显著的结果在于NaHCO₃盐碱胁迫对紫花苜蓿植株维管系统影响较大,使贯通于根、茎、叶3个器官的维管组织变小,导致木质部和韧皮部输导能力锐减,极大地限制了由根系吸收的溶解有盐离子的水分向地上部分的运输。此外,在NaHCO₃盐碱胁迫下,各营养器官的其他组织也发生了相应的改变。盐碱胁迫使苜蓿叶片整体变薄,对海绵组织的影响强于栅栏组织,造成栅栏组织在叶片中所占比例相对增加;使茎的横切面变为不规则形,表皮细胞变小变薄,胞壁角质层加强,且使位于茎中央的髓薄壁组织细胞直径减小,数量增加,而髓细胞的内含物浓度增加;在盐碱胁迫下促进了根部的发育,根部直径显著变粗,木质导管直径显著变小但数量增多。

The anatomical structure responses in alfalfa to salinity-alkalinity stress of NaHCO3

Seedlings of alfalfa were treated with NaHCO₃ solution at three different concentrations levels (0, 100 and 150 mmol/L) and anatomical structure characteristics of three organs (roots, stems and leaflets) were observed using paraffin section techniques and photomicrograpy. There was an obvious difference in the vascular system of alfalfa at different NaHCO₃ levels. Vascular tissue throughout the roots, stems and leaflets was reduced compared to controls, conductive capability of phloem and xylem was also much reduced and in particular, transportation of water and dissolved ions absorbed by roots was greatly restrained. Changes in other tissues of vegetative organs were also observed. The NaHCO₃ treatments made leaflets thin, with more influence on spongy tissue than on palisade tissues. Stem cross section became irregular in shape, epidermis cells became smaller and thinner, and cell wall cutinization appeared. Parenchyma cells of pith located in the center of stems were decreased in diameter, increased in number and the concentration of their inclusion was rasied. Saline and alkaline stress of NaHCO₃ promoted growth of roots, root diameter of treated plants was significantly greaterthan controls, and the diameter of xylem vessels became smaller but number of xylem vessels was increased.