繁殖期半叶马尾藻中国变种的形态结构观察

Morphological observation and structual analysis of Sargassum hemiphyllum( Turn. ) var. chinense J. Agardh in breeding season

半叶马尾藻中国变种Sargassum hemiphyllum(Turn.)var.chinense J.Agardh是构成南麂海域生态系统重要的大型海藻之一,目前关于半叶马尾藻中国变种的形态学观察尚无报道。以南麂海域繁殖期的半叶马尾藻中国变种为对象,实地跟踪观察和制作组织切片相结合,对该藻的假根、茎、叶、生殖托、气囊的形态结构进行了观察描述和分析。其中通过对不同发育阶段的生殖托的观察,发现了生殖窝的发生特点以及性母细胞分裂为配子的方式。根据半叶马尾藻的营养结构观察,推测半叶马尾藻的髓质部分细胞大部分为死细胞,仅留胞壁结构起支撑作用,藻体表皮以下的一层紧密排列的柱状细胞才进行光合作用及其它生命活动。

Sargassum hemiphyllum （Turn.）var.chinense J.Agardh is an important member of marine ecosystem in Nanji sea area,but there is no morpholigical observation on Sargassum hemiphyllum （Turn.） var.chinense J.Agardh at present.To understand and comprehend the morphological structure characteristics is helpful in learning life history of this brown alga living in Nanji Islands,and laying foundation for seaweed bed restoration.This paper took Sargassum hemiphyllum （Turn.） var.chinense J.Agardh as research object,combing field observation and tissue slice together,described and analyzed organs and structures of this brown alga.Especially,the occurring feature of genital fossa and division method of auxocyte was discovered through observation at different developmental stages.Transection of mature receptacles had six genital fossas which looked similar and grew synchronously and all were connected with the middle axle.All six genital fossas came from the sole occurring point deflecting from the center.Some daughter cells of metrocyte of genital fossa differentiated into auxocytes while others differentiated into separated structures.Based on vegetative organ＇ s observation of Sargassum hemiphyllum （Turn.） var.chinense J.Agardh,it was speculated that most of medulla were dead cells whose remaining cell walls played the role of supporting.Only a layer of the closely packed columnar cells under frond skin carried out photosynthesis and other life activities.