池杉种皮特性和种子休眠原因_杨治华.pdf

第 58 卷 第 4 期2 0 2 2 年 4 月林业科学SCIENTIASILVAESINICAEVol.58,No.4Apr.,2 0 2 2doi:10.11707/j.1001-7488.20220402收稿日期:2020-10-21;修回日期:2021-11-27。基金项目:重庆市科技局项目(cstc2018jszx-zdyfxmX0021-02);重庆市科技兴林首席专家团队项目(TD2020-2);重庆市住房和城乡建委科技项目(Chengkezi 2019-1-4-2);西南山地生态农业国家培育基地开放基金项目(5330200076);中央林业改革发展资金科技推广示范项目(渝林科推 2020-2);宁夏重点研发项目(2020BFG03006);宁夏自然科学基金项目(2020AAC03107)。李昌晓为通讯作者。池杉种皮特性和种子休眠原因杨治华陈雪梅陈春桦张丽苗董智谭雪李昌晓(三峡库区生态环境教育部重点实验室重庆市三峡库区植物生态与资源重点实验室西南山地生态循环农业国家级培育基地西南大学生命科学学院重庆 400715)摘要:【目的】研究池杉种皮和种子休眠的关系,明确其种子休眠原因,为池杉种子育苗提供理论依据。【方法】对新鲜采收的池杉种子,通过种子和种皮结构观察,萌发试验、氯化三苯基四氮唑(TTC)活力、种皮透水性测定、种子内源抑制物的提取以及浸提液对白菜幼苗生长的生物测定试验,研究种皮特性对池杉种子休眠的影响。【结果】1)种皮由外到内依次为:外表皮、外种皮、中种皮和内种皮;与对照相比,热水处理会促进外表皮脱落,但对种皮结构无明显影响,种皮透性无明显改变;酸蚀处理会使种皮表面出现腐蚀裂痕和腐蚀坑,且腐蚀裂痕和腐蚀坑随酸蚀处理时间延长而增多,种皮结构进一步受损,种皮透性增加。2)新采收种子生活力为 80.95%,但不萌发,具有显著休眠现象。3)种皮具有一定的透水性,种仁能吸收到部分水分,酸蚀处理利于促进种仁吸水,而坚硬的种皮在一定程度上阻碍种仁吸水膨胀,使种仁吸涨缓慢,并可能对胚根的伸长和生长产生机械阻力。4)种子含有内源抑制物质,各浓度甲醇浸提液对幼苗和根生长的抑制强度均表现为:种皮种仁,说明种子内的抑制物质主要存在于种皮,种仁中含量较少。5)种皮甲醇浸提液的分离和白菜幼苗的生物测定结果表明,池杉种皮甲醇浸提液各分离相均对白菜幼苗生长有不同程度的抑制作用。各分离相浓度为 1 g mL-1对白菜苗高的抑制强度表现为石油醚相乙酸乙酯相乙醚相甲醇相水相,对白菜根长的抑制强度表现为石油醚相甲醇相水相乙酸乙酯相乙醚相,即石油醚相抑制白菜苗高和根长的作用最强。【结论】池杉种皮的透水性不是引起池杉种子休眠的主要因素,但种皮的机械束缚可能导致种子发芽迟缓。池杉种皮的抑制物质主要集中于甲醇浸提液的石油醚相中,它们可能是一些极性较小的物质。因此,池杉种皮的结构和内源抑制物质是导致种子休眠的主要原因,池杉种子可能是兼具物理休眠和生理休眠的复合休眠。关键词:池杉;种子休眠;扫描电镜;种皮透性;内源抑制物质中图分类号:S718.43文献标识码:A文章编号:1001-7488(2022)04-0011-11Characteristics of Taxodinm distichum var.imbricatum Seed Coat and Their Effects on Seed DormancyYang ZhihuaChen XuemeiChen ChunhuaZhang LimiaoDong ZhiTan XueLi Changxiao(Key Laboratory of Eco-Environments in Three Gorges Reservoir Region(Ministry of Education)Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir RegionSchool of Life Sciences,Southwest UniversityState Cultivation Base of Eco-Agriculture for Southwest Mountainous LandChongqing 400715)Abstract:【Objective】The seed germination of pond cypress is slow,uneven andthus leading to a low seedling rate,which brings certain difficulties to production management.The present study is to identify the causes of seed dormancy of pond cypress by studying the relationship between seed coat and seed dormancy,so as to provide a theoretical basis for the practical application of pond cypress seed and a technical guidance for ecological restoration in the Three Gorges Reservoir area.【Method】The relationship between seed coat and seed dormancy of pond cypress was studied through observing the structure of seed and seed coat,germination test,TTC activity test,water permeability test,extraction and bioassay of endogenous inhibitors in different parts of seeds,as well as extraction,separation and bioassay of inhibitors contained in seed coat.【Result】1)The seed coat of pond cypress from outer to inner in order is:epicuticle,sarcotesta,sclerotesta,and endotesta.Compared with the control,the hot water treatment could promote the abscission of epicuticle,but had no 林业科学58 卷obvious effect on the structure of seed coat,and the seed coat permeability had no obvious change.After 15 minutes of acid treatment,corrosion cracks and pits appeared on the seed surface,the structure of seed coat was damaged,the seed coat became thinner and the seed coat permeability increased;After 30 minutes of acid treatment,a large number of corrosion cracks and pits appeared on the surface of seed coat,which further damaged the seed coat structure while enhancing the seed permeability.2)The viability of newly harvested pond cypress seeds was at 80.95%,but the seeds did not germinate and had significant dormancy.3)The seed coat of pond cypress has a certain degree of water permeability,and the kernel can absorb part of the water.Although the acid treatment is conducive to promoting the seed kernel to absorb water,the hard seed coat hinders the water absorption and expansion of the kernel to a certain extent,which makes the kernel absorb water slowly,and may produce mechanical resistance to the elongation and growth of the radicle.4)The seeds of pond cypress contain endogenous inhibitors.The inhibition intensity of methanol extracts from different parts on seedling and root growth was as follows:seed coat kernel.The result showed that the inhibitive substances mainly existed in the seed coat instead of seed kernel.5)The methanol extract from seed coat of pond cypress was separated and bioassayed by systematic separation method.The result showed that the methanol extracts from seed coat inhibited the growth of Brassica chinensis seedlings at different degrees.When the concentration of each separation phase was 1 gmL-1,the inhibition intensity of Brassica chinensis seedling height was petroleum ether phase ethyl acetate phase ether phase methanol phase aqueous phase,and the inhibition intensity of Brassica chinensis root length was petroleum ether phase methanol phase water phase ethyl acetate phase ether phase.Petroleum ether phase and methanol phase are the main phases with inhibitory effect.【Conclusion】The water permeability of seed coat of pond cypress may not be the