Seed Germination Characteristics of Caragana Species with Geographical Alternate Distribution
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【Author in Chinese】 张娟娟；
【Author's Information】 兰州大学， 生态学， 2018， 硕士
【Abstract in Chinese】 锦鸡儿属（Caragana Fabr.）为豆科灌木,广泛分布于我国荒漠区、草原区和森林区,具有重要的经济和生态价值。本论文以干旱地区分布的柠条锦鸡儿（C.korshinskii）、半干旱地区分布的中间锦鸡儿（C.intermediate）和小叶锦鸡儿（C.microphylla）、半湿润地区分布的树锦鸡儿（C.aborescens）和扁刺锦鸡儿（C.boisi）以及湿润地区分布的柄荚锦鸡儿（C.stipitata）为材料,研究了种子形态、种皮结构、种皮透水性及脱落酸（ABA）的含量,揭示了种子萌发特性存在差异的原因,以及种皮结构的差异促进种子萌发的作用。主要结果如下:1、干旱地区分布的柠条锦鸡儿种子萌发率高,达90%以上,而湿润地区分布的柄荚锦鸡儿种子处于休眠状态,不萌发;种子萌发速率从干旱地区分布种向湿润地区分布种逐渐递减。2、干旱地区分布的柠条锦鸡儿种子内源ABA含量低,而湿润地区分布的柄荚锦鸡儿种子内源ABA含量高,从干旱地区分布种向湿润地区分布种递增,且与种子最大萌发率线性负相关。ABA拮抗剂赤霉素（GA3）、ABA合成抑制剂氟啶酮（Fluridone）和二氢愈创木酸（NDGA）处理柄荚锦鸡儿种子后,萌发率从0%提高到53.3%、26.7%、30.0%,而ABA分解抑制剂烯效唑（Uniconazole）处理柠条锦鸡儿种子后,萌发率下降了一半,结果均证实ABA抑制了锦鸡儿属植物种子的萌发。3、干旱环境中分布的柠条锦鸡儿、中间锦鸡儿和小叶锦鸡儿种子表皮结构排列疏松,上表皮和下表皮之间的石细胞有明显的管状结构;半湿润、湿润地区分布的树锦鸡儿、扁刺锦鸡儿和柄荚锦鸡儿种子表皮结构排列致密,上表皮和下表皮之间的石细胞呈片状结构。种子吸水染色实验证实干旱地区分布种种皮吸水迅速,湿润地区分布种种皮不吸水,从而制约了种子的萌发。4、对柠条锦鸡儿进行喷雾,种子对表皮形成凝结水吸收迅速;土壤相对含水量为20%时,种子吸收的凝结水将种子萌发率提高了一倍,证实了凝结水显著促进了干旱地区分布种的种子萌发。
【Abstract】 Caragana Fabr.is leguminous shrub widely distributed in desert,grassland and forest areas in China,which has important ecological and economic value.In this paper,C.korshinskii distributed in arid regions,C.intermediate and C.microphylla distributed in semi-arid areas,C aborescens and C.boisi distributed in semi-humid areas,and C.stipitata distributed in humid areas were used to explored the seed morphology,seed coat structure,water permeability,and ABA content.Taking this as the standard to reveal the difference in seed germination,and the difference in seed coat structure promots the germination of seeds.The main results are as follows:1.Germination rate of C.korshinskii distrbuting in arid regions has a strong germination ability,which is more than 90 %,while the seeds of C.stipitata in humid areas were dormant and did not germinate.The seed germination rate exhibited a significant decline from the arid to the humid regions.2.The seeds of C.korshinskii distrbuting in arid regions had low endogenous ABA concentration than C.stipitata distrbuting in humid regions.Furthemore,the increasing of endogenous ABA in seeds from the arid region to the humid region,and it produced a negatively correlated with the maximum seed germination rate in each species.The seeds germination rate of C.stipitata increased from 0 % to 53.3 % 、26.7 % and 30.0 % after treated with the ABA antagonist gibberellin(GA3),ABA synthesis inhibitor(fluridone)and dihydroguaiaretic acid(NDGA).However,the seeds germination rate of C.korshinskii was reduced by half after treated with the ABA decomposition inhibitor(Uniconazole).Those results all confirmed that ABA inhibited the germination of Caragana seeds.3.The seeds epidermal structure of C.korshinskii,C.intermedia and C.microphylla distributed in arid environment was loose,and the stone cells between epidermis and epidermis had obvious tubular structures;However,C.aborescens,C.boisi and C.stipitata distributed in the semihumid and humid regions was dense,and the stone cells between the epidermis and the lower epidermis had obvious sheet-like structure.Water dye absorption indicated that the seed coats distributed in the arid environment were water-absorbing quickly,on the contrary,and the seed coats distributed in the humid environment were not water-absorbent,which restricted the germination of seeds.4..Spraying water on the suface of seeds of C.korshinskii,the seeds epidermis absorbs condensate formed water rapidly,at same time,the germination rate is twofold higher than control level when the soil relative water content maintained at 20 %.Those shown that condensed water significantly promoted the seeds germination of species distrbuted in arid regions.