摘 要

为探明乌桕种子低温层积过程中抑制物活性的变化及其与种子休眠的关系，本研究以层积30d、60d、90d和未层积（对照）的乌桕种子为材料，采用甲醇作为提取剂，浸提种皮和胚乳中的抑制物，分析比较各浸提液对白菜籽发芽的影响。研究结果表明：乌桕种子的种皮和胚乳中均含有抑制白菜籽发芽的内源抑制物，并且这种抑制作用主要体现在抑制白菜籽胚根的生长。随着层积时间的延长，乌桕种子各部位抑制物的活性发生了不同的变化，胚乳浸提液对白菜籽萌发的抑制作用逐渐减弱，而种皮浸提液对白菜籽萌发的抑制作用先增强后减弱，其原因可能是种子在层积过程中，内源抑制物发生了从胚乳到种皮的转移。层积90d后，乌桕种子内源抑制物的活性显著降低，但此时种皮和胚乳的浸提液对白菜籽的发芽指数仍有显著的抑制作用，表明此时种子中仍含有一定量的抑制物质。乌桕种子的发芽率随着低温层积时间的延长而逐渐提高，但层积90d后，种子发芽率仅有30%，表明此时乌桕种子的休眠并未完全解除。

关键词：低温层积；抑制物；浸提液；种子休眠；发芽试验

Changes of inhibitory activity during cold stratification in Sapium sebiferum seeds

Abstract

In this study, Sapium sebiferum seeds were stratified at 5°C for 0d, 30d, 60d, and 90d. After that the seeds were extracted by 80% (v/v) methanol to compare the effects of different extracting solutions on the germination of cabbage seeds and to further explore the relationship between changes of inhibitory activity in the process of cold stratification. The results showed that seed coats and endosperm of S. sebiferum seeds contained endogenous inhibitors, and the inhibitory effects were mainly affected the suppression of radicle growth of cabbage seeds. With the extension of stratification time, different parts of S. sebiferum seeds had undergone various changes of inhibitory activity. The inhibitory activity of endosperm extracting solutions decreased with the extension of stratification time, while that of the seed coat extracting solutions increased first and then weakened after stratification for 90d. The reason may be that endogenous inhibitors had shifted from the endosperm to the seed coat while seeds were in the process of stratification. After stratification for 90d, the inhibitory activity of extracting solutions of S. sebiferum seeds decreased significantly, but the extracting solutions of seed coats and endosperm still had a significant inhibitory effect on the germination index of cabbage seeds, indicating that seed coats and endosperm still contained a certain amount of inhibitors at this time. The germination percentages of S. sebiferum seeds increased gradually with the extension of stratification time. However, the germination percentage of S. sebiferum seeds was only 30% after stratification for 90d, which indicated that dormancy of S. sebiferum seeds was not completely broken at this time.

Keywords: cold stratification; inhibitory substances; extracting solutions; seed dormancy; germination test 目 录

1. 文献综述 1

1.1 选题依据 1

1.2 国内外同类研究概况 1

1.2.1 种子休眠原因 1

1.2.2 乌桕种子休眠原因的探索 2

1.2.3内源抑制物与种子休眠 1

1.2.4 低温层积与种子休眠 2

1.3 研究内容、目的及意义 3

2 材料与方法 4

2.1 材料与处理方法 4

2.1.1 实验材料 4

2.1.2 低温层积处理 4

2.2 提取剂对白菜籽发芽的影响 4

2.3 乌桕种皮和胚乳浸提液的制备 4

2.4 种皮和胚乳浸提液抑制物活性测定 5

2.5 层积不同时间乌桕种子的发芽实验 5

2.6数据统计分析 5

3 结果与分析 6

3.1 提取剂对白菜籽发芽的影响 6

3.2 低温层积过程中种皮浸提液抑制物活性的变化 6

3.3 低温层积过程中胚乳浸提液抑制物活性的变化 8

3.4 层积不同时间下乌桕种子发芽率的变化 9

4 讨论 11

4.1 抑制物对种子休眠的影响 11

4.2 抑制物存在部位及活性的差异 11

4.3 层积处理对种子中抑制物的活性及种子萌发的影响 12

4.3.1 乌桕种子低温层积过程中抑制物活性的变化 12

4.3.2 层积处理对解除种子休眠的作用 12

5 结论 14

致 谢 15

参考文献 16

1. 文献综述

1.1 选题依据

乌桕(Sapium sebiferum ( Linn.) Roxb.) 为大戟科落叶乔木，产于我国秦岭、淮河流域以南，东至台湾，南至海南岛，西至四川中部海拔1000 m以下，西南至贵州、云南等地海拔2 000 m以下地区。乌桕是一种色叶树种，集观形、观叶、观果于一体，具有极高的观赏价值，已成为长江流域主要的秋景树种^［1］。乌桕种子黑色、圆球形，外被白色蜡质假种皮，可制油漆，假种皮为制蜡烛和肥皂的原料。同时乌桕种子含油，是重要的工业木本油料树种。乌桕种皮表面白色的蜡层可以榨取固体的油脂叫桕脂或皮油; 黑色的种皮内是种仁，可以榨取液体油叫桕油或梓油^［2］，乌桕还具有广泛的药用价值，已有1400多年的栽培历史，是我国特有的重要经济树种。

生产上，乌桕以播种繁殖为主，采种时间通常在11月中旬，当70-80%果实完全裂开，露出种子时为最佳采种期。然而实际生产过程中发现，乌桕种子具有明显的休眠习性，成熟的种子通常需要层积两个月以上才能部分解除其休眠，乌桕种子的这一习性给乌桕的生产带来了极大地不便，延长了乌桕播种的时间，同时大大降低了乌桕种子的田间发芽率。李淑娴等^[3]对乌桕种子休眠原因的研究发现其种皮及胚乳中都存在内源抑制物质且对种子的萌发具有显著抑制作用。