光皮桦种子超干储藏及回湿处理的研究

【作者】 方莹；

【导师】 周坚；

【作者基本信息】 南京林业大学 ， 植物学， 2007， 硕士

【摘要】 光皮桦(Betula luminifera)属桦木科桦木属落叶大乔木,具有生态幅较宽,耐干旱瘠薄的特点,同时还有材质优良、用途广、栽培容易、病虫害少等一系列优良性状。这一树种近几年成为安徽、福建、湖北等亚热带省份新发掘的优良乡土速生树种。因为其种子颗粒小,内含营养物少,导致种子储藏难度较大。种子超干储藏有利于种质资源的保存。超干种子的贮藏特性在不同种类、不同品种间有较大差异。所以本研究以光皮桦为材料,对光皮桦种子的生物学特性、成分分析、超干储藏最佳含水量、空气回湿处理最佳湿度和时间、PEG回湿处理最佳浓度和时间、种子萌发初期酶活性变化等做了初步研究,主要涉及以下几个方面:(1)生物学特性、成分分析方面的研究。安徽省绩溪县种源种子千粒重均值为0.2225g,净度为72.76%,种子初始含水量为8.03%,种子发芽试验的发芽率为67%。通过对种子中蛋白质、粗脂肪、可溶性糖和淀粉含量的测定,确定种子中含量最高的是可溶性糖,为干重的18.5%,其次是淀粉14.76%,粗脂肪3.15%,蛋白质2.0%。各成分指标不仅说明了种子内含物少,是短命种子。(2)光皮桦种子最佳超干贮藏含水量测定。将种子含水量由8.03%降至6.0%~2.5%,储藏种子一年。研究结果表明光皮桦种子适于超干储藏,其最适保存的超干燥含水量为4%~ 5%。在此条件下,其活力保持较高水平,且其种子抗老化的能力显著提高。主要表现在种子发芽率、发芽指数、细胞膜完整性、脱氢酶活性等指标均保持较高水平,丙二醛含量较低。而当含水量为2.0%~3.5%或6.0%,种子活力则显著下降。(3) PEG渗透调节处理最佳浓度和时间的研究。利用不同浓度的PEG浸泡超干燥种子,对其种子活力进行测定。结果表明,适宜的浓度PEG对种子有一定修复作用,提高了种子活力。短时间的PEG处理(2d~4d)更易提高种子活力,长时间PEG处理反而会降低种子活力。5%PEG处理4天效果最好。(4)根据不同处理对种子萌发初期影响,研究了种子萌发初期生理指标的变化。结果表明:在种子萌发初期,POD同工酶出现新酶谱带,随着萌发的推进,一些原有的谱带加深; CAT同工酶在萌发过程中没有新的谱带出现,但原有谱带颜色不断加深,表明酶代谢合成的增强。更多还原

【Abstract】 Betula luminifera is categorized into Betulaceae,Betula L. defoliation broadleaf species. It not only has wide ecology breadth and can endure drought and barren, but also has many other good properties such as fine timber, wide use, easy growth, few plant diseases and insect pests,etc. And in recent years it has become fine species of fast-growing-in-countryside-soil, according to the practical result discovered in some subtropical provinces like Anhui, Fujian, Hubei, etc.Having small size and poor nutrimental content, Betula luminifera seeds are difficult to be stored. Ultra-dried treatment helps to storage germplasm resources. There are big differences in characteristics of ultra-dried storage treatment among different species and types. Thus, this paper took Betula luminifera seeds as research target, and did a pilot research on areas covering the seeds’biological characteristics, component analysis, optimal moisture content for ultra-dried storage, optimal density and time for PEG treatment, accordingly changes of enzyme activity at the early stage of seed germination. The results showed as follows:(1) Seeds’biological characteristics and components were studied. The average weight of one thousand seeds from Jiqi county Anhui province was 0.2225g;pure rate was 72.76%;initial moisture content was 8.03%; germination rate was 67%. The analysis result showed that the highest content in a seed was soluble sugar, which accounts for 18.5% of its dry weight; the second highest content was starch, 14.76%; then crude fat, 3.15%; and the lowest, protein, only 2.0%. The above result suggested that Betula luminifera seeds might be ephemeral because of poor contents.(2)The optimal moisture content of ultra-dry storage treatment for Betula luminif- era seeds were studied. Preserved Betula luminifera seeds for one year after lessening their moisture content from 8.03% to range of 6.0%~2.5%. The result showed that the ultra-dry storage were suitable for Betula luminifera seeds, and the optimal moisture content for the treatment lied in the range of 4%~5%。Under this condition, the seed vigor keeped relatively high level, and the aging-resistance increased remarkably. The results above were mainly embodied by relatively high germination percentage, germination index, cell membrane integrality, the activity of dhase, as well as relatively lower MDA content. However, when the seed moisture content become 2.0%~3.5% and 6.0%, the seed vigor decreased significantly.(3) Different density and time of PEG treatment for ultra-dried Betula luminifera seeds were studied. PEG of different density was utilized to soak the ultra-dried seeds, and then measured the conductance of seed and seed vigor. The result indicateed, PEG of fitting concentration had definite function in repairing on the aging seed, improving the vigor of seeds. The PEG of different density had different effect on all kinds of seeds. The shorter time(2d~4d)PEG treatment was tend to improve the vigor of seeds, but the longer time PEG treatment would hinder sucking water, then reduce the vigor of seeds.(4) According to the effect of seed germination for different PEG treatment, we disscussed the accordingly changes of physiology index. It showed that POD isozyme appeared a new isozyme trand at the early stage of seed germination, and later some of the intrinsic isozyme trands deepened. There wasn’t any new isozyme trand of CAT isozyme appearing in the seed germination, but the color of the intrinsic isozyme trands continuously deepened, which indicateed the inhancement of the enzymatic metabolism.更多还原