老化处理和种子含水率对香椿萌芽特性的影响

Effects of Aging Treatment and Seed Moisture Content on Seed Germination Characteristics of Toona sinensis

【目的】香椿(Toona sinensis)种子不耐贮藏,常温下贮藏半年后,发芽率由90%下降至50%。因此,研究香椿种子在人工老化和超干处理条件下的活力和生理生化指标变化,初步探索香椿超干种子抗老化能力,以期增强种子的耐贮性。【方法】用硅胶干燥法对香椿种子进行超干燥处理,制备含水量为10.1%(初始含水量)、4.5%、3.5%和2.5%的种子后,在40℃的老化箱内老化0、20、40、60、80和100 d,试验采用双因素(老化时间×含水量)设计。测定各处理的发芽率、发芽指数、活力指数、幼苗长度、幼苗干物质量;测定人工老化0、40和100 d各含水量种子的相对电导率、丙二醛(MDA)含量和过氧化氢酶(CAT)活性。【结果】除老化时间和含水量2个主效应外,交互作用对香椿种子的发芽指标、幼苗形态指标和生理生化指标也有极显著影响(P<0.01)。与0 d相比,老化40 d的初始含水量种子几乎丧失发芽能力(发芽率为3.50%),而超干含水量(4.5%、3.5%、2.5%)种子仍保持一定的发芽率(75%~85.50%)。人工老化20~40 d时,4.5%和3.5%含水量种子的发芽率、发芽指数、活力指数、幼苗长度和幼苗干物质量均高于2.5%含水量;老化60~100 d时,虽然2.5%含水量种子保持了更高的发芽能力和发芽速度,但种子的活力仍趋近于0。老化40和100 d时,初始含水量种子的相对电导率和MDA含量均显著高于其他超干含水量(P<0.05),且随老化时间延长而上升。各含水量香椿种子CAT活性随老化时间先升高后降低,超干种子CAT活性升高幅度高于初始含水量种子。【结论】香椿种子超干处理后能够在人工老化过程中保持一定活力,初步认为3.5%~4.5%含水量范围的超干香椿种子具有更强的抗老化能力。

【Objective】The seeds of Toona sinensis are storage-sensitive.After six months storage under room temperature,the germination rate would decrease from 90%to 50%.Therefore,the changes of vigor and physiological and biochemical indexes of T.sinensis seeds under artificial aging and ultra-drying treatment conditions were studied to initially explore the aging resistance of T.sinensis ultra-drying seeds with a view to enhancing the storage resistance of the seeds.【Method】The seeds were subjected to the silica gel drying method.The moisture content of seeds were then dehydrated from the original 10.1%to 4.5%,3.5%,and 2.5%,before their artificial aging at 40℃for 0,20,40,60,80,and 100 days.This present study adopted the two-factor(aging time×moisture content)design.The germination rate,germination index,vigor index,seedling length,seeding dry mass of aged seeds were then measured.The relative electrical conductivity,malondialdehyde(MDA)content,and catalase(CAT)activity of aged seeds after 0,40,and 100 days were then measured.【Result】In addition to the two main effects of aging time and moisture content,the interaction effect also had highly significant effects on germination index,seedling morphological index and physiological and biochemical index of T.sinensis seeds(P<0.01).After 40 days of artificial aging,the seed with 10.1%moisture content almost lost the germination ability(germination rate is 3.50%),while the ultra-dry moisture content(4.5%,3.5%,2.5%)seeds still maintained a certain germination ability(75%~85.50%).To be specific,the germination rate,germination index,vigor index,seedling length and seedling dry mass of seeds with 4.5%and 3.5%moisture content were higher than those of seeds with 2.5%moisture content after 20~40 days of artificial aging.However,after 60~100 days of artificial aging,seeds with 2.5%moisture content maintained higher germination ability and germinating speed,seedvigor gradually approached 0.After 40 and 100 days of aging,the relative electrical conductivity and MDA content of control seeds were significantly higher than treatments of other ultra-dry moisture content(P<0.05),and the relative electrical conductivity and MDA content increased with aging time.The CAT activity of the seeds with different moisture content increased first and then decreased with aging time,and the increases of CAT activity of the ultra-dry seeds were higher than that of the 10.1%moisture content treatment.【Conclusion】The ultra-dry treatment of T.sinensis seeds can maintain certain vitality during artificial aging,and it is tentatively believed that ultra-dried T.sinensis seeds in the range of 3.5%to 4.5%moisture content have stronger anti-aging ability.