极小种群野生植物海南风吹楠种子萌发对高温高湿的响应

Response of seed germination to high temperatureand humidity of extremely small population of wild plant Horsfieldia hainanensis

关键词:  海南风吹楠, 高温高湿, 种子萌发, 抗氧化酶, 内含物质, 渗透调节物质

Key words:  Horsfieldia hainanensis, high temperature and humidity, seed germination, antioxidant enzyme, substance, osmotic adjustment

摘要:

为探究高温高湿(HTH)胁迫下海南风吹楠(Horsfieldia hainanensis)种子萌发特性和生理生化特征,该文对海南风吹楠种子进行不同高温高湿胁迫时间(0、1、3、5、7 d)处理,5个处理分别为CK、HTH-1、HTH-3、HTH-5、HTH-7,测定种子萌发和幼苗生长指标,并对种子内含物质、抗氧化酶活性进行研究。结果表明:(1)相对于CK,高温高湿胁迫均显著抑制海南风吹楠种子萌发率(GP)、萌发势(GE)、萌发指数(GI)和活力指数(VI),延长种子平均萌发时间(MGT),CK、HTH-1、HTH-3、HTH-5、HTH-7处理的萌发率分别为63.3%、40.0%、33.3%、31.7%和26.7%; 高温高湿显著抑制幼苗株高(PH)、根长(RL)和地径(BD)生长,以及幼苗地上生物量(AB)、地下生物量(UB)和根冠比(RSR)且以HTH-7为最低。(2)随胁迫时间增加,淀粉(St)、可溶性糖(SS)、可溶性蛋白(SP)含量和超氧化物歧化酶(SOD)活性较CK显著降低,过氧化物酶(POD)活性、丙二醛(MDA)和脯氨酸(Pro)含量显著增加。(3)相关性分析表明,高温高湿胁迫下海南风吹楠种子萌发参数(GP、GE、GI、VI)和幼苗生长指标(PH、RL、BD、AB、UB、RSR)与SS、SP和SOD呈正相关,与POD、MDA和Pro呈负相关。综上认为,随胁迫时间延长,海南风吹楠种子内含物质分解、渗透调节物质含量增加、膜脂过氧化加剧且抗氧化酶活性提高,海南风吹楠种子活力与幼苗生长均受到抑制,这为海南风吹楠种质资源保护及选择野外回归环境提供了理论依据。

Abstract:

In order to investigate the seed germination characteristics and physiological and biochemical characteristics of Horsfieldia hainanensis seeds under high temperatures and humidity(HTH)stress, in this paper, the seeds of H. hainanensis were used as the research objects, the seeds of H. hainanensis were treated with different high temperatures and humidity stress time(0, 1, 3, 5, 7 d). Then the indexes of seed germination and seedling growth were measured, and the substance and antioxidant enzyme activities of seeds were studied. The results were as follows:(1)Compared with CK, high temperature and humidity stress significantly inhibited seed germination percentage(GP), germination energy(GE), germination index(GI)and vitality index(VI), and prolonged the mean germination time(MGT)of seeds. The cumulative germination rates of CK, HTH-1, HTH-3, HTH-5 and HTH-7 treatments were 63.3%, 40.0%, 33.3%, 31.7% and 26.7%, respectively. High temperature and humidity significantly inhibited plant height(PH), root length(RL)and basal diameter(BD)growth, and aboveground biomass(AB), underground biomass(UB)and root-shoot ratio(RSR)of seedlings, and HTH-7 was the lowest.(2)With the increase of stress time, the contents of starch(St), soluble sugar(SS), soluble protein(SP), and superoxide dismutase(SOD)activity were significantly decreased compared with CK, while the contents of peroxidase(POD)activity, malondialdehyde(MDA)and proline(Pro)were significantly increased, implying heightened oxidative stress and membrane lipid peroxidation, as well as an upregulated osmotic adjustment mechanism in response to stress.(3)Correlation analysis showed that seed germination parameters(GP, GE, GI, VI)and seedling growth indexes(PH, RL, BD, AB, UB, RSR)were positively correlated with SS, SP and SOD, and negatively correlated with POD, MDA and Pro under high temperature and humidity stress, indicating that oxidative damage and osmotic stress play crucial roles in limiting seed vigor and seedling establishment. In conclusion, with the prolongation of stress time, the decomposition of seed substance, the content of osmotic adjustment, the membrane lipid peroxidation and the activity of antioxidant enzymes are increased, and the seed vitality and seedling growth are inhibited, which provides a theoretical basis for the protection of H. hainanensis germplasm resources and the selection of wilderness return environments return environment.