Global climate change will increase surface soil temperature, with consequences on plant seedling growth and population dynamics. In this study, we carried out a field experiment to investigate the effects of 2 ℃ soil warming on the growth and physiological characteristics of 1- and 2-year-old seedlings of a dominant tree species in broadleaved Korean pine forest, Juglans mandshurica. The results showed that soil warming significantly increased basal diameter, root length, total leaf area, leaf dry weight, root dry weight, total biomass, apparent photosynthetic electron transfer rate (ETR), PSⅡ actual photochemical efficiency (ΦPSⅡ), and apparent photosynthetic electrophotochemical quenching coefficient (qP) of 1-year-old seedlings by 18.3%, 66.7%, 94.4%, 105.9%, 95.8%, 37.8%, 89.5%, 100.0%, and 71.4%, respectively. Soil warming significantly increased basal diameter, total leaf area, leaf dry weight, total biomass, leaf superoxide dismutase activity, peroxidase activity, catalase activity and free proline content, ETR, ΦPSⅡ, and qP of 2-year-old seedlings by 12.5%, 180.5%, 97.3%, 42.5%, 23.9%, 20.4%, 14.9%, 20.7%, 66.7%, 283.3% and 284.6%, respectively. There was an interaction between seedling age and soil warming on the root-shoot ratio and the ΦPSⅡ and qP in chlorophyll fluorescence parameters, in that soil warming significantly reduced the root-shoot ratio of 2-year-old seedlings and that the increase of chlorophyll fluorescence parameters of 2-year-old seedlings (4.1-4.6 times) was much higher than that of 1-year-old seedlings (1.5-1.8 times). Soil warming of 2 ℃ was beneficial to the growth of 1- and 2-year-old J. mandshurica seedlings and increased their regeneration potential. In particular, 2-year-old J. mandshurica seedlings responded to soil warming by increasing leaf area, improving leaf photochemical efficiency, and enhancing protective enzyme activity to increase resistance.
全球气候变化将增加地表土壤温度,从而影响植物幼苗生长和种群动态。本研究以温带地带性顶极植被——阔叶红松林的优势树种胡桃楸为对象,研究野外土壤增温2 ℃对1年生和2年生胡桃楸幼苗生长与生理特性的影响。结果表明: 与对照相比,土壤增温使1年生胡桃楸幼苗的基径、根长、总叶面积、叶干重、根干重、总生物量、表观光合电子传递速率(ETR)、PSⅡ实际光化学效率(ΦPSⅡ)和表观光合电光化学淬灭系数(qP)分别显著增加18.3%、66.7%、 94.4%、105.9%、 95.8%、37.8%、89.5%、100.0%和71.4%;土壤增温使2年生幼苗的基径、总叶面积、叶干重、总生物量、叶片超氧化物歧化酶活性、过氧化物酶活性、过氧化氢酶活性和游离脯氨酸含量、ETR、ΦPSⅡ和qP分别显著增加12.5%、180.5%、97.3%、42.5%、23.9%、20.4%、14.9%、20.7%、66.7%、283.3%和284.6%。苗龄和增温对幼苗的根冠比以及叶绿素荧光参数中的ΦPSⅡ、qP存在交互作用,表现为土壤增温显著降低了2年生幼苗的根冠比,2年生幼苗叶绿素荧光参数的增幅(4.1～4.6倍)远高于1年生幼苗(1.5～1.8倍)。野外土壤增温2 ℃有利于1年生和2年生胡桃楸幼苗生长,提高胡桃楸幼苗的更新潜力,尤其是2年生胡桃楸幼苗通过大幅增大叶面积、提高叶片光化学效率和提升体内的保护酶活性产生抗逆性来应对土壤增温。.
Keywords: antioxidant substance; biomass; chlorophyll fluorescence parameter; leaf area index.