【作者】 陈海波；

【导师】 王政权； 卫星；

【作者基本信息】 东北林业大学 ， 森林培育， 2008， 硕士

【摘要】 氮是植物生长发育中所不可缺少的,但也通常是土壤中的限制资源,在氮素胁迫条件下,植物根系能够通过自身调节做出形态、结构和生理上的适应性反应,以增加其在胁迫条件下的生存机会。细根是植物吸收水分和养分的重要器官,水曲柳苗木细根形态、解剖及生理对不同的氮水平将产生怎样的反应我们并不清楚?因此,本研究采用温室沙培技术,以1年生水曲柳苗木为试验材料,设计3个供N水平(其中1,16 mmol·L^-1为胁迫处理,8 mmol·L^-1为对照),通过测定整株苗木根系形态对氮胁迫的反应、1-3级根形态对氮胁迫的反应以及1-3级根C,N含量及生理指标对氮胁迫的反应,来分析苗木对不同N水平的响应机制,以期为水曲柳林分的经营管理和苗木的培育提供理论基础。主要研究结果如下:单株苗木根系总表面积和总长度在各生长时期（7、8、9月）随着氮浓度的提高而显著增大;各个氮处理（N1、N8、N16）在不同的生长时期也随着时间的增长而增大。根系平均直径在7,8月份时低氮处理显著高于对照和高氮处理,而9月份时高氮处理下平均直径显著大于对照和低氮处理;而各个氮处理在不同的生长时期单株根系的平均直径差异不显著。根系比根长在7月份时随着氮浓度的提高而增大,8,9月份时比根长表现为对照大于低氮处理和高氮处理;各个氮处理整株根系比根长随着生长期的延长而显著减小。在水曲柳苗木各个生长时期,与对照相比低氮处理显著降低了单株苗木的高生长、地径、地上、地下、总的生物量以及冠根比,而高氮处理与对照相比使苗木的各生长指标显著增大,且不同氮处理苗木的各个生长指标除了冠根比随着生长期的延长而变小外,其他生长指标都随着时间的增长而增大。水曲柳苗木1-3级根表面积和长度在各生长时期随着氮浓度的提高而增大;各个氮处理在不同的生长时期也随着时间的增长而增大。1-3级根平均直径在各生长时期的变化为低氮处理明显高于对照和高氮处理;而各个氮处理在不同的生长时期1-3级根平均直径几乎没有变化。7,8月份时,与对照相比低氮处理明显降低了1-3级根的比根长,9月份时与对照相比低氮和高氮处理均使比根长明显减小;各个氮水平在不同生长时期1-3级根比根长随着生长期的延长而显著减小。1-3级根皮层厚度和维管束直径随着根序升高而显著增大。各生长时期,与对照相比,低氮处理使皮层厚度增加,高氮处理使维管束直径增大;随着根序的升高,皮层细胞层数变大,在各个月份不同氮处理对同一根序根的皮层细胞层数影响均不显著,而低氮处理使得皮层细胞直径变大。1-3级根细胞长度在不同氮水平处理下各个月份均是随着氮浓度提高而显著减小。水曲柳苗木1-3级根氮含量随根序升而高减小,在不同的生长期随着供N水平的提高而显著增加;不同的氮处理随着生长时间的延长1-3级根氮含量显著增加。可溶性糖、淀粉、非结构性碳水化合物（TNC）含量随根序升高而增加,在不同的生长时期随着氮水平的提高而下降,而随着生长时间的延长而不断增加。9月份根系活力在同一级别根中对照显著大于高氮处理,高氮处理大于低氮处理;质膜透性表现为低氮处理显著大于高氮处理,高氮处理大于对照。综上,不同氮水平对水曲柳苗木根系的形态、结构、生理均产生了显著影响,低氮胁迫和高氮胁迫都对水曲柳苗木产生了不利影响,但苗木对这些不利环境产生了较强的调节和适应能力。更多还原

【Abstract】 Nitrogen is indispensable to plant growth and development, but it is usually confine resource in the soil, the plant roots can be made morphology, structure and physiological adaptive response through self-regulation at nitrogen stress, by which root can increase the chances of survival in the stress condition. Fine root absorb nutrients and water from soil, which is vital organs of plant, how the root morphology, structure and physiological of Ash response to the different N availability does is ambiguous? Therefore, in this study, one-year-old seedlings of Ash were studied by sand-cultured in pots with three nitrogen (N) level treatments (1,8,16 mmol/L ) in greenhouse. We measured the parameters of morphology of total roots and the first three order roots, anatomical properties, the N, C contents and roots physiological, then analyzed the mechanism of seedlings response to the nitrogen level treatments, these results may improve the technology of forestry management and production of seedlings. The main results were below:Morphology of total seedling roots was significant changed under different N treatment. The total surface area and total length increased significantly with increasing N concentrations supplied at July, August and September; which increased significantly along with the extension of time at every N level. The mean diameter was higher in low N treatment than in control and high N treatments at July and August, while it was higher in high N treatment than in control and low N treatments at September; the mean diameter had insignificant change along with the extension of time at every N level. The specific root length (SRL) increased significantly with increasing N concentrations supplied at July; however, it was higher in control than in low N treatment and high N treatments at August and September; which decreased significantly along with the extension of time at every N level. At the seeding different growth phase, significant decrease in height, collar diameter, overground, underground, total biomass and S/R in low N treatment compared to the control, while the high N treatments just the opposite whit low N treatment; The above growth Index increased along with the extension of time at every N level besides of the S/R.The mean surface area and length of the first three order individual roots increased significantly with increasing N concentrations supplied at July, August and September; which increased significantly along with the extension of time at every N level. Low N treatment resulted higher diameter comparing with control or high N treatments at the seeding different growth month; the mean diameter had also insignificant change along with the extension of time at every N level. The SRL decreased obvious in low N treatment at July and August; while it was the highest in control at September; the SRL of the first three order individual roots decreased significantly along with the extension of time at every N level. The low N treatment in the first three order roots increased cortical thickness, while high N treatment increased vascular bundle significantly at the seeding different growth phase. The layer of cortical thickness had insignificant change in the same root order indifferent N concentrations at the seeding different growth month, so the low N treatment increase the diameter of cortical thickness cell compare to the control and high N treatments. The cell lengths in the first three order roots were decreased markedly with the increasing N concentrations supplied at the seeding different growth phase.The N contents decreased with increasing the root order, which increased significantly with increasing N concentrations supplied at July, August and September; N contents increased significantly along with the extension of time at every N level. The soluble sugar, starch and total non-structural carbohydrate content of 1-3 order roots increased with increasing the root order, which decreased obvious with increasing N concentrations supplied the seeding different growth phase; and they increased along with the extension of time at every N level. The root vigor at low N treatment were the greatest of three N levers at first three order individual roots, and it higher at high N treatment then low N treatment; the membrane penetration showed that: low N treatment > high N treatment >control.In conclusion, the effects of N on morphology, structure and physiological of Ash seedling roots’ are significant. The low N stress and high N stress all negative to seedling’s growth ability, but the seedlings also have the acclimation and adaptation to the disadvantage environment.更多还原