| This study is located in erdos key research station which is for field observation of ecological environment on sandy grassland and belongs to ministry of agriculture. In this study, we made 2-3 years seedlings of Sabina vulgaris Ant. be the research objects, combined field observation and indoor experiment to study the fine root longevity through micro root canal technology and studied the changes about morphological characteristics, anatomical structure and physiological function of fine roots. We aimed to analyze the biological reactions during aging process of fine roots of Sabina vulgaris Ant. and explore the inner mechanism about aging of fine roots of Sabina vulgaris Ant.. The main results were as follows:1.Fine root length production and mortality of Sabina vulgaris Ant. exhibited strong seasonal patterns. The research showed that the production was about 52.91% in the whole growing season peaked in summer. And in 2015, the production which was small in early spring(April、May) and autumn was less than 10% in the whole growing season. The mortality of fine roots varied in different seasons. In 2015, the mortality which was about 26.37% in the whole death season peaked in September.2. Survival analysis showed that, with the increase of fine root diameter, order and the deepening of the soil layer, the longevity extended. Cox proportional hazards regression suggested that root order, diameter and soil depth significantly influenced fine root survivorship. The risk of fine root mortality decreased 67.3% with a 1 cm increase in soil depth, and fine root longevity increased 35.9% with a 1 mm diameter increase. At the same time, when the root order increased, the fine root longevity could increase 62.6%. So, from the increasing of fine root longevity, we can get that soil depth strongest influenced on fine root longevity, root order followed and root diameter was last.3. The result showed that after 40 days’drought treatment, the primary roots and the secondary roots changed significantly. And with the diameter of catheter, vascular bundle and root growing thick, secondary organization which improved the capacity of fine roots to resist drought treatment to live better turned to be perfect. What’s more, with the increase of root sequence, the effects of drought treatment on diameter of catheter, root and vascular bundle declined. By the result, primary roots whose metabolic rate was much faster changed more obviously than secondary roots. It could be seen that primary roots could better adapt to drought environment than the secondary roots.4. Short-term drought stress increased root vigor and the content of soluble protein, reduced the membrane permeability and enhanced oxidation resistance to promote the growth of fine root. Long-term drought stress made fine root age, which mainly reflected on the decreasing of root vigor, soluble protein and the increasing of membrane permeability,etc. The result showed that the activities in the primary roots were higher than secondary roots and the antioxidant enzymes of primary roots decreased more apparently than secondary roots, which proved the possible that aging occurred more easily in primary roots than in secondary roots. And it could be seen that root aging sequence order was just opposited to the sequence of development. The study foud that the decreasing of root vigor was closely related to the increasing of membrane permeability. |
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