Subjects: Geosciences >> Geography submitted time 2024-04-29 Cooperative journals: 《干旱区研究》
Abstract： Five typical vegetation types (i.e., coniferous forests, meadow grasslands, alpine shrubs, alpine meadows, and sparse vegetations of limestone flat) along a vertical belt of the Qilian Mountains were selected to explore the spatial elevational patterns of soil carbon, nitrogen, and phosphorus and their stoichiometric ratios. Results showed that: (1) The contents of total carbon (C), nitrogen (N), and phosphorus (P) at the 0~40 cm depth were 15.33~83.46, 1.63~7.76, and 0.37~0.74 mg·kg-1, respectively. Soil C and N decreased gradually with increasing altitudes, following the order coniferous forests > meadow steppes > alpine shrubs > alpine meadows > sparse vegetations of limestone flat. Soil P in alpine scrubs was significantly higher than that in alpine meadows, but the other three vegetations showed no significant difference. (2) The contents of NH+ 4-N, NO- 3-N and available phosphorus at the 0~40 cm depth were 11.01~14.73, 2.78~12.46, and 4.35~13.57 mg·kg-1, respectively. Ammonium was the main inorganic nitrogen form in all vegetation types. The nitrite content decreased gradually with increasing altitude. The content of soil available phosphorus was higher in sparse vegetations of limestone flats. (3) The ratios of soil C:N, C:P, and N:P at the 0~40 cm depth were 9.52~10.11, 29.89~320.24, and 3.18~29.63, respectively. Soil C:N decreased with elevation. Soil C:P and N:P were significantly lower in the soil of sparse vegetations of the limestone flat than in other vegetations, indicating that carbon and nitrogen were the limiting nutrients in the limestone flat. By contrast, the limestone flat was in a phosphorus-rich state. Elevational variations in soil C, N, and P contents and their stoichiometric ratios reflect the joint control of multiple environmental factors, thereby affecting the biochemical processes of soil C, N, and P.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2021-01-26 Cooperative journals: 《干旱区研究》
Abstract：以塔里木河流域中游季节性洪水漫溢的天然胡杨林为研究对象，以野外原位采样的方法研究胡杨林在洪水漫溢条件下叶渗透调节物质及抗氧化酶活性的变化特征，为初步研究天然胡杨林耐水淹生理机制提供科学依据。结果表明：（1）洪水漫溢初期（8 d），胡杨叶中Na+含量、K+含量、游离脯氨酸（Pro）含量、可溶性糖（SS）含量及超氧化物歧化酶（SOD）活性降低，而Cl-含量、可溶性蛋白（SP）含量、过氧化物酶（POD）及过氧化氢酶（CAT）活性提高，说明在洪水漫溢初期，胡杨通过增加Cl-、SP等渗透调节物质含量来维持叶片渗透势，同时通过提高POD和CAT酶活性来清除由水淹胁迫而积累的活性氧，共同提高植物抗性；（2）随着洪水漫溢时间的延长（18 d），胡杨叶中K+含量、Cl-含量、SS含量、SP含量、SOD活性等均增加，而Na+含量、Pro含量、POD活性及CAT活性均降低，说明随着水淹胁迫的加剧，植物通过增加K+、SS、SP含量及提高SOD活性来增强抗逆性；（3）随着洪水漫溢时间的进一步延长（35d），胡杨叶中Na+在叶组织中含量增加，而SS含量、SOD活性、POD活性及CAT活性均降低，但与洪水漫溢前含量相当。综上所述，胡杨在洪水漫溢的水淹逆境下，通过渗透调节物质与抗氧化酶系统共同增强植物抗性。渗透调节物质中，Na+、K+和SP在胡杨整个洪水漫溢过程中发挥了重要的渗透调节作用，而Cl-与SS主要在漫溢初、中期发挥作用，维持叶片液泡渗透势平衡。在抗氧化酶系统中，洪水漫溢前期，POD与CAT在清除胡杨叶中受胁迫而积累的活性氧自由基中发挥重要作用，SOD则在洪水漫溢末期发挥了较强清除作用。
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture submitted time 2017-11-10 Cooperative journals: 《中国生态农业学报》
Abstract：中亚滨藜是一种典型的盐生植物, 广泛分布在我国盐碱地区。前期研究中, 我们发现盐胁迫显著诱导了中亚滨藜幼苗根尖类黄酮的累积, 但其中的生理机理尚不完全清楚。在不同盐浓度(50 mmol·L1、100 mmol·L1、250mmol·L1、500 mmol·L1、600 mmol·L1 NaCl)处理下, 通过添加KNO3(25 mmol·L1、35 mmol·L1)和外源槲皮素 (100 nmol·L1 quercetin), 采用植物生理学和生物化学等研究方法, 分析了盐诱导的类黄酮累积在调节中亚滨藜幼苗耐盐性中的生理机理。研究结果表明, 使用外源类黄酮类物质——槲皮素进行处理, 一方面更加抑制了盐胁迫下幼苗主根的生长, 同时还显著降低了根部H2O2 的累积和幼苗在盐胁迫下的MDA 水平, 但使可溶性糖含量显著升高。这些结果表明, 槲皮素通过抑制主根生长, 影响了中亚滨藜根系结构; 通过降低氧化伤害,提高了中亚滨藜幼苗对盐胁迫的耐受性。盐胁迫还显著诱导了中亚滨藜幼苗对硝酸盐(NO3)的累积, 使用25mmol·L1 和35 mmol·L1 KNO3 处理, 可显著诱导其幼苗根尖类黄酮的累积。这些结果表明, 硝态氮可能通过影响类黄酮途径, 从而参与调控了中亚滨藜幼苗的耐盐性。本研究为进一步揭示中亚滨藜耐盐的生理与分子机制, 以及类黄酮参与调控中亚滨藜耐盐性的生理与分子机理提供了理论基础; 同时为使用现代生物技术和农艺措施提高作物耐盐性、改良盐碱地提供了理论依据和技术支持。
Hits
Hits
Downloads
Comment