盐胁迫下3种滨海盐生植物的根系生长和分布

我国广大滨海地区的盐土上发育着大量的盐生植物,这些植物的根系对维持土壤稳定性,减小风蚀和水蚀具有重要作用。在水培条件下,针对碱蓬、盐角草和盐地碱蓬3种滨海盐生植物,研究它们在不同盐浓度条件下根系分布的差异。结果表明:一定浓度的盐分可以促进3种盐生植物生长,但较高浓度的盐抑制其生长,特别是对根系生长的抑制作用更大。在同样盐浓度下,盐地碱蓬的生长最快,生物量也最大。在盐分浓度较低时,3种盐生植物的主根长和总根长都有所增加,与对照相比,盐角草增加的幅度较大,但高浓度的盐会抑制根系总长度的增加,其中盐角草较碱蓬和盐地碱蓬抑制的程度轻。盐分对3种植物的根系平均直径没有显著的影响,但有减小的趋势。在水培条件下,碱蓬和盐角草的根系上、中、下部分布的较均匀,而盐地碱蓬的根系中部比上部和下部有显著的增加,盐分对每种植物的根系的分布没有显著的影响。从根系的分布特征可以推断:盐角草比碱蓬和盐地碱蓬具有较强的抗盐性和耐瘠薄能力;碱蓬的耐盐能力较其它两种植物差,盐角草的耐盐性最强。根据3种滨海盐生植物的根系生长和分布特征,证明这3种植物的根系分属于2种功能型,碱蓬是浅根系功能型,盐角草和盐地碱蓬是深根系功能型。根系分布的参数表明3种滨海盐生植物中盐地碱蓬是用来加强土壤稳定性最好的植物。     

东北羊草草原耐盐碱植物的研究

东北羊草草原的耐盐碱植物主要有１０种,分别属于藜科、禾本科和菊科,其生态分布与土壤中的ｐＨ值和电导率有密切关系。在１０种耐盐碱植物中,碱蓬、刺沙蓬、角碱蓬、翅碱蓬、碱蒿和碱地肤具有较大的细胞膜透性和对Ｎａ＋、Ｋ＋的富集能力,是重要的耐盐碱植物,在治理退化草原的过程中,有重要的应用价值。     

青海湖鸟岛盐碱地植被演替的初步研究

利用聚类分析和演替度分析方法,研究青海湖鸟岛地区湖水退缩形成的盐碱地植物群落类型及其演替过程。结果表明,青海湖鸟岛湖水退缩形成的盐碱地植被有四大主要群落类型为碱蓬单优群落,碱蓬 西伯利亚蓼群落,西伯利亚蓼 碱茅 碱蓬群落和碱茅 西伯利亚蓼 碱蓬群落;青海湖鸟岛盐碱地植被有两条演替线路,为盐碱沙地群落演替线路(碱蓬单优群落经碱蓬 西伯利亚蓼群落,向西伯利亚蓼 碱茅 碱蓬群落演替)和盐碱草地演替线路(碱蓬单—优势种群落,经碱蓬 西伯利亚蓼群落,向碱茅 西伯利亚蓼 碱蓬群落演替);随着植物群落的演替,物种多样性增加,均匀度提高,而丰富度在不同的演替线路表现不同的规律。     

塔里木盆地10种藜科植物种子萌发对干旱胁迫的响应及其抗旱性评价

以塔里木盆地分布的碱蓬、硬枝碱蓬、盘果碱蓬、五蕊碱蓬、星花碱蓬、刺藜、盐节木、盐穗木、盐角草、白茎盐生草等10种藜科植物的种子为材料,利用PEG-6000模拟干旱,研究种子萌发对干旱胁迫的响应规律,并对抗旱性进行综合评价。结果表明:(1)随渗透势的下降,干旱胁迫加重,10种藜科植物种子的最终萌发率受到不同程度的抑制,平均萌发时间逐渐延长,种子的胚根长度受到抑制;解除干旱胁迫后,碱蓬、硬枝碱蓬、盘果碱蓬、盐节木、盐穗木、盐角草和白茎盐生草种子可恢复萌发;(2)10种藜科植物种子萌发期抗旱(PEG)极限值从大到小依次为:盐穗木白茎盐生草盘果碱蓬硬枝碱蓬盐角草五蕊碱蓬盐节木星花碱蓬刺藜碱蓬;(3)采用隶属函数法,选取种子最终萌发率、平均萌发时间、胚根长度和恢复萌发率为主要评价指标,进行抗旱性综合评价,10种藜科植物种子抗旱性由强到弱依次为:盐穗木白茎盐生草硬枝碱蓬盐节木盘果碱蓬星花碱蓬盐角草刺藜碱蓬五蕊碱蓬;抗旱性较强的盐穗木、白茎盐生草、硬枝碱蓬和盐节木的隶属函数加权平均值分别为0.915、0.793、0.762和0.737。     

盐胁迫对不同生境盐地碱蓬光合及离子积累的影响

为了探讨盐地碱蓬(Suaeda salsa)适应不同生境的生理机制, 研究了盐处理(1、200和600 mmol·L^-1 NaCl)对盐碱地和潮间带两种生境盐地碱蓬地上部分及根系有机干重、叶片叶绿素含量及光合放氧速率、叶片和根中离子积累的影响。结果表明: 200 mmol·L^-1 NaCl对两种生境盐地碱蓬地上部分及根系的有机干重无显著影响, 说明两种生境盐地碱蓬均具有较强的抗盐性; NaCl处理显著降低了两种生境盐地碱蓬叶片的光合放氧速率; 各浓度NaCl处理下, 盐碱地生境盐地碱蓬叶片的光合放氧速率均高于潮间带生境的, 潮间带生境盐地碱蓬叶片中叶绿素a与叶绿素b的比值均高于盐碱地生境的; 各浓度NaCl处理下, 潮间带生境盐地碱蓬叶片中的Cl^-含量均低于盐碱地生境的; 与叶片中情况相反, 高盐处理下, 潮间带生境盐地碱蓬根中的Cl^-含量均高于盐碱地生境的。说明与盐碱地生境盐地碱蓬相比, 潮间带生境盐地碱蓬的根系可能对Cl^-具有较强的积累或限制其向地上部分运输的能力, 这些特征可能是盐地碱蓬适应不同生境的结果。     

3种碱蓬属植物种子含油量及其脂肪酸组成研究

应用重量法和气相色谱-质谱联用技术（GC-MS）对吉林省西部盐碱地生长的碱蓬、角碱蓬和翅碱蓬3种野生植物的种子含油量及脂肪酸成分进行了测定和分析。结果表明：碱蓬、角碱蓬和翅碱蓬种子含油量分别为24．39％、15．67％和15．80％。不饱和脂肪酸含量分别为88．65％、88．30％、88．50％。尤其是亚油酸含量较高,分别达56．94％、59．35％和60．86％。利用盐碱荒地种植碱蓬属植物。充分开发其在食用、医疗保健方面的应用价值。具有巨大潜力和广阔前景。     

不同生境盐地碱蓬出苗及幼苗抗盐性比较

研究了盐胁迫对不同生境盐地碱蓬出苗、幼苗生长、离子积累和荧光参数等的影响.盐地碱蓬种子具有二型性,即外种皮柔软而半透明的棕色种子和外种皮坚硬的黑色种子.两种生境盐地碱蓬棕色种子的出苗率均明显高于黑色种子.与黑色种子相比,潮间带生境盐地碱蓬棕色种子在高盐环境下的出苗速率和出苗率高于盐碱地生境盐地碱蓬.各处理盐分浓度下,潮间带生境盐地碱蓬叶片的最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)和地上部分生物量均低于盐碱地生境盐地碱蓬.高盐浓度下,潮间带生境盐地碱蓬叶片Na+和Cl-含量低于盐碱地生境盐地碱蓬.这些特征可能是盐地碱蓬长期适应不同生境的结果.     

松嫩平原两种碱蓬群落土壤种子库通量及幼苗死亡的分析

角碱蓬和翅碱蓬都是１ａ生耐碱性较强的藜科植物。在松嫩平原碱化草甸２个固定的单优碱蓬群落土壤中有活力种子的数量动态和种群动态的研究结果表明：土壤种子库存量在尚未萌发输出以前为最大,角碱蓬群落为２２２６０粒／ｍ＾２,翅碱蓬群落为３７２３０粒／ｍ＾２。整个生长季均有种子输出,２群落的种子库存率随着时间呈渐近形式规律地下降。现存植株数量角碱蓬种群以５月上旬最大,为１９４８０株／ｍ＾２,翅碱蓬则在４月上旬最     

碱蓬浮床对海水养殖尾水中氮磷修复效果研究

海水养殖尾水中总氮、总磷超标是引起沿海水体富营养化的主要原因,为研究碱蓬浮床对海水养殖尾水中氮磷的去除效果,该研究设计加入碱蓬(Suaeda salsa)浮床和不加浮床的两组对比实验,通过比较修复前后碱蓬株高、生物量、含水率、根长以及各部位氮、磷的含量变化,以及水体中总氮(TN)和总磷(TP)的去除效果,探究浮床中碱蓬对总氮和总磷的吸收及其生长特性,验证碱蓬浮床对海水养殖废水中氮、磷等的去除能力。结果表明:浮床中碱蓬株高、鲜重、干重、含水率、根长较修复前均有显著增加,说明浮床中盐生植物碱蓬能够适应含海水养殖尾水水培环境;经碱蓬浮床修复,水体中总氮、总磷均明显下降,其中碱蓬对海水养殖尾水中的总氮总磷去除贡献率分别为16.10%和78.15%,浮床中碱蓬会在叶片和根系中积累氮磷。     

湿地翅碱蓬生长及渗透调节物质对盐度的响应

辽河口翅碱蓬湿地是濒危物种黑嘴鸥的主要栖息地,其生长情况受海陆交汇带的盐分影响显著,近年来退化严重。探究适宜翅碱蓬生长的盐分范围对保护黑嘴鸥有重要意义。采用生长模拟装置,在翅碱蓬生长期内施用浓度为0、150、300、450和600 mmol·L~(-1)盐溶液,模拟不同盐环境条件下,翅碱蓬生长状况及生理指标对盐度的响应。结果表明:盐浓度为300 mmol·L~(-1)时,翅碱蓬地上高度及根长达到最大,分别为45.6 cm和14 cm;地上部分和根部的游离脯氨酸、可溶性糖和可溶性蛋白质3种渗透调节物质含量均达到最大值,分别为0.82和0.58、8.46和6.86、22.26和19.36 mg·g-1;盐浓度达到450 mmol·L~(-1)时,翅碱蓬植株的株高和根长降低,渗透调节物质含量也有减少;在浓度为600 mmol·L~(-1)时,表现出生长缓慢、茎枝枯黄、叶片脱落等现象,甚至出现翅碱蓬植株死亡。在盐浓度低于300mmol·L~(-1)时,翅碱蓬各项生长指标和渗透调节物质都处于上升趋势。研究表明,适当的盐浓度可促进翅碱蓬生长,辽河口湿地翅碱蓬生长的适宜盐度范围是150~450 mmol·L~(-1),在盐浓度为300 mmol·L~(-1)时长势最好,超过600 mmol·L~(-1)时翅碱蓬无法生长。     

Prospects for prophylaxis of parasitism

The turmoil in agriculture is relevant to our assessment of prospects for prophylaxis as a whole. The driving forces for innovation are economic, and it is not hard to trace the paths which spectacular advances in agriculture in the industrialized western world have taken towards their application in both human and animal health in the third world. Research on parasitic diseases, whether publicly or privately supported, must hold some promise for improving the lot of livestock producers and people, and erosion of these prospects in agriculture will have far-reaching implications for antiparasite prophylaxis in general. There is a clear need for our research programs to focus on and adjust to the demands of real-world problems at field level, and for a much greater awareness of the challenges involved in translating biological research breakthroughs into practical, implementable, measures that can eventually affect the lives and livelihoods of the intended beneficiaries.     

Varietal mixtures: a viable strategy for sustainable productivity in subsistence agriculture

Remarkable parallels link the development of varietal mixtures across subsistence farming systems. Mixtures are grown and persist because they prolong harvest and income flow and provide diversity of diet. From our review of research on agronomic and disease aspects of mixtures in modern agriculture, it is also clear that improved stability and decreased disease severity are common features of mixtures relative to their components in monoculture. Such advantages are of value to both modern and subsistence agriculture. However, in the majority of cases, the yield advantage of mixtures is small. Overall, we conclude that varietal mixtures are presently a viable strategy for sustainable productivity in subsistence agriculture, have potential for improvement without sacrifice of diversity, are an important resource for future global food production and may have an expanding role in modern agriculture in situations where qualitative uniformity is not the guiding priority.     

有机农业与可持续发展

从国内外有机农业研究与生产发展状况出发,阐述了我国绿色食品研究的目标、生产中坚持的原则;结合国外有机农业和可持续农业的争论,论证了“替代农业”的理论和实践意义．与常规农业高强度农业生产方法相比。有机农业生产方式能够培肥土壤,对环境的影响很小．有机农业为代表的“替代农业”的研究与实践已近一个世纪,我国的绿色食品事业的发展已历时十几年．讨论有机农业“环境友好”和对人体健康为主要宗旨的食品生产方式,以及维持农业系统的可持续性问题,对我国绿色食品产业的发展具有积极的指导作用。     

农业生态系统杂草多样性保持的生态学功能

杂草是农业生态系统中的重要生物组成部分 ,也是影响农林作物生长和导致产量下降的重要因素之一。过去人们一直努力将杂草从农业生态系统地中清除出去 ,对杂草的研究往往也更多地注重其危害性和防治途径。近年来保护农业生产区域中杂草等野生植物的多样性以及发挥其在维持生态平衡中的作用逐渐为人们所重视[1～4] 1) ,2 ) 。本文对国内外有关农业生态系统中杂草多样性保护及其生态学功能的研究报道作一简要概述 ,以供参考。1　农业生态系统杂草多样性保护早在 1 982年Ｈｉｂｉｇ提出不使用除草剂、不铲除杂草等办法保持农田周围、草地、园林…     

Agricultural modifications of hydrological flows create ecological surprises

Agricultural expansion and intensification have altered the quantity and quality of global water flows. Research suggests that these changes have increased the risk of catastrophic ecosystem regime shifts. We identify and review evidence for agriculture-related regime shifts in three parts of the hydrological cycle: interactions between agriculture and aquatic systems, agriculture and soil, and agriculture and the atmosphere. We describe the processes that shape these regime shifts and the scales at which they operate. As global demands for agriculture and water continue to grow, it is increasingly urgent for ecologists to develop new ways of anticipating, analyzing and managing nonlinear changes across scales in human-dominated landscapes.     

Factors affecting Common Quail’s Coturnix coturnix occurrence in farmland of Poland: is agriculture intensity important?

Over the last four decades, the majority of European farmland birds have shown marked population declines attributed to the intensification of agriculture. The Common Quail is a widespread farmland breeder across most of Europe. Its populations have shown marked decline, particularly pronounced at the end of the previous century. Ongoing agriculture intensification may be the factor responsible for the observed declines; however, links between species occurrence and farming intensification have not been addressed so far. We analyzed factors affecting the occurrence of the Quail in Poland using data from 722 1 × 1-km study plots and a set of 22 environmental variables, including proxies for agriculture intensification. Predictors were aggregated using PCAs and related to species presence/absence data using GAMs. The best-supported model of the species’ occurrence included eight variables and was clearly better (AIC weight = 0.54) than other models. Quails preferred open fields, showing high photosynthetic activity in March or June, with rather low precipitation and often at relatively high altitudes (up to 900 m a.s.l.). Importantly, quails were more frequent on plots located in regions with rather high inorganic fertilizer input, and showed no avoidance of areas with a high level of agriculture mechanization. We postulate that singing male quails are attracted to areas with medium or high intensity of agriculture but it may represent a maladaptive habitat choice enhanced by changing agriculture practices and peculiarities of the quail’s breeding strategy. Given the results, the quail cannot be classified as a good indicator of extensive traditional agriculture.     

Use and misuse of nitrogen in agriculture: the German story

Nitrogen (N) fertilization in agriculture has been discussed controversially in Germany for almost two centuries. The agronomist Carl Sprengel, who published his theory on the mineral nutrition of plants in 1828, advocated the use of mineral N fertilizers. Chemist Justus von Liebig, on the other hand, vehemently denied around 1850 the need for N fertilization. Although it soon became evident that Sprengel was right and Liebig was wrong, not much synthetic N fertilizer was used in German agriculture until around 1915, when the Haber-Bosch technique enabled the commercial production of NH3. The use of N fertilizers since then has grown, especially since 1950. To increase agricultural productivity, German governments have promoted, directly and indirectly, the use of N in crop and in animal production. Unfortunately, it was overlooked that N surpluses in agriculture increased rapidly; around 1980 they amounted yearly to more than 100 kg ha(-1). The extensive use of N in agriculture is causing environmental damage and is contributing substantially to the external costs of present agriculture. The main N compounds that affect the environment are N2O, NH3, and NO3. These compounds are considered to contribute one third to the external costs of agriculture. Additionally, the high rate of human intake of animal proteins and lipids has adversely affected the health of the country's population. Fundamental corrections in German farm policy appear inevitable.     

黄土高原集水农业研究进展

回顾了黄土高原集水农业理论与技术体系的研究成果．分析评价了集水农业的研究进展。随着黄土高原集水农业研究方法的改进、研究内容的深入、研究领域的扩充．提出了广义性集水农业研究范畴。在黄土高原集水农业理论研究的基础上．应加强微集雨微灌溉应用技术、现代集雨技术、计算机控制技术与集雨网络等高新技术手段的技术集成．以提高雨水汇集与利用效率。同时．黄土高原集水农业的研究已经从微生境条件下的农业生态系统延伸至区域生态环境保育。利用汇集雨水合理调配生态用水．进行小流域综合治理。农林牧综合发展。生态环境重建的集水型生态农业是黄土高原集水农业的发展趋势。     

Energy and Environmental Issues in Organic and Conventional Agriculture

Humanity is facing possibly the greatest challenge in its history. Population is expected to reach 9 billion in 2030. At the same time agricultural land is becoming scarcer and poorer in quality. Furthermore, the environmental impact of intensive agriculture and the effects of climate change are threatening food security in many regions of the globe. Further, shortage of fossil fuels will have dramatic effects on the performance of intensive agriculture. There is an urge to develop more ecological agricultural practices both to meet the need to preserve agroecosystems health and to deal with the reduced availability of “cheap” energy from fossil fuels. This paper reviews a number of studies comparing the performances of conventional and organic agriculture in light of energy use, CO ₂ emission and other environmental issues. Organic agriculture, along with other low input agriculture practices, results in less energy demand compared to intensive agriculture and could represent a means to improve energy savings and CO₂ abatement if adopted on a large scale. At the same time it can provide a number of important environmental and social services, such as preserving and improving soil quality, increasing carbon sink, minimizing water use, preserving biodiversity, halting the use of harmful chemicals, thereby guaranteeing healthy food to consumers. We claim that more work should be done in terms of research and investment to explore the potential of organic farming for reducing environmental impact of agricultural practices. However, in the case of organic agriculture, the implications of a reduced productivity for the socioeconomic system should be considered and suitable agricultural policies worked out.     

The Relative Decline in Women's Contribution to Agriculture with Intensification

This paper suggests why the intensification of agriculture is associated with a relative decline in women's participation in agriculture. The statistical evidence described here is consistent with the theory that women contribute relatively less to agriculture when it becomes intensive because their domestic work and fertility have increased. It is also argued that most men may be able to contribute more to agriculture in societies cultivating intensively because hunting, warfare, and trade are not so likely to pull them away from crop production [women's contribution to subsistence, agricultural intensification, time allocation, fertility, cross-cultural]