外源钙对盐胁迫下苦豆子(Sophora alopecuroides)种子萌发和幼苗生长的影响

研究了盐胁迫和外源钙对苦豆子(Sophora alopecuroides)种子萌发和幼苗生长的影响。结果表明:低浓度的NaCl胁迫可以促进苦豆子种子的萌发和幼苗根茎的生长,浓度增加会不同程度地抑制种子萌发。0. 5 mg·L-1NaCl胁迫促进苦豆子幼苗茎和根的生长,高浓度Na Cl胁迫则具有明显的抑制效应,抑制作用对茎生长的效应大于对根生长的效应。幼苗根、茎中富集的钙、钠含量随着外源钙浓度的增加而增加,富集的钙含量随着NaCl溶液浓度的增加而减小。高浓度的CaCl2处理显著提高了萌发率,促进了幼苗根茎的生长。     

超干处理与保存温度对黄花补血草种子的影响

 采用室温硅胶干燥法超干处理黄花补血草(Limonium aureum）种子,将种子含水量由8.92%分别降至 4.67%、3.54%、2.88%和 1.24%,在室温和5 ℃条件下保存12个月后,测定不同含水量超干种子经缓湿处理后的活力指标变化。试验结果表明:适度超干处理的黄花补血草种子在发芽率、发芽指数及活力指数等几项指标上均高于未超干处理的对照种子,不同含水量的超干种子相对电导率低于对照,脱氢酶活性高于对照,丙二醛含量也低于对照处理种子。在试验中种子含水量不低于3.54%时,超干处理对种子的发芽率、发芽指数和活力指数没有影响。通过对电导率、脱氢酶活性和丙二醛含量的研究表明,适度超干处理对种子细胞膜的完整性没有破坏,相反,可以使黄花补血草种子保持较高的活力,因此,利用超干技术保存黄花补血草种子是一种较为理想的种子保存方法。     

沙冬青种子萌发期抗逆性研究

 利用不同浓度的聚乙二醇(PEG)和NaCl溶液处理沙冬青种子,测定种子发芽率、发芽势、发芽指数、活力指数、幼苗叶片电导率、可溶性蛋白含量及丙二醛(MDA)含量。结果表明,随着胁迫强度增加,沙冬青种子萌发能力下降,幼苗叶片电导率上升,MDA含量上升。PEG浓度由5%升至15%时可溶性蛋白质含量上升,超过15%时,可溶性蛋白含量下降; NaCl浓度在0到1.5%范围内,沙冬青幼苗可溶性蛋白含量随NaCl浓度增大而上升。对两种胁迫条件下生长及生理指标的综合分析表明,沙冬青在种子萌发期和幼苗期有较强的抗旱和抗盐能力。     

蒙古沙冬青和霸王种子超干保存效果的研究

采用硅胶干燥法对蒙古沙冬青和霸王种子进行超干处理,以研究超干处理对种子活力和种子生理特性的影响。试验结果表明,蒙古沙冬青和霸王种子有较高耐脱水性,含水量分别降至4.67%和3.89%,种子活力虽略有下降,但明显高于对照,细胞膜也能够保持较好的完整性,脱氢酶活性、a-淀粉酶活性、呼吸强度也都较对照高,可见4.67%和3.89%分别是蒙古沙冬青和霸王种子超干保存的最适含水量。     

浸种温度对红芪(Hedysarum polybotrys)种子发芽的影响

采用初始温度不同的水浸红芪(Hedysarum polybotrys)种荚12h,然后发芽,以不浸种为对照,旨在探寻提高种子发芽质量的预处理方法,为规范化生产提供科学依据。结果表明:红芪种子发芽率进程符合Logistic方程,浸种荚对红芪种子发芽特性具有极显著影响。与对照比较,在20~80℃的水中自然冷却浸种12h均不同程度改善了种子发芽特性。随水温的提高,种子发芽质量先提高后下降;当水温为60℃时发芽质量最佳,发芽率、发芽势和发芽指数分别达80.7%、34.7%和4.994,较对照发芽率34.7%、发芽势4.0%和发芽指数1.865分别增加46.0%、30.7%和3.128;但当水温达80℃时,发芽质量出现下降趋势,但仍显著高于对照和20℃水浸处理的水平。60℃热水浸种12h可软化红芪种荚,增强种子吸水吸胀能力,并稀释降低发芽抑制物,有效提高种子出苗质量和育苗成效。水浸种预处理还可有效精选种子,但经浸种后的种子需拌土小心播种,严防机械损伤。     

准噶尔无叶豆地理种群种子萌发特性

准噶尔无叶豆种子具有明显的地理种群大小变异的现象。对大、小种子在3种光照(持续光照,12/12小时光照/黑暗,全黑暗)、5个温度梯度(10℃,15℃,20℃,25℃,30℃)条件下的最适萌发条件进行研究,结果表明:大、小种子萌发的适宜光照条件均为12/12小时光照/黑暗,在持续黑暗与持续光照条件下的萌发率无显著差异;最适温度范围是20~25℃,大种子在20℃、25℃下的萌发率(>85%),萌发指数均显著高于相同温度条件下小种子的萌发率(<35%)和萌发指数。大种子存在种皮硬实所导致的物理性被迫休眠,而小种子除物理性休眠外,可能还存在其他形式的深度生理休眠。准噶尔无叶豆自然状态下萌发率极低(≤3%),经综合分析,认为种子硬实和深度生理休眠可能是自然状态下种子萌发的困难主要因素,而土壤的光照、温度及湿度不存在明显的对种子萌发的限制。     

行距与施氮量对不同采种时期虉草种子生活力的影响

在通辽地区,对不同采种时期通草1号虉草(Phalaris arundinacea L.cv.Tongcao No.1)种子的生活力,进行了行距与施氮量影响的研究,旨在揭示虉草生活力对行距和氮肥的响应规律,为虉草种子生产提供理论依据。结果表明,虉草种子发芽势、发芽率、发芽指数和幼苗胚芽长、胚芽鲜质量和活力指数等都随行距和施氮量增加而增长。在适宜采种期(6月30日),施氮量92 kg/hm2处理下,虉草种子发芽指数和幼苗活力指数显著高于不施氮处理(p0.01)。在施氮条件下,在行距70 cm处理下,虉草种子发芽指数和幼苗活力指数都显著高于行距30cm(p0.01),而在行距50 cm和70 cm处理下,虉草种子和幼苗的上述指标差异不显著。采种时期对虉草种子生活力影响明显,盛花后13~15 d采集的种子生活力较高,提前或推迟采种都使虉草种子生活力下降。     

盐胁迫对红砂(Reaumuria soongorica)种子吸胀过程中生理特性的影响

以0%、0.5%、1.0%、1.5%、2.0%、2.5%、3.0%的NaCl和CaCl2溶液处理红砂(Reaumuria soongorica)种子,探讨了两种盐胁迫对种子吸胀过程中生理特性的影响及对种子的伤害程度。结果表明:红砂种子发芽率随两种盐胁迫的加剧极显著下降。种子丙二醛(MDA)含量在NaCl溶液胁迫后先下降后上升,在盐溶液浓度为1.0%时达到最小值,在2.5%处达到最大值;经不同浓度的CaCl2溶液胁迫后,MDA含量呈上升趋势,且均高于对照,最大值出现在3.0%处;种子内可溶性糖含量随NaCl和CaCl2溶液浓度的增大先下降后上升,分别在盐溶液浓度为1.0%和2.0%时达到最小值;种子过氧化氢酶(CAT)活性的变化较小;过氧化物酶(POD)活性随两种盐浓度的增加显著降低;超氧化物歧化酶(SOD)的活性随两种盐溶液浓度的增加先下降再上升又下降,但总体低于对照。经综合分析得出,CaCl2对红砂种子的伤害程度大于NaCl。     

红砂种子萌发对盐胁迫及适度干旱的响应

对红砂（Reaumuria soongorica (Pall.) Maxim）种子进行室内萌发实验,采用双因素正交法,设置NaCl 10个梯度(mmol·L-1):0、25、50、75、100、125、150、175、200、250;以PEG模拟干旱胁迫两个PEG浓度（g·L-1）: 0和75,测定种子萌发的12个指标,分析红砂种子萌发对NaCl胁迫及适度干旱的响应。结果表明,盐胁迫降低红砂种子萌发的发芽率,减弱种子活力,抑制胚根和胚轴生长。然而一定程度干旱胁迫（PEG75 g·L-1）可提高种子发芽率,增大种子活力,促进干重累积。耐盐隶属函数分析显示, PEG75处理下红砂种子的耐盐性高于PEG0,由此推测红砂进化出了盐胁迫与干旱胁迫的交叉适应策略。     

新疆生态经济系统的能值分析及其可持续性评估

运用能值理论与方法,对新疆1991～1999年的净能值产出率、能值投入率、环境负荷率、能值-货币比、能值使用强度、电力能值使用量比、可持续发展指数、人均能值用量和人口承载力等9个指标及其变化趋势进行分析,并与其他国家和地区的有关指标进行比较研究。分析结果表明：(1)1991～1999年新疆的净能值产出率曲线为非匀速下降趋势,从1991年的23.6下降到1999年的11.7。尽管净能值产出率有所下降,但仍然大大高于1,这表明新疆向外界输出的能值高于区外对其投入的能值,是一个资源输出型的生态经济区域;(2)新疆的可持续发展指数曲线与净能值产出率变化趋势一致,为非匀速下降趋势,从1991年的262.0下降到1999年的64.1。这表明从1991～1999年新疆的资源被开发和利用的程度有所增加,经济有了一定程度的发展,但开发程度仍较低,经济上还处于极不发达的阶段;(3)环境负荷率的变化曲线呈上升趋势。环境负荷率上升的主要原因是新疆的进口资源及劳务的能值用量增大,尽管如此,由于环境负荷率较低,因此,新疆的经济发展还有较大的潜力。     

Imbibition temperatures affect bitterbrush seed dormancy and seedling vigor

Bitterbrush first-year seedling survival is low. To determine whether imbibition temperatures affected seedling vigor, I compared post-imbibition seed weight, germination, and early growth among untreated, thiourea-treated, and cool-moist-treated seeds from three collections. Seedling axial lengths from untreated seeds averaged 28 mm among all imbibition temperatures. This compared to 31 mm from thiourea-treated seeds, 68 mm from seed held at 5°C for 14 days, and 118 mm from seeds held at 2°C for 28 days. There was no imbibition temperature for untreated or thiourea-treated seeds that compensated for the lack of a cool-moist treatment. Seed treatments or seedbed conditions which fully remove dormancy and reduce dormant-seed respiration appear likely to increase seedling survival during the first growing season.     

不同温度和沙埋深度对砂生槐种子萌发及幼苗生长的影响

在沙地环境中,沙埋是影响植物种子萌发和幼苗存活的一个重要因素。砂生槐是西藏特有的沙生植物,主要分布在雅鲁藏布江中游地区及拉萨河、年楚河等主要支流宽谷区。对砂生槐幼苗进行了控制沙埋试验,研究了不同温度和沙埋深度对砂生槐种子萌发特性的影响。结果表明,温度和沙埋深度显著影响砂生槐种子的萌发率和出苗率。在15～30 ℃的温度范围内,随着温度的升高,种子萌发率显著下降,15 ℃时,其种子萌发率达到最高值;砂生槐种子能在深度≤10 cm的沙埋中萌发,≤8 cm的沙埋中出苗,在此范围内,随着沙埋深度的增加,砂生槐种子的萌发率和出苗率逐渐降低。沙埋深度在植株高度的33％时,砂生槐幼苗能够存活,且总生物量大于未沙埋幼苗;当沙埋深度增至植株高度的66％时,砂生槐幼苗存活率降至43％,生长受到抑制;而当沙埋深度增至植株高度的100％和133％时,没有砂生槐幼苗存活。可见砂生槐植株在适应沙埋环境方面主要采用调整生物量分配模式的生态对策。     

Study on Seed Bank Composition and Seedling Emergence Regularity in Placer Iron Ore Soil

The mining of placer iron ore greatly influences the surrounding desert grassland. In Agdala Town, Qinghe County, Xinjiang, the soil seed bank is severely damaged, and the utilization and productivity of desert grasslands are almost zero, which seriously affects the safety of the ecological environment and the development of local animal husbandry. It is very important to supplement soil seed banks to enhance the species composition of desert grasslands after ecological restoration. In this study, the effects of the seed bank, species composition, and seed burial depth on the seedling emergence rate at placer iron ore site before and after artificial seed bank replenishment were compared using the germination tray method. The original soil seed bank in the study area contained only four species, which were all annual plants. The dominant species were Salsola ruthenica and Corispermum orientale, and the soil seed bank density was very small. The emergence regularity of the soil seed bank was closely related to water content, and the emergence of annual vegetation was explosive. Seed burial depth affected the emergence rate of perennial grass, and we determined that a burial depth of 0-5 cm was the most effective for emergence. This indicates that seedling emergence of artificially supplemented soil seed bank can be completed within 7 days if the sowing depth is appropriate; sowing depths greater than 5 cm affect seed germination. These findings provide a basis for selecting species to populate large areas.     

昆虫寄生对柠条种子命运的影响

在腾格里沙漠东南缘荒漠草原区研究了昆虫寄生对柠条种子命运的影响, 结果表明:①种子库的虫寄生率高达69.7％,寄生性昆虫为柠条豆象(Kytorrhinus immxitus Motschulsky),柠条坚荚螟(Etiella zinckenella Treitschke),柠条种子小蜂(Bruchophagus neocaragae Liao),刺槐种子小蜂(Bruchophagus philorobinae Sphov);②整个种子库的发芽率为38.35%, 无虫寄生的种子的发芽率为88.6%,柠条豆象寄生完全阻断种子的发芽率; 种子小蜂类和柠条坚荚螟取食寄生的种子发芽率分别为19.2%和5.3%。③完好的种子和不同昆虫寄生的种子之间长度、宽度和重量之间有显著的差异。和正常种子相比较,柠条豆象寄生引起种子体积增大; 柠条坚荚螟和种子小蜂寄生均使种子体积减小; 柠条豆象、柠条坚荚螟和种子小蜂寄生引起种子的重量损耗分别为57.64%,49.13%和39.30%。结果证明昆虫寄生对种子的命运有重要影响,是影响种群更新的关键因素之一。     

Pre- and post-dispersal seed loss and soil seed dynamics of the dominant Bulnesia retama (Zygophyllaceae) shrub in a sandy Monte desert of western Argentina

In deserts and semi-deserts dominant plants seldom rely on a persistent seed bank to ensure their recruitment from sexual reproduction, which is generally based on the seeds produced in the last reproductive event. We studied pre- and post-dispersal seed loss of Bulnesia retama, a dominant shrub of the sandy Monte deserts (western Argentina). We hypothesised that pre- and post-dispersal seed depletion in B. retama regulate soil seed density and in turn decrease soil seed reserves. We also hypothesised that spatial patches induced by standing vegetation and other microsites additionally affect post-dispersal seed loss and soil seed density.We observed that as much as half the total seed production was lost due to pre-dispersal seed predation. Seed dispersal plus predation showed a negative exponential function with 61% of seeds falling during the first 28 days, and 99% after 90 days, when 34% of the seeds remained inside excluded branches. A significant patch effect was observed on soil seed density and seed dynamics, with a greater number of seeds and increased seed depletion rates below B. retama shrubs. However, spatial patches did not affect seed germination although they increased with burial time, from 22% to 70% after 75 and 276 days, respectively. Likewise, a similar trend was found in potential seed germination; seeds collected directly from mother plants had a low germination rate (less than 25%), which increased to 75% after 276 days of soil burial. About 15% of the dispersed seeds should persist to the next rainy season, thus contributing to a low-density but persistent seed bank.The delay in seed germination and temporal decrease in soil seed density that we observed for B. retama suggest that a set of mechanisms have been developed promoting germination events whenever soil water is available, at any moment of the year.     

Seed and Fruiting Phenology Plasticity and Offspring Seed Germination Rate in Two Asteraceae Herbs Growing in Karst Soils with Varying Thickness and Water Availability

Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions. Annual herbs are pioneers adapted to these areas; however, little is known about the responses of their seeds and infructescence, and the germination of their offspring to these limited water and soil resources. In this study, we investigated how the seed and fruiting phenology plasticity and offspring seed germination rates of two annual Asteraceae herbs (Xanthium sibiricum and Bidens pilosa) respond to the harsh karst soil environment, by assessing the seed number, seed biomass and offspring seed germination rate. X. sibiricum and B. pilosa were grown under three soil thicknesses and three water availability levels in a full two-way randomized block design. The key results were as follows: (1) The number and biomass of progenies (infructescence and seeds) of X. sibiricum decreased with the decline of soil thickness and/or water availability (P <0.05). The infructescence and seed biomass of B. pilosa increased with the decline of water availability. (2) Seed quantity and seed biomass of X. sibiricum showed no correlation after their parents experienced resource reductions. A significant positive relationship between seed number and seed biomass was observed in B. pilosa (P <0.05). (3) The offspring seed germination rate of X. sibiricum did not change with the decrease of soil thickness under three levels of water treatment. However, the offspring seed germination rate of B. pilosa decreased significantly with the decrease of soil thickness under the control water level (P<0.05). The results show that X. sibiricum tends to improve its competitiveness by ensuring the quantity and quality of offspring in order to adapt to the shallow karst soils and dry karst habitats. In contrast, B. pilosa adapts to the unfavorable karst habitats by a risk-sharing strategy. B. pilosa produces more and bigger seeds to in an attempt to expand its survival range and escape from the unfavorable living environment, but this results in a lower seed number and germination rate of its progeny under the karst soil resource reduction.     

黄土高原子午岭林区油松林种子雨强度及时空动态特征

通过布设种子收集器（接种框）,对黄土高原子午岭林区的油松密林、油松林缘和单株油松（孤立木）的种子雨强度、种子雨历时、种子散播的时空分布特征进行了分析研究。结果表明：（1）油松林内、林缘、孤立木输入地面的种子总量分别为85.5、191.5、178.0粒·m^-2,不同母树类型种子雨强度有明显差异;（2）油松种子降落从10月初开始,11月初结束,种子雨历时约32 d;种子雨在10 d左右达到峰值;（3）林内种子雨强度有较大的空间异质性,种子分布呈聚集分布格局（扩散系数C=33.618）;（4）种子雨过程中不同类型种子的消长趋势及所占比重不同,完整种子在种子雨初期占有优势,未成熟种子在种子雨后期急剧增加,而残缺种子在整个种子雨过程中占的比重变化不大,完整、未成熟和残缺种子累积总量与种子雨强度呈线性相关;（5）林缘和孤立木的种子雨集中在距母树1～3 m的冠幅范围内,这说明油松种子雨扩散以重力传播为主。     

古尔班通古特沙漠南缘32种藜科植物种子萌发策略初探

对古尔班通古特沙漠南缘32种藜科植物的萌发特性（萌发率、萌发开始时间、平均萌发时间和萌发持续时间）进行研究,以探讨藜科植物的不同萌发对策及其生态适应意义。结果表明,32种植物萌发率呈双峰型,其中萌发率大于80%,或小于20%的种占大多数;萌发开始时间呈单峰型,28种植物在1~3 d内开始萌发;平均萌发时间也呈单峰型,平均萌发时间小于5 d的植物21种,最大的为杂配藜（23.7 d）;萌发持续时间种间差异较大,其中15种植物萌发持续时间小于15 d,10种植物持续时间在15~30 d,5种植物大于30 d。主成分分析和聚类分析结果表明,32种植物可划分为4种萌发类型:爆发型、过渡型、缓萌型和低萌型。以上结果揭示出32种藜科植物种子萌发策略不尽相同,表现为机会主义萌发策略、下注萌发策略和谨慎萌发策略,这与植物所处土壤盐渍化程度存在差异有关。此外,Log尺度下32种藜科植物种子大小及其变异范围较小（10-2~101）,暗示多数藜科植物多为小种子,其容易沿缝隙进入土壤形成短暂或永久种子库,这也是沙漠植物生存策略的重要一环。     

水盐胁迫对花花柴种子萌发的影响

 水盐胁迫直接影响盐生植物的种子萌发,本研究通过对盐生植物花花柴种子带冠毛与否及不同胁迫处理下种子萌发率的比较分析,探讨花花柴种子萌发期的耐盐特性。对花花柴带冠毛和不带冠毛种子在蒸馏水中的对比萌发结果表明,冠毛对花花柴种子的最终萌发率无影响,但明显延长种子的萌发时间,可能与阻碍种子吸水有关。花花柴种子经过冷处理,成熟的种子没有出现生理休眠现象,有利于种子在条件适宜时迅速起始萌发。采用不同浓度NaCl和等渗的PEG6000 (聚乙二醇) 处理花花柴种子,结果表明：①NaCl和PEG胁迫对花花柴种子的萌发具有非常明显的抑制作用,主要表现为降低种子的萌发率,延长种子的萌发时间,抑制胚根和胚芽的生长;②NaCl对花花柴种子萌发的抑制作用明显地大于等渗的PEG,说明离子胁迫是影响花花柴种子萌发的主要因素;③花花柴种子萌发的耐盐临界值为213 mM,极限值为340 mM;④低浓度的NaCl溶液（50 mM）不影响花花柴种子的萌发和胚芽的生长,表明花花柴种子适宜在低盐条件下萌发;⑤盐胁迫下未萌发种子的复水实验结果表明,高盐处理后未萌发的种子具有较高的复萌率,但各处理下种子最终萌发率没有显著差异,表明高盐能使种子休眠,但种子的活力仍能保持,有利于种群的维持。     

种子预处理对唐古特白刺出苗和幼苗生长的影响

 采用不同方法对唐古特白刺种子预处理,以不处理为对照,再行60 ℃浸种24 h后育苗,通过测定出苗动态和生长指标,探寻促进白刺种子出苗和幼苗生长的技术途径。结果表明,唐古特白刺种子出苗率变化动态均呈“S”型曲线,符合Logistic曲线方程,出苗质量随种子处理不同而异,出苗期为38～55 d,极限出苗率为30.2%～57.8%。沙搓和沙碾均可显著提高白刺种子出苗质量,为培育壮苗奠定良好基础,出苗率较对照分别提高15.6%和13.4%,出苗势分别提高60.1%和6.9%,出苗指数分别提高35.2%和13.2%,活力指数分别提高41.5%和23.3%。尤其沙搓种子出苗集中,较对照缩短5 d。而掐尖、20%醋酸和5%碱水浸泡均抑制发芽。将种子与沙子混合后手搓和棍碾压均可破坏白刺种子坚硬致密的内果皮结构,破除休眠,促进出苗和幼苗生长,但需注意的是沙碾操作不当会造成种子内部结构被破坏。