Germination Ecology of Cenchrus biflorus Roxb.: Effects of Environmental Factors on Seed Germination

Better understanding related to germination and seedling emergence of plant species assists in predicting the potential distribution and provides insight for efficient management. Cenchrus biflorus Roxb. has been considered as potential forage species in arid environment due to its high nutritive values, prolific seed production, and tolerance to extreme temperature and prolonged drought conditions. A series of laboratory and greenhouse assays were conducted to determine the effect of different environmental factors, such as temperature, light, pH, salinity, osmotic potential, and seed burial depth on the germination and seedling emergence of C. biflorus. The maximum germination (95%) was recorded at 35°C/25°C, followed by 40°C/30°C; however, minimum germination was observed at 45°C/35°C (17.5%). Light significantly promoted the germination with maximum percentage (97.5%) when seeds were exposed to altering light and dark conditions (12/12 h). The osmotic potential for the 50% inhibition of C. biflorus germination was –0.4 MPa, although some seed germinated at –0.8 MPa (12.5%). Germination decreased from 97.5% to 12.5% as salinity stress increased from 0 mM to 200 mM sodium chloride (NaCl) with no germination > 200 mM. Seed germination was significantly affected by pH levels and was between 27.5% and 92.5% at 5–8 pH, respectively. No seedling emerged when seeds were placed on the soil surface; maximum seedling emergence (90%) at 2-cm burial depth and emergence decreased considerably as seeding depth increased above 2 cm. Its tolerance to drought and salinity make C. biflorus a potential candidate to be used as an alternative source during periods of forage scarcity under harsh climatic conditions, and it could possibly be used for rangeland rehabilitation purposes in arid environments.     

模拟干旱胁迫及温光对海乳草种子萌发的影响

试验以海乳草种子为材料,通过设置有无光照(光照周期为12h,光照强度为7200lx,12h黑暗)7种恒温和3种变温(5℃、10℃、15℃、20℃、25℃、30℃、35℃;10~20℃、15~25℃、25~35℃)筛选海乳草种子适宜的萌发条件,在此条件上模拟干旱及设置不同盐碱梯度,通过发芽率、发芽指数、活力指数探讨不同盐碱和干旱胁迫对海乳草种子萌发的影响。结果表明:(1)海乳草种子萌发属于光促型,在有光条件下,25℃或20~30℃萌发效果最好,并且变温有助于发芽;(2)海乳草种子的活力及生活力均随渗透势升高呈下降趋势,-0.735MPa渗透处理下,其种子几乎不发芽;(3)不同渗透势即不同盐碱浓度对海乳草种子萌发初期影响显著,随盐碱浓度升高,种子的发芽力及生活力均逐渐降低。低渗处理(-0.46Mpa)下,Na2CO3对种子萌发的抑制作用显著高于NaCl,且随渗透势升高抑制效果加重。     

温度、光照和水分对飞扬草种子萌发和幼苗生长的影响

为明确热带常见杂草飞扬草(Euphorbia hirta)的种子萌发特性,本研究运用培养皿滤纸法和盆栽法,分别研究温度、光照和水分条件对飞扬草种子萌发和幼苗生长的影响。结果表明,飞扬草种子在20~40℃范围内均可萌发,其中30℃为种子萌发的最适温度(萌发率和萌发指数均最大),25℃时幼苗生长最好(根长/苗长为1.031)。恒温条件(25℃)下,光照8~24h时的种子萌发率无显著差异(平均值94.07%)、光/暗0h/24h时萌发率降至52%(P0.05),萌发指数随光照时间缩短先增大后降低,光/暗16h/8h时最大(93.93),0h/24h最低(30.59);有光照时幼苗的根长均显著大于苗长,无光照时苗长显著大于根长(P0.05)。变温条件(光/暗,35℃/25℃)下,光照时长对飞扬草种子萌发率和幼苗苗长无显著影响(P0.05),随光照时长缩短萌发指数和幼苗根长均显著减低(P0.05)。综合各指标,12~16h光照为飞扬草种子萌发和幼苗生长的最佳光照条件。25℃、光/暗12h/12h条件下,飞扬草在土壤最大持水量60%时的种子出苗率达39%、幼苗根长苗长比为1.10∶1。     

古尔班通古特沙漠钠猪毛菜种子异型性及其萌发行为研究

钠猪毛菜在我国仅分布在新疆,具有很强的抗干旱和抗盐碱能力。研究钠猪毛菜不同类型种子形态及其萌发特性,结果表明,钠猪毛菜产生3种类型的种子,其形态特征、萌发特性均有显著差异。A型种子绿色,圆形,着生方式为横生,直径为(1.294±0.089) mm,百粒重(90.71±0.42) mg,花被背部有翅状附属物;B型种子红色,圆形,着生方式为直立,直径为(1.166±0.069) mm,百粒重(85.52±0.49) mg,花被背部有短/无翅状附属物;C型种子黄色,圆形,着生方式为直立,直径为(1.044±0.062) mm,百粒重(83.84±0.31) mg,花被背部无翅状附属物。A型种子在5 ℃/15 ℃、10 ℃/20 ℃、 15 ℃/25 ℃、 20 ℃/30 ℃、 25 ℃/35 ℃(光/暗=12 h/12 h)变温条件下萌发率均>92%,B型种子在5种变温条件下萌发率<60%,为非深度生理休眠,低温层积2周后可打破休眠;C型种子在5种变温条件下萌发率<5.3%,为深度生理休眠,划破种皮可打破休眠。浓度低于0.2 mol·L^-1的NaCl溶液对A型种子萌发的影响不大,但从0.8 mol·L^-1起,萌发率随着浓度增高而降低,直至为零,将在0.05~4.00 mol·L^-1NaCl溶液中处理的A型种子转移至蒸馏水后,仍有一定的恢复萌发率。苞片延缓A型种子吸胀,影响种子的最终萌发率,去除苞片可显著提高种子的萌发率。通过研究钠猪毛菜种子异型性及其萌发行为,为揭示其生态适应机制提供科学依据,并为新疆荒漠地区生态建设提供基础资料。     

荒漠半灌木白滨藜种子的萌发特性及其生态意义

白滨藜是具有抗旱、抗盐碱和耐贫瘠能力的半灌木,为新疆地区的良等牧草。通过研究温度、贮藏时间、苞片及盐分对白滨藜种子萌发的影响,结果表明：白滨藜种子萌发的最适温度为20／30℃和25／35℃。室温干藏2～8个月显著提高种子的萌发速率,干藏10个月后,种子萌发速率与萌发率显著降低。苞片延缓种子吸胀,对种子的最终萌发率有显著影响;去除苞片可以明显促进种子的萌发。浓度低于0．8 mol／L 的 NaCl 溶液对种子萌发的影响不大;但从0．8 mol／L 起萌发率随着浓度增高而降低,直至为零;将在0．05～4．00 mol／L 盐溶液中处理的种子转移至蒸馏水后,仍有一定的萌发恢复率,表明 NaCl 处理后的部分种子有保持活力的能力,部分种子丧失活力。对白滨藜种子萌发特性的研究,为揭示其萌发行为进化和生态适应机制提供科学依据,也为新疆荒漠盐碱地区饲用半灌木引种改良,良种繁育提供基础资料。     

Relationship Between Seed Mass and Young-Seedling Growth and Morphology Among Nine Bluebunch Wheatgrass Populations

To better match plant materials to ecological sites for the purpose of rangeland seedling establishment, we examined the relationship between seed size and growth and morphological traits in young seedlings of bluebunch wheatgrass (BBWG) (Pseudoroegneria spicata [Pursh.] Á. Löve), a perennial Triticeae bunchgrass native to the Intermountain West. Traits examined included onset of germination, seedling biomass traits, and seedling surface-area traits. We grew seeds of nine BBWG populations that varied for seed size and were produced in a common environment under 2 contrasting d/n temperature regimes (20/15°C; 10/5°C). Lighter-seeded populations germinated and initiated shoots earlier. Heavier-seeded populations displayed high levels of biomass-related traits (e.g., shoot and root biomass and shoot length), while lighter-seeded populations displayed high levels of surface area ? related traits (e.g., specific leaf area and specific root length [SRL]). Correlations between seed size and young-seedling traits were mostly similar under the two temperature regimes. However, root length ? related traits showed more positive correlations with seed size under the low-temperature regime, which is more similar to actual field-emergence conditions during early spring. P-24, a light-seeded population, originated from the most arid site and exhibited the highest SRL at low temperature, while T-17t, a heavy-seeded population, originated from the most mesic site and exhibited moderate SRL. Three populations used for rangeland revegetation, “Whitmar,” “Goldar,” and Anatone Germplasm, all exhibited low seed mass and high SRL. However, only Anatone displayed high root-to-shoot length ratio under both temperature regimes, perhaps explaining its wide and successful use in rangeland seedings.     

光照、温度、土壤水分和播种深度对披针叶黄华种子萌发及幼苗生长的影响

披针叶黄华(Thermopsis lanceolate)是我国北方草地广泛分布的一种有毒多年生草本植物,且具有一定的药用价值。本研究分析了光照、温度、水分和播种深度等环境因子对披针叶黄华种子萌发的影响。结果表明,持续光照、持续黑暗和16 h/8 h光暗交替时披针叶黄华种子萌发最适宜的温度为25 ℃;16 h/8 h光暗交替下,25 ℃/15 ℃日夜变温是披针叶黄华种子萌发最适宜温度;其种子萌发对光照不敏感;种子萌发最适宜的土壤含水量为7%～12%,最适宜播深为0.5～2.0 cm。     

温度对垂穗披碱草种子萌发的影响

在恒温、变温和光照3种处理因素6个梯度水平的条件下,对取自4个不同海拔高度垂穗披碱草（Elymus nutans）种子的适宜发芽条件进行了研究。结果表明,垂穗披碱草的适宜发芽温度范围为15~25 ℃;变温可显著提高种子发芽率和发芽整齐度,最佳变温组合为20 ℃/10 ℃,发芽率和发芽势分别较20 ℃恒温条件提高20.2%;垂穗披碱草种子萌发对光照条件反应不敏感;在低温条件下,低海拔种子的总体发芽能力要优于高海拔种子,而在高温条件下则表现为高海拔优于低海拔的态势,但在中等温度条件下,各海拔高度的种子间无显著差异。     

Salinity Effects on Germination of Artemisia herba–alba Asso: Important Pastoral Shrub from North African Rangelands

Artemisia herba–alba Asso (known in Arabic as Shih) is an evergreen aromatic shrub endemic in North African rangelands with high pastoral and medicinal relevance. The present work was designed to determine the effect of four soluble salts (NaCl, Na₂SO₄, MgCl₂, and CaCl₂) on germination of A. herba–alba seeds. Four concentrations (0, 50, 10, and 150 mM) of each salt were used to test the influence of salinities on germination percentage (GP), rate of germination (RG), and germination tolerance index (GTI %). The experiment was conducted in a controlled incubator with a 12h–photoperiod under 15°C dark/25°C light. The results showed that both GP and (RG) decreased significantly with salinity, and the highest GP was observed in the distilled water control (~ 80%). The germination tolerance index (GTI %) revealed that A. herba–alba seeds were more tolerant to CaCl₂ than other soluble salts. Comparatively, at high salt concentrations, MgCl₂ and Na₂SO₄ were generally the most toxic salts followed by NaCl and CaCl₂. The germination of A. herba–alba over a wide range of soluble salts suggests that this species can establish in salt-degraded soils. Therefore, this species appears a promising candidate for the rehabilitation of rangeland with saline soils.     

长芒草种子适宜萌发条件

研究了不同光照、温度以及二者之间的互作对长芒草（Stipa bungeana）种子萌发与幼苗生长的影响,结果表明,1）长芒草种子在10~30 ℃温度范围内均能萌发,萌发最适温度为20 ℃,在光照与黑暗条件下的萌发率分别为72%与88%;2）光照显著抑制长芒草种子的萌发,且相比适宜温度条件下,光照对亚适宜温度下种子的萌发具有更强的抑制作用。     

甘肃贝母种子吸水及发芽特性研究

对经后熟处理的甘肃贝母种子吸水规律进行测定,并设置不同温度(10,15,20,25,10/20℃变温)进行发芽试验,旨在为其人工驯化栽培提供依据。结果表明,甘肃贝母种子千粒重为0.72～0.82g。经20℃保湿储藏45d基本完成形态后熟,沙子与种子(4∶1)混合5～10℃层积150d基本完成生理后熟,种子吸水过程符合Logistic曲线,分急剧吸水期、稳定吸水期和饱和吸水期3个阶段。温度对经后熟处理的甘肃贝母种子发芽质量具有显著影响。黑暗下10～15℃内,随温度升高发芽质量显著改善,15℃发芽最佳,发芽率和发芽势分别达90.67%和89.33%。当温度超过15℃,发芽质量又显著降低,高温还抑制芽的伸长。以上结果说明经后熟处理后,温度是决定甘肃贝母种子发芽质量的关键因素。建议生产中当土温达15℃是甘肃贝母种子最佳播期,育苗期应保湿遮阳。     

荒漠半灌木白滨藜种子的萌发特性及其生态意义

白滨藜是具有抗旱、抗盐碱和耐贫瘠能力的半灌木,为新疆地区的良等牧草。通过研究温度、贮藏时间、苞片及盐分对白滨藜种子萌发的影响,结果表明:白滨藜种子萌发的最适温度为20/30℃和25/35℃。室温干藏2~8个月显著提高种子的萌发速率,干藏10个月后,种子萌发速率与萌发率显著降低。苞片延缓种子吸胀,对种子的最终萌发率有显著影响;去除苞片可以明显促进种子的萌发。浓度低于0.8 mol/L的NaCl溶液对种子萌发的影响不大;但从0.8 mol/L起萌发率随着浓度增高而降低,直至为零;将在0.05~4.00 mol/L盐溶液中处理的种子转移至蒸馏水后,仍有一定的萌发恢复率,表明NaCl处理后的部分种子有保持活力的能力,部分种子丧失活力。对白滨藜种子萌发特性的研究,为揭示其萌发行为进化和生态适应机制提供科学依据,也为新疆荒漠盐碱地区饲用半灌木引种改良,良种繁育提供基础资料。     

盐碱胁迫冬油菜的主导因素分析

用4种盐分为A因素（NaCl、Na2SO4、Na2CO3和NaHCO3的依次盐分组成摩尔比为A1（1∶9∶9∶1）、A2（1∶1∶1∶1）、A3（9∶1∶1∶9）和A4（1∶1∶9∶9）与5种盐浓度为B因素（盐浓度B1、B2、B3、B4和B5 分别为10、20、30、40和50 mmol·L-1）的双因素试验,模拟20种不同盐度和pH的盐碱条件处理冬油菜“陇油6号”（Brassica campestris cv.Longyou No.6）的种子和幼苗7 d后,测定其种子发芽率、幼苗叶片细胞膜透性、丙二醛、脯氨酸、可溶性蛋白含量和根系活力等指标。结果表明,随着处理盐浓度的增加,种子发芽率、幼苗根系活力和可溶性蛋白含量降低,叶片细胞膜透性和脯氨酸的含量增加;降低和增加程度由A1～A4大体增强,不同盐组成处理间差异显著（P＜0.05）。用盐度(Na+)、pH值、CO32-和Cl-代表盐碱混合条件所有胁迫因素,胁迫因素与胁变指标间均具有高度线性相关性。pH值、盐度(Na+)和CO32-是盐碱混合条件对冬油菜胁迫的主导因素,而Cl-的胁迫作用也不可忽略。     

湘杂芒2号种子发芽条件的研究

以人工远缘杂交新品种湘杂芒2号(Miscanthus sinensis×lutarioriparia)为材料,研究了温度、发芽床、光照、贮藏条件、带颖壳与去颖壳等处理对芒属植物种子发芽的影响.结果表明,湘杂芒2号种子在15和45℃条件下不发芽,在变温条件下(20℃/30℃)发芽率最高,为96％;纸上发芽的平均发芽率最高,为94％;在光照和黑暗条件下发芽率和发芽指数差异均不显著;在4℃的冰箱冷冻和在室温下非密封保存1年后,平均发芽率超过85％,而在-20℃条件下保存1年后萌发率为0;种子去颖壳后发芽率由66％提高到86％.该结果能为芒属植物种苗繁殖体系的建立提供基础.     

Freezing Stress Influences Emergence of Germinated Perennial Grass Seeds

In sagebrush rangelands perennial bunchgrasses are typically seeded in fall and a high proportion of planted seeds germinate prior to winter onset but fail to emerge in spring. Our objectives were to evaluate freezing tolerance of germinated but nonemergent bluebunch wheatgrass seeds under laboratory conditions. We used data from a 2-yr pilot study to determine overwinter freezing temperature and duration for soils in southeastern Oregon. We then conducted two experiments to assess freezing tolerance. In experiment 1, bluebunch wheatgrass seeds were planted in control pots and compared to seeds planted at early, mid, or late postgermination stages. Pots from each treatment were placed in a grow room maintained at 12 h 40 min light/11 h 20 min dark photoperiod, with a constant temperature of 22°C for 30 d either immediately or following a 30-d freeze. In experiment 2, germinated bluebunch wheatgrass seeds were planted in pots that were left nonfrozen or were frozen for a specified duration prior to a 30-d period in the grow room. Emergence density and tillers · seedling^?1 were quantified for both experiments. The number of days per year for freezing soil conditions in the pilot study ranged yearly from 25 to 51; maximum duration of continuous freezing was 16.5 and 11.2 d. Freezing reduced or eliminated seedling emergence at all postgermination stages (P < 0.001) and tiller density was reduced by at least 50% (P < 0.001). Maximum reduction in seedling density (P < 0.001) was realized within 4 d of initiation of freezing and tillers · seedling^?1 were reduced 30–70% with > 6 d of freezing (P = 0.001). Our data indicate that freezing-associated mortality of germinated but nonemergent bluebunch wheatgrass seedlings can be extremely high and suggest that management practices to reduce prewinter germination of seeds could improve subsequent emergence and seeding success.     

松嫩草地羊草种子发育进程、休眠特性及与盐碱耐性关系的研究

羊草(Leymus chinensis)是禾本科赖草属根茎型优质禾草,不但营养价值高、适口性好,而且具有较强的耐旱、耐寒和耐盐碱性。羊草既是东北松嫩平原的优势种,也是干旱与半干旱地区建植人工草地的优良草种。近年来,随着畜牧业的发展及生态环境治理力度的加大,人工羊草草地不断建植,为此,人们对羊草种子的需求量与品质的要求也越来越高。本文通过研究羊草种子的发育进程、休眠特性及与盐碱耐性的关系,一方面明确羊草种子的最适宜收获时间,为农业生产上收获高品质羊草种子提供科学依据,另一方面挖掘羊草种子的发芽潜能、深入解析抗逆机理,为提高其利用率及抗逆新品种的选育提供理论基础。主要研究结果与结论如下:(1)通过对羊草种子发育动态的研究结果表明,羊草种子在发育过程中,随着成熟度的不断提高,种子的颜色由绿色变为浅绿色,再变成黄色,最后变为棕黑色。种子千粒重不断增加,在盛花后33 d达到最大值,之后趋于恒定。含水量与种子浸出液电导率则呈下降趋势,含水量在盛花后36 d达到最小值,而2个试验年份电导率值有所差异,分别在盛花后27和30 d达到最小值。标准发芽试验结果显示,羊草种子在盛花后39 d发芽率最高,此时种子的开始发芽时间、50%种子发芽时间、发芽势等指标均为最优。尽管加速老化试验的发芽指标与标准发芽试验略有差异,但是盛花后39 d的种子同样具有最强的抗老化能力。上述试验结果表明,盛花后39 d羊草种子活力最高,品质最佳,是种子最适宜的收获时间。 (2)不同成熟度的羊草种子对土壤埋深与盐碱胁迫具有不同的响应方式。羊草种子出苗与其后的幼苗生长能力随着种埋深度的增加而降低,1 cm是最适宜的播种深度,此时的出苗率最高、出苗时间最短,并且叶片与根系长度与生物量最大;另外不同成熟度的羊草种子表现出不同的出土成苗能力,盛花后39 d的羊草种子活力最大,其上述各项幼苗生长指标均为最优。种子的成熟度与盐、碱胁迫及其交互作用显著影响羊草种子的发芽率与发芽势,盛花后39 d的羊草种子在胁迫下具有最高的发芽率与发芽势,特别是在高浓度(400 mM)盐胁迫下,尤为明显。复萌试验结果显示,盛花后39 d的羊草种子在盐碱胁迫(特别是高盐环境)解除后同样具有最高的发芽率。上述结果表明,尽管不同成熟度的羊草种子均具有发芽能力,但是盛花后39 d的羊草种子出苗及抵御盐碱胁迫伤害的能力最强,这也进一步支撑了39 d是羊草种子适宜收获时间这一结论。另外羊草适宜浅播,1 cm是其最适宜的播种深度。 (3)通过人工手段处理可以明显打破羊草种子的休眠特性。研究结果表明,除了热水浸种处理外,其余方法如浓硫酸、冷层积、PEG,GA₃,KNO₃及清水浸种均能一定程度上提高羊草种子的发芽率,发芽速率、开始发芽时间及50%种子发芽时间。但是在生产实际中,既要考虑高效性也要考虑经济耗费,结合本试验的研究结果,我们推荐在生产中采用低温浸种20 d的方法来打破羊草种子的休眠,提高其发芽率。 (4)稃是抑制羊草种子萌发的重要因素,但同时也一定程度提高了种子的抗盐性。通过测定稃对羊草种子吸水、脱水、不同温度条件下的发芽响应以及不同持续时间盐胁迫对种子发芽的影响,结果发现稃可以显著提高羊草种子的吸水量,并同时减缓种子在干旱环境下的脱水速率,使种子不会过度脱水而死亡。稃、不同温度处理及两者交互作用显著降低羊草种子的发芽率与发芽速率,表明稃对羊草种子萌发具有一定的抑制作用。在不同持续时间的盐胁迫处理下,未萌发的带稃种子复萌率均高于去稃种子,特别是在长时间及高盐胁迫下尤为明显,表明稃对羊草种子耐盐性起着重要的调节作用,一旦雨水、融雪等条件降低了土壤盐浓度,带稃种子就可以继续萌发出土。 (5)20~30℃是羊草种子最适宜的发芽温度,高温、低温均显著降低种子的发芽率与发芽速率,并且此温度可一定程度上减缓盐胁迫与碱胁迫对种子发芽的抑制效应。随着盐、碱胁迫浓度的增加,羊草种子发芽率与发芽速率均呈下降趋势,且在碱胁迫下的下降幅度更大。在盐胁迫下,当盐浓度<200 mM时,低温是影响种子萌发的主要因素,随着盐浓度的不断增加,高温则更加剧了盐胁迫对种子萌发的抑制作用;而在碱胁迫下,即使碱浓度较低,高温与其交互作用也大大加剧了对种子发芽的抑制。盐胁迫下未萌发的羊草种复萌率随盐浓度增加而增加,而在碱胁迫下则随着碱浓度增加呈先上升后下降的趋势,高浓度碱胁迫使羊草种子失去活力而死亡,并且碱胁迫下种子的复萌率低于盐胁迫,25~35℃同样不利于种子的复萌。幼苗生长对温度与盐碱胁迫交互作用的响应方式与发芽阶段相似,20~30℃同样是最适宜温度;另外,盐碱胁迫均对羊草幼苗根生长的抑制作用更强。基于以上研究结果,我们建议在初夏(7月上旬),高降雨过后,温度与土壤条件适宜的情况下进行播种,以提高羊草种子的发芽率,更好的达到恢复退化草地的效果。 (6)在混合盐碱胁迫下,羊草种子的发芽率与发芽速率均随着盐浓度的增加不断下降,且碱性盐比例越大下降越明显。在250 mM盐浓度下,无碱性盐的A组处理发芽率为6.5%,而其余5组处理发芽率均为0。羊草幼苗生长阶段同样受盐浓度、pH及2者交互作用影响,并且根系对胁迫伤害更敏感,所受抑制作用更强。逐级回归分析结果表明,在种子萌发阶段,盐浓度是羊草种子在混合盐碱胁迫下能否萌发的决定性因素,而一旦胚根突破种皮进入幼苗生长阶段,pH就转变为主导因素。上述研究表明,混合盐碱胁迫对羊草种子萌发与早期幼苗生长阶段的抑制机理有所不同,其中高盐浓度与高pH的交互作用对种子萌发与幼苗生长的抑制效应最强。 (7)盐胁迫与碱胁迫均显著降低羊草幼苗的长度、鲜重与含水量,且碱胁迫抑制作用更强。2种胁迫均造成羊草幼苗Na⁺浓度与Na⁺/K⁺升高,并且K⁺浓度下降,但是在碱胁迫下,Na⁺ 浓度、Na⁺/K⁺上升幅度与K⁺下降幅度均大于盐胁迫。另外,在盐胁迫下,羊草幼苗大量积累Cl^-,有机酸含量变化不大;而在碱胁迫下,Cl^-,NO₃^-与H₂PO₄^-均呈下降趋势,而有机酸则大量积累,其中苹果酸、柠檬酸是主要的有机酸组分,可溶性糖是羊草幼苗在两种胁迫下共同的渗透调节物质。上述结果表明,碱胁迫由于具有高pH,对羊草早期幼苗生长的抑制作用更强,Cl^-与有机酸积累特征的差异表明羊草早期幼苗在盐胁迫与碱胁迫下具有不同的适应策略。     

GA3浸种对露蕊乌头种子破眠及萌发生理特性的影响

露蕊乌头具有重要的药用价值,但自然条件下其种子的萌发率极低。本试验以露蕊乌头种子为材料,在光照和黑暗条件下,用不同浓度的赤霉素（GA₃）溶液浸种,探讨GA₃浸种对露蕊乌头种子破眠及萌发生理特性的影响。研究表明：GA₃浸种可以提高种子的萌发率,其中1 000 mg·L^-1 GA₃处理下种子的萌发率达到最大值,光照和黑暗条件下分别为91.66%和95.67%。黑暗比光照条件下露蕊乌头种子的发芽势、发芽指数和活力指数分别提高72.19%、26.58%、32.60%。与对照相比,1 000 mg·L^-1 GA₃浸种可提高α-淀粉酶,蛋白酶,脂肪酶的活性和可溶性蛋白的含量,降低可溶性糖含量,提高SOD、POD及CAT的活性,可见适宜浓度的GA₃浸种可有效促进露蕊乌头种子的萌发。     

GA3浸种对入侵植物节节麦种子破眠及发芽特性的影响

节节麦入侵已严重威胁到我国小麦的生产。节节麦种子具有较强的休眠特性,探讨赤霉素(GA₃)浸种对其破眠及发芽特性的影响,旨在为节节麦的后续研究提供参考。在光照和黑暗条件下,分别利用0、100、200、300、400、500 mg·L^-1的GA₃对种子进行处理,首先进行种子发芽率及发芽势的测定,并检测了500 mg·L^-1 GA₃及蒸馏水处理节节麦种子发芽过程中保护酶活性、MDA及内源激素含量的变化。结果表明:1)GA₃浸种处理提高了种子的发芽率及发芽势,其中以500 mg·L^-1 GA₃处理最为显著。此外,光照条件下种子的发芽率及发芽势均明显高于黑暗条件,表明节节麦种子的发芽需要一定光照条件;2)与蒸馏水处理相比,500 mg·L^-1的GA₃处理提高了种子内SOD及POD活性,减轻了质膜氧化损伤程度,致使MDA含量持续下降,从而促使种子朝有利于发芽的方向发展。此外,500 mg·L^-1GA₃处理在提高种子内促进生长内源GA₃、IAA及ZR含量的同时,并降低了抑制生长的内源ABA含量,致使GA₃/ABA、IAA/ABA和ZR/ABA值均明显高于蒸馏水处理,最终促进了节节麦种子的发芽。     

Smoke Water and Heat Shock Influence Germination of Shortgrass Prairie Species

Smoke or heat from fire can act as a cue that affects seed germination. We examined germination responses of 10 plant species (six forbs, two shrubs, two grasses) native to the southern High Plains in the United States, to smoke, heat, and their interaction in a laboratory experiment. Smoke treatments were applied by soaking seeds in 1∶5, 1∶10, or 1∶100 (v/v) Regen 2000® smoke solution for 20 h. Heat treatments were applied by placing seeds in an oven at 50°C or 80°C for 5 min. Nine species responded to smoke, heat, or both. Results showed that smoke can enhance, inhibit, or not affect seed germination. Germination capacities of Gutierrezia sarothrae (Pursh) Britton & Rusby and Astragalus crassicarpus Nutt. were promoted by 1∶5 and 1∶100 dilutions of smoke water, respectively; Coreopsis tinctoria Nutt., G. sarothrae, Salvia reflexa Hornem., Digitaria ciliaris (Retz.) Koeler, and Panicum virgatum L. were inhibited by high and/or moderate concentrations of smoke water either in germination percentage or in mean germination time. Germination percentage of Solanum elaeagnifolium Cav. increased following an 80°C heat treatment. Interaction effects between smoke and heat on germination also were detected. Smoke and heat treatments might be useful as management tools for promoting or suppressing specific target species of shortgrass prairie communities in future habitat management.     

异花柽柳种子萌发对温周期和盐分的响应

以新疆吐鲁番沙漠植物园的异花柽柳(Tamarix gracilis)为研究材料,设置4个温周期、10个NaCl溶液浓度梯度,在实验室条件下研究了温周期和盐分对异花柽柳种子萌发的影响。结果显示,1)异花柽柳种子在5℃/15℃、10℃/20℃、15℃/25℃、20℃/30℃温周期下均快速萌发,温度越高,萌发速度越快。2)异花柽柳种子在低于0.4mol·L~(-1)的NaCl溶液处理下萌发率均高,且处理之间无显著差异(P0.05);而高于0.6mol·L~(-1)的处理则显著抑制种子的萌发(P0.05),且NaCl溶液的浓度越高,最终萌发率越低,大于1.6 mol·L~(-1)的溶液处理中未见种子萌发。3)异花柽柳种子在解除盐分胁迫后恢复萌发率低。0.6~1.2 mol·L~(-1)的NaCl溶液处理下未萌发的种子恢复萌发率在2.1%~34.5%,大于1.2mol·L~(-1)的NaCl溶液处理后种子未见萌发,表明1.2 mol·L~(-1) NaCl为异花柽柳种子的最大耐盐浓度。综上,异花柽柳种子适宜萌发的温周期范围宽,种子萌发耐盐能力属于中耐盐性,耐盐机制为耐盐型。