Effects of Seed Dispersal by Three Ateline Monkey Species on Seed Germination at Tinigua National Park, Colombia

We examined the effect of seed ingestion by three ateline primates: woolly monkeys, Lagothrix lagothricha; spider monkeys, Ateles belzebuth; and, red howler, Alouatta seniculus on germination rates and latency periods of seeds of several plant species in Tinigua National Park, Colombia. We collected dispersed seeds from feces and control seeds from the parental trees and washed them for germination trials. For the majority of plants, dispersed seeds germinated as well or better than control seeds did. Although spider monkeys depend more heavily on fruits than the other monkey species do, they were not more efficient than howlers or woolly monkeys at improving germination rates. A considerable proportion of the seeds dispersed by howlers and woolly monkeys showed reduced latency periods to germination, but spider monkeys showed less effect on reducing germination time. This result may be related to longer gut retention times, but such a trend has not been observed in other primate species. We conclude that, like many other primates, ateline monkeys are effective seed dispersers in terms of their effects on the seeds they swallow because they rarely decrease their germination rates. We discuss problems that make interspecific comparisons difficult, such as inappropriate control seeds and differences associated with germination substrates, and we stress the importance of studying other components of seed dispersal effectiveness.     

Seed dispersal by the Florida box turtle (<Emphasis Type="Italic">Terrapene carolina bauri</Emphasis>) in pine rockland forests of the lower Florida Keys,United States

Seed dispersal by animals is one of the most important plant-animal mutualisms, but saurochory, the dispersal of seeds by reptiles, has received little attention. We investigated the role of the Florida box turtle (Terrapene carolina bauri) as a seed dispersal agent in pine rockland forests of the lower Florida Keys and examined the effect of turtle digestion on seed germination. We obtained seeds of 11 species with fleshy fruits and 2 species with non-fleshy fruits (a grass and legume) from the feces of 145 box turtles collected on Key Deer National Wildlife Refuge from 1999 to 2000. We planted the seeds of nine species and germination percentage (percentage of seeds that germinated during the experiment) varied from 10% to 80%. Comparative germination experiments were conducted with Thrinax morrissii, Serenoa repens, and Byrsonima lucida. We compared the germination percentage and germination rate (number of days from planting to seedling emergence) of seeds from three treatments (seeds recovered from feces, control seeds with pulp, and control seeds without pulp) and continued these experiments for up to 2 years. Passage through the box turtle digestive tract greatly enhanced the germination percentage and germination rate of S. repens, but decreased the germination percentage of B. lucida and T. morrissii, and decreased germination rate for T. morrissii. Subsequent destructive seed viability tests revealed that many ungerminated T. morrissii seeds remained viable, suggesting long-term seed dormancy may occur, even after passage through the turtle digestive system. In addition, the proportion of ungerminated seeds which remained viable was greater for seeds recovered from turtle feces than from control seeds with pulp. Furthermore, removal of fleshy pulp either manually or by the turtle digestive system may allow T. morrissii to escape insect predation.     

Seed dispersal and predation by Yakushima macaques, Macaca fuscata yakui, in a warm temperate forest of Yakushima Island, southern Japan

The relationships between fruit morphology and the foraging behavior of the Yakushima macaque, Macaca fuscata yakui were studied during a 9-month field study and series of laboratory experiments on Yakushima Island, southern Japan. These relationships may affect seed germination traits through seed dispersal. The macaques foraging behavior was observed in order to obtain data concerning the treatment of pulp and seeds. Seeds in feces and spat seeds were collected and analyzed. A linear discriminant analysis of the data led to the following results: (i) an increase in the relative flesh volume of a fruit was one of the potential factors which increased the probability of seed dispersal by the macaques; and (ii) seed size was an important parameter in relation to the type of seed dispersal (by defecation or spitting out). The germination test was conducted in a laboratory, then the germination rates and delays of dispersed seeds were compared with those of seeds collected directly from trees. The germination of dispersed seeds of Ficus thunbergii, Eurya japonica, and Vaccinium bracteatum, was significantly enhanced by passage through the macaques gut. The enhanced germination behavior was not seen in larger seeds, such as those of Psychotria serpens, Myrsine seguinii, Diospyros morrisiana, and Neolitsea sericea. The germination enhancement in small-seeded plants could be due to a sorting effect from the passage through the gut, which selects seeds with a narrower range of germination traits.     

Endomelanconiopsis microspora发酵产物乙酸乙酯提取物对人参核盘菌的抑制机理

【背景】人参菌核病是人参的主要病害之一,严重影响人参的产量。【目的】探索白花蒲公英内生菌(Endomelanconiopsis microspora)发酵产物乙酸乙酯提取物对人参核盘菌的抑制机理。【方法】采用人参核盘菌菌丝生长和孢子萌发试验测定抑制效果;采用显微镜观察菌丝形态变化,通过电导率和核酸含量的变化测定细胞膜通透性,通过丙二醛(malondialdehyde,MDA)含量和超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(peroxidase,POD)和过氧化氢酶(catalase,CAT)活力的变化测定膜脂过氧化程度。【结果】内生菌E. microspora发酵产物乙酸乙酯提取物能显著抑制人参核盘菌菌丝生长,最小抑菌浓度为3.75 mg/mL,培养6 d后抑制率为76.22%。该提取物能显著抑制人参核盘菌孢子萌发,15.00 mg/mL时抑制效果最好,抑制率达90.69%。提取物影响菌丝形态,增加人参核盘菌细胞膜通透性,造成菌丝内含物外渗,7.50 mg/mL处理10 h后电导率和核酸含量分别比对照组增加30.11%和62.85%。同时提取物显著增加人参核盘菌MDA含量和SOD、POD、CAT活力,7.50 mg/mL处理组呈现先上升后下降的变化趋势,并在12 h时达到最高值。【结论】内生菌E. microspora发酵产物乙酸乙酯提取物通过改变人参核盘菌细胞膜通透性,加剧膜脂过氧化,破坏细胞膜完整性,导致细胞内含物流失,显著抑制孢子萌发和菌丝生长。     

Amino acids,polyamines and proteins during seed germination of two species of Dipterocarpaceae

Summary Amino acid, polyamine and protein concentrations in seeds and their evolution during seed germination of two dipterocarp species, Hopea odorata and Dipterocarpus alatus, were determined with the help of a multianalytical system. Glutamic acid and glutamine were the major amino compounds present. Hopea seeds also contain high levels of aspartic acid/asparagine, serine, threonine, arginine and alanine, while those of Dipterocarpus contain high levels of alanine, arginine and threonine. These species were quite different in their germination behavior and thus in their protein and amine metabolism rates. In Hopea, polyamines increased during the first 3 days of germination and reached a maximum by the 3rd day, 1 day before maximum germination rate. In Dipterocarpus polyamines reached their maximum at the 6th day while maximum germination rate is observed by the 7th day. This suggests that polyamine compounds could play a role in the early part of the germination process in Hopea and Dipterocarpus seeds. The possibility that control of polyamine biosynthesis could be used for the establishment of biochemical methods to improve seed storage and to control germination of these recalcitrant seeds is discussed.     

Nitrate and nitrate reductase in Erythrina caffra seeds: Enhancement of induction by anoxia and possible role in germination

The nitrate level in seed embryonic axes of Erythrina caffra Thunb. which is capable of anaerobic germination, was about 2.5 times higher than in seed axes of Pisum sativum L. a species incapable of anaerobic germination. Nitrate levels in E. caffra seeds decreased during germination and this was not due to leaching. Both NADH- and NADPH-dependent nitrate reductase (NAR) activities increased during germination. The increase was prevented by cycloheximide. The activity of NADH-NAR (EC 1.6.6.1) was higher than that of NADPH-NAR (EC 1.6.6.3). Both NAR activities were higher in anoxia than in air during germination. The NAR activities in Pisum seeds were very much lower than in Erythrina seeds. Anoxia (N₂ or argon) enhanced the induction of NAR by KNO₃ in germinated E. caffra axes. The NADH- and NADPH-NAR activities were induced to equally high levels by KNO₃ under anoxia. The enhancement was depressed by cycloheximide. It is concluded that nitrate and NAR activity may play a role in the anaerobic germination of E. caffra seeds.Abbreviation NAR nitrate reductase Financial support was obtained from the University of the Orange Free State and the Foundation for Research Development     

Effect of Temperatures on Dormancy and Germination in Three Species in the Lamiaceae Occurring in Northern Wetlands

In the temperate region temperature is the main factor influencing the germination period of plant species. The purpose of this study was to examine effects of constant and fluctuating temperatures on dormancy and germination under laboratory and field conditions in the three wetland species Lycopus europaeus, Mentha aquatica and Stachys palustris. The results should give indications if the temperature-dependent regulation of dormancy and germination is phylogenetically constrained. Tests for germination requirements showed a minimum temperature for germination of 9 °C in Mentha and 12 °C in Lycopus and Stachys, and a maximum temperature of 33 °C for Lycopus and 36 °C for Mentha and Stachys. Fluctuating temperatures promoted germination in all three species but the amplitude required for high germination (>50%) differed: it was 8 °C in Mentha, 10 °C in Stachys and 14 °C in Lycopus (mean temperature 22 °C). The effect of temperatures on the level of dormancy was examined in the laboratory by imbibing seeds at temperatures between 3 °C and 18 °C for periods between 2 and 28 weeks, as well as by a 30-month burial period, followed by germination tests at various temperatures, in light and darkness. In the laboratory only low temperatures (≤12 °C) relieved primary dormancy in seeds of Lycopus, while in Mentha and Stachys also higher temperatures lead to an increase of germination. Dormancy was only induced in Lycopus seeds after prolonged imbibition at 12 °C in the laboratory. Buried seeds of all species exhibited annual dormancy cycles with lower germination in summer and higher germination from autumn to spring. Exhumed seeds, however, showed considerable differences in periods of germination success. Dormancy was relieved when ambient temperatures were below 12 °C. Ambient temperatures that caused an induction of dormancy varied depending on species and test condition, but even low temperatures (8 °C) were effective. At high test temperatures (25 °C) in light, exhumed seeds of all three species showed high germination throughout the year. The three species showed various differences in the effects of temperatures on dormancy and germination. Similarities in dormancy and germination found among the species are in common with other spring-germinating species occurring in wetlands, so it seems that the temperature dependent regulation of dormancy and germination are related to habitat and not to phylogenetic relatedness.     

Germination and seed water status of four grasses on moss-dominated biological soil crusts from arid lands

Biological soil crusts dominated by drought-tolerant mosses are commonly found through arid and semiarid steppe communities of the northern Great Basin of North America. We conducted growth chamber experiments to investigate the effects of these crusts on the germination of four grasses: Festuca idahoensis, Festuca ovina, Elymus wawawaiensis and Bromus tectorum. For each of these species, we recorded germination time courses on bare soil and two types of biological soil crusts; one composed predominantly of the tall moss Tortula ruralis and the other dominated by the short moss Bryum argenteum. On the short-moss crust, the final germination percentage was about half of that on bare soil. Also, the mean germination time was 4 days longer on short-mosses than on bare soil. In contrast to the short-moss crust, the tall-moss crust did not reduce the final germination percentage but increased the mean germination time. Similar results were observed in the four grasses studied. To investigate the mechanism by which moss crusts affected germination, we analyzed the water status of seeds on bare soil and moss crusts. Six days after seeding, the water content of seeds on bare soil was approximately twice that of seeds on tall- or short-moss crust. Analysis of the time course of changes in seed weight and water potential in Bromus tectorum revealed that overtime seeds on tall mosses reached higher water content than those on short mosses. The increase in the water content of seeds on tall mosses occurred as the seeds gradually fell through the moss canopy. Taken together, our results indicate that biological soil crusts with distinct structural characteristics can have different effects on seed germination. Furthermore, this study revealed that a biological soil crust dominated by short mosses had a negative effect on seed water status and significantly reduced seed germination.     

Gibberellins regulate seed germination in tomato by endosperm weakening: a study with gibberellin-deficient mutants

The germination of seeds of tomato [Lycopersicon esculentum (L.) Mill.] cv. Moneymaker has been compared with that of seeds of the gibberellin-deficient dwarf-mutant line ga-1, induced in the same genetic background. Germination of tomato seeds was absolutely dependent on the presence of either endogenous or exogenous gibberellins (GAs). Gibberellin A₄₊₇ was 1000-fold more active than commercial gibberellic acid in inducing germination of the ga-1 seeds. Red light, a preincubation at 2°C, and ethylene did not stimulate germination of ga-1 seeds in the absence of GA₄₊₇; however, fusicoccin did stimulate germination independently. Removal of the endosperm and testa layers opposite the radicle tip caused germination of ga-1 seeds in water. The seedlings and plants that develop from the detipped ga-1 seeds exhibited the extreme dwarfy phenotype that is normal to this genotype. Measurements of the mechanical resistance of the surrounding layers showed that the major action of GAs was directed to the weakening of the endosperm cells around the radicle tip. In wild-type seeds this weakening occurred in water before radicle protrusion. In ga-1 seeds a similar event was dependent on GA₄₊₇, while fusicoccin also had some activity. Simultaneous incubation of de-embryonated endosperms and isolated axes showed that wild-type embryos contain and endosperm-weakening factor that is absent in ga-1 axes and is probably a GA. Thus, an endogenous GA facilitates germination in tomato seeds by weakening the mechanical restraint of the endosperm cells to permit radicle protrusion.Abbreviations GA(s) gibberellin(s) - GA₃ gibberellic acid     

朱唇种子吸水特性及其在干旱胁迫下萌发特性

种子粘液质是植物在长期适应环境过程中形成的,该物质对于种子的扩散、定居、生存力的改善、萌发、幼苗生存乃至抵御有毒化学物质毒害等都具有重要的生态学意义。朱唇为唇形科鼠尾草属多年生草本植物,原产美洲热带地区,现已广泛栽植于世界各地。为了理解朱唇种子表面的粘液物质吸水特性和种子在干旱胁迫下的萌发特性,该研究以朱唇种子为材料,运用光学显微镜和扫描电子显微镜观察以及种子萌发试验的方法,对种子和粘液层的形态结构、粘液质对种子萌发的影响进行了研究。结果表明:朱唇种子为卵形,表面为负网状结构,千粒重为(1.611±0.0084)g,无粘液种子吸水倍数为3,粘液种子吸水倍数为25,粘液层吸水倍数为122。粘液和无粘液种子及粘液层的重量都随吸水时间的延长而增长,但脱水过程要远长于吸水过程。朱唇种子吸水2 h达到饱和,经过36 h可干燥失水恢复原重。不同浓度PEG对朱唇种子的萌发均有影响,发芽势随PEG浓度升高而显著降低。朱唇种子在5%PEG胁迫下发芽率最高达(90.00±8.66)%,20%PEG胁迫下发芽率最低为(76.67±10.41)%,低浓度PEG对朱唇种子萌发有一定促进作用。这说明朱唇种子为速萌型种子,其粘液质在种子吸水过程中起到举足轻重的作用,能保证短时间内有充足的水分供其萌发。     

Multiple allelopathic activity of the crustose coralline algaLithophyllum yessoenseagainst settlement and germination of seaweed spores

A study was made to investigate possible formation by the crustose coralline algaLithophyllum yessoenseof multiple allelopathic-related substances against the settlement and germination of spores of various seaweeds. Seven different solvents (n-hexane, diethyl ether, acetone, ethyl acetate, acetonitrile, methanol, distilled water) and seawater were used to obtain crude extracts and secretory exudates from the coralline alga. The extracts and the algal conditioned seawater were tested for inhibitory activity against the settlement and germination of spores from 17 species representing 15 genera. Spore settlement of 14 species was inhibited over 90% by one or more extracts of the six organic solvents and conditioned seawater. The germination of spores from 13 species was inhibited by one or more extracts of all seven solvents and conditioned seawater. The species where spore settlement was not significantly affected showed strong inhibition of germination, andvice versa.     

Large African herbivores,bruchid beetles and their interactions with Acacia seeds

This study investigated the interactions of large African herbivores and bruchid seed beetles with Acacia seeds. The germination of bruchid-infested and uninfested seeds was compaed. The effects of pod consumption by large herbivores on bruchid infestation and seed germination was also assessed. Bruchid-infested seeds did germinate, and the germination of bruchid-infested and uninfested A. tortilis, A. nilotica and A. hebeclade seeds did not differ. Pod ingestion by large herbivores lowered the bruchid infestation of consumed and defaecated seeds compared to uningested seeds. Uninfested, ingested and voided A. tortilis seeds germinated seeds. Furthermore, infested A. tortilis seeds egested by giraffe, kudu and ostrich germinated better than infested, uningested seeds. Pod ingestion by large herbivores may reduce bruchid infestation, increase Acacia seed germination and therefore increase potential Acacia seedling recruitment.     

Salinity and Temperature Effects on Germination for Three Salt-resistant Euhalophytes, Halostachys caspica, Kalidium foliatum and Halocnemum strobilaceum

The effects of three salinities (0, 100 and 500 mM NaCl) and four constant temperatures (10, 20, 30 and 35 °C) on seed germination of Halostachys caspica (M. B.) C. A. Mey., Kalidium foliatum (Pall.) Mop. and Halocnemum strobilaceum (Pall.) Bieb. were investigated. After seeds were treated with different concentrations of NaCl at constant temperatures of 10–35 °C for 16 days, ungerminated seeds were transferred to distilled water for 10 days to investigate the total germination; after this time, the ungerminated seeds from the 10 and 20 °C treatments were then moved to 35 °C for another 5 days to determine the final germination. The three plant species in the present experiment are salt-resistant euhalophytes growing in high saline soils in the Zhungur Basin in Xinjiang, a northwest province of China.Compared with germination under control conditions, germination percentages of all three species were not affected by 100 mM NaCl at 10–35 °C, while severely inhibited by 500 mM NaCl; germination percentages were very low at 10 °C up to 100 mM NaCl for all species; the optimum temperature for germination of H. caspica and K. foliatum was 20–30 °C, while 35 °C for H. strobilaceum, up to 100 mM NaCl; seeds did not suffer ion toxicity for all species, as evidenced by the high total germination after ungerminated seeds pretreated with 500 mM NaCl were transferred to distilled water at constant temperatures of 10–35 °C for 10 days, and the high final germination after the ungerminated seeds from the 10 and 20 °C treatments were subsequently moved to 35 °C for another 5 days; Halostachys caspica had greater sensitivity to increasing temperatures from 10 and 20 °C to 35 °C compared with the other two species.     

Field response of mycorrhizal and nonmycorrhizal Medicago sativa var. local in the F1 generation

Seeds were collected from plants of Medicago sativa var. local inoculated with Glomus macrocarpum and G. fasciculatum separately in pot experiments. These seeds were sown in garden soil and the percentage germination, general health and yield of subsequent plants (the F1 generation) were studied. The percentage germination was highest in seeds of G. macrocarpum-inoculated parents followed by those inoculated with G. fasciculatum; seeds of uninoculated parent plants showed the lowest germination. Vegetative yield of the progeny decreased in the order of plants inoculated with G. fasciculatum, with G. macrocarpum, and uninoculated. On the other hand, reproductive yield was highest for plants whose parents were inoculated with G. macrocarpum, followed by G. fascicullatum, and lowest for seeds of uninoculated parent plants.     

Use of Ethylene-Producing Bacteria for Stimulation of Striga spp. Seed Germination

Striga spp. are obligate root-parasitic flowering plants that threaten cereal and legume production, and consequently human well-being, in Africa. Successful control depends on eliminating the seed reserves of Striga spp. in soil and preventing parasitism. A proven method of eliminating these seed reserves is soil-injection of ethylene gas. This method was used successfully in the United States to control Striga asiatica, but injection of ethylene gas is potentially dangerous, very costly, and generally unsuitable in Africa. The bacterium Pseudomonas syringae pathovar glycinea synthesizes relatively large amounts of ethylene. In this study a laboratory procedure was developed for testing strains of P. syringae pv. glycinea for efficacy in stimulating germination of seeds of Striga spp. The procedure allows comparisons among bacteria, volatile compounds, root exudates, and synthetic stimulants for germination of Striga spp. seeds. Seeds of three Striga spp. were tested over a 10-month period. No seed germination was ever observed with sterile water. When compared across Striga spp. the bacterial strains were consistently better stimulators of germination of seeds of the parasites than ethylene gas or root pieces of a Vigna unguiculata cultivar known to stimulate germination of parasite seeds. The strains were as effective in germinating S. aspera and S. gesnerioides seeds as a synthetic germination stimulant. Our results showing that ethylene-producing bacteria are highly effective in promoting seed germination in Striga spp. suggest that these bacteria may provide a practical means of biological control of Striga spp. in Africa and other locations.     

豚草和三裂叶豚草不同植株部位种子萌发与入侵扩散关系

豚草(Ambrosia artemisiifoliaLinn.)和三裂叶豚草(A. trifidaLinn.)是我国恶性入侵物种,分布常呈高密度单一种群,且结实量庞大。探讨二者不同植株部位种子萌发(休眠)与扩散特点,对了解二者入侵机制具有重要意义。以新疆伊犁新源县发生的豚草和三裂叶豚草为材料,在种子成熟期,根据植株高度、枝条长度,按比例从上到下分为9个部位,对不同植株部位种子的形态特征、数量和萌发特性进行比较,分析这两种植物不同植株部位种子萌发与扩散的共性和差异性,研究二者种群密度调节和入侵的关系。结果表明:1)两个物种内不同植株部位间种子的长、宽、百粒重无显著差异,但三裂叶豚草种子的长度和宽度分别是豚草的2—3倍,百粒重高7倍。结合两个物种在伊犁地区分布差异,认为种子大小是两个物种分布区域性差异的原因之一。2)豚草和三裂叶豚草植株外部的上顶、中顶、上中部位种子数占植株总种子数量的50%,中中、下顶占比约23%,而下部的上基、中基、下中、下基的种子数占比约27%,表明当年生产的种子有近73%的比例具有远距离扩散的潜力。3)豚草和三裂叶豚草不同植株部位种子的萌发率具有上端中端下端的趋势;初始萌发时间为下端中端上端;萌发持续时间为上端中端下端。这种萌发方式避免了同一生长季大批种子同时萌发有可能导致高密度死亡的风险。基于上述研究分析,认为豚草和三裂叶豚草不同植株部位种子具有不同的适应功能。其中,上部所产生的种子具较强的扩散能力和低休眠性,有利于两物种快速占据新生境并扩大种群;而中、下部位的种子在母株周围就近扩散,翌年萌发率低,缓解了种群竞争。豚草和三裂叶豚草不同植株部位生产的种子特性和萌发差异是两个物种进行种群密度调节和扩散入侵的重要原因。     

Imbibition phases and germination response of Mimosa bimucronata (Fabaceae: Mimosoideae) to water submersion

Mimosa bimucronata is a pioneering tree that occurs predominantly in moist lowlands, floodplains and on margins of rivers and lakes in Latin America. The effect of submergence on seed germination in M. bimucronata was firstly studied. Patterns of water absorption by M. bimucronata seeds were investigated thereafter to assess the imbibition phases of scarified and unscarified seeds. The germination percentage was significantly higher in scarified than in unscarified seeds, and the velocity of seed germination also increased considerably in scarified seeds. Submergence duration did not significantly affect germination percentages of scarified and unscarified seeds. Therefore, seed viability after submersion suggests that M. bimucronata may display hydrochorous dispersal and also that seeds are able to germinate successfully in areas with frequent seasonal flooding. With respect to imbibition phases, phase II was very short or even absent for scarified and unscarified seeds; therefore, a plateau, where water absorption by seeds is established, was not observed. Finally, we verified that the passage from phase I to III was very tenuous and took a long time in seeds without scarification.     

模拟水分胁迫对不同种源麻楝种子萌发能力的影响

以麻楝6个种源种子为试验材料,用不同浓度的聚乙二醇(PEG)溶液模拟干旱胁迫,探讨干旱胁迫对种子发芽率、发芽势、发芽指数、活力指数以及幼苗苗高和胚根长及根苗比的影响,为麻楝的引种和推广种植提供依据。结果显示:(1)不同水势胁迫处理均降低了麻楝种子的发芽率和发芽势,当水势为-0.40MPa时延缓了种子萌发进程;种子的发芽率、发芽势、发芽指数和活力指数均随干旱胁迫强度的增加呈明显下降的趋势;当胁迫水势为-0.86MPa时,干旱胁迫处理的种子在试验结束时仍未能萌发,即-0.86MPa是麻楝种子萌发的临界水势。(2)当胁迫水势高于-0.40MPa时,麻楝幼苗的胚根长度与对照组差异不显著且长于对照组,说明高于-0.40MPa的水势有利于麻楝种子胚根的生长;麻楝幼苗苗高生长则是随着PEG浓度的升高而逐渐减缓。(3)适当的干旱胁迫可以增大各种源麻楝幼苗根苗比,且在胁迫水势高于-0.20MPa时都达到最大值。研究表明,麻楝种子具有一定的抗干旱胁迫的萌发能力,并以来自缅甸的Khin Aye Pale和泰国的Phu Wiang材料较强,来源于中国三亚和马来西亚Ulu Tranan的较弱。     

The effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of Suaeda salsa under saline conditions

Suaeda salsa, a leaf succulent shrub in the family Chenopodiaceae, is one of the most important halophytes in China. Suaeda salsa produces dimorphic seeds (soft brown seeds and hard black seeds). Seeds of S. salsa were collected from the coastal salt flats near Huanghua City, China. Experiments were conducted to determine the salinity-alleviating effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of S. salsa. Brown seeds had a higher germination rate than black seeds in all experiments. Black seeds were more sensitive to salt in the absence of light in comparison to brown seeds. Brown seeds absorbed water more quickly in comparison to black seeds and were found to be more tolerant of salt stress. Our results showed that 1-aminocyclopropane-1-carboxylate (ACC, the immediate precursor of ethylene), nitrite, GA₄ and BA improved seed germination in the presence of salt. However, nitrate, GA₁, GA₃ failed to alleviate salt stress. ABA inhibited seed germination and seedling growth. Possible mechanisms involved in the alleviation of salt stress in S. salsa seeds and the ecological adaptation of the seeds to the environment are discussed.