Search

The role of seed mucilage in the moist environments of monsoonal subtropics is poorly understood. We studied germination of six forb species from subtropical monsoonal China. Mucilage presence had little to no effect on germination percentage (G%), except for a significant decline for the large-seeded Prunella vulgaris. Dark treatments reduced G% for all species, while the combination of mucilage removal and high temperatures delayed the mean germination time (MGT). Seed fresh mass was negatively correlated with G%, but only for intact seeds incubated at 12/12 hours of 25/35 [degrees]C. The MGT of de-mucilaged seeds varied with seed shape index, also under the warmer temperature regime. Temperature and light are fundamental to drive germination processes, and the presence of mucilage influences MGT of subtropical monsoonal species. Presence or absence of mucilage had little to no difference in germination percentage, but can be important to drive germination timing, also promoting water uptake and seed adhesion to soil. Key words: mucilage, germination, photoperiod, seed traits, temperature, forbs Le role du mucilage des graines dans les environnements humides des regions subtropicales de mousson est mal compris. Les auteurs ont etudie la germination de six especes d'herbes non gramineennes de la Chine subtropicale de mousson. La presence de mucilage n'avait que peu ou pas d'effet sur le pourcentage de germination (G%), a l'exception d'une baisse significative chez Prunella vulgaris a grosses graines. Les traitements a l'obscurite reduisaient le G% chez toutes les especes, tandis que la combinaison de l'elimination du mucilage et des temperatures elevees retardait le temps moyen de germination (TMG). La masse fraiche des graines etait negativement correlee avec le G%, mais seulement chez les graines intactes incubees 12/12 heures a 25/35 [degrees]C. Le TMG des graines demucilaginees variait en fonction de l'indice de forme des graines, egalement sous un regime de temperatures plus chaudes. La temperature et la lumiere sont fondamentales pour mener les processus de germination, et la presence de mucilage influence le TMG des especes subtropicales de mousson. Il n'y avait que peu ou pas de differences dans le pourcentage de germination en fonction de la presence ou de l'absence de mucilage, mais celui-ci peut etre important pour determiner le moment de la germination, favorisant egalement l'absorption d'eau et l'adhesion des graines au sol. [Traduit par la Redaction] Mots-cles : mucilage, germination, photoperiode, caracteristiques des graines, temperature, herbes non gramineennes, Introduction The production of mucilage on a seed/fruit dispersal unit during hydration (myxodiaspory) can serve one of several functions. It may protect the seed from predators and pathogens (Kreitschitz 2012; [...]

As habitats change, species with higher intraspecific variation have more resources to adapt. Medicinal plants in the Himalayas are increasingly threatened by climate change and other anthropogenic influences. The intraspecific variation within and among 17 populations of the high-elevation herb Trillium govanianum Wall. ex D.Don was studied as an indicator of adaptability. The variation in 19 traits of population structure, morphology, and phytochemistry was assessed across habitats that varied in elevation (2452-3432 m a.s.1.), aspect, latitude (30.1-31.7[degrees]N), and arboreal community. The morphology and population structure were conserved among populations but varied among regions. The populations in the lower elevation mixed forests of Tirthan Valley produced smaller rhizomes but larger plant densities, such that plant biomass per square metre was conserved. The phytochemistry varied among regions and populations within regions, indicating significant variation among habitats. The aboveground morphology of the species masks considerable variations in belowground morphology and phytochemistry. The observed variations can help the species to adapt to the changing environmental conditions by provoking a functional response. Key words: adaptation, anthropogenic pressure, conservation, high-elevation medicinal plant, natural variations. Lorsque les habitats changent, les especes qui presentent une plus grande variation intraspecifique ont davantage de ressources pour s'adapter. Les plantes medicinales de l'Himalaya sont de plus en plus menacees par les changements climatiques et d'autres influences anthropiques. La variation intraspecifique au sein et entre 17 populations de Trillium govanianum Wall. ex D.Don, une herbe de haute altitude, a ete etudiee comme indicateur de l'adaptabilite. La variation de 19 traits de la structure de la population, de la morphologie et de la phytochimie a ete evaluee dans des habitats qui varient en matiere d'altitude (2452-3432 m a.s.1.), d'aspect, de latitude (30, 1 a 31, 7[degrees]N) et de peuplement frodicole. La morphologie et la structure de la population etaient conservees parmi les populations, mais elles variaient selon les regions. Les populations des forets mixtes de basse altitude de la vallee de Tirthan produisaient des rhizomes plus petits, mais des densites de plantes plus importantes, de sorte que la biomasse vegetale par [m.sup.2] etait conservee. La phytochimie variait entre les regions et les populations au sein des regions, indiquant une variation significative entre les habitats. La morphologie aerienne de l'espece masque des variations considerables dans la morphologie souterraine et la phytochimie. Les variations observees peuvent aider les especes a s'adapter aux conditions environnementales changeantes en provoquant une reponse fonctionnelle. [Traduit par la Redaction] Mots-cles : adaptation, pression anthropique, conservation, plante medicinale de haute altitude, variations naturelles., Introduction The rate at which species adapt to new or changing environments is dependent on their phenotypic plasticity and genetic variation (Fox et al. 2019). Species with a more flexible [...]

Understanding variation of seed germination in wild populations can assist restoration projects through improved seed source selection. Recruitment of artificially distributed seed can be improved by selecting for suitable dormancy and germination characteristics. We investigated seed germination and emergence responses of three Astragalus sieberi DC. (Fabaceae) populations (Abdali, Liya, and Salmi) to in situ storage for five months at depths of 0 and 5 cm, pre-sowing hydration for 12 and 24 hours, and chemical scarification with concentrated sulfuric acid for 5, 10, and 15 min. The germination percentage was low for freshly collected seed ( Key words: arid desert, dormancy, scarification, seedling survival, legumes. La comprehension de la variation de la germination des semences dans les populations sauvages peut aider les projets de restauration grace a une meilleure selection des sources de semences. Le recrutement de semences distribuees artificiellement peut etre ameliore en selectionnant des caracteristiques de dormance et de germination appropriees. Les auteurs ont etudie la germination et la levee des semences de trois populations d' Astragalus sieberi DC. (Fabaceae) (Abdali, Liya, et Salmi) a un stockage in situ de cinq mois a des profondeurs de 0 et 5 cm, a une hydratation de 12 et 24 heures avant ensemencement et a une scarification chimique avec de l'acide sulfurique concentre de 5,10, et 15 min. Le pourcentage de germination etait faible pour les graines fraichement recoltees ( Mots-cles : desert aride, dormance, scarification, survie des semis, legumineuses., Introduction Restoration of native vegetation in arid regions is challenging due to high temperatures, low and erratic rainfall, high soil salinity, and low nutrient availability (Yasseen 2011; Podda et al. [...]

Regeneration of native species is the first priority for biodiversity conservation and restoration. To this end, it is key to have seeds properly conserved in seed banks and knowledge of seed longevity and (or) dormancy alleviation at different storage time intervals. In addition, understanding the germination response of the stored seeds to environmental conditions improves the efficiency of restoration and rehabilitation projects. We investigated the influence of storage duration (1-5 years), light (0 or 12 h of illumination), thermoperiod (night/day temperatures of 15/20 and 20/25 [degrees]C), and salinity (0, 100, 200. and 400 mmol/L of NaCl) on seed germination of Rhanterium epapposum, a glycophytic species from the Arabian Peninsula. Seeds maintained viability after five years of storage indoors at room temperature. Three years of storage alleviated seed dormancy. Exposure to 12 h light per day and thermoperiods of 15/20 [degrees]C enhanced seed germination. The seeds were glycophytic; after-ripened seeds exposed to salinity exhibited reduced rates of germination that did not recover after the salinity was alleviated. Key words: after-ripening, desert, glycophyte, restoration. La regeneration des especes indigenes est une priorite pour la conservation et la restauration de la biodiversite. A cette fin, il est essentiel de disposer de semences correctement conservees dans des banques de semences et de connaitre la longevite et (ou) l'attenuation de la dormance des semences a differents intervalles de temps de stockage. En outre, la comprehension de la germination des semences stockees aux conditions environnementales ameliore l'efficacite des projets de restauration et de rehabilitation. Les auteurs ont etudie l'influence de la duree de stockage (1 a 5 ans), de la lumiere (0 ou 12 h de lumiere), de la thermoperiode (temperatures nuit/jour de 15/20 et 20/25 [degrees]C) et de la salinite (0, 100, 200 et 400 mmol/L de NaCl) sur la germination des semences de Rhanterium epapposum, une espece glycophytique de la peninsule arabique. Les graines conservaient leur viabilite apres cinq ans de stockage a l'interieur, a temperature ambiante. Trois annees de stockage permettaient de reduire la dormance des semences. L'exposition a 12 heures de lumiere par jour et a des thermoperiodes de 15/20 [degrees]C favorisait la germination des semences. Les graines etaient glycophytiques ; les graines post-maturees exposees a la salinite presentaient une germination reduite qui ne se retablissait pas apres la diminution de la salinite. [Traduit par la Redaction] Mots-cles : post-maturation, desert, glycophyte, restauration., Introduction The Arabian desert is one of the most inhospitable ecosystems in the world. Climate change is predicted to exacerbate temperature extremes and reduce the already low rainfall (Ribot et [...]

Knowledge of optimal conditions for germination facilitates more efficient practices, such as fodder production and restoration. We assessed seeds of three grass species harvested in winter and summer 2018. Germination ability was assessed under two night/day temperature regimes (15 [degrees]C/20 [degrees]C, 20 [degrees]C/30 [degrees]C) and two photoperiod regimes (0, 12 h light per day). Winter-maturing seeds had a slightly lower mass and reduced germination. Temperature and light requirements for optimal germination were dependent on species and harvest-time. Summer-maturing seeds of all three species had higher germination rates regardless of germination temperature. Interactions among treatment temperatures and species were 0.7- to 5.4-times higher than the control, as shown by heatmaps. Therefore, attention to these factors will improve the efficiency of seedling establishment for rehabilitation work. Key words: germination speed, grasses, halophyte, mean germination time, synchrony. La connaissance des conditions optimales de germination facilite la mise en oeuvre de pratiques plus efficaces telles que la production et la restauration des fourrages. Les auteurs ont evalue les semences de trois especes de graminees, recoltees a l'hiver et a l'ete 2018. La capacite de germination a ete evaluee sous deux regimes de temperature (15 [degrees]C/20 [degrees]C et 20 [degrees]C/30 [degrees]C) et deux regimes de photoperiode (0 et 12 heures de lumiere par jour). Les graines arrivant a maturite a l'hiver avaient une masse legerement plus faible et une germination reduite. Les exigences de temperature et de lumiere pour une germination optimale etaient dependantes de l'espece et de la periode de recolte. Les graines des trois especes arrivant a maturite a l'ete avaient des taux de germination plus eleves, quelle que soit la temperature de germination. Les interactions entre les temperatures de traitement et les especes etaient de 0,7 a 5,4 fois superieures a celles du temoin, comme le montrent les cartes thermiques. Ainsi, l'attention portee a ces facteurs permettra d'ameliorer l'efficacite d'etablissement des semis pour des travaux de rehabilitation. [Traduit par la Redaction] Mots-cles: vitesse de germination, graminees, halophyte, temps de germination moyen, synchronie., Introduction Successful reproduction is essential for a plant species population to persist. Germination is under strong genetic control and environmental influence (Chiang et al. 2009; Kendall and Penfield 2012; Huang [...]

In this study, salt tolerance during germination of Aeluropus lagopoides (L.) Trin. was tested using fresh seeds collected from three different maternal habitats under three thermoperiods and two light regimes. Additionally, we tested the ability of non-germinated seeds that had been exposed to different concentrations of NaCl to recover their germination in distilled water. The results showed a significant effect of seed source, temperature, and salinity, and some of their two- and three-way interactions on final germination and recovery percentage. The seeds from non-saline provenances had the highest percentages for germination (ca. 79%) under the 35/25 [degrees]C temperature regime, whereas the lowest percentages for germination (ca. 21%) was recorded for seeds from saline conditions under the 25/15 [degrees]C treatment. Additionally, percent germination was significantly lower for the seeds incubated in the saline solutions (100, 200, 400, and 600 mmol/L NaCl) and germinated under colder conditions (15/25 [degrees]C), compared with the seeds incubated in non-saline solutions (control group, 0 mmol/L NaCl) and germinated under warmer conditions (35/25 [degrees]C). The highest recovery percentage was recorded for seeds of the hyper-saline habitat incubated at 35/25 [degrees]C. Thus, seeds maintained their viability despite experiencing a range of saline conditions and were able to germinate upon the arrival of suitable conditions, which can be an adaptation to its saline arid desert habitat. Key words: Aeluropus lagopoides, germination recovery, maternal habitat, photoperiod, salinity, thermoperiod. Resume : Dans cette etude, la tolerance au sel lors de la germination de Aeluropus lagopoides (L.) Trin. a ete testee sur des semences fraiches recoltees de trois habitats maternels differents, selon trois thermoperiodes et deux regimes de luminosite. De plus, la capacite de semences non germees de recuperer leur potentiel de germination dans l'eau distillee apres avoir ete soumises a differentes concentrations de NaCl a ete testee. Les resultats ont montre un effet significatif de la source des semences, de la temperature et de la salinite prises separement, deux a deux ou toutes les trois, sur la germination et le pourcentage de recuperation. Les semences provenant d'habitats non salins presentaient la germination la plus elevee (environ 79 %) a un regime de temperature de 35/25 [degrees]C, alors que la germination la plus faible (environ 21 %) etait enregistree chez les semences en conditions salines a des temperatures de 25/15 [degrees]C. Par ailleurs, la germination etait significativement plus faible a partir d'une incubation dans une solution non saline - controle (0 mmol/L NaCl) a des temperatures plus chaudes (35/25 [degrees]C) vers une incubation dans des solutions salines (100, 200, 400 et 600 mmol/L NaCl) a des temperatures plus froides (15/25 [degrees]C). Le pourcentage de recuperation le plus eleve etait enregistre chez les semences provenant d'un habitat hypersalin incubees a 35/25 [degrees]C. Ainsi, les semences maintenaient leur viabilite malgre le fait d'etre exposees a un spectre de conditions salines et elles etaient capables de germer lors de l'arrivee de conditions adequates, ce qui peut constituer une adaptation a leur habitat aride salin desertique. [Traduit par la Redaction] Mots-cles : Aeluropus lagopoides, recuperation de la germination, habitat maternel, photoperiode, salinite, thermoperiode., Introduction Desert plants generally experience extreme aridity, large fluctuations of water availability, and a relatively short growing season (Omar and Bhat 2008). For several desert plant species, the availability of [...]