Artemisia ordosica Krasch. is a dominant shrub occurring mainly on stable sand dunes in the Gobi Desert of China, in the Mongolian phytogeographic region. Achenes of A. ordosica germinate in light but poorly in ...Artemisia ordosica Krasch. is a dominant shrub occurring mainly on stable sand dunes in the Gobi Desert of China, in the Mongolian phytogeographic region. Achenes of A. ordosica germinate in light but poorly in dark and light is the limiting factor regulating the achene germination in sand depth. Achenes germinate in spring or autumn with an optimal temperature of 20 ℃. Achene mucilage can absorb large amounts of water and has important ecological function. Salt concentrations and sand moisture may regulate achene germination in sand. A. ordosica, A. sphaerocephala Krasch. and A. monosperma Delile. from different climates have similar responses to light, the underground location of achene, and sand moisture. Percentage of seedling emergence from different levels of sand depth is depends on the specific, temperature and intensity of light penetrating through the sand depths, as well as on sand moisture. The desert sand habitat seems to have had a dominant influence on the evolution of the germination strategies of these 3 Artemisia species.展开更多
Aim Mirabilis himalaica(Nyctaginaceae)is an endangered medicinal plant mainly distributed in the plateau region of northern Tibet,China.The outer surface of M.himalaica achenes is covered by a pectinaceous mucilaginou...Aim Mirabilis himalaica(Nyctaginaceae)is an endangered medicinal plant mainly distributed in the plateau region of northern Tibet,China.The outer surface of M.himalaica achenes is covered by a pectinaceous mucilaginous layer upon hydration.However,the role of the achene mucilage is poorly understood.in this study,we inves-tigated the effects of mucilage on achene germination and sprout growth under abiotic stress to explain how M.himalaica survive the alpine environment.Methods We investigated the effect of mucilage on achenes germination by contrast the capacity of water absorption,dehydration and respira-tion of intact achene and the achene with mucilage removal.We performed abiotic stresses experiments including drought stress,salt stress,cold stress and high temperature stress,and quantified the effects of mucilage removal on achene germination rate,root and shoot lengths of seedlings.Important Findings Mucilage is extremely hydrophilic,and the mass of intact achenes can be 9-fold greater than that of demucilaged achenes.The removal of the mucilaginous layer did not significantly change final germination percentages under ideal conditions,but intact achenes(i.e.with muci-lage)took longer to germinate.The mucilage significantly decreased seed respiration rates by acting as a physical barrier that prevented oxygen diffusion.Germination rates,shoot and root growth of intact achenes were higher than those of demucilaged ones during exposures to cold,heat,osmotic and salt stresses.Achene mucilage presumably plays an ecologically important role in the life cycle of M.himalaica by aiding the critical achene germination and early seedling growth in the stressful habitats of the plateau region of northern Tibet.展开更多
为明确欧洲葵螟Homoeosoma nebulellum Denis et Schiffermüller寄主选择的物理机制,通过对14个向日葵品种(系)筒状小花及瘦果的形态指标观察,采用籽粒被害虫情指数进行田间寄主选择性试验,研究了向日葵的形态性状和欧洲葵螟寄主...为明确欧洲葵螟Homoeosoma nebulellum Denis et Schiffermüller寄主选择的物理机制,通过对14个向日葵品种(系)筒状小花及瘦果的形态指标观察,采用籽粒被害虫情指数进行田间寄主选择性试验,研究了向日葵的形态性状和欧洲葵螟寄主选择的关系。欧洲葵螟对不同向日葵品种(系)具有明显的选择性,且对食葵品种(系)的选择性均显著高于油葵品种(系)。食葵瘦果多为中长或长形(≥1.5cm),油葵瘦果则属于短或特短形(<1.5 cm)。向日葵各形态指标在不同品种(系)间均存在极显著差异,食葵的花盘直径、筒状小花开口、子房壁厚度、瘦果果壁厚度、瘦果果壁茸毛密度均大于油葵,且各指标与籽粒被害虫情指数之间、各指标互相之间也均呈显著正相关关系。表明选育较小花盘的向日葵品种(系)可减少葵螟对向日葵的为害。展开更多
The achene wail anatomy and surface sculpturing of 14 species representing Lactuca L. and related genera were Investigated to evaluate inter-and Intrageneric relationships. The achene wall anatomy of the studied speci...The achene wail anatomy and surface sculpturing of 14 species representing Lactuca L. and related genera were Investigated to evaluate inter-and Intrageneric relationships. The achene wall anatomy of the studied species can be divided Into two types： winged and ribbed. The winged type is present in Lactuca L., Pterocypsela Shlh, Clcerblta Wallr., Chaetoserls Shlh and Stenoseris Shlh, and is characterized by protruding wings and costae in transverse section. Winged type achene mesocarps are composed of parenchymatous cells and fiber ceils, and the distinct fibrous strands are confined to the costae or wings of the achenes. The ribbed type is present in Notoseris Shih and Paraprenanthes Chang ex Shih, and Is characterized by only having costae In transverse section. Fiber cells are continuous in the costae and intercostae, in surface sculpturing, the ornamentation and the shape of epidermal cells are different among these genera. The results Indicate that L. altalca and L. serrlola should be conspeclfic, and that L. dollchophylla is probably an Intermediate taxon between Lactuca and Chaetoserls. The results also support the separation of Pterocypseia, Paraprenanthes, Notoseris, Chaetoseris and Stenoserls from Lactuca and Clcerblta as independent entitles. Close affinities between Pterocypsela and Lactuca, Paraprenanthes and Notoserls, and Chaetoserls and Stenoserls are also proposed.展开更多
文摘Artemisia ordosica Krasch. is a dominant shrub occurring mainly on stable sand dunes in the Gobi Desert of China, in the Mongolian phytogeographic region. Achenes of A. ordosica germinate in light but poorly in dark and light is the limiting factor regulating the achene germination in sand depth. Achenes germinate in spring or autumn with an optimal temperature of 20 ℃. Achene mucilage can absorb large amounts of water and has important ecological function. Salt concentrations and sand moisture may regulate achene germination in sand. A. ordosica, A. sphaerocephala Krasch. and A. monosperma Delile. from different climates have similar responses to light, the underground location of achene, and sand moisture. Percentage of seedling emergence from different levels of sand depth is depends on the specific, temperature and intensity of light penetrating through the sand depths, as well as on sand moisture. The desert sand habitat seems to have had a dominant influence on the evolution of the germination strategies of these 3 Artemisia species.
基金This work was financially supported by the National Science Technology Support Program(2011BAI13B06)the National Natural Science Foundation of China(31270737)+1 种基金Beijing Municipal Natural Science Foundation(KZ20150020021,6112016)111 Project(B13007)and Program for Changjiang Scholars and Innovative Research Team in University(IRT13047).
文摘Aim Mirabilis himalaica(Nyctaginaceae)is an endangered medicinal plant mainly distributed in the plateau region of northern Tibet,China.The outer surface of M.himalaica achenes is covered by a pectinaceous mucilaginous layer upon hydration.However,the role of the achene mucilage is poorly understood.in this study,we inves-tigated the effects of mucilage on achene germination and sprout growth under abiotic stress to explain how M.himalaica survive the alpine environment.Methods We investigated the effect of mucilage on achenes germination by contrast the capacity of water absorption,dehydration and respira-tion of intact achene and the achene with mucilage removal.We performed abiotic stresses experiments including drought stress,salt stress,cold stress and high temperature stress,and quantified the effects of mucilage removal on achene germination rate,root and shoot lengths of seedlings.Important Findings Mucilage is extremely hydrophilic,and the mass of intact achenes can be 9-fold greater than that of demucilaged achenes.The removal of the mucilaginous layer did not significantly change final germination percentages under ideal conditions,but intact achenes(i.e.with muci-lage)took longer to germinate.The mucilage significantly decreased seed respiration rates by acting as a physical barrier that prevented oxygen diffusion.Germination rates,shoot and root growth of intact achenes were higher than those of demucilaged ones during exposures to cold,heat,osmotic and salt stresses.Achene mucilage presumably plays an ecologically important role in the life cycle of M.himalaica by aiding the critical achene germination and early seedling growth in the stressful habitats of the plateau region of northern Tibet.
文摘The achene wail anatomy and surface sculpturing of 14 species representing Lactuca L. and related genera were Investigated to evaluate inter-and Intrageneric relationships. The achene wall anatomy of the studied species can be divided Into two types： winged and ribbed. The winged type is present in Lactuca L., Pterocypsela Shlh, Clcerblta Wallr., Chaetoserls Shlh and Stenoseris Shlh, and is characterized by protruding wings and costae in transverse section. Winged type achene mesocarps are composed of parenchymatous cells and fiber ceils, and the distinct fibrous strands are confined to the costae or wings of the achenes. The ribbed type is present in Notoseris Shih and Paraprenanthes Chang ex Shih, and Is characterized by only having costae In transverse section. Fiber cells are continuous in the costae and intercostae, in surface sculpturing, the ornamentation and the shape of epidermal cells are different among these genera. The results Indicate that L. altalca and L. serrlola should be conspeclfic, and that L. dollchophylla is probably an Intermediate taxon between Lactuca and Chaetoserls. The results also support the separation of Pterocypseia, Paraprenanthes, Notoseris, Chaetoseris and Stenoserls from Lactuca and Clcerblta as independent entitles. Close affinities between Pterocypsela and Lactuca, Paraprenanthes and Notoserls, and Chaetoserls and Stenoserls are also proposed.
