Fruit polymorphism in ephemeral species of Namaqualand: III. Germination differences between the polymorphic diaspores

Beneke, Karen; Rooyen, M.W. van; Theron, G.K.; Venter, H. A. van de

doi:10.1006/jare.1993.1029

Cited by 27 publications

(14 citation statements)

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“…In Asteraceae, absence of germination of some achene types can be due to the presence of either inhibitors in surrounding tissues (Beneke et al, 1993), thick pericarp (McEvoy, 1984;Tanowitz et al, 1987) or innate dormancy (Negbi and Tamari, 1963, as cited by Sun et al, 2009). The embryo germination test showed that embryos from fresh dark achenes reached significant germination percentages (57 -71%), although lower than those of embryos from fresh white achenes.…”

Section: Discussionmentioning

confidence: 99%

Morphology, anatomy and germination response of heteromorphic achenes ofAnthemis chrysanthaJ. Gay (Asteraceae), a critically endangered species

et al. 2011

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This study demonstrates that Anthemis chrysantha, a 'Critically Endangered' annual plant, produces two morphs of achenes: white and dark achenes, which differ in size, mass, anatomy and germination behaviour. Fresh white achenes germinated at all temperatures assayed from 10 to 258C in both continuous darkness and 12-h photoperiod, ranging between 24% at 258C in darkness and 89% at 12/208C in light, whereas fresh dark achenes did not germinate under any temperature or light conditions. To identify differences in dormancy type between the two morphs, germination of dry-stored achenes, and achenes stratified at 5 or 258C for 2 months were tested in both darkness and light at 5, 15 and 12/208C for drystored and warm-stratified (258C) achenes; and at 15, 25 and 12/208C for cold-stratified (58C) achenes. Of the white achenes, 90% germinated during the cold stratification period. In general, dry storage and warm stratification did not increase germination compared to fresh achenes. However, dark achenes did not germinate under any conditions. Dark achene dormancy was only broken by mechanical scarification or by excising the embryo (germination reached 71%). An anatomical study showed that the mesocarp of dark achenes had no intercellular spaces and was much thicker and stronger than that of white achenes, making the entry of water difficult, and also preventing germination by mechanical restriction. This study demonstrated that dormancy in the dark achenes is likely caused by the thickness of their pericarp, physically impeding germination and hampering imbibition of water.

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Section: Discussionmentioning

confidence: 99%

Morphology, anatomy and germination response of heteromorphic achenes ofAnthemis chrysanthaJ. Gay (Asteraceae), a critically endangered species

et al. 2011

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“…This compares with other species which need far more specific conditions for both seed dispersal and germination, or a 'cautious strategy' for both (Koller and Roth 1964;Evenari et al 1977;Loria and Noy-Meir 1979/80;Gutterman 1980/81 a;Venable and Levin 1985;Venable et al 1987;Beneke 1991). One of these is Schismus arabicus, which produces a very large number of extremely small seeds (Sect.…”

Section: High-or Low-risk Strategies For Seed Dispersal and Germinationmentioning

confidence: 93%

“…Heteromorphism and different germination was found in Israel in Hedypnois cretica (Feinbrun-Dothan and Danin 1991) in populations from the Mediterranean (Jerusalem) to the desert (Arad) region (Kigel 1992) and in South Africa (Beneke 1991…”

Section: Polymorphic Seeds and Germinationmentioning

confidence: 98%

“…In the Namaqualand desert of South Africa, the three types of diaspores of Dimorphotheca polyptera also enable the species to spread germination in time and location (Beneke 1991). …”

Section: Position Heteromorphism and Germinabilitymentioning

confidence: 99%

“…In polymorphic diaspores of Dimorphotheca sinuata, D. polyptera and Ursinia cakilejolia, collected from populations in the Namaqualand Broken Veld near Springbok, South Africa -162 mm mainly winter rainfall -morphological as well as germination differences were observed (Beneke 1991;Beneke et al 1992). …”

Section: Heterocarpy and Species Survivalmentioning

confidence: 99%

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Seed Germination in Desert Plants

Gutterman

1993

Adaptations of Desert Organisms

320

188

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PrefaceThis book is based on the author's 30 years of research in the desert, as well as on the research of others, on the dispersal and germination of annual angiospermae, geophytes and other perennial desert plants of the Negev Desert Highlands and the other deserts of Israel and the Sinai Peninsula. The findings are compared with the results of research that has been carried out in other hot deserts of the world. The focus of the book is on the extreme and unpredictable environmental conditions which influence the germination and survival of plants in the desert. These include the wide variation in the amount and distribution of rain and the differences in the length of the growing season from one year to the next, wide fluctuations in temperature, high salinity and the pressures of seed predation. The book presents ·an overview of the environmental factors influencing seed germination during plant development ~nd seed maturation, the mechanisms of seed dispersal and storage of the seed bank as well as those that affect germination during seed imbibition and seedling survival.The survival of plants under desert conditions is connected mainly with the germination mechanisms which ensure germination and seedling development at the right time and in a suitable place. Thus, during the plant life cycle the seed has the highest resistance to extreme environmental factors, whereas the seedling has the lowest. Are there special mechanisms in some species which are able to predict the best time and place for germination? It seems that there are two main directions in which evolution has taken place: 1. Plants with survival mechanisms that will enable seeds to be dispersed and/or germinate when the chance of seedling establishment is very high and the risk relatively low. Seeds of these plants only germinate after relatively large amounts of rain and, in many cases, have relatively large seeds which are well protected against many granivores. 2. In the opposite direction of evolution are species which produce tiny seeds in very large numbers, and many of these seeds germinate after even less than 10 mm of rainfall. These are condi-VI Preface tions of high risk for seedling establishment if additional rain does .not follow fairly quickly.One of the main topics considers what is special about the dispersal and germination of the seeds of plants that are found in deserts.The dispersal and germination strategies and mechanisms discussed focus mainly on annual plants in which germination is the most critical process before each growing season.Limited seed separation -synaptospermyis common among plant species inhabiting extreme deserts. Many synaptospermic species disperse their seeds by rain. At least two advantages of species with synaptospermic seed dispersal are seen particularly in extreme deserts: the retention of seeds in the favourable microhabitat where the mother plant had successfully completed its life cycle; and the protection of these seeds against seed collectors during the period from seed maturation to germi...

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Ultraviolet-B irradiation of seeds affects photochemical and reproductive performance of the arid-environment ephemeral dimorphotheca pluvialis

Musil

1994

Environmental and Experimental Botany

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Fruit polymorphism in ephemeral species of Namaqualand: III. Germination differences between the polymorphic diaspores

Cited by 27 publications

References 0 publications

Morphology, anatomy and germination response of heteromorphic achenes ofAnthemis chrysanthaJ. Gay (Asteraceae), a critically endangered species

Morphology, anatomy and germination response of heteromorphic achenes ofAnthemis chrysanthaJ. Gay (Asteraceae), a critically endangered species

Seed Germination in Desert Plants

Ultraviolet-B irradiation of seeds affects photochemical and reproductive performance of the arid-environment ephemeral dimorphotheca pluvialis

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