Seed Germination

10 Key excerpts on "Seed Germination"

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  eBook - PDF

  Advances in Seed Science and Technology

  • Prasad, Shukla P S(Authors)
  • 2018(Publication Date)
  • Biotech

    (Publisher)

  Chapter 4 : Biochemistry of Seed Germination Samindra Baishya 1 , Surojit Sen 2 and Sunayana Rathi 3 1 Department of Biochemistry and Agricultural Chemistry, 3 Department of Plant Breeding and Genetics, Assam Agricultural University, Jorhat-785013, Assam, India 2 Department of Zoology, Mariani College, Mariani – 785634, Jorhat, Assam, India Plants, as sessile life forms have evolved diverse mechanisms to circumvent unfavorable growth conditions, among them interruption of life cycle is one of the most successful strategies. Spermatophytes, or seed plants, are characterized by the formation of the seed. Embryogenesis within the seed allows the entry into a quiescent state that represents an evolutionary advantage as it facilitates dispersal and resuming of growth under optimal environmental conditions. Seed formation is an intricate process that can be divided into proper embryogenesis (cell division and morphogenesis), followed by maturation phase characterized by storage compound accumulation, acquisition of desiccation tolerance, growth arrest and the entry into a dormancy period of variable length that is broken upon germination. A seed is a marvelous adaptation for survival of the embryo for long period, often under adverse environmental conditions. With most species the survival period is comparatively short and is within the range of 5-30 years. Survival periods greater than 30 years for occasional seeds have also been recorded. As for example, Lotus ( Nelumbo ) species seeds evidenced to be 250 years old and recovered from the bed of dried lake were found to germinate. This ebook is exclusively for this university only. Cannot be resold/distributed. Seed Germination is defined as the sum of events that commence with the uptake of water by the quiescent dry seed and terminates with/culminates in elongation, emergence of embryonic axis (usually the radicle) from the seed coat.

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  Seeds Handbook

  Processing And Storage

  • Babasaheb B. Desai(Author)
  • 2004(Publication Date)
  • CRC Press

    (Publisher)

  33. M. T. S. Eira and L. S. Caldas, Seed dormancy and germination as concurrent process, Seed Physiology Papers-Presented at the VII Brazilian Plant Physiology Congress, Brasilia, July 1999. Seed Abstr. 25:211 (2002). 34. M. Jensen and E. M. Eriksen, Development of primary dormancy in seeds of Prunus aviun'z during maturation, Seed Sci. Technol. 29:307, (2001). 35. J. A. Plumer, A. D. Rogers, D. W. Turner and D. T. Bell, Light, nitrogenous compounds, smoke and GA3 break dormancy and enhance germination in the Australian everlasting daisy, Shoenia filifolia, subsp. subulifolia, Seed Sci. Technol. 29:321, (2001). 36. J. D. Hitchmough, J. Gough and B. Corr, Germination and dormancy in a wild collected genotype of Trollius europaeus, Seed Sci. Technol. 28:549, (2000). 4 Seed Germination I. INTRODUCTION Germination may be defined as an emergence of embryo from the seed by starting a variety of anabolic and catabolic activities, including respiration, protein synthesis, and mobilization of food reserves after it has absorbed water. To the seed analyst, germination means the emergence and development from the seed embryo of the essential structures that indicate the seed's ability to produce a normal plant under favorable conditions (1). The presence of oxygen is necessary to allow some aerobic respiration, as is a temperature suitable to permit various metabolic processes to proceed. Seeds of many plant species, however, fail to germinate in spite of favorable conditions owing to dormancy. The mobilization offood reserves is not strictly a component of germination, but only a uniquely associated aspect. An individual seed mayor may not have the ability to germinate, but for a seed population, it is possible to express its capacity to germinate (germinability) in terms of the percentage of seeds that germinate under favorable conditions.

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  Germination Control. Metabolism, and Pathology

  • T.T. Kozlowski(Author)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  It will be worth bearing in mind throughout that physiology of germination is almost exclusively studied under conditions which are (at least in part) practically non-existent in the natural environment of the greatest majority of seeds. Seeds germinate (or do not) in contact with a soil-water-atmosphere system which normally surrounds them on all sides, and not more or less immersed in water. In Petri dishes the water usually evaporates and has to be replenished, exposing the seeds to a highly unnatural cycle of water availability and aeration. The composition of the atmosphere, the water potential, its components and the changes in them with time in the natural submicroenvironment of the seed, are not duplicated in laboratory studies, 14 DOV KOLLER with the exception of those few which are specifically designed to examine their effects. It will become apparent that strong interactions may occur which greatly modify the effectiveness of a given environmental factor in controlling germination and may result in misleading interpretations and conclusions. III. Immediate Responses From an agricultural viewpoint germination is a process which starts when the dry seed is planted in wet soil and ends when the seedling emerges above ground. However, since it was found that failure to emerge could be a result of seedling mortality or soil impedance, the concept of germination was narrowed down to exclude the problems which confront the seedling. As a result, the physiological concept of germination be-came that of a process which starts with supply of liquid water to the dry seed and ends where the growth of the seedling starts, most commonly by protrusion of the embryonic radicle through the seed coat. The criterion of radicle protrusion as the end of germination has gen-erally proved to be a very useful one, but a few exceptions necessitate caution in applying it indiscriminately.

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  Plant Physiology 6C

  A Treatise: Physiology of Development: From Seeds to Sexuality

  • F.C. Steward(Author)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  Germination necessarily involves the induction of activity in a reproductive system (i.e., excluding the resumption of activity in cells of vegetative storage organs) which had previously persisted without morphological change, and to some authorities this is all that is implied by the term germination. A variety of considerations suggest, however, that the term must be applied in a wider context. T h e course of dry weight change with time indicates that the phase in the life history of the plant between activation and the establishment of an independent seedling is distinctive. Whereas after the establish-ment of a seedling in normal circumstances dry weight increases, before this stage is reached the dry weight of the whole seed complex decreases. Second, the early development of the axis occurs in at least two well defined stages, and it is doubtful whether either the first or the second can be understood without reference to the other. Third, if germination covers the process of activation only, then it does not involve the mobilization of the nutrient reserves, and this is certainly one of the central features of the development that leads to the establishment of a seedling. For these reasons the term ger-mination is used here as referring to the complex of processes that include and follow activation as far as the stage when a potentially independent seedling has been formed. At the same time, although the term is used in this sense, the data that are presented and discussed below do not cover the whole succession of phases in the process. T h e y refer primarily to the earlier phases. Although it is undeniably important, little or nothing can be said about the final transforma-tion into the independent seedling since this phase has attracted remarkably little attention. T h e gross morphological changes that occur during germination in outline are the same in all seeds.

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  eBook - ePub

  Seeds

  Ecology, Biogeography, and, Evolution of Dormancy and Germination

  • Carol C. Baskin, Jerry M. Baskin(Authors)
  • 2014(Publication Date)
  • Academic Press

    (Publisher)

  By pooling data from many authors and using our own experience, some guidelines for conducting studies on Seed Germination ecology have been developed. First, seed dormancy will be defined, and then we will consider things that need to be kept in mind when laboratory experiments are conducted to determine the dormancy-breaking and germination requirements of seeds. Finally, we will discuss how laboratory studies can be done to supplement those done in the field, slathouse, nonheated greenhouse or transplant garden.

  Definition of Seed Dormancy

  To many people, seed dormancy simply means that a seed has not germinated, but we will soon see that this definition is inadequate. Unfavorable environmental conditions are one reason for lack of Seed Germination. That is, seeds could be in a paper bag on the laboratory shelf (i.e., lack of water), buried in mud at the bottom of a lake (i.e., insufficient oxygen and/or light) or exposed to temperatures that are above or below those suitable for plant growth. These obviously unfavorable conditions for germination are examples of how the environment rather than some factor associated with the seed per se prevents germination.

  A second reason why seeds may not germinate is that some property of the seed (or dispersal unit) prevents it. Thus, the lack of germination is a seed rather than an environmental problem (Eira and Caldas, 2000 ). Dormancy which results from some characteristic of the seed is called organic (versus imposed) dormancy (Nikolaeva, 1969 , 1977 ), and this kind of dormancy usually is of most interest to seed biologists and ecologists. In fact, throughout this book, we will be concerned with organic seed dormancy.

  There are many definitions of seed dormancy, but often the term means the failure of seeds to germinate although environmental conditions including water, temperature, light and gases are favorable for germination (Koornneef and Karssen, 1994 ;

  Vleeshouwers et al. , 1995

  ; Bewley, 1997a ; Eira and Caldas, 2000 ; Geneve, 2005 ). The ecological consequence of seed dormancy is that germination is prevented (although conditions are favorable for germination) at a time of the year when the environment does not remain favorable long enough for seedlings to become established and thus survive (

  Vleeshouwers et al. , 1995

  ; Eira and Caldas, 2000 ; Cmelik and Perica, 2007 ). Therefore, seed dormancy plays an important role in regulating the timing of germination so that environmental conditions are favorable for seedling survival and eventually maturation of the plant (Geneve, 2003 ; Finch-Savage and Leubner-Metzger, 2006 ). Not surprisingly, then, an “interesting feature of seed dormancy is that plants have evolved different mechanisms for inducing dormancy” (Penfield and King, 2009 ), and also, as we will explore in this book, the different ways of breaking dormancy that have evolved in plants. It should be noted, however, that dormancy also is found in Monera, Protista, fungi and animals (see Footitt and Cohn, 2001

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  Abiotic Stress And Physiological Process In Plants

  • A. Bhattacharya(Author)
  • 2021(Publication Date)
  • NEW INDIA PUBLISHING AGENCY (NIPA)

    (Publisher)

  Under proper conditions, the seed begins to germinate and the embryonic tissues resume growth, developing towards a seedling. Seed Germination depends on both internal and external conditions. The most important external factors include temperature, water, oxygen and sometimes light or darkness (Raven et al., 2005) . Various plants require different variables for successful Seed Germination. Often this depends on the individual seed variety and is closely linked to the ecological conditions of a plant’s natural habitate. For some seeds, their future germination response is affected by environmental conditions during seed formation; most often these responses are types of seed dormancy. Water is required for germination. Mature seeds are often extremely dry and need to take in significant amounts of water, relative to the dry weight of the seed, before cellular metabolism and growth can resume. Most seeds need enough water to moisten the seeds but not enough to soak them. The uptake of water by seeds is called imbibitions. which leads to the swelling and the breaking of the seed coat. When seeds are formed, most plants store a food reserve within the seed, such as starch, proteins or oils. This food reserve provides nourishment to the growing embryo. When the seed imbibes water, hydrolytic enzymes are activated which break down these stored food resources into metabolically useful chemicals (Raven et al. , 2005). After the seedling emerges from the seed coats and starts growing roots and leaves, the seedling’s food reserves are typically exhausted; at this point photosynthesis provides the energy needed for continued growth and the seedling now requires a continuous supply of water, nutrients, and light. Seed Germination, Seedling Growth and Root Development 7 Oxygen is used in aerobic respiration, the main source of the seedling’s energy until it grows leaves (Raven et al. , 2005).

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  Embryology of Flowering Plants: Terminology and Concepts, Vol. 2

  The Seed

  • T B Batygina(Author)
  • 2005(Publication Date)
  • CRC Press

    (Publisher)

  PART FIVE—SEED DORMANCY AND GERMINATION Seed Dormancy (Plate LXII) Plant growth begins with Seed Germination. M ature seeds located in adequate conditions (humidity, temperature, aeration) sprout rather quickly Nevertheless seeds of an overwhelming majority of wild, as well as many cultivated plants undergo a state of dormancy, of which two types have been distinguished: conditional and organic dormancy (Grebinsky, 1961; Nikolaeva, 1967). Conditional dormancy is induced by external causes (lack of moisture, temperature and light conditions), unfavourable for germination. Seeds under organic dormancy fail to germinate even in the presence of all conditions suitable for this process. In some species seed dormancy is so deep that it is a special preparation before sowing needed for their germination. In natural environments the germination of such seeds commences for several months or not infrequently for 1 or 2 years after sowing, and seedling emergence may be strained for several years. The ability to gain the state of conditional or organic dormancy prevents premature Seed Germination, encouraging survival of species and creation of a seed bank in the soil. The following point, usually overlooked in the literature devoted to this problem, should be emphasized. Having arisen in the evolutionary process as an adaptive character for survival in unfavourable environmental conditions, passing through dormancy (latent period) became a necessary stage of ontogenesis. Normal plants cannot appear from seeds bearing dormancy until appropriately treated. Otherwise the seedlings occasionally formed from dormant seeds are characterized by dwarfism and disturbance of normal intemode development. Ordinarily they give rise to plants of the rosette type, as shown on the example of seeds in Acer tataricum (Nikolaeva et al, 1974). The depth of organic seed dormancy, the reasons for its inducement and the conditions for its interruption vary greatly in different species.

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  Advances in Seed Biology

  • Jose C. Jimenez-Lopez(Author)
  • 2017(Publication Date)
  • IntechOpen

    (Publisher)

  Section 2 Seed Dormancy and Germination Chapter 5 Seed Dormancy Mustafa Yildiz, Ramazan Beyaz, Mehtap Gursoy, Murat Aycan, Yusuf Koc and Mustafa Kayan Additional information is available at the end of the chapter http://dx.doi.org/10.5772/intechopen.70571 Abstract Dormancy is when there is a lack of germination in seeds or tubers even though the required conditions (temperature, humidity, oxygen, and light) are provided. Dormancy is based on hard seed coat impermeability or the lack of supply and activity of enzymes (internal dormancy) necessary for germination. Dormancy is an important factor limiting production in many field crops. Several physical and chemical pretreatments are applied to the organic material (seeds/tubers) to overcome dormancy. Physical and physiologi-cal dormancy can be found together in some plants, and this makes it difficult to pro -vide high-frequency, healthy seedling growth, since the formation of healthy seedlings from the organic material (seeds/tubers) sown is a prerequisite for plant production. This chapter will focus on the description of four different methods we have not seen reported elsewhere for overcoming dormancy. Keywords: dormancy, magnetic field strength, squirting cucumber fruit juice, sodium hypochlorite, gamma radiation 1. Introduction Seeds germinate to grow and survive from seedlings at a favorable time and place. The pre -vention of germination in unfavorable circumstances is described as dormancy. Dormancy is where there is a lack of germination in a seed/tuber even though the required conditions (tem-perature, humidity, oxygen, and light) are provided [1]. Dormancy is a trait gained during evolution to survive in adverse conditions such as heat, cold, drought, and salinity. Dormancy enables plant species to adapt to different geographical regions, showing variations in pre -cipitation and temperature [2 ].

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  Handbook of Seed Physiology

  Applications to Agriculture

  • Roberto Benech-Arnold(Author)
  • 2004(Publication Date)
  • CRC Press

    (Publisher)

  Initiation of growth is therefore a moisture-sensitive, rate-limiting step that determines *¥b and ensures that in many species germination under variable soil conditions occurs only when sufficient moisture is likely to be available for subsequent seedling growth (Hegarty, 1977; Ross and Hegarty, 1979; Finch-Savage and Phelps, 1993, Finch-Savage, Steckel, and Phelps, 1998). Below 'I'*,, seed priming or advancement in the soil (Wilson, 1973; Allen, White, and Markhart, 1993; Rowse, McKee, and Higgs, 1999) means that germination can be rapid when water becomes available. In the absence of additional water, there is only a brief opportunity for the completion of ger-mination and seedling growth before the surface soil layers dry again. Fol-lowing germination, initial growth is downward in both epigeal and hypo- geal seedlings, to maintain contact with soil moisture as it dries from the surface layers. As this drying occurs the hydraulic conductivity of soil in the surface layer quickly falls to a very low value, and this will tend to reduce the rate of water loss from deeper layers (e.g., Lascano and van Babel, 1986). The seedling root will therefore grow into increasingly wet soil and the seedling may become less dependent on moisture content of the surface layers (Bierhuizen and Feddes, 1973). This pattern may occur because hypocotyl extension is more sensitive than radicle extension to low matric potential which initially favors the growth of roots (Dracup, Davies, and Tapscott, 1993). The initial period of downward seedling growth following germination is therefore critical to successful seedling establishment. Up-ward growth often occurs in a deteriorating seedbed that has increasing soil strength. Even if water potential is not directly limiting, because the grow-ing root maintains contact with adequate moisture, there can be a large indi-rect effect because soil strength above the seed will increase as water con-tent decreases.

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  Handbook of Plant and Crop Physiology

  • Mohammad Pessarakli(Author)
  • 2014(Publication Date)
  • CRC Press

    (Publisher)

  39 Seed Dormancy, Germination, and Seedling Recruitment in Weedy Setaria temporal behavior. Spatial plant structure extends through the morphological (embryo to plant) and genetic (plant to metapopulation). Temporal life history behavior begins in anthesis/fertilization and embryogenesis; development continues with inflorescence tillering, seed dispersal in space and time, and resumption of embryo growth with seedling emergence. The interaction of self-similar plant components leads to functionally adapted traits, self-organization. These heritable functional traits are the physical reservoirs of information guiding life history development, emer-gent behavior. Information contained in structural and behavioral traits is communicated directly between seed and soil environment during development. The specific nature of Setaria is eluci-dated in Figure 2.2. 2.2.1 S EED –S EEDLING L IFE H ISTORY 2.2.1.1 Threshold Events Several discrete threshold events characterize Setaria summer annual life history. These threshold events provide time points allowing individual comparison in the elucidation of development. The threshold life history events begin and end with successful fertilization, and continue with seed abscission, germination, and seedling emergence when the new vegetative plant develops to fertil-ization of new progeny. 2.2.1.2 Germination and Seedling Emergence One of the most important events in a plant’s life history is the time of Seed Germination and seedling emergence, the resumption of embryo growth and plant development. Emergence timing is crucial; it is when the individual plant assembles in the local community and begins its struggle for existence with neighbors. Resumption of growth at the right time in the community allows the plant to seize and exploit local opportunity at the expense of neighbors, allowing development to reproduction and replenishment of the local soil seed pool at abscission.

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