Computer simulation of cell division patterns in the apical region of fern gametophytes illustrates the development of a concave apical front and the subsequent heart shape when the division ratio is below a certain threshold. Here, I apply the concept of division ratio to the gametophytes of three fern species and show that the same relationship between cell division pattern and global shape exists. This indicates that the method of quantitative analysis of cell division patterns is a promising addition to existing methods for two-dimensional growth analysis.
{"title":"The Relationship between Cell Division Pattern and Global Shape of Young Fern Gametophytes. II. Morphogenesis of Heart-Shaped Thalli","authors":"M. D. Boer","doi":"10.1086/337843","DOIUrl":"https://doi.org/10.1086/337843","url":null,"abstract":"Computer simulation of cell division patterns in the apical region of fern gametophytes illustrates the development of a concave apical front and the subsequent heart shape when the division ratio is below a certain threshold. Here, I apply the concept of division ratio to the gametophytes of three fern species and show that the same relationship between cell division pattern and global shape exists. This indicates that the method of quantitative analysis of cell division patterns is a promising addition to existing methods for two-dimensional growth analysis.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"7 1","pages":"435 - 439"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337843","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sun and shade leaves of Quercus velutina Lam. were evaluated with respect to differences in gross anatomy, morphology, and cuticle (cuticular membrane [CM]) ultrastructure and micromorphology. Sun leaves are smaller, with more deeply lobed margins, and have more stomata, thicker mesophylls, and thicker CMs when compared with shade leaves. Cuticular membranes are thicker on both the adaxial and abaxial surfaces of sun leaves as a result of deposition of more cuticular components and scaly epicuticular wax. Both the adaxial and abaxial epidermises have the same basic fine structure in sun and shade leaves with respect to the outer periclinal cell wall and overlying CM. The cell wall is lamellate and the CM is composed of a two-zoned, reticulate cuticular layer and an amorphous cuticle proper. The outer periclinal wall and associated CM of the adaxial epidermis is thicker than that of the abaxial epidermis with both epidermal layers thicker in sun leaves compared with shade leaves. Difference in thickness of both epidermal layers, between sun and shade leaves, can be attributed to an increase in the inner reticulate region of the CM of sun leaves. Cells of the abaxial epidermis have ultrastructurally different CMs. Nonstomatal epidermal cells have a distinct amorphous cuticle proper whereas subsidiary cells have reticulations that traverse most of the outer CM. Guard cells have radially aligned reticulations through the entire outer CM and, therefore, lack an amorphous cuticle proper. Moreover, an internal CM, which is only sparsely reticulate, lines substomatal chambers. The internal CM of sun leaves is thicker and extends considerably deeper into substomatal chambers.
{"title":"Morphological and Ultrastructural Studies of Plant Cuticular Membranes. I. Sun and Shade Leaves of Quercus velutina (Fagaceae)","authors":"J. Osborn, T. N. Taylor","doi":"10.1086/337846","DOIUrl":"https://doi.org/10.1086/337846","url":null,"abstract":"Sun and shade leaves of Quercus velutina Lam. were evaluated with respect to differences in gross anatomy, morphology, and cuticle (cuticular membrane [CM]) ultrastructure and micromorphology. Sun leaves are smaller, with more deeply lobed margins, and have more stomata, thicker mesophylls, and thicker CMs when compared with shade leaves. Cuticular membranes are thicker on both the adaxial and abaxial surfaces of sun leaves as a result of deposition of more cuticular components and scaly epicuticular wax. Both the adaxial and abaxial epidermises have the same basic fine structure in sun and shade leaves with respect to the outer periclinal cell wall and overlying CM. The cell wall is lamellate and the CM is composed of a two-zoned, reticulate cuticular layer and an amorphous cuticle proper. The outer periclinal wall and associated CM of the adaxial epidermis is thicker than that of the abaxial epidermis with both epidermal layers thicker in sun leaves compared with shade leaves. Difference in thickness of both epidermal layers, between sun and shade leaves, can be attributed to an increase in the inner reticulate region of the CM of sun leaves. Cells of the abaxial epidermis have ultrastructurally different CMs. Nonstomatal epidermal cells have a distinct amorphous cuticle proper whereas subsidiary cells have reticulations that traverse most of the outer CM. Guard cells have radially aligned reticulations through the entire outer CM and, therefore, lack an amorphous cuticle proper. Moreover, an internal CM, which is only sparsely reticulate, lines substomatal chambers. The internal CM of sun leaves is thicker and extends considerably deeper into substomatal chambers.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"151 1","pages":"465 - 476"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337846","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have investigated the relationship between cell division and shape in mathematical models of fern gametophyte development. In particular, we attempted to infer what properties of cell division patterns are responsible for the development of heart-shaped thalli. We focused on those types of gametophytes that develop from an initial cell, splitting off segments alternately to the left and to the right. Computer simulations showed that a heart shape developed when the ratio between the rates of anticlinal and periclinal divisions in segments (the division ratio) was below a certain threshold. In the computer simulations we used map L-systems for the generation of cell division patterns and a center-of-gravity algorithm for the computation of cell shapes. The division ratio provided a quantitative characterization of the tendency of the cell division pattern to develop a heart shape. Together with map DOL-systems it can be applied to real gametophytes to investigate their morphogenesis.
{"title":"The Relationship between Cell Division Pattern and Global Shape of Young Fern Gametophytes. I. A Model Study","authors":"M. de Does","doi":"10.1086/337842","DOIUrl":"https://doi.org/10.1086/337842","url":null,"abstract":"We have investigated the relationship between cell division and shape in mathematical models of fern gametophyte development. In particular, we attempted to infer what properties of cell division patterns are responsible for the development of heart-shaped thalli. We focused on those types of gametophytes that develop from an initial cell, splitting off segments alternately to the left and to the right. Computer simulations showed that a heart shape developed when the ratio between the rates of anticlinal and periclinal divisions in segments (the division ratio) was below a certain threshold. In the computer simulations we used map L-systems for the generation of cell division patterns and a center-of-gravity algorithm for the computation of cell shapes. The division ratio provided a quantitative characterization of the tendency of the cell division pattern to develop a heart shape. Together with map DOL-systems it can be applied to real gametophytes to investigate their morphogenesis.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"151 1","pages":"423 - 434"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337842","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The influence of water stress at two soil temperatures on allocation of net photoassimilated carbon in soybean (Glycine max [L.] Merr.) was investigated using compartmental analysis. The experimental phase employed classical 14C labeling methodology with plants equilibrated at soil water potentials of -0.04, -0 25 and -0.50 MPa; and soil temperatures of 25 and 10 C. Compartmental analysis followed that of McCoy et al. (1989). Carbon immobilization in the shoot apex generally followed leaf elongation rates with decreases in both parameters at increasing water stress at both soil temperatures. However, where moderate water stress resulted in dramatic declines in leaf elongation rates, carbon immobilization rates were sharply decreased only at severe water stress levels. Carbon immobilization was decreased in the roots and nodules of the nonwater stressed treatment by the lower soil temperature. This relation was reversed with severe water stress, and carbon immobilization in the roots and nodules was increased at the lower soil temperature. Apparently, the increased demand for growth and/or carbon storage in these tissues with increased water stress overcame the low soil temperature limitations. Both carbon pool sizes and the partitioning of carbon to the sink tissues increased with moderate water stress at 25 C soil temperature Increased pool sizes were consistent with whole plant osmotic adjustment at moderate water stress. Increased partitioning to the sinks was consistent with carbon translocation processes being less severely influenced by water stress than is photosynthesis.
{"title":"Net Carbon Allocation in Soybean Seedlings as Influenced by Soil Water Stress at Two Soil Temperatures","authors":"E. Mccoy, L. Boersma, M. Ekasingh","doi":"10.1086/337849","DOIUrl":"https://doi.org/10.1086/337849","url":null,"abstract":"The influence of water stress at two soil temperatures on allocation of net photoassimilated carbon in soybean (Glycine max [L.] Merr.) was investigated using compartmental analysis. The experimental phase employed classical 14C labeling methodology with plants equilibrated at soil water potentials of -0.04, -0 25 and -0.50 MPa; and soil temperatures of 25 and 10 C. Compartmental analysis followed that of McCoy et al. (1989). Carbon immobilization in the shoot apex generally followed leaf elongation rates with decreases in both parameters at increasing water stress at both soil temperatures. However, where moderate water stress resulted in dramatic declines in leaf elongation rates, carbon immobilization rates were sharply decreased only at severe water stress levels. Carbon immobilization was decreased in the roots and nodules of the nonwater stressed treatment by the lower soil temperature. This relation was reversed with severe water stress, and carbon immobilization in the roots and nodules was increased at the lower soil temperature. Apparently, the increased demand for growth and/or carbon storage in these tissues with increased water stress overcame the low soil temperature limitations. Both carbon pool sizes and the partitioning of carbon to the sink tissues increased with moderate water stress at 25 C soil temperature Increased pool sizes were consistent with whole plant osmotic adjustment at moderate water stress. Increased partitioning to the sinks was consistent with carbon translocation processes being less severely influenced by water stress than is photosynthesis.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"151 1","pages":"497 - 505"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pediomelum subacaule (Leguminosae) is a tuberous root geophyte endemic to cedar glades of the southeastern United States. The annual shoot of P. subacaule emerges in early spring and dies with the onset of drought in late spring or early summer, by which time a small (< 1.0 mm in length) perennating bud has formed at the top of the root, about 50 mm below the soil surface. In a phenology study conducted in a non-temperature-controlled greenhouse, little bud growth occurred in July and August (ca. 32/21 C), but by mid-November the buds had reached a height of about 20 mm. The buds grew very little from mid-November to mid-February. From mid-February to late March, however, they grew an additional 30 mm and emerged at the soil surface in March. New absorbing roots were produced in March. After 36 wk, buds on roots incubated at 15/6, 20/10, and the simulated summer-autumn-winter-spring temperature sequence elongated 50 mm, while those incubated at 5, 25/15, 30/15, 30/20, and 35/20 C elongated to only 11-31 mm. New absorbing roots were produced only by roots incubated at 15/6, 20/10, and the sequence of simulated habitat temperatures. The temperature relationships of bud growth in P. subacaule are a phenological adaptation of this drought-intolerant species to its summer-dry habitat.
{"title":"Temperature Relations for Bud Growth in the Root Geophyte Pediomelum subacaule and Ecological Implications","authors":"J. Baskin, C. Baskin","doi":"10.1086/337850","DOIUrl":"https://doi.org/10.1086/337850","url":null,"abstract":"Pediomelum subacaule (Leguminosae) is a tuberous root geophyte endemic to cedar glades of the southeastern United States. The annual shoot of P. subacaule emerges in early spring and dies with the onset of drought in late spring or early summer, by which time a small (< 1.0 mm in length) perennating bud has formed at the top of the root, about 50 mm below the soil surface. In a phenology study conducted in a non-temperature-controlled greenhouse, little bud growth occurred in July and August (ca. 32/21 C), but by mid-November the buds had reached a height of about 20 mm. The buds grew very little from mid-November to mid-February. From mid-February to late March, however, they grew an additional 30 mm and emerged at the soil surface in March. New absorbing roots were produced in March. After 36 wk, buds on roots incubated at 15/6, 20/10, and the simulated summer-autumn-winter-spring temperature sequence elongated 50 mm, while those incubated at 5, 25/15, 30/15, 30/20, and 35/20 C elongated to only 11-31 mm. New absorbing roots were produced only by roots incubated at 15/6, 20/10, and the sequence of simulated habitat temperatures. The temperature relationships of bud growth in P. subacaule are a phenological adaptation of this drought-intolerant species to its summer-dry habitat.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"160 1","pages":"506 - 509"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337850","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Maze, K. A. Robson, S. Banerjee, L. R. Bohm, R. Scagel
In this study, developmental constraint was estimated by the correlation matrices for three developmental stages for achenes and ovules for two plants in two species of Balsamorhiza, B. sagittata and B. hookeri. Two comparisons were made, a statistical test of the equality of correlation matrices for contiguous stages of development and a graphic comparison of variable interrelationships for each stage of development for each individual plant. Individual instances of both developmentally related changes and stasis in correlation matrices were encountered more often in achenes than in ovules and in B. sagittata more than in B. hookeri. Based on these results, the concept of developmental constraints seems to refer to a specific relationship among variables at any one time as well as the way that relationship changes with time. In this context, developmental constraints may form the intrinsic "rules" that organisms follow as they develop. In formal explanations of evolution and ontogeny, developmental constraints--the "rules"--are part of the premises and cannot be a causal agent. In other words, the rules of a developmental "grammar" do not, by themselves, provide a full explanation for the "language" of morphogenesis. In the view that the increasing complexity accompanying development reflects the dissipation of energy into the characteristic form of an organism, the primary causal agent of development may be the second law of thermodynamics.
{"title":"Quantitative Studies in Early Ovule and Fruit Development: Developmental Constraints in Balsamorhiza sagittata and B. hookeri","authors":"J. Maze, K. A. Robson, S. Banerjee, L. R. Bohm, R. Scagel","doi":"10.1086/337841","DOIUrl":"https://doi.org/10.1086/337841","url":null,"abstract":"In this study, developmental constraint was estimated by the correlation matrices for three developmental stages for achenes and ovules for two plants in two species of Balsamorhiza, B. sagittata and B. hookeri. Two comparisons were made, a statistical test of the equality of correlation matrices for contiguous stages of development and a graphic comparison of variable interrelationships for each stage of development for each individual plant. Individual instances of both developmentally related changes and stasis in correlation matrices were encountered more often in achenes than in ovules and in B. sagittata more than in B. hookeri. Based on these results, the concept of developmental constraints seems to refer to a specific relationship among variables at any one time as well as the way that relationship changes with time. In this context, developmental constraints may form the intrinsic \"rules\" that organisms follow as they develop. In formal explanations of evolution and ontogeny, developmental constraints--the \"rules\"--are part of the premises and cannot be a causal agent. In other words, the rules of a developmental \"grammar\" do not, by themselves, provide a full explanation for the \"language\" of morphogenesis. In the view that the increasing complexity accompanying development reflects the dissipation of energy into the characteristic form of an organism, the primary causal agent of development may be the second law of thermodynamics.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"7 1","pages":"415 - 422"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Development of stigma and the pollen tube transmitting tract in column and ovary is described in Lemboglossum maculatum and L uro-skinneri. The most immature stigma examined comprises a shallow depression lined by an epidermis and two to three layers of isodiametric, densely staining, nonvacuolate subepidermal cells. A thin, homogeneous cuticle overlies the epidermis. The stylar and ovarian transmitting tracts are less differentiated than the stigma. Development is marked by an increase in complexity of the stigmatic cuticle and amount of intercellular secretion and by a reduction in cell-cell attachment. A basipetal developmental gradient is apparent along the length of the pistil. The mature stigma is an oval, fluid, and cell-filled depression. The stigma tissue type is fully continuous with that in the tripartite stylar transmitting tract, which traverses the column and branches at the entrance to the ovary to produce six ovarian transmitting tracts. A pair of tracts is associated with each of three placental ridges which, in the unpollinated pistil, bear undifferentiated ovular tissue. In the mature stigma, four layers have been identified. The first layer is a highly modified cuticle, comprising cutin and lipid, enclosing islands of polysaccharide-rich secretory products. Beneath the cuticular layer, an unbroken epidermis overlies a subepidermal "alveolar secretory zone" in which cells are bathed in polysaccharide-rich intercellular secretion. The innermost "transition zone" of small tightly packed cells borders the column cortex. At anthesis the epidermal layer becomes disrupted, and adaxial linkages in the subepidermal layer become weaker. The stylar and ovarian transmitting tissues are anatomically and histochemically similar to the stigma. A cuticular layer is present in only the top half of the style and is progressively less complex than its stigmatic counterpart. Stigma, stylar, and transmitting tract secretions stain positively for protein, carbohydrate, acidic polyanions, and pectic substances. The aspects of the transmitting tract described appear to be common throughout the genera Lemboglossum, Odontoglossum, and Oncidium.
{"title":"The Stigma, Style, and Ovarian Transmitting Tract in the Oncidiinae (Orchidaceae): Morphology, Developmental Anatomy, and Histochemistry","authors":"S. Clifford, S. Owens","doi":"10.1086/337844","DOIUrl":"https://doi.org/10.1086/337844","url":null,"abstract":"Development of stigma and the pollen tube transmitting tract in column and ovary is described in Lemboglossum maculatum and L uro-skinneri. The most immature stigma examined comprises a shallow depression lined by an epidermis and two to three layers of isodiametric, densely staining, nonvacuolate subepidermal cells. A thin, homogeneous cuticle overlies the epidermis. The stylar and ovarian transmitting tracts are less differentiated than the stigma. Development is marked by an increase in complexity of the stigmatic cuticle and amount of intercellular secretion and by a reduction in cell-cell attachment. A basipetal developmental gradient is apparent along the length of the pistil. The mature stigma is an oval, fluid, and cell-filled depression. The stigma tissue type is fully continuous with that in the tripartite stylar transmitting tract, which traverses the column and branches at the entrance to the ovary to produce six ovarian transmitting tracts. A pair of tracts is associated with each of three placental ridges which, in the unpollinated pistil, bear undifferentiated ovular tissue. In the mature stigma, four layers have been identified. The first layer is a highly modified cuticle, comprising cutin and lipid, enclosing islands of polysaccharide-rich secretory products. Beneath the cuticular layer, an unbroken epidermis overlies a subepidermal \"alveolar secretory zone\" in which cells are bathed in polysaccharide-rich intercellular secretion. The innermost \"transition zone\" of small tightly packed cells borders the column cortex. At anthesis the epidermal layer becomes disrupted, and adaxial linkages in the subepidermal layer become weaker. The stylar and ovarian transmitting tissues are anatomically and histochemically similar to the stigma. A cuticular layer is present in only the top half of the style and is progressively less complex than its stigmatic counterpart. Stigma, stylar, and transmitting tract secretions stain positively for protein, carbohydrate, acidic polyanions, and pectic substances. The aspects of the transmitting tract described appear to be common throughout the genera Lemboglossum, Odontoglossum, and Oncidium.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"151 1","pages":"440 - 451"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337844","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60237718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Plants of Thlaspi arvense L. flowered over a long period of time during summer. Plants of the early-flowering strain (EF) that emerged in the fall and overwintered flowered first, followed by overwintered plants of the late-flowering strain (LF). About 1 mo later, plants of both EF and LF strains that germinated in the spring began to flower Spring-emerging plants grew taller and had more branches but fewer lateral shoots than plants that had overwintered. In addition, the spring-emerging plants produced larger numbers of smaller seeds with no difference in total seed dry weight. LF plants grew taller than those of the EF strain. Under field conditions, seeds from these plant sources had their highest germination rates the first fall. In subsequent years, germination rates were greatest in spring with a secondary peak in the fall and little germination during the summer. Also, seeds from LF plants germinated at a faster rate than did those of the EF strain over a 3-yr period. Strain and germination period had significant effects on T. arvense, increasing the variability in phenology and morphology among populations, and likely increasing the species' tolerance to a wide range of environmental conditions. Variability in time to flower within strains appears to be under polygenic control.
{"title":"Influence of Emergence Date and Strain on Phenology, Seed Production, and Germination of Thlaspi arvense L.","authors":"L. Hume","doi":"10.1086/337851","DOIUrl":"https://doi.org/10.1086/337851","url":null,"abstract":"Plants of Thlaspi arvense L. flowered over a long period of time during summer. Plants of the early-flowering strain (EF) that emerged in the fall and overwintered flowered first, followed by overwintered plants of the late-flowering strain (LF). About 1 mo later, plants of both EF and LF strains that germinated in the spring began to flower Spring-emerging plants grew taller and had more branches but fewer lateral shoots than plants that had overwintered. In addition, the spring-emerging plants produced larger numbers of smaller seeds with no difference in total seed dry weight. LF plants grew taller than those of the EF strain. Under field conditions, seeds from these plant sources had their highest germination rates the first fall. In subsequent years, germination rates were greatest in spring with a secondary peak in the fall and little germination during the summer. Also, seeds from LF plants germinated at a faster rate than did those of the EF strain over a 3-yr period. Strain and germination period had significant effects on T. arvense, increasing the variability in phenology and morphology among populations, and likely increasing the species' tolerance to a wide range of environmental conditions. Variability in time to flower within strains appears to be under polygenic control.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"151 1","pages":"510 - 515"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337851","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developing sporocarps are less likely to mature if the relative humidity is not near saturation. Sporocarps that do mature under dryer conditions usually produce fewer spores. For some genotypes this detrimental effect is much greater than for others. Isolates were collected from around the world and cultured. Spore production at 100% and 80% relative humidity was measured, and 10 populations, representing the variety of tolerances to dryer conditions, were chosen. Single mycelial isolates from each population were cultured under identical conditions to constitute 10 putatively distinct genotypes Genetically identical emerging sporocarps of each genotype were excised and desiccated in a 16 C chamber that held relative humidity at 80%. Surface area and weight were measured at excision and weight remeasured after 6, 12, and 24 h of desiccation. Dry weight was measured after 2 more d under silica gel. Water loss rates decreased with sporocarp surface area. The rate of water loss was proportional to about the 3/4 power of surface area However, surface area varies significantly among genotypes, and intrinsic resistance to water loss may also vary among genotypes. To separate these effects, a global surface area effect and average, genotype-specific intrinsic resistances to water loss were estimated simultaneously. Water loss was then proportional to about the 7/8 power of surface area. These proportionality constants (intrinsic water loss rates) were calculated for each sporocarp. They varied significantly among genotypes. Hydration (water content expressed in units of dry weight), with an initial average of about 10, varied significantly among genotypes. Genotypes with initially fastest intrinsic water loss rates tended to have smaller and less well hydrated sporocarps that dried out quickly. Because of these contrary trends, hydration was not correlated with water loss rate during the first 6 h. During the next 6 h, water loss rates remained uncorrelated with hydration for wetter sporocarps, but for dryer sporocarps decreased with decreasing hydration. Time from emergence until hydration of each sporocarp would fall to various thresholds below five (when critical drying might be presumed to have occurred) was estimated for each sporocarp and varied significantly among genotypes; those taking longer usually have slower intrinsic drying rates, larger size, higher initial hydration, and greater spore production in dryer environments.
{"title":"Adaptations of Sporocarps of the Basidiomycete Flammulina velutipes (Agaricales) to Lower Humidity","authors":"K. McKnight, G. Estabrook","doi":"10.1086/337854","DOIUrl":"https://doi.org/10.1086/337854","url":null,"abstract":"Developing sporocarps are less likely to mature if the relative humidity is not near saturation. Sporocarps that do mature under dryer conditions usually produce fewer spores. For some genotypes this detrimental effect is much greater than for others. Isolates were collected from around the world and cultured. Spore production at 100% and 80% relative humidity was measured, and 10 populations, representing the variety of tolerances to dryer conditions, were chosen. Single mycelial isolates from each population were cultured under identical conditions to constitute 10 putatively distinct genotypes Genetically identical emerging sporocarps of each genotype were excised and desiccated in a 16 C chamber that held relative humidity at 80%. Surface area and weight were measured at excision and weight remeasured after 6, 12, and 24 h of desiccation. Dry weight was measured after 2 more d under silica gel. Water loss rates decreased with sporocarp surface area. The rate of water loss was proportional to about the 3/4 power of surface area However, surface area varies significantly among genotypes, and intrinsic resistance to water loss may also vary among genotypes. To separate these effects, a global surface area effect and average, genotype-specific intrinsic resistances to water loss were estimated simultaneously. Water loss was then proportional to about the 7/8 power of surface area. These proportionality constants (intrinsic water loss rates) were calculated for each sporocarp. They varied significantly among genotypes. Hydration (water content expressed in units of dry weight), with an initial average of about 10, varied significantly among genotypes. Genotypes with initially fastest intrinsic water loss rates tended to have smaller and less well hydrated sporocarps that dried out quickly. Because of these contrary trends, hydration was not correlated with water loss rate during the first 6 h. During the next 6 h, water loss rates remained uncorrelated with hydration for wetter sporocarps, but for dryer sporocarps decreased with decreasing hydration. Time from emergence until hydration of each sporocarp would fall to various thresholds below five (when critical drying might be presumed to have occurred) was estimated for each sporocarp and varied significantly among genotypes; those taking longer usually have slower intrinsic drying rates, larger size, higher initial hydration, and greater spore production in dryer environments.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"151 1","pages":"528 - 537"},"PeriodicalIF":0.0,"publicationDate":"1990-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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