摘要:

The fresh weights of suspension cultures of pear (Pyrus communis) and quince (Cydonia oblonga) increased exponentially for 30 to 40 days after subculturing. Transferring pear cultures to media in which quince cultures had grown for 10 days resulted in a 70% inhibition of callus growth. Transferring quince cultures to media in which pear cultures had grown for 10 days resulted in less than a 20% inhibition of growth. Addition of the cyanogenic glycosides amygdalin and prunasin (as 50 ppm CN_) killed pear cultures, while growth of quince cultures was inhibited by only approximately 50%. Addition of 50 ppm CN‐ severely inhibited growth of both cultures. These results indicate that 1) suspension cultures of quince release factor(s) that significantly inhibit growth of pear cultures, 2) quince cultures are relatively unaffected by metabolites released by pear cultures, 3) the severe inhibition of pear growth by quince metabolites is mimicked by the addition of cyanogenic glycosides ubiquitous to vegetative portions of quince, 4) direct cellular contact is not necessary to elicit incompatibility between pear and quince, and 5) incompatibility between pear and quince need not be associated with any particular stage of graft development.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09673.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Seeds of the monocarpic perennialFrasera caroliniensisripen in late summer, and most of them are dispersed in late autumn and winter. However, some viable seeds may remain undispersed for more than a year. Embryos are underdeveloped (ca. 1.1–1.3 mm long) at seed maturity and do not grow while seeds remain on plants in the field. Dormancy in freshlymatured seeds was broken by 12 to 14 weeks of cold stratification at 5 C, during which the embryos elongated. On the other hand, seeds collected in January and March required a period of warm stratification followed by a period of cold stratification to germinate. Seeds collected in September and sown in a nonheated greenhouse germinated to 83% the first spring after maturation, whereas those collected and sown in January and March did not germinate until the second spring. Thus, seeds that remained on plants in the field until winter entered a deepened state of dormancy, and a warm (summer) followed by a cold (winter) stratification period was required to overcome it.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09674.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

An analysis of the relationships between plant size and survivorship and reproductive success was carried out by sampling four populations of the herbaceous perennial milkweedAsclepias exaltatain Virginia from 1980 to 1982. The annual survivorship rate (about 65%) is the lowest measured for any species ofAsclepias.Survivorship was strongly size‐dependent but showed no clear relationship with previous history of fruit production. Non‐flowering plants were significantly smaller than flowering plants and showed very strong (r>0.87) correlations between root dry weight and stem or leaf dry weight. Flowering plants were similar to nonflowering plants in root: shoot ratio (approximately 1:1) but differed in that root dry weight was not strongly correlated with stem or leaf dry weight. Components of inflorescence size were strongly correlated within a given level of comparison (e.g., stems per plant with flowers per plant) but less strongly correlated between levels (e.g., stems per plant with flowers per stem). Number of fruits per plant and percentage fruit‐set were positively correlated with every component of inflorescence size. Although overall fruit‐set was low (about 2%), fruits that were initiated had a high probability of surviving to maturity. There was no evidence of an early period of high fruit abortion: a relatively constant proportion of fruits aborted between each age class.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09675.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

The life cycle ofPodophyllumcan be divided into two phases, a subterranean phase during which a conspicuous winter mixed terminal bud forms at the end of a rhizome, and an aerial phase, during which the primordia of the structures within the winter bud give rise the next spring to an aerial shoot composed of a stem, 2 leaves, and a single flower. The transition from a vegetative to a floral apex occurs at the end of July, when the apical meristem becomes a globoid structure. During the first and second weeks of August, the floral organs are laid down along the sides of an elongated floral apex. The order of initiation of the floral organs is sepals, petals, stamens, gynoecium, and stamens. Petal primordia are initiated in early August, but growth ceases after they attain a height of about 2 mm. This inhibition persists until the middle of May in the next growing season, when the petals grow to 12 mm within 2 weeks. At anthesis the petals have enlarged to a length of 2 cm or more. The gynoecium is usually composed of a single terminal carpel. The ovules are chiefly supplied by branches from a ventral bundle complex, but that is supplemented by medullary bundles that are formed in the base of the gynoecium, below the loculus. It could be argued that these medullary bundles are surviving remnants of the vascular supply to a second carpel, no longer extant. A transmitting tract extends from the stigma about half the distance to the loculus. The tract is lined with unicellular glandular cells and is open from the stigma to the loculus.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09676.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Chromosome numbers are reported for 111 species of Compositae from Argentina, Chile, Costa Rica, Guatemala, Mexico, Paraguay, and Peru. These include first reports for 46 taxa, including 3 genera (KyrsteniopsisK.&R.:N= 10,EupatoriastrumGreenman:N= 16, andPiptothrixB. L. Robins.:N= ca. 17). The new combination, Decachaeta pyramidalis (B. L. Robins.) Sundberg, Cowan,&Turner, based onPiqueria pyramidalisB. L. Robins. is proposed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09677.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Reproductive characteristics of three sympatric species ofGentianaexhibiting perennial and non‐perennial life histories were studied in alpine meadows of the White Mountains of California during three consecutive years. High fruit and seed set and the production of a relatively large number of seeds characterized the alpine biennials,Gentiana tenellaandG. prostrata.In contrast, fruit and seed set were considerably reduced and yearly seed production was relatively low in the alpine perennial,G. newberryi.Successful seed production in the biennial species was a result of low rates of flower predation, self‐pollination, and the allocation of a comparatively high proportion of biomass to reproductive structures. Seed production in the perennial species was limited by high rates of flower predation, insufficient amounts of pollen reaching stigmas, an unusually late flowering period, and by the relatively small proportion of biomass allocated to reproduction.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09678.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

The location and activity of a K+‐ATPase in mature, dormant peas were investigated using two ultracytochemical techniques, as well as biochemical assays of plasma membrane fractions from separate seed parts. Both the Wachstein and Meisel (1957) and the Ernst (1972) cytochemical methods showed plasma membrane‐associated reaction product located primarily on the exterior surfaces of the entire pea embryo, except for the stem apex and tip‐most cells of the radicle. No plasma membrane‐assocated reaction product was found in the seed coat, which typically consists of cells with degenerating protoplasts. Biochemical results showed the highest specific K+‐ATPase activity in the radicles (775 nmol Pi/mg protein/hr), followed by epicotyls (168 nmol Pi/mg protein/hr) and cotyledons (147 nmol Pi/mg protein/hr). It is proposed that the entire pea embryo may function in the active absorption of nutrients during the initial phases of germination. Additional functions of the enzyme may include cell wall loosening prior to cell elongation, regulation of cytoplasmic pH, and the generation of turgor.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09679.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

The number of oil ducts in freehand sections of roots of eight carrot (Daucus carotaL.) genetic lines was compared to the levels of major volatile terpenoids. There was a high correlation (0.79) between number of ducts per unit area and total terpenoid amount. Individual compounds exhibited varying degrees of correlation, probably due to genetic difference between lines. Oil ducts often exhibited distinct patterns of concentric rings or radial lines, but this feature was not closely related to duct number. Oil ducts are present only in the phloem, and can form a highly interconnected network.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09680.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Isozyme analysis of 18 Northern Flint populations supports the previously published hypothesis that Northern Flint was derived from maize races of the southwestern U.S. and northwestern Mexico. Isozyme data also show that during its short evolutionary history (approx. 1,000 yr) Northern Flint obtained a degree of genetic differentiation from other North American maize landraces more typical of a separate species than of landraces of the same cultigen. Genetic drift, changes in selection pressure associated with movement into a new environment, and reproductive isolation from other maize races may have contributed to the genetic dissimilarity of Northern Flint.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09681.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

The gynoecium ofPhaseolus acutifoliusvar.latifolius, a self‐compatible legume, is characterized by a wet non‐papillate stigma, an intermeditae hollow/solid style type, and secretory cells on the ventral surface of the ovary which direct pollen tube growth. The stigma is initially receptive 5–6 days prior to anthesis. Production of stigmatic secretions, composed primarily of carbohydrates and lipids, fragment the cuticle covering epidermal cells of the stigma early in ontogeny; the lipidic aspect of the copious secretions apparently serves to inhibit desiccation after the cuticle is ruptured. Stylar canal development occurs as a combination of elongation of a basal canal present early in development, and dissolution of part of a solid transmitting tract tissue just below the stigma. Anthers dehisce and the tricolporate pollen is released onto the receptive stigma one day before anthesis. Following initial growth in intercellular spaces in the transmitting tract of the stigma, pollen tubes adhere to epidermal secretory cells along the ventral side of the stylar canal and upper ovary; here the transmitting tract is apparently limited in the number of tubes it can accommodate, providing a possible site of selection of male gametes.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb09682.x

出版商:Wiley    

年代:1986

数据来源: WILEY