摘要:

Genetic differentiation, physiological homeostasis, and heterozygosity were contrasted in the closely related octoploid speciesFragaria chiloensisandF. virginiana, and in one of their putative diploid progenitorsF. vesca. Plants from 27 natural sites supporting strawberry colonies were collected and grown in a common greenhouse. They were analyzed for 18 quantitative traits and three enzyme loci. Intra‐ and inter‐populational variation was measured using analysis of variance techniques. Micro‐ and macro‐environmental measurements were made at each site. Phenotypic stability of octoploid and diploid individuals was contrasted across four environmental regimes. The octoploids displayed more morphological variation, were more heterozygous, had greater physiological homeostasis, and were found across a broader range of environments. Octoploid strawberries may have broader ecological ranges than the diploids, both because they have higher levels of physiological homeostasis, and also because they have undergone more genetic differentiation. The higher levels of physiological homeostasis may be due to the fact that they are more heterozygous than the diploids.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06348.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

Seedlings ofSpartina alternifloraLoisel., from seed harvested from nine marshes ranging from Maine to Virginia, were grown for three seasons in plots established on two different soils in Delaware and were flooded regularly with water from two estuarine sources. Substantial differences in the time of flowering were observed. Each year plants from Maine seed flowered first and were followed by those from Connecticut and New York. Last to flower were plants from Virginia seed. The latter initiated flowering after flowering of the Maine source had been completed. These two would not cross‐pollinate under this circumstance. The phenology of anthesis and number of seeds set on inflorescences enclosed in bags indicate that this species is largely open pollinated.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06349.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

Reduction in the supply of photosynthate to the roots of tomato, barley, and wheat plants was achieved indirectly by lowering the intensity of sunlight striking the foliage of test plants. The decrease in sugar and starch concentrations in the roots was verified by appropriate extraction and colorimetric analysis, and a corresponding reduction in the total respiratory rate of the roots was confirmed using an oxygen tension monitor. Other processes measured directly include the rate of uptake of potassium, the mitotic quotient in the root tip—a measure of growth—and the rate of accumulation of dry matter in the root. The study demonstrated that of the metabolic activities observed, root growth is the process first limited when the supply of photosynthetic fuel is decreased. Root growth was severely inhibited under conditions that did not significantly affect either the active uptake of potassium per gram of root or total respiration per gram of root. With greater restriction of photosynthesis, growth was completely halted while the uptake of potassium was strongly decreased and total respiration was still affected only moderately. As the light intensity is reduced significantly, most of the reduced energy supply in the root appears to be used in support of processes critical to maintenance of the organ and the organism.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06350.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

Vegetative plants were induced to flower by 16‐hr‐long days. Apical buds were collected at intervals during several developmental phases up to 63 hr. A stereologic analysis and mitotic index study was conducted on median longitudinal sections of shoot apical meristems. A rise in the mitotic index occurred between 12 and 24 hr within central, peripheral and pithrib meristem zones. Preceding the floral stage a second increase in the mitotic index was observed in peripheral and central zones, but not in the pith‐rib meristem zone. A significant rise in apical volume, cell number, height, and width began in the transitional stage and continued to the floral stage. Significant correlation coefficients were observed between these apical parameters. Relative volume and cell population of each zone remained constant from the vegetative to the reproductive stage. Volume fraction occupied by the nucleus and nucleolus remained constant within each zone during the same time period. In each zone the volume of the nucleus was significantly correlated to volume of the nucleolus. It appears a pre‐inflorescence apex, while larger, is structurally similar to a vegetative apex.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06351.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

A 22‐year‐old stand of coastal sage scrub in the coastal mountains of southern California had a peak standing aboveground biomass of 1,417 g/m2, determined by dimension analysis. Annual aboveground net primary production was 255 g/m2/yr, determined by monthly twig harvests of dominant species and the clipping production of subordinate species. The stand was codominated by two drought‐deciduous species,Salvia leucophyllaandArtemisia californica, which together comprised 81% of the biomass. Annual litterfall was measured at 194 g/m2/yr. These biomass, production, and litterfall values are less than those measured in most evergreen chaparral communities in California.Seasonally, the two dominant shrubs began aboveground production in the winter soon after the first rains and continued growth for six months until early summer. A massive leaf fall occurred in May–June as the summer drought began, but twig and inflorescence production for both species continued at a high rate into the summer months.Salvia leucophyllahad two shoot types: 1) an early spring canopy shoot that elongated rapidly, produced the inflorescence, and died in mid‐summer; and 2) a short side shoot produced in late spring with small dense leaves that were retained during the summer drought and early winter.Artemisia californicaproduced a single cohort of twigs in the early spring, most of which carried inflorescences by late summer.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06352.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

Fertilization inPeridinium cinctumf.ovoplamtmhas been investigated at both the light and electron microscopic levels. Gamete formation occurs when vegetative cells are placed into nitrogen deficient media. The majority of gametes observed possess thin thecal plates; however, some are naked. Gametes have few chloroplasts as compared to vegetative cells, numerous membrane bounded storage bodies, many starch grains, and chromosomes which appear slightly unwound. Gamete fusion is observed to peak 7–10 days after inoculation into nitrogen deficient media. Fusion occurs in an area of the sulcus devoid of reticulate thecal plates at or adjacent to the flagellar pores. A fertilization tube is formed and proceeds to widen along the sulcus. Karyogamy occurs within the fertilization tube before plasmogamy is completed. The resulting planozygote is a two walled structure containing two longitudinal flagella. It enlarges over a 2‐week period giving rise to the hypnozygote.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06353.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

The proteins in the oilseeds of species from 11 families, including sunflower, mustard, linseed, almond, lupin, peanut, cucumber, Brazil nut, hazelnut, yucca, castor bean, and cottonseed were studied. Sucrose gradient centrifugation showed that a substantial proportion of the total seed protein from each species migrated with a 2S sedimentation coefficient. The 2S proteins, being water‐soluble and thus termed albumins, comprised 20–60% of the total seed proteins, while faster migrating globulins comprised the rest. The amino acid compositions of the 2S proteins were characterisitic of storage proteins by having a high amide content. However, the 2S proteins are different from the classical globulin storage proteins in having a high content of cysteine. It is proposed that 2S albumins are seed storage proteins with a wide distribution and with chemical properties distinct from those of the globulin storage proteins. They play an additional and unique role of providing sulfur reserve for germination.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06354.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

Tapeinochilospollen, like that of most angiosperms, is spared by the standard acetolysis treatment because the sporoderm is impregnated with sporopollenin. This genus and its allies in the Costaceae are the only taxa in the eight families of Zingiberales that have acetolysis‐resistant pollen. The sporoderm in most of the order is characterized by exine reduced to a wispy coating or layer with delicately anchored spinules and a highly elaborated intine. Ultrastructural studies on the pollen ofTapeinochilosreveal a pattern of wall development that is significantly different from the generalized angiosperm type; namely, there are no columellae, nor is there any significant accretion of sporopollenin following the dissolution of callose and release of microspores. The primexine is composed of rodlets which build up solidly between apertures and become packed into layers to form a thick, stratified exinous covering. No secondary exine develops during the free spore period and the juvenile primexine persists as the protective coat on the mature pollen grain. This pattern of pollen development is viewed as an example of neoteny in which a juvenile or immature character is retained in adulthood.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06355.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

Glandular trichomes occur on both surfaces of leaves of all examined genera and species of the subtribe Pleurothallidinae (Orchidaceae). Trichome initiation is effected by one periclinal division of a protodermal cell, producing a thin‐walled, globose apical cell with a relatively large nucleus and a subapical stalk cell with heavily cutinized lateral walls. In some species a second periclinal division produces a third small basal cell also having thick lateral walls but thin transverse walls. As leaf development proceeds, the trichome apparatus assumes a sunken position due to continued anticlinal divisions of protoderm. Prior to laminar expansion and guard‐mother‐cell division on the abaxial surface, the wall of the apical cell ruptures and is replaced by a brown opaque residue. Finally, after vascular tissue differentiation and the cessation of meristematic activity, two or more pitted foot cells develop at the base of the trichome and adjacent to the water‐storing hypodermal layers. Preliminary investigations indicate that the trichome apparatus is absorptive throughout its development and similar in function to tillandsioid scales in Bromeliaceae.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06356.x

出版商:Wiley    

年代:1981

数据来源: WILEY

摘要:

Throughout the range ofIpomoea panduratain North and South Carolina, ants and wasps are attracted to the pedicellar extrafloral nectaries. These hymenopterans are aggressive toward phytophagous insects that visit the plants. Protection of the plant is afforded by these pugnacious hymenopteran nectar feeders.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1981.tb06357.x

出版商:Wiley    

年代:1981

数据来源: WILEY