摘要:

Gillett, GeorceW. (Michigan State U., East Lansing.)An experimental study of variation in the Phacelia sericea complex.Amer. Jour. Bot. 48(1): 1–7. Illus. 1961.—ThePhacelia sericeacomplex consists of 2 diploid (n= 11), intergrading species,P. idahoensisandP. sericea.The experimental culture of several races of this complex demonstrated that differences in pubescence, leaf shape, and flower shape persist in plants grown in a common environment. Experimental interspecific F1hybrids demonstrated high fertility; portrayed intermediate expressions of pubescence, leaf shape, and flower shape; and were found to be, in many cases, indistinguishable from many wild intermediates. A study of herbarium specimens revealed numerous intergrades in which pubescence, leaf shape, and flower shape are highly variable, though loosely correlated. The evidence obtained from herbarium specimens, greenhouse cultures, field investigations, chromosome studies, and experimental hybridizations suggests a hybrid origin for the wild intermediates, recognized asPhacelia sericea(Graham) A. Gray subsp.ciliosa(Rydb.) Gillett.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11595.x

出版商:Wiley    

年代:1961

数据来源: WILEY

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11596.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Paolillo, DominickJ., Jr., and ErnestM. Gifford, Jr. (U. California, Davis.)Plastochronic changes and the concept of apical initials in Ephedra altissima.Amer. Jour. Bot. 48(1): 8–16. Illus. 1961.—The occurrence of distal mitoses and the differentiation of derivatives of the distal cells of the apex ofE. altissimaare correlated with stages of the plastochronic cycle. The relative rates of growth of elements within the various regions of the apex are characterized in terms of elongation gradients. The numbers of mitoses found in median sections of individual apices are recorded. It is concluded that the distal zone is the source of all other cells of the apex and should be regarded as a zone of initials. The concept of“méristème d'attente”and“anneau initial”is discussed in relation to the observations made onE. altissima.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11597.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Gowing, DonaldP. (Pineapple Research Institute of Hawaii, Honolulu.)Experiments on the photoperiodic response in pineapple.Amer. Jour. Bot. 48(1): 16–21. 1961.—The initiation of flowering of ‘Smooth Cayenne’ pineapple plants is neither strictly a response to photoperiod (day lengths of 10 hr. 51 min.–13 hr. 24 min.) nor to a minimum temperature (minima from 50° to 72°F. in different areas) under natural Hawaiian conditions. Depending on the kind of planting material used and the time of planting, natural initiation of flowering may take place any month of the year. Slips planted in the fall generally initiate flowering in December of the following year. However, exposure of an 8‐mo.‐old slip‐planting to a day length of 8 hours for 40 days starting Sept. 8 induced flowering irrespective of night temperatures from about 60 to 80°F. Interruption of the dark period by illumination at 30 ft.‐c. from midnight to 1 a.m. suppressed the inductive effect. Lowering the night temperature to 60°F. was, of itself, non‐inductive. Field‐grown, 11‐mo.‐old plants treated in place responded similarly, in that 25 periods of 8‐hr. day length starting Sept. 5 induced 60% of the plants to flower, and the night illumination suppressed the inductive effect as before. Daily application of 0.12 mg. of the major native pineapple auxin (indole‐3‐acetic acid) at the beginning of the dark period had no detectable effect on the short‐day treatment, and similar application of an antiauxin (4‐chlorophenoxyisobutyric acid) did not affect the suppression of flowering by the light‐break. Supplemental illumination of field‐grown 12‐mo. plants to provide a photoperiod of more than 15 hr. daily from Nov. 4 to Jan. 30 did not suppress the natural initiation of flowering which occurred in early December (day length about 10 hr. 50 min.). ‘Smooth Cayenne’ pineapple is therefore a quantitative, but not an obligate, short‐day plant.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11598.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Zabka, GeorgeG. (State U. Iowa, Iowa City.)Photoperiodism in Amaranthus caudatus. I. A re‐examination of the photoperiodic response.Amer. Jour. Bot. 48(1): 21–28. Illus. 1961.—Under the conditions described in this study,Amaranthus caudatusis not subject to inductive short days until it has reached its “sensitive period” or age which is approximately 30 days after the time of germination. Beyond this sensitive period, 2 days are sufficient to initiate inflorescence primordia. Macroscopic identification of this response is possible 2–3 days later, if the plants are retained on short photoperiods. Continued development of the inflorescence is also promoted by short days. This species will also initiate inflorescence primordia on long days of 18 hours duration approximately 60 days beyond germination. Consequently, this is not an obligate short‐day plant as previously described. AlthoughA. caudatuswill initiate primordia on long days, subsequent normal development of the inflorescence proceeds only under short photoperiods. Plants initiating primordia on long or short photoperiods and then placed on long photoperiods will produce inflorescences which are stubby, generally recurved and spread at the apices. Subsequent flowering and seeding is also delayed. Plants initiating primordia on long days and then placed on short days develop mature inflorescences rapidly but they are divided at the apices and exhibit numerous basal branches.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11599.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Jaranowski, J. K. (Coll. of Agriculture, ul. Wojska Polskiego 71c, Poznan, Poland.)Semisterility in the interspecific hybrid Melilotus polonica × M. alba.Amer. Jour. Bot. 48(1): 28–35. Illus. 1961.—Interspecific hybrids betweenMelilotus polonica(n= 8) andM. alba(n= 8) are readily secured. The F1hybrids are intermediate between the parents and partially sterile with a mean percentage of 58.8 (ranging from 46.8 to 72.6) defective pollen grains. Six bivalents and a chain or ring of 4 chromosomes occur at diakinesis and metaphase‐I of microsporogenesis. A crossshaped configuration characteristic of a reciprocal translocation is present at pachytene, indicating that one of the parents is homozygous for an interchange of relatively large section between two of the members of the chromosome complex. Chromosome bridges, lagging chromosomes, movement of the univalents to the same pole and precocious division of the univalents lead to aberrant chromosome distribution during the course of meiosis. Reduction in self‐fertility indicates a corresponding aberrant distribution of chromosomes during megasporogenesis. Pollen sterility in the F2generation ranged from 24.8% to 72.5% with a mean value of 54.6%. Two plants in the F2generation which had relatively low pollen sterility proved to be aneuploids (2n+ 1). Meiotic irregularities in the F2plants were comparable to those exhibited by the F1plants.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11600.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Alston, R. E. (U. Texas, Austin), and H. S. Irwin.The comparative extent of variation of free amino acids and certain “secondary” substances among Cassia species.Amer. Jour. Bot. 48(1): 35–39. Illus. 1961.—Five species ofCassia, selected to include 4 sections of the genus, were examined by chromatographic methods for free amino acids and for substances visible in ultraviolet light, visible light and after spraying with a general reagent for phenols. The latter, representing a heterogeneous group, are referred to as “secondary” substances (implying that they are not intimately involved in basic energy transfer or assimilative activity of all tissues). Among the species examined there was definite but only moderate variation in the free amino acids present, and differences were predominantly quantitative. In contrast, a minimum of 25 “secondary” substances appeared on the chromatograms when viewed in ultraviolet light and ammonia vapor, with no more than 9 of the spots present in a single species. While free amino acid patterns may be useful in themselves, it seems that patterns of variation of “secondary” substances offer a greater potential in taxonomic work.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11601.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Klingensmith, M. J. (Colgate U., Hamilton, N. Y.)The effect of certain benzazole compounds on plant growth and development.Amer. Jour. Bot. 48(1): 40–45. Illus. 1961.—A number of benzazoles, in particular benzimidazole, benzothiazole, and benzotriazole, were examined for their effects on growth of seedlings and established plants. Benzothiazole was the most active in repressing elongation of the primary root of cucumber. Benzimidazole and benzotriazole were about 1/10 as active. Adenine was without effect in reversing the benzazole‐induced inhibition of cucumber root elongation and, in fact, supplemented the inhibition caused by benzimidazole and benzothiazole. Application of benzotriazole to the root medium of bean, coleus, tomato, oat and wheat caused a pronounced inhibition of internodal elongation with a stimulation of axillary development. Distinct morphological changes were observed which did not correspond to those produced by other growth regulators. Application of benzimidazole to the root medium of several genera of plants resulted in injury to laminar tissue followed by desiccation, with no concomitant effect on the stem. Application of benzothiazole to the root medium induced development of adventitious roots in bean and tomato. This compound also caused initiation of roots on cultures of tobacco‐stem segments, while not suppressing bud development. The benzazoles tested seem to be of a different class of compounds from other growth regulators which have been studied. The responses elicited by treatment with each of the 3 benzazoles are distinctly characteristic and are dependent on the structure of the azole portion of the molecule.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11602.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Wilson, JamesF. (Hartnell Coll., Salinas, Calif.)Micrurgical techniques for Neurospora.Amer. Jour. Bot. 48(1): 46–51. IIlus. 1961.—Procedures for carrying out micrurgical operations on the mold,Neurospora crassa, are described. These procedures include interstrain transfer of protoplasm, micro‐injection of fluids, excision and culture of injected cells. The special microtools and culture methods for these micrurgical procedures are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11603.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Stebbins, G. L., and G. S. Khush. (U. California, Davis.)Variation in the organization of the stomatal complex in the leaf epidermis of monocotyledons and its bearing on their phylogeny.Amer. Jour. Bot. 48(1): 51–59. Illus. 1961.—Using macerated pieces of epidermal tissue from living plants and herbarium specimens, stomatal complexes of 192 species belonging to 49 families of monocotyledons were studied. Four categories are recognized, 2 with 4 or more subsidiary cells surrounding the guard cells, 1 with 2 subsidiaries, and 1 with none. Development of the 2‐subsidiary type, studied in acetocarmine preparations ofJuncus effususandSagittaria montevidensis, resembles that in Gramineae previously described. No correlation was found between type of stomatal complex and either leaf shape or type of xylem vessel, but some correlation exists between this character and type of seed germination, vascular anatomy of seedling, growth habit of mature plant, and geographic distribution. Types with 4 or more subsidiaries are most commonly phanerophytes with tropical distribution, many vascular bundles in the cotyledon, and hypogeal germination. Complexes with 2 subsidiaries occur in many families of a diverse nature, but the most primitive plants with this type are hydrophytes or helophytes with tropical or temperate distribution, 1 vascular bundle in the cotyledon, and epigeal germination. Stomatal complexes without subsidiaries are almost confined to the Liliales and their more specialized derivatives. These plants are predominantly geophytes with temperate or tropical distribution, 2 bundles in the cotyledon, and epigeal germination. Reasons are advanced for suggesting that the type with many subsidiaries is the most primitive and the other 2 types have been derived from it independently by reduction of the number of subsidiary cells.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11604.x

出版商:Wiley    

年代:1961

数据来源: WILEY