摘要:

Reciprocal crosses of Upland cotton with a hybrid derived from (Gossypium anomalum×G. thurberi) ×G. hirsutumproduced progenies differing significantly in anther development and in the production of supernumerary ovules outside the ovary. Plants withG. anomalumcytoplasm produced fewer anthers than the reciprocal hybrids withG. hirsutumcytoplasm, had a higher percentage of sterile anthers, and were far more likely to form external ovules on an abnormally thickened tip of the staminal tube. The number of locules and ovules within the ovary was not significantly affected by cytoplasm.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06688.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

The life cycle of 2 varieties ofNetrium digitus,a saccoderm desmid, was studied in pure culture on mineral media.Netrium digitusvar.digitusfrom Indiana is homothallic, andNetrium digitusvar.lamellosumfrom Minnesota is heterothallic. Previous observations by other investigators on the events of the sexual cycle are confirmed and extended. Zygospores of both varieties are formed in the conjugation tube. Fusion of gametic nuclei occurs after the dormant period of zygospores, and meiosis occurs at the time of germination. Conjugation is induced in a reliable manner in both varieties by omitting nitrogen from the medium and by exposing the cultures to the proper conditions of light and temperature. The relationship between photoperiod, nitrogen depletion, and induction of conjugation is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06689.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

The carpels inCrataegus, Hesperomeles, Mespilus,andOsteomelesappear to constitute a morphologically related group: all have bony pits, ovules that tend to be acollateral (usually superposed), and clearly separate ovular and wing bundles, i.e., no “ventral” bundles, at the level of ovular insertion. In species whose carpels have no sutural opening, the integuments are more extensively fused with one another, the degree of intercarpellary fusion tends to be greater, and the carpels are fused with the floral cup to relatively higher levels than in those species whose carpels have a sutural opening. In the few cases in which wing and ovular bundles are adnate at the locular base (Crataegus monogyna, Mespilus, Osteomeles anthyllidifolia, O. Schwerinae), the extent of inter‐ and extracarpellary fusion and sutural closure is among the most advanced.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06690.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

A mosaic pattern of leaf variegation in a sector on a normal green tobacco seedling resulted from maturation of both green and white cells within the tissue derived from the second histogenic layer (L–II) of the shoot apex. While mature cells of L–II origin contained either green plastids or colorless plastids, single cells in young leaves contained both normal green plastids and colorless, defective mutant plastids. The genetic determiner of the defective plastid type, designated DP1, was located in the plastid itself. Only a small number of mutant plastids were found in anyone cell. A threshold number of DP1above which green plastids were inhibited and below which they developed normally is suggested. Random segregation of DP1and dP1in cytokinesis, close to the threshold value and without loss of either determiner, could account for the small, intermingled patches of green and white cells derived from the mosaic histogenic layer. The mosaic histogen usually remained mosaic; however, complete segregation during mitosis to DP1or dP1occasionally occurred in sectors within which lateral buds developed in a stabilized condition, either normal or mutant (green or white). Occasional replacement of L–III by L–II apparently introduced the mosaic condition into L–III of the original variegated plant and resulted in an additional pattern of variegation. Patterns of variegation in which the sporogenous tissue was derived from a stable L–II with homoplastidic cells produced only green or only white offspring. Variegated seedlings were obtained only when L–II was mosaic. Contrasting statements on the inheritance of variegations appearing in the literature result from failure to describe accurately the pattern of variegation. Description in terms of plastid types in mature histogens is essential, and plastid segregation in somatic tissue of mosaic L–II must be determined. Variegation should only be used as a general term and further described as stable when the histogens are homoplastidic or mosaic when the histogens are heteroplastidic. Complete description of the inheritance of a plastid mutant must record inclusion or loss in successive cell generations of sexual seedlings. DP1is inherited only maternally and is found in fewer of the offspring than expected on the basis of its segregation in mitosis. When present in the egg cell and, therefore, the zygote, DP1can be included in all 3 histogenic layers of the seedling, thereby producing many more variegated patterns than were possible from the original mosaic plant.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06691.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

The tolerance ofMusa balbisianaColla seeds to gamma irradiation was found to be considerably greater than that of rhizomes of the parthenocarpic variety ‘Gros Michel': e.g., 11.8 krad reduced the germination of rhizomes 92% and of seeds approximately 15%. Intact seeds exposed to doses higher than 48 krad did not germinate in non‐sterile soil, but, when scarified and cultured axenically after irradiation, seeds which received doses as high as 70 krad germinated. Embryos excised from seeds exposed to doses as high as 285 krad formed callus, indicating that not all metabolic processes were inhibited by these extremely high doses. There was considerable variation in radiation tolerance between seed lots which was not related to their age, moisture content, or pre‐exposure viability. Germination of intact seeds appeared to be stimulated by doses of 3 or 9 krad. No lasting differences attributable to the level of irradiation were apparent in the development of seedlings derived from either intact or scarified seeds nor of plantlets derived from excised embryos. Conversely, there was a significant reduction, proportional to irradiation dose, in the growth of plants developing from rhizomes, emphasizing the greater radiation sensitivity of the vegetative propagule. The radiation tolerance of seed‐borne microorganisms was considerably higher than that of the plant materials, indicating that gamma irradiation is not effective as a means of obtaining pathogen‐free rhizomes or surface‐sterilizing seeds ofM. balbisiana.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06692.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Apogamous sporophytes formed onPteridiumgametophytes in response to concentrations of certain sugars which supported gametophytic growth. High osmotic concentration of the medium inhibited apogamy, while variations in the basic medium were not stimulatory. Agar, autoclaving, the ammonium ion, and dry media were not required for apogamy. Renewing the medium during an experiment enhanced the apogamous response. Changing the medium at set intervals facilitated the separation of apogamous plant development into gametophytic, initiative, and developmental phases, thus enabling testing of various factors at each of these stages. Apogamy was light‐initiated, while the actual development of apogamous sporophytes was caused by light, succinic acid or sugar.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06693.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Inorganic and organic metabolites, including carbohydrates, amino acids, and organic acids, may be leached from the foliage of 125 diverse plant species by the action of rain, dew, and mist. Ca45, P32, and Sr89absorbed by roots, and C14absorbed as C14O2by foliage were leached from squash leaves and were subsequently reabsorbed by the roots and translocated to the aboveground parts of several plant species. This phenomenon of nutrient recycling is apparently a widespread natural phenomenon and has implications in plant nutrition. Bean plants were grown through 1 complete generation on the leachates from squash leaves. Leaching and reabsorption of the leachates are important in the distribution of fallout products, in the stimulation and suppression of plants beneath the spread of other plants, in plant competition, and in the development of plant associations.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06694.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Excised shoot apices ofOsmunda claytonianawere grown under controlled sterile conditions. Histological examination of the normal shoot apex shows that it is comprised of: (1) a promeristem, which possesses 1 or more apical initiating cells at its center; (2) a prestelar tissue consisting of an incipient vascular tissue which flanks the pith‐mother‐cell zone; the pith‐mother‐cell zone gives rise to the pith rib meristem and subsequently to the fundamental parenchyma of the pith; (3) the fundamental parenchyma of the cortex and the fundamental parenchyma of the dermal system both arising from flank cells of the promeristem. Apical initial cells of meristems irradiated with a 127,000 rad acute exposure of a deuteron beam having a diameter of 25μ, histologically examined at 7‐day intervals for a 12‐week period, as early as 3 weeks’ postirradiation, showed the apical initiating cell(s) together with certain of the cells of the pith‐mother‐cell zone to be destroyed. A wound response develops peripherally to the destroyed initials. In addition, an isolated, organized growth center is observed to develop from normal promeristem cells. Incipient vascular tissue and a new pith‐mother‐cell zone are also observed to develop in association with the new center of growth. Implications of the role of the interrelationships between apical initiating cell(s) and other cells of the meristem and the role they may play in maintenance of meristematic integrity within the shoot meristem are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06695.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

A new technique for estimating pollen viability utilizing Nitro Blue Tetrazolium (Nitro‐BT) is given. Pollen of 16 taxa was studied and scored for stainability. A comparison was made between Nitro‐BT‐stained pollen samples and aniline‐blue‐lactophenol‐stained samples, because the validity of the latter stain has been questioned in recent years. It is demonstrated that Nitro‐BT can discriminate between pollens which have a capacity for oxidative metabolism, representing potential viability, and those which do not. Suggestions for pollen stainability studies are given.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06696.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Manometric methods were developed to allow short‐time measurements on relatively small amounts of cell material. The methods provided measurement of the nitrogen uptake and oxygen evolution attributable to nitrogen fixation either in the presence or absence of carbon dioxide. The methods were applied to observe effects of cell history, light intensity, temperature, pH, and ammonia on nitrogen fixation and photosynthesis with 2 new and significant findings. Nitrogen fixation is markedly accelerated by a preceding period of cellular nitrogen depletion. Nitrogen fixation is depressed by light intensities greater than those required to saturate photosynthesis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06697.x

出版商:Wiley    

年代:1964

数据来源: WILEY