摘要:

Six F1"grass-clump" hybrids, two "grass-clump" selections, three normal varieties (Timstein, Redman, and Federation), and three dwarf varieties (Sonora 64, CB 151, and Norin 10) were grown in growth cabinets under 1200 ft-c of continuous light at various temperatures. The normal and dwarf varieties grew tallest at 16 °C and produced maximum shoot and seed yields at 16–19 °C.The Marquillo × Timstein "grass-clump" dwarf selection (F6) tillered extensively in temperature regimes that included 16 h of 16 °C in 24 h or 16 h of 21 °C and 8 h of 16 °C. Fertile tillers were produced in all temperature regimes except 16 °C. Growth at temperatures above 21 °C was essentially normal. The Redman × Federation "grass-clump" dwarf selection (F6) produced many tillers, but no fertile tillers when grown in a temperature regime that included 16 h of 16 °C. Fertile tillers were produced in all other temperature regimes, but extensive tillering was observed if the temperature treatment included 8 h of 16 °C. Completely normal growth was observed at temperatures above 26 °C.The six F1"grass-clump" hybrids elongated and produced seed when grown at 30 °C.All "grass-clump" dwarf hybrids and dwarf selections investigated to date differ from normal varieties of wheat in that they are sterile dwarfs when grown at low temperature but grow essentially "normal" above a threshold temperature. Depending on the particular hybrid or selection the required temperature may be 21, 26, or 30 °C. In general, if the precise temperature requirements are not known, it appears probable that elongation and seed production by "grass-clump" dwarf can be induced by growing them under continuous light at 26 to 30 °C.

ISSN:0008-4026    

DOI:10.1139/b69-001

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The dikaryotic phase ofU. hordei, generally considered to be obligately parasitic, was forced to grow in culture by mixing auxotrophs of opposite mating types together in pairs on minimal medium. This in vitro system was used to carry out complementation tests with a group of 58 different arginine-requiring mutants, which were thus classified into 10 different complementation groups. More efficient methods for mating type determination and for screening of particular mutants from certain crosses were described.

ISSN:0008-4026    

DOI:10.1139/b69-002

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The ultrastructure of the chlorenchymatous tissues around the vascular bundles of three different types of grass leaves is described. In the temperate grass leaf, as exemplified by wheat, the inner mestom sheath contains proplastids. Normal chloroplasts are found only within the mesophyll cells. Smaller chloroplasts occur in cells of the ill-defined parenchymatic bundle sheath. This type of leaf has the photosynthetic pathway described by Calvin and a high carbon dioxide compensation value. In the tropical grasses,SorghumandAristida, the new photosynthetic pathway proposed by Hatchet al. and low carbon dioxide compensation are correlated with development of the parenchymatic bundle sheath. Cytological evidence indicates that cells of the bundle sheath are much more active than the surrounding mesophyll tissue. The specialized chloroplasts of the bundle sheath cells may be responsible for the physiological and biochemical differences between leaves of tropical and temperate grasses.

ISSN:0008-4026    

DOI:10.1139/b69-003

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A study of the histogenesis of the flower ofAgave parryiwas made using serial sections as well as three-dimensional views of dissected floral primordia. It is shown that floral ontogeny supports the appendicular interpretation of the inferior ovary ofAgave parryiin that the flower parts do not arise from a smooth, ring-like meristem located at the tip of the pedicel but, rather, the flower parts arise as separate primordia. This study corroborates an investigation by Kaplan which shows that ontogeny can be used to support, rather than contradict, floral vasculature in interpreting the appendicular nature of the inferior ovary.

ISSN:0008-4026    

DOI:10.1139/b69-004

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Canonical correlation analyses were performed to determine relationships among seed-viability, fungi, and environment in two bulk grain ecosystems. Measurements of 20 variables were made on 8135 samples from two wheat bulks in a farm granary in Winnipeg during 1959–1967. The canonical vectors were interpreted by correlating each set of two canonical variates with the original variates on which they were based. The highest and the second highest significant (P < 0.001) canonical correlation for each combination were field fungi and germination vs. non-biological environment, 0.91 and 0.32; storage fungi vs. non-biological environment, 0.77 and 0.42; field fungi and germination vs. storage fungi, 0.78 and 0.35. In aging grain bulks the attack of the storage fungiChaetomium funicolum, Streptomyces griseus, Aspergillusspp., andRhizopus arrhizusinvolves the loss of grain viability and decrease in the field fungi,Alternaria tenuis, Cochliobolus sativus, andGonatobotrys simplex. Collectively grain temperature and the granary conditions are most important in the reduction of the field fungi; whereas temperature, moisture content, and time are most involved in the infestation ofS. griseus, Penicilliumspp.,C. funicolum, Aspergillusspp., andR. arrhizus.

ISSN:0008-4026    

DOI:10.1139/b69-005

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Marquillo × Kenya Farmer wheat dwarfs 1 and 2 were grown at 16 °C (inhibited "grass-clump" habit), at 21 °C and at 26° (normal habit). The parent varieties were grown under the same conditions for comparison.Analysis of the dwarf strains grown at 16 °C revealed that there was no deficiency of soluble carbohydrate, amino acids, organic acids or chlorophyll when compared to the parent varieties or to the dwarf strains grown at 26 °C. Rather there was marked accumulation of most of these substances in the non-growing plants at 16 °C. The results are consistent with the view that the suspension of growth in the dwarf plants is not due to the lack of ability to synthesize organic metabolites but rather that an inhibitor is accumulated during the low temperature treatment that blocks growth by some other mechanism.

ISSN:0008-4026    

DOI:10.1139/b69-006

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Crumenulopsisnom. nov. is proposed to replace the illegitimate nameCrumenulaRehm, together with a discussion of the nomenclatural problems involved. Two new combinations,Crumenulopsis pinicola(Fr.) andC. sororia(Karst.), are proposed.

ISSN:0008-4026    

DOI:10.1139/b69-007

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A "grass-clump" dwarf wheat, Marquillo × Kenya Farmer 2 was grown in growth cabinets under continuous light or a 16-h photoperiod and a temperature regime of 8 h 21 °C and 16 h 16 °C. Plants were treated singly or with combinations of gibberellic acid (GA), indolebutyric acid, and kinetin. Indolebutyric acid and kinetin had no effect on plant height or development and did not alter the response to gibberellic acid. Gibberellic acid treatment increased culm height and induced plants to flower earlier but suppressed final yields of shoot and seed. Continuous light decreased plant height, time to ear emergence, and tiller number but did not alter shoot or seed yields.Marquillo × Kenya Farmer wheat dwarf 2 and Marquillo × Kenya Farmer wheat dwarf 1 were grown in growth cabinets under continuous illumination at various combinations of soil and air temperature. Plants were treated with gibberellic acid at 2-day intervals. The primary low temperature lesion in the grass dwarfs appears to affect early vegetative growth and leads to a premature cessation of the development of each tiller. If growth ceases before sufficient leaves are produced, the plants cannot become reproductive. Continuous light and GA treatment promotes reproductive development because both promote floral initiation at an earlier vegetative stage, i.e. a lower leaf number. Thus, if the temperature conditions allow the plants to grow to this vegetative stage before growth ceases, they will become reproductive if treated with GA but will not become reproductive if untreated. At 26 °C, where control plants develop normally, GA treatment results in earlier heading but much reduced seed yields.

ISSN:0008-4026    

DOI:10.1139/b69-008

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

In the fernOsmunda cinnamomea, leaf primordia may be excised and grown in sterile culture before or after their irreversible determination as leaves. It has been demonstrated that P3primordia (third most recently formed primordia) are not irreversibly determined as leaves at the time of excision for they exhibit a tendency to develop as whole shoots (approximately 67.0% of the time) whether grown singly, or as pairs grown in physiological contact. Results from the present investigation support the hypothesis that a morphogenetic factor(s) is found in older primorida which is transmitted to younger primordia to influence the latter to develop as leaves rather than shoots, for P3's grown in physiological contact (as pairs) with P10, P12, or P13primordia are expressed as leaves at a level approximately twofold or greater than P3's grown singly (controls). Results from the present investigation donotsupport the hypothesis that increased bulk of tissue, and therefore increased capacity for nutrient productivity by older and larger primordia, is responsible for imposition of leafness on undetermined P3primordia, for P14primordia grown in physiological contact with P3primordia (as pairs) are observed to increase the percentage of P3's expressing leafness at a levelonly slightly greaterthan P3's grown singly, and slightly less than when P3's are grown in physiological contact with other P3's as pairs. The slight enhancement in leafness exhibited by undetermined P3's grown as pairs with other P3's, or with P14's has been shown to be non-significant at the 5% level (P < 0.05) by the standardttest and Kramer's (1956) modification of Duncan's (1955) new multiple range test.

ISSN:0008-4026    

DOI:10.1139/b69-009

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Further evidence is presented in support of the hypothesis that a morphogenetic factor, or factors, is present in older primordia which is transmitted to younger primordia to influence the latter to develop as leaves rather than shoots. P3primordia, undetermined at the time of excision, are expressed asleavesat a level of 60.0% when explanted to a simple, defined medium containing, in addition, homogenate of determined P12primordia and at a level of 70.0% when grown on medium containing homogenate of P13primordia. By contrast, undetermined whole P3's are expressed asshootsapproximately 70.0% of the time when excised and explanted to: (1) a homogenate-free medium, or (2) medium containing homogenate of undetermined P3's. Of greater significance is the observation that undetermined P3's are expressed asshootsat approximately the same level when excised and explanted to medium containing homogenate of determined P14primordia. The relevance of these phenomena to a physiological aging process is briefly discussed.

ISSN:0008-4026    

DOI:10.1139/b69-010

出版商:NRC Research Press    

年代:1969

数据来源: NRC