摘要:

Translocation of each of seven amino acids and three amides was measured for periods of 5 minutes or less after introduction through the cut petiole of a primary leaf. The compounds used were asparagine, urea, glutamic acid, glutamine, glycine, norleucine, arginine, serine, alanine, and aspartic acid. During the short times of these experiments it was found that each compound was translocated downward as such. The amount of carbon-14 in the stem decreased logarithmically from the point of introduction. Each compound was translocated with unchanged velocity past a short section of stem killed with steam. There was no translocation of aspartic acid through a stem that had an entire internode killed with steam. Potassium cyanide (10−2 M) did not inhibit the velocity of translocation of any of the compounds although the logarithmic pattern of distribution of arginine was altered. The minimum velocity of translocation was different for each compound and varied between 350 cm per hour for asparagine and 1400 cm per hour for aspartic acid.

ISSN:0008-4026    

DOI:10.1139/b59-034

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Each of 10 C14-labelled amino acids or amides was introduced into young soybean plants through the cut petiole of one primary leaf. The compounds used were asparagine, glutamine, urea, aspartic acid, glutamic acid, glycine, serine, alanine, norleucine, and arginine. The rates of uptake of all the solutions except arginine were in the range 1.0 to 1.5 μl per minute. After 1 to 5 minutes, the distribution of C14throughout the plants was determined. Each amino acid was translocated as such without conversion to other compounds. From the point of introduction, translocation of each amino acid or amide was mainly downward toward the root; very little was translocated upward. The amount of asparagine or glutamine that was translocated into the primary leaf opposite the cut petiole increased as the leaf aged, while the amount of the other eight compounds decreased as the leaf aged. When asparagine and serine were administered together, serine moved into the young primary leaf while asparagine was excluded. Both excision of the roots and chilling the roots decreased the velocity of downward translocation of aspartic acid indicating that the roots exert a strong "demand" which favors translocation in a downward direction more than an upward direction in the stem.

ISSN:0008-4026    

DOI:10.1139/b59-035

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Peroxidase is detectible in all tissues but is most reactive, in the basophilic cells of the histogens. Oxidation of applied phenols and aminophenols by peroxidase produces quinones and quinonediimines that are adsorbed by nucleic acids and other basophilic substances in the formative centers of primordia. Localized reactions for peroxidase occur in the axils of leaf primordia prior to bud formation and on the surface of apical meristems in a spiral pattern marking the points for the future development of leaf primordia. Peroxidase is detectible in advance of or accompanying cell division and declines after the division phase; decline of peroxidase at the end of the division phase is related to the increase of phenols, naphthols, and phenolases. Peroxidase declines in all tissues except the phloem; a continuous peroxidase system in the phloem connects primordia with adult tissue. The hypothesis is offered that the cellular units of the phloem peroxidase constitute a continuous system between primordia and adult tissue and is functional in catalyzing the reduction of hydrogen acceptors essential to cell division and the initiation of primordia.

ISSN:0008-4026    

DOI:10.1139/b59-036

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Experiments were carried out to determine the role ofPratylenchus penetrans(Cobb, 1917) Filip. & Stek. 1941 in the peach replant problem. It is shown that this nematode is a true plant pathogen since it invades and causes necrosis of peach roots in the absence of bacteria and fungi. Necrosis of the root tissue occurs rapidly and appears to take place in advance of the invading nematode. The main mechanism involved in the formation of the lesion is the production of phytotoxic substances through hydrolysis of the cyanophoric β-glucoside, amygdalin.P. penetransis capable of hydrolyzing this substance in vitro. It is concluded that, althoughP. penetransis the most important primary parasite and a true plant pathogen, its main role in peach replant failure appears to be its ability to incite root degeneration by providing extensive infection courts for soil microorganisms.

ISSN:0008-4026    

DOI:10.1139/b59-037

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Three synthetic growth-promoting substances were administered to cauliflower plants (Brassica oleracea) to determine their effect on flower weight and flower growth. A Youden square experimental design was employed to set up treatment groups for all possible combinations of three substances at four concentration levels and three frequencies of application, and an untreated control group. The substances employed were 3-indolylbutyric acid (IBA), 2,3,5-tri-iodobenzoic acid (TIBA), and β-naphthoxyacetic acid (NOXA); concentrations used were 0.01, 0.2, 4.0, and 80.0 parts per million; and frequencies adopted were 2, 3, and 6 times in a 12-day period. Final flower weights were analyzed by an analysis of variance which showed that the treatments differed significantly (P <.01). Treatments with NOXA and IBA produced flowers weighing significantly more than those of the control group. Flower growth was characterized by a rapid initial rise, which subsequently levelled off in the control group. For treated groups, the initial rise continued throughout the flowering period. The results suggest that the use of certain synthetic growth-promoting substances may be feasible commercially for enhanced production of cauliflower crops.

ISSN:0008-4026    

DOI:10.1139/b59-038

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The generic limits ofMormolycaFenzl are extended to includeCyrtoglottisSchltr., on the basis of intermediate species. A previously misunderstood species,Maxillaria galeataScheidw., is included in the genusMormolyca, and the relationship of this genus to the rest of theMaxillaria-alliance is discussed. One new species,Mormolyca polyphylla, is described, and a synopsis of the genus is presented.

ISSN:0008-4026    

DOI:10.1139/b59-039

出版商:NRC Research Press    

年代:1959

数据来源: NRC

ISSN:0008-4026    

DOI:10.1139/b59-040

出版商:NRC Research Press    

年代:1959

数据来源: NRC