摘要:

A study was made of the capacity for synthesis of vitamin B12by 70 strains representing six species ofRhizobium, namely,R.meliloti,R.trifolii,R.leguminosarum,R.japonicum,R.lupini, andR.phaseoli.Rhizobium melilotiwas sharply distinguished from the other species by its ability to produce significantly higher quantities of the vitamin, one strain producing, under the experimental conditions, over 1000 mμgm. per ml. of culture liquid. The remaining species did not show significant differences in B12synthesizing capacity. No correlation was noted between vitamin-producing capacity and effectiveness of the individual strains with respect to nitrogen fixation.

ISSN:0008-4026    

DOI:10.1139/b52-037

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

The inheritance of resistance to loose smut races Tr and Ts (a new race) was studied in several barley crosses and backcrosses in which the varieties Jet and Titan were the resistant parents. Jet is resistant to race Tr and race Ts, Titan to race Tr only. Genetical analyses were based (a) on a classification ofF2plants according to the smut reaction of theirF3progeny, and (b) on the reaction of selfed generation backcrosses involving recessive (susceptible) parents. The resistance of Titan and of Jet to Tr was found in each case to be due to a single, dominant gene, designated asUnandUn3, respectively. The resistance of Jet to Ts was also found to be due to a single, dominant gene. This is probably a "new" gene and has been provisionally designatedUn6. Resistance was found to be determined by the genetic constitution of the developing embryo rather than by that of surrounding floral structures.

ISSN:0008-4026    

DOI:10.1139/b52-038

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Many overwintering cultivated and native plants proved susceptible to the low-temperature basidiomycete which causes winter crown rot or snow mold of forage legumes and grasses in Alberta. Tests were made by inoculation in the late fall, or by planting in infested land. In the legumes, high resistance was found only inMedicago falcataand a Siberian strain ofTrifolium pratense.T.hybridum,Melilotusspp., and the commonly grown varieties of alfalfa were particularly susceptible.Bromusspp. andAgropyronspp. proved highly resistant. Resistance was moderate inElymusspp.,Poa pratensis, andFestuca elatior; and slight inF.rubraandPhleum pratense.Agrostis alba, winter wheat, and winter rye were highly susceptible. In tests on horticultural plants, rhubarb and chives appeared to be immune; raspberry, peony, and columbine were resistant; and strawberry, parsnip, iris, and tulip were highly susceptible. A wide range of native plants and weeds suffered severe damage, and onlyThalictrumspp. proved highly resistant. Shrubs and trees were not attacked.Following severe damage, crop rotation proved to be essential for the control of winter crown rot. The pathogen did not persist in the soil to any extent for longer than two to three years in land which was summer-fallowed or planted to annual crops or resistant grasses. Brome and other resistant grasses proved helpful in maintaining forage stands. Fertilizer treatments did not reduce the damage. Uncut tops and debris favored spread of the disease in alfalfa stands.

ISSN:0008-4026    

DOI:10.1139/b52-039

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Of four seedling-clones ofDianthus barbatusL. tested for susceptibility to tobacco ring spot virus, two were consistently infected, one occasionally missed infection, and the fourth was insusceptible. Symptoms of infection were primary local lesions, followed by systemic chlorosis and death of the growing point. Further adventitious growth was symptomless, but still contained the virus and was protected from reinfection. Intracellular inclusions of the amorphous type occurred in diseased leaves. Difficulty in transmitting tobacco ring spot virus fromD.barbatusto tobacco was caused by an inhibitor in healthyD.barbatusleaves. Some of the physical characteristics of this inhibitor were studied. It had no effect on transmission of tobacco ring spot virus toD.barbatus, but in cucumber,Datura stramonium, and snapdragon, it caused either a delay of symptom expression or an insusceptibility of a proportion of inoculated plants. The inhibitor reduced infectivity of tobacco mosaic, cucumber mosaic, and tobacco etch viruses.

ISSN:0008-4026    

DOI:10.1139/b52-040

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

The respiration rate, R.Q., and the water content of each of the developing quarters of the first leaf of Khapli wheat have been measured at different ages and found to change as the tissue ages. In general the respiration rate declines as the tissue ages. The R.Q. is usually close to unity except in the basal quarter around the fifth day. The water content of the quarters tends to decline as the mature leaves become older. In the basal quarter of four- and five-day-old leaves the oxygen uptake appears to reach its peak when calculated on a dry weight basis. In the five-day-old leaves the rate of water uptake is very high and the R.Q. very low. These properties are thought to be correlated with the phase of elongation which is occurring in this quarter at that stage.

ISSN:0008-4026    

DOI:10.1139/b52-041

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

This paper is a taxonomic study of the genusTympaniswith a discussion of its history, morphology, conidial relations, parasitism, and distribution. Thirty-six species and one variety are recognized, of which 23 species have been studied in cultures. Sixteen new species are described and one new name is proposed. The conidial states ofTympanisspecies belong in the form genusPleurophomellav. Höhn. In a section on doubtful and excluded species an attempt is made to account for all theTympanisnames in the literature.

ISSN:0008-4026    

DOI:10.1139/b52-042

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

The effect of different living host and nonhost plants 21 days old, soil amendments, andTrichoderma lignorum(Tode) Harz on the persistence of a heavy artificial infestation ofRhizoctonia solaniKühn in a natural virgin Edmonton black loam of optimum moisture content, held at 61° F., was studied under controlled laboratory conditions, A disease rating of host plants was found to be a satisfactory measure of the persistence ofR.solani, whereas data from buried glass slides and from root colonization of indicator plants were unreliable for the purpose intended. In natural, unamended soil, a heavy infestation ofT.lignorumdid not check the growth ofR.solaniperceptibly, but with the addition of cornmeal it was practically suppressed for several days. In the presence of living potato plants,R.solanipersisted as well in natural untreated soil as it did when cornmeal, sodium nitrate, or calcium hydroxide was added. The living or dead roots of potato or wheat plants did not aid or suppress the pathogen. ApparentlyR.solanidisappeared from the soil in 120 days or less when associated with wheat, oat, barley, or corn plants replanted every 21 days, but it was still fairly abundant in soils bearing potato, bean, or pea plants. When potato plants were absent, a heavy soil infestation in the late autumn practically disappeared by the following June. Results indicate thatR.solanidepends essentially on parasitic nutrition for its persistence in the soil. The hyphae ofR.solanicommonly inhabited the living roots of host and nonhost plants, but no nutritional relationship with them was detected.

ISSN:0008-4026    

DOI:10.1139/b52-043

出版商:NRC Research Press    

年代:1952

数据来源: NRC