摘要:

A pathogenic change, explainable only on the assumption of mutation, has occurred in a uredial culture of race 52 ofPuccinia graminis Tritici, which had previously remained constant in pathogenicity for nearly two years. The mutation appears to have taken place during a six-month period of storage of the urediospores in a refrigerator maintained at a temperature of about 8 °C. When cultured in the greenhouse, at the end of this period, the rust appeared to be a mixture of race 52 and a hitherto undescribed physiologic race, with the latter predominating. The original culture was left in storage for a further period of four months, after which it gave rise to a pure culture of the new race without any indication of the presence of race 52. The new race has been assigned the number 178.

ISSN:1923-4287    

DOI:10.1139/cjr39c-027

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

Measurements of 80 to 90 leaves of each of four varieties of spring wheat at various stages of development indicate a fairly close statistical relation between area, and length and width, of the leaf blade. This relation was found to be essentially the same for all four varieties, and from a knowledge of length (L) and median width (W½), the area of an individual leaf was given by the Least Squares relation log.A = 0.0094 + 0.934 log.L + 1.071 log.W½, with a standard error of 4.2% of the antilog. Inclusion of a third measurement, width at three-quarters of the distance from base to tip (W¼), led to the relation log.A = − 0.0438 + 0.970 log.L + 0.880 log.W½ + 0.189 log.W¼, giving estimated values having a standard error of 3.7% of the actual area per leaf.This method of estimating leaf areas (i) is rapid in execution and (ii) does not necessitate removing the leaves from experimental plants, which may accordingly be maintained intact for a series of physiological observations.

ISSN:1923-4287    

DOI:10.1139/cjr39c-028

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

Indolylbutyric acid and oestrone were applied in dusts to dormant stem cuttings ofLonicera tartarica,Spiraea Vanhouttei, andCornus alba, and in both dusts and solutions to cuttings ofRibes odoratum. Indolylbutyric acid had significant effects on the number of cuttings rooted and the number and length of roots per rooted cutting of three species. Further observations indicated that it also affected the fresh root weight of cuttings ofSpiraea Vanhoutteiand the green leaf weight ofRibes odoratum. Oestrone had no significant effect on rooting, but in solution treatment showed significant effects on the green leaf weight ofRibes odoratum, both alone and in interaction with indolylbutyric acid. Cuttings ofCornus albafailed to show any significant treatment effects.Dust and solution methods of treating cuttings were compared through the responses ofRibes odoratum. Dust treatment effected 62% rooting, solution 42%; there also was markedly greater leaf development following the use of dusts.

ISSN:1923-4287    

DOI:10.1139/cjr39c-029

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

Norway spruce cuttings were treated with phytohormone dusts, and nutrient solution was added to the sand in which some of the cuttings were planted. The nutrient treatment greatly increased the number of rooted cuttings and the number that developed new growth, and reduced the number that died. Although talc alone increased top growth, indolylacetic acid, present in three concentrations in talc, had no significant effect on the number of cuttings rooted or dead. However, the hormone dust treatment effected a significant reduction in the length of root per rooted cutting and the mean root length. The results indicate that nutrient salts may, under certain conditions, have a marked influence on the rooting and growth of Norway spruce cuttings.

ISSN:1923-4287    

DOI:10.1139/cjr39c-030

出版商:NRC Research Press    

年代:1939

数据来源: NRC