THE INFLUENCE OF LIGHT AND CERTAIN OTHER ENVIRONMENTAL FACTORS ON THE MATURE-PLANT RESISTANCE OF HOPE WHEAT TO STEM RUST

1940 ◽  
Vol 18c (8) ◽  
pp. 357-371 ◽  
Author(s):  
T. Johnson ◽  
Margaret Newton
Keyword(s):  
Soil Moisture ◽  
Light Intensity ◽  
Plant Resistance ◽  
Mineral Nutrients ◽  
Light Period ◽  
Mature Plant ◽  
Effect Of Temperature ◽  
Mature Plant Resistance ◽  
Growing Period ◽  
Complete Breakdown

Experiments have been conducted to determine the degree to which the mature-plant reaction of Hope wheat to race 21 of P. graminis Tritici Erikss. and Henn. is affected by variation in light intensity, length of daily light period, temperature, soil moisture, and supply of mineral nutrients. All these factors gave evidence of influencing rust reaction. A 60% reduction in light intensity during the whole growing period of the plants tended to influence their rust reaction in the direction of increased susceptibility and caused a modification in the morphology of the plants in that they were softer, less rigid, and higher in moisture content than plants grown in full daylight. The shift towards susceptibility was, however, not very marked, and in only one experiment did the reaction of the plants approach complete susceptibility. Reduction in length of daily light period also influenced the rust reaction of the plants towards susceptibility. Plants receiving six hours of light daily were less resistant than plants receiving ten hours of light and these, in turn, were slightly less resistant than plants receiving full daylight for the period of the experiment (February to June). Experiments on the effect of temperature on the reaction of Hope wheat have shown that constant high temperature (75° to 80° F.) is capable of causing a partial or even complete breakdown of mature-plant resistance. Some evidence was secured that abundance of soil moisture and of mineral nutrients diminished rust resistance.

scholarly journals Response of Brassica oleracea var. capitata to Wound and Spray Inoculations with Xanthomonas campestris pv. campestris

HortScience ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 47-49 ◽  
Author(s):  
Phillip D. Griffiths ◽  
Cathy Roe
Keyword(s):  
Brassica Oleracea ◽  
Plant Resistance ◽  
Xanthomonas Campestris ◽  
Field Experiments ◽  
Field Resistance ◽  
Mature Plant ◽  
Black Rot ◽  
Mature Plant Resistance ◽  
Breeding Lines ◽  
Spray Inoculation

Eighteen cabbage breeding lines and cultivars were evaluated for resistance to black rot caused by Xanthomonas campestris pv. campestris following wound and spray inoculations at the juvenile and mature stages. Plants were evaluated using four inoculation procedures (juvenile wound, juvenile spray, mature wound, and mature spray) in replicated greenhouse and field experiments. The breeding lines Badger #16, Cornell 101, Cornell 102, NY 4002 and accession PI 426606 exhibited high levels of resistance following all inoculation procedures. `Silver Dynasty' was the most resistant commercial cultivar based on the four tests, yet ranked 12th following the juvenile wound inoculation. The juvenile spray inoculation had a high correlation with both wound and spray inoculations in field experiments (0.89 and 0.86, respectively); however, the juvenile wound inoculation did not correlate well with mature wound and spray inoculations (0.58 and 0.51, respectively). The results indicate that the juvenile wound inoculation is not the most appropriate approach for determining field resistance in Brassica oleracea, and that resistant material could be selected against using this approach. A high correlation between juvenile spray inoculation disease severity ratings and mature plant resistance indicates that plants can be evaluated effectively at the juvenile stage for mature plant resistance to black rot.

Investigations in the Triticinae IV. Disease reactions of species of Triticum and Aegilops and of amphidiploids between them

1955 ◽  
Vol 46 (2) ◽  
pp. 232-246 ◽  
Author(s):  
G. D. H. Bell ◽  
F. G. H. Lupton
Keyword(s):  
Plant Resistance ◽  
Triticum Monococcum ◽  
Mature Plant ◽  
Field Observations ◽  
Wheat Species ◽  
Sources Of Resistance ◽  
Seedling Resistance ◽  
Mature Plant Resistance ◽  
Numerous Species ◽  
Aegilops Caudata

1. Observations have been made of the seedling reactions of species of Triticum and Aegilops and of amphidiploids between them to races of Puccinia glumarum, P. triticina, P. graminis and Erysiphe graminis. These observations have been compared with field observations on mature plants. The work on P. graminis and much of that on P. triticina was carried out by Dr R. C. McGinnis of the Dominion Rust Research Laboratories, Winnipeg, Canada.2. Seedling and mature plant resistance to P. glumarum has been found in Triticum monococcum, Aegilops caudata and A. ovata. Resistance was not shown by amphidiploids of T. monococcum and A. caudata with susceptible species of Triticum, but was shown by some amphidiploids involving A. ovata; T. timopheevi and A. speltoides were susceptible to certain races as seedlings but resistant as mature plants in the field.3. Seedling resistance to all the races of P. triticina used in these investigations was shown by A. caudata and resistance to certain races by certain other species. Amphidiploids involving A. caudata were resistant to all races, but other amphidiploids were resistant to some races and susceptible to others.4. Seedling and mature plant resistance to P. graminis was shown by A. caudata. A. ovata and A. speltoides were resistant as mature plants, and only slightly infected as seedlings. None of the amphidiploids tested was completely resistant at the seedling stage; certain amphidiploids involving these three species were, however, only slightly infected as mature plants, and may be useful as sources of resistance to race 15B.5. Resistance to E. graminis was shown by T. carthlicum, T. dicoccum, T. timopheevi and by numerous species of Aegilops. Amphidiploids of T. carthlicum, T. dicoccum, T. timopheevi and A. caudata with diploid wheat species were resistant to E. graminis, but those with susceptible tetraploid wheats were susceptible. Other intergeneric amphidiploids (with two exceptions) were resistant.

scholarly journals Plant Age and Isolate Source Affect Expression of Downy Mildew Resistance in Broccoli

HortScience ◽  
1993 ◽  
Vol 28 (7) ◽  
pp. 730-731 ◽  
Author(s):  
M.H. Dickson ◽  
R. Petzoldt
Keyword(s):  
New York ◽  
South Carolina ◽  
Downy Mildew ◽  
Plant Resistance ◽  
The United States ◽  
Plant Age ◽  
Mature Plant ◽  
Seedling Resistance ◽  
Mature Plant Resistance ◽  
Almost Continuous

Resistance to downy mildew [Peronospora parasitica (pers.) ex. Fr.] in broccoli (Brassica oleracea L. Italica Group) depends on plant age. Seedling resistance seems to be independent of mature-plant resistance, where a mature plant is defined as having eight or more leaves. Our results suggest that, by using mature-plant resistance, an almost continuous variation instable levels of mature-plant resistance can be developed. Similarities in the response of mature plants of various lines to isolates from California, Washington, New York, and South Carolina indicated that the predominant race was the same at all locations. Correlations between resistant and susceptible responses to isolates from California, Washington, New York, and South Carolina varied from r = 0.48 to 0.74 depending on isolate source. The results indicated that selecting for high levels of resistance in mature plants at one location should result in good resistance elsewhere in the United States. Selecting immature plants (three to six leaves) may provide less reliable results due to the transitional status of the plant; i.e., between seedling and mature plant.

Sign in / Sign up

Export Citation Format

Share Document