STUDIES ON THE SEEDLING DISEASE OF BARLEY CAUSED BY HELMINTHOSPORIUM SATIVUM P.K. &amp; B.

1969. A study of factors influencing the genetics of reaction of barley to root rot caused by Helminthosporium snrivu177. Can. J. Botany, 47: 4 2 9 4 3 . The inheritance of seedling reaction to root rot, caused by the 514 isolate of Helrninthospori~ct~ sntiv~tn~, was studied in crosses and backcrosses among the barley varieties CI.8969 and CI.8873, which show resistance, and the variety Olli, which is susceptible. The study was carried out under a controlled environment in growth cabinets. The data from reaction tests of F3 and backcross families were analyzed by Elston's procedure for testing a one-locus hypothesis, and by Powers' partitioning method. Polygenic inheritance for seedling reaction was indicated, but subsequent experiments showed that seed weight strongly influenced the reaction, which could account for the polygenic interpretation. Based on a drastic reduction of resistance in greenhouse-produced seed, irrespective of seed weight, a high positive correlation of seed weight with resistance in field-produced seed, and other evidence of a similar nature, it was assumed that resistance was related to a principle, present in the seed or on the seed surface, the quantity of which was influenced by seed size and modified by environment. Whether there was a genotypic influence on the quantity of the resistance principle, aside from that affecting seed weight, was not established conclusively. A field study involving the same materials, made in an area known to produce natural root-rot infection, showed that no correlation existed between the disease indices of the entries in the seedling stage in the growth-cabinet tests, and their reaction to the disease in the field. CI.8873 showed field resistance, whereas CI.8969 did not.

Section: Discussionmentioning

confidence: 99%

“…(29), and this was mixed in a cement mixer with white silica sand in a 1:14 ratio. (29), and this was mixed in a cement mixer with white silica sand in a 1:14 ratio.…”

Section: Methodsmentioning

confidence: 99%

A study of factors influencing the genetics of reaction of barley to root rot caused by Helminthosporium sativum

Cohen¹,

Helgason²,

McDonald³

1969

“…After the toxin treatment all varieties became highly susceptible and sho~ved considerable root damage (Figs. 1,5,7,8,9,10,12).…”

Section: Observations a N D Resultsmentioning

confidence: 99%

“…Detectable anlounts of phytotoxins occur most frequently in and around clu~nps and fragments of decomposing plant debris and low parts of the field where drainage is poor (12,13). I t has long been suspected that phytotoxic substances of biologic origin play an important role in the etiology of certain root rots (3,8,10,17). The similarity of environmental conditions causing severe blaclc root rot t o those that are most favorable for the type of plant residue decomposition which gives rise to the forn~ation of phytotoxic substances suggests possible relationships between increased susceptibility of tobacco to black root rot and the occurrence of phytotoxic substances in the soil.…”

Section: Introductionmentioning

confidence: 99%

The Adverse Influence of Phytotoxic Substances From Decomposing Plant Residues on Resistance of Tobacco to Black Root Rot

Patrick¹,

Koch²

1963

Exposure of tobacco plants to phytotoxic solutions obtained from decomposing rye and timothy residues increased their susceptibility to black root rot caused by Tlzielaviopsis basicola (Berk. & Br.) Ferraris. In greenhouse experiments 16 tobacco varieties, ranging from susceptible to highly resistant to black root rot in the field, were exposed to rye and timothy toxins and their relative resistance and severity of disease development were determined. Exposure t o the toxins resulted in an apparent brealtdown of resistance. 'There were no signihcant differences among the varieties and the disease was equally severe on roots of the resistant and the susceptible varieties after the toxin treatment. These results might explain in part, a t least, the apparent breakdown of resistance that has a t times been noted in the field with black root rot resistant varieties. The effect of the toxic coinpounds appears to be largely on the host rather than on the fungus. The precise biochemical and physiological changes which are induced in the root tissues by the toxins t o make then1 more favorable for fungus i11vasio11 and colonization are a t present not known. This study suggests, however, that phytotoxi~ls may be importai~t host-conditioning factors in the development of root diseases.

“…In 1956, Ludwig et al (13) reported non-specific toxicity of culture filtrates towards barley seedlings. Some relationship between toxin production and phytopathogenicity towards barley seedlings was noted by Ludwig (12).…”

Section: Introductionmentioning

confidence: 99%

Role of toxins in etiology of root rot disease of wheat

Pringle¹

1977