Abstract
This study is concerned with the resistance of tobacco seedlings to a second attack of downy mildew caused by Peronospora tabacina Adam. Observations were made on the development and duration of resistance following recovery of tobacco seedlings from downy mildew. The duration of the period of resistance is variable and the observations indicate that plants in the greenhouse recovering during the summer remain resistant longer than do plants recovering from an initial attack during the winter. Samples of leaf tissue from recovered (resistant), infected and previously uninfected (susceptible) plants grown in soil in the greenhouse were analyzed for ammonia-nitrogen, nitrate-nitrogen, reducing sugars and total sugars. Similar analyses were made of samples of leaf tissue from tobacco plants grown in crocks of quartz sand and irrigated with nutrient solutions and from plants grown in crocks of sand-peat mixture to which various mixed fertilizers were added. There was no correlation between the ammonia-nitrogen content of tobacco plants, as determined in these experiments, and the response of the tobacco plant and its susceptibility to attack by P. tabacina, but there was a strong indication that such a relationship exists. Recovered plants contained a higher ratio of total sugar to nitrate-nitrogen than did comparable plants which had never been infected. Furthermore the ratio of total sugar to nitrate-nitrogen was lower in plants infected for a second time than it was in plants from the same lot shortly after they had recovered from the initial attack. It seems probable however that the changes in the nitrate-nitrogen and sugar content in recovered tobacco leaves are an indication of recovery and are not responsible for the resistance possessed by such plants. A series of experiments were performed to test the immediate effect of several nutrient salts and of sugar upon the sporulation of the fungus on the leaves of diseased tobacco plants. There was a very definite response in sporulation to some of these treatments, especially to potassium nitrate, calcium nitrate, and sucrose, but it is not known whether the response of sporulation of the fungus to such treatment is related to the type of resistance possessed by recovered plants. Sodium chloride and calcium chloride were dissolved in water and applied to the soil in which young tobacco plants were growing in the greenhouse. Although increased chloride in one of the sand cultural experiments seemed to protect the plants somewhat against downy mildew, application of solutions of these salts to the soil at the rates used (100 lbs. And 138 lbs. Per acre respectively) produced no noticeable effect on the severity of the disease or subsequent recovery of the plants. The leaves of recovered (resistant) tobacco plants are usually reduced in number, the lower ones having been killed by the initial attack of the fungus. Removal of the leaves from healthy tobacco plants in imitation of this condition did not produce resistance to an attack by P. tabacina. The artificial production of necrotic areas on healthy tobacco leaves in simulation of those usually following sporulation of P. tabacina on diseased leaves had no effect either on the susceptibility of the plants to infection or upon sporulation of the fungus on leaves already infected at the time the necrotic areas were induced. Results of attempts to confer immunity from downy mildew upon an entire plant by infection of a single leaf of the plant were inconclusive, since under the conditions of the experiment it was impossible to be sure that the single leaf was infected. However, the indication is that infection of a single leaf will not render the entire plant immune from a second attack by the fungus.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 16
Claim · model-written summary
Summer-recovering greenhouse tobacco remained resistant longer than winter-recovering plants.
- Taxon
- tobacco
Nicotiana tabacumt0 - Outcome
- resistante0
- Direction
- longere0
- Comparator
- plants recovering from an initial attack during the wintere0
- Setting
- greenhousee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plants in the greenhouse recovering during the summer remain resistant longer than do plants recovering from an initial attack during the winter”
t0“tobacco”
Claim · model-written summary
Measured tobacco ammonia-nitrogen content did not correlate with response and susceptibility to P. tabacina, although a relationship was suggested.
- Taxon
- tobaccoNicotiana tabacume0
- Interactor
- P. tabacina
Peronospora tabacinae0pathogen - Compound
- ammonia-nitrogene0
- Outcome
- susceptibility to attack by P. tabacinae0
- Qualifier
- but there was a strong indication that such a relationship existse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was no correlation between the ammonia-nitrogen content of tobacco plants, as determined in these experiments, and the response of the tobacco plant and its susceptibility to attack by P. tabacina, but there was a strong indication that such a relationship exists.”
Claim · model-written summary
Recovered tobacco had a higher total sugar to nitrate-nitrogen ratio than never-infected plants.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- ratio of total sugar to nitrate-nitrogene0
- Direction
- highere0
- Comparator
- plants which had never been infectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Recovered plants contained a higher ratio of total sugar to nitrate-nitrogen than did comparable plants which had never been infected.”
t0“tobacco”
Claim · model-written summary
The sugar to nitrate-nitrogen ratio was lower after a second infection than shortly after initial recovery.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- ratio of total sugar to nitrate-nitrogene0
- Direction
- lowere0
- Comparator
- plants from the same lot shortly after they had recovered from the initial attacke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ratio of total sugar to nitrate-nitrogen was lower in plants infected for a second time than it was in plants from the same lot shortly after they had recovered from the initial attack”
t0“tobacco”
Claim · model-written summary
Nitrate-nitrogen and sugar changes probably indicate recovery rather than cause tobacco resistance.
- Taxon
- tobaccoNicotiana tabacume0
- Compound
- nitrate-nitrogen and sugare0
- Outcome
- resistancee0
- Qualifier
- It seems probablee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It seems probable however that the changes in the nitrate-nitrogen and sugar content in recovered tobacco leaves are an indication of recovery and are not responsible for the resistance possessed by such plants.”
Claim · model-written summary
Potassium nitrate produced a definite sporulation response on diseased tobacco leaves, with direction unspecified.
- Taxon
- funguse1
- Organ / stage
- leavese1
- Treatment
- potassium nitratee0
- Interactor
- tobaccoNicotiana tabacume1host
- Outcome
- sporulatione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a very definite response in sporulation to some of these treatments, especially to potassium nitrate, calcium nitrate, and sucrose”
e1“sporulation of the fungus on the leaves of diseased tobacco plants”
Claim · model-written summary
Calcium nitrate produced a definite sporulation response on diseased tobacco leaves, with direction unspecified.
- Taxon
- funguse1
- Treatment
- calcium nitratee0
- Interactor
- tobaccoNicotiana tabacume1host
- Outcome
- sporulatione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a very definite response in sporulation to some of these treatments, especially to potassium nitrate, calcium nitrate, and sucrose”
e1“sporulation of the fungus on the leaves of diseased tobacco plants”
Claim · model-written summary
Sucrose produced a definite sporulation response on diseased tobacco leaves, with direction unspecified.
- Taxon
- funguse1
- Treatment
- sucrosee0
- Interactor
- tobaccoNicotiana tabacume1host
- Outcome
- sporulatione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a very definite response in sporulation to some of these treatments, especially to potassium nitrate, calcium nitrate, and sucrose”
e1“sporulation of the fungus on the leaves of diseased tobacco plants”
Claim · model-written summary
Increased chloride appeared to offer some protection against downy mildew in a sand culture experiment.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- increased chloridee0
- Outcome
- downy mildewe0
- Direction
- protecte0
- Qualifier
- seemede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased chloride in one of the sand cultural experiments seemed to protect the plants somewhat against downy mildew”
t0“tobacco”
Claim · model-written summary
Soil-applied sodium chloride had no noticeable effect on disease severity or subsequent recovery.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- Sodium chloridee0
- Outcome
- severity of the disease or subsequent recoverye1
- Direction
- no noticeable effecte1
- Value
- 100 lbs.e1
- Setting
- greenhousee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sodium chloride and calcium chloride were dissolved in water and applied to the soil in which young tobacco plants were growing in the greenhouse.”
e1“application of solutions of these salts to the soil at the rates used (100 lbs. And 138 lbs. Per acre respectively) produced no noticeable effect on the severity of the disease or subsequent recovery of the plants”
Claim · model-written summary
Soil-applied calcium chloride had no noticeable effect on disease severity or subsequent recovery.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- calcium chloridee0
- Outcome
- severity of the disease or subsequent recoverye1
- Direction
- no noticeable effecte1
- Value
- 138 lbs. Per acree1
- Setting
- greenhousee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sodium chloride and calcium chloride were dissolved in water and applied to the soil in which young tobacco plants were growing in the greenhouse.”
e1“application of solutions of these salts to the soil at the rates used (100 lbs. And 138 lbs. Per acre respectively) produced no noticeable effect on the severity of the disease or subsequent recovery of the plants”
Claim · model-written summary
Recovered tobacco generally had fewer leaves because lower leaves were killed by the initial fungal attack.
- Taxon
- tobaccoNicotiana tabacume0
- Interactor
- funguse0pathogen
- Outcome
- leavese0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The leaves of recovered (resistant) tobacco plants are usually reduced in number, the lower ones having been killed by the initial attack of the fungus.”
Claim · model-written summary
Leaf removal did not induce tobacco resistance to P. tabacina.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- Removal of the leavese0
- Interactor
- P. tabacinaPeronospora tabacinae0pathogen
- Outcome
- resistancee0
- Direction
- did not producee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Removal of the leaves from healthy tobacco plants in imitation of this condition did not produce resistance to an attack by P. tabacina.”
Claim · model-written summary
Artificial necrotic areas did not affect tobacco susceptibility to infection.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- artificial production of necrotic arease0
- Interactor
- P. tabacinaPeronospora tabacinae0pathogen
- Outcome
- susceptibility of the plants to infectione0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The artificial production of necrotic areas on healthy tobacco leaves in simulation of those usually following sporulation of P. tabacina on diseased leaves had no effect either on the susceptibility of the plants to infection or upon sporulation of the fungus on leaves already infected at the time the necrotic areas were induced.”
Claim · model-written summary
Artificial necrotic areas did not affect fungal sporulation on already infected leaves.
- Taxon
- P. tabacinaPeronospora tabacinae0
- Treatment
- artificial production of necrotic arease0
- Interactor
- tobaccoNicotiana tabacume0host
- Outcome
- sporulation of the funguse0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The artificial production of necrotic areas on healthy tobacco leaves in simulation of those usually following sporulation of P. tabacina on diseased leaves had no effect either on the susceptibility of the plants to infection or upon sporulation of the fungus on leaves already infected at the time the necrotic areas were induced.”
Claim · model-written summary
Single-leaf infection experiments were inconclusive, but suggested that infection would not confer whole-plant immunity to a second attack.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- infection of a single leafe1
- Outcome
- immune from a second attacke1
- Direction
- will not rendere1
- Qualifier
- inconclusivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Results of attempts to confer immunity from downy mildew upon an entire plant by infection of a single leaf of the plant were inconclusive, since under the conditions of the experiment it was impossible to be sure that the single leaf was infected.”
e1“However, the indication is that infection of a single leaf will not render the entire plant immune from a second attack by the fungus.”
t0“tobacco”
The same questions in other papers
calcium chloride dihydrate · disease · Nicotiana tabacum (tobacco)Positive and negative results
1 in the opposite direction
- positive
sodium chloride · disease · Nicotiana tabacum (tobacco)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- negative
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.