Abstract
SUMMARY An investigation was made of the expansion of the leaf surface of cucumber at temperatures of 12o, 18°, 24o, and 30o C. with two levels of visible radiation (40 and 80 cal. cm.-2 day-1). The relative rate of expansion of the leaf surface increased with temperature up to 24o but was lower at 30o than at 24o. It was slightly greater with the higher than the lower level of radiation at the lower temperatures only. This rate was the resultant of the rate of unfolding of new leaves and the rate of expansion of the component leaves. The rate of leaf pro duction increased with increasing temperature up to 240 and was constant there- , after, but leaves unfolded from the terminal bud more rapidly with increase in temperature over the entire range. The rate of expansion of individual leaves was greatest at 240, being less at both lower and higher temperatures. Differences in this rate between temperatures increased in the order: cotyledon, leaf 1, leaf 2. Leaf production and unfolding was greater with the higher level of radiation but the expansion of individual leaves was not influenced. These results suggested the following interpretation of the expansion of the leaf surface. Its potential rate is set by the rate of unfolding of leaves from the terminal bud, which depends mainly on the temperature and the rate of assimila tion by the upper leaves and the terminal bud, the demand for assimilate exceed ing the supply in this region. The demand for mineral substrates by the terminal bud is low and not influenced by a wide variation in potential supply. After un folding from the terminal bud, the leaf provides most of its own supply of carbo hydrate by assimilation and this can be met at a low level of radiation. Surplus assimilate is diverted to the roots and stems which respond much more to in creased radiation than does the leaf surface. The demand for mineral substrates by expanding leaves, however, is high—the greater the number expanding at any time the more likely is the demand by any one leaf to exceed the supply. This leads to a reduction in the number of cell divisions and, consequently, a reduced rate of expansion and a smaller leaf. The optimum level of any environmental factor is that at which the most effective compromise between these conflicting processes is reached.
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Claims 10
Claim · model-written summary
Relative leaf surface expansion increased with temperature up to 24o, then was lower at 30o.
- Taxon
- cucumber
Cucumis sativuse1 - Treatment
- temperaturee0
- Outcome
- relative rate of expansion of the leaf surfacee0
- Direction
- increasede0
- Value
- 24oe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The relative rate of expansion of the leaf surface increased with temperature up to 24o but was lower at 30o than at 24o.”
e1“leaf surface of cucumber”
Claim · model-written summary
Higher radiation slightly increased relative leaf surface expansion at lower temperatures only.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- highere0
- Outcome
- leaf surfacee1
- Direction
- slightly greatere0
- Qualifier
- at the lower temperatures onlye0
- Comparator
- lower level of radiatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It was slightly greater with the higher than the lower level of radiation at the lower temperatures only.”
e1“leaf surface of cucumber”
Claim · model-written summary
Leaf production increased with temperature up to 240 and then stayed constant.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- increasing temperaturee0
- Outcome
- rate of leaf pro ductione0
- Direction
- increasede0
- Value
- 240e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of leaf pro duction increased with increasing temperature up to 240 and was constant there- , after”
e1“leaf surface of cucumber”
Claim · model-written summary
Leaves unfolded from terminal buds more rapidly as temperature rose across the range.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- increase in temperaturee0
- Outcome
- leaves unfolded from the terminal bude0
- Direction
- more rapidlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaves unfolded from the terminal bud more rapidly with increase in temperature over the entire range”
e1“leaf surface of cucumber”
Claim · model-written summary
Individual leaf expansion was greatest at 240 and lower at both cooler and warmer temperatures.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- temperaturese0
- Outcome
- rate of expansion of individual leavese0
- Direction
- greateste0
- Value
- 240e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of expansion of individual leaves was greatest at 240, being less at both lower and higher temperatures.”
e1“leaf surface of cucumber”
Claim · model-written summary
Temperature differences in individual leaf expansion increased from cotyledon to leaf 1 to leaf 2.
- Taxon
- cucumberCucumis sativuse1
- Organ / stage
- cotyledon, leaf 1, leaf 2e0
- Outcome
- Differences in this rate between temperaturese0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Differences in this rate between temperatures increased in the order: cotyledon, leaf 1, leaf 2.”
e1“leaf surface of cucumber”
Claim · model-written summary
Higher radiation increased leaf production and unfolding.
- Taxon
- cucumberCucumis sativuse1
- Treatment
- higher level of radiatione0
- Outcome
- Leaf production and unfoldinge0
- Direction
- greatere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf production and unfolding was greater with the higher level of radiation”
e1“leaf surface of cucumber”
Claim · model-written summary
Higher radiation did not change expansion of individual leaves.
- Taxon
- cucumberCucumis sativuse2
- Treatment
- higher level of radiatione1
- Outcome
- expansion of individual leavese0
- Direction
- not influencede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the expansion of individual leaves was not influenced”
e1“Leaf production and unfolding was greater with the higher level of radiation but the expansion of individual leaves was not influenced.”
e2“leaf surface of cucumber”
Claim · model-written summary
The authors proposed that unfolding from the terminal bud sets potential leaf surface expansion.
- Taxon
- cucumberCucumis sativuse1
- Organ / stage
- terminal bude0
- Outcome
- potential ratee0
- Qualifier
- rate of unfolding of leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Its potential rate is set by the rate of unfolding of leaves from the terminal bud”
e1“leaf surface of cucumber”
Claim · model-written summary
The authors proposed that reduced cell division lowers leaf expansion and leaf size when mineral demand exceeds supply.
- Taxon
- cucumberCucumis sativuse2
- Outcome
- reduced rate of expansion and a smaller leafe0
- Qualifier
- demand by any one leaf to exceed the supplye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This leads to a reduction in the number of cell divisions and, consequently, a reduced rate of expansion and a smaller leaf.”
e1“The demand for mineral substrates by expanding leaves, however, is high—the greater the number expanding at any time the more likely is the demand by any one leaf to exceed the supply.”
e2“leaf surface of cucumber”
The same questions in other papers
radiation · yield · Cucumis sativus (cucumber)Positive and negative results
4 papers in the same direction as this paper · 3 in the opposite direction
- positive
- negative
- negative
4 papers more in this group
See all 8 papers →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.