Daily Variations in Products of Photosynthesis, Water Content, and Acidity of Leaves Toward End of Vegetative Period

Stanescu, Paul P.

doi:10.1002/j.1537-2197.1936.tb08998.x

Cited by 11 publications

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“…GREGORY and his coworkers have found increased water content in leaves with less potassium (7,8,9). STANESCU (20) associates high water content with synthesis of carbohydrates, a point that will be considered later. Although both the fresh and dry weights of these tobacco leaves were generally greater when potassium was furnished, the relationship of dry weight to fresh weight is the important point that inust be considered.…”

Section: Discussionmentioning

confidence: 99%

Starch Formation in Tobacco Plants Deficient in Potassium1

Day

1940

Plant Physiology

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Potassium is important in the growing of fine tobacco. Not only is it the nutrient removed from the soil in the greatest quantity, but it is essential for the vigorous growth of the plant (3). Potassium is also more important than any other element in producing good combustion of the dried leaf (1) and is necessary for choice aroma (5).This value of potassium to the finished tobacco product has a curiously paradoxical aspect, for it has long beeln assumed that much of the importance of this element to any plant lay in its relation to carbohydrate synthesis or translocation. But the type of tobacco grown in the Connecticut Valley is low in carbohydrates, especially starch. Consequently, there is a special interest in the problem of the relationship of potassium to the formation of starch in tobacco plants.It was the aim in this study, as in much recent work, to test the leaves soon after the effects of potassium deficiency had been definitely established but well before the plant had died from lack of this element. From preliminary trials with tobacco, it appeared that seedlings started in soil, transplanted to sand, and treated with a nutrient solution, could be grown normally with the usual elongation of the internodes; or that similar plants, treated in a like manner except for the absence of potassium, would show evidence of a lack of this element during the latter part of the vegetative period. Methods Tobacco (Nicotiana tabacurm, var. Rosenberg) 2 was germiniated and grown in quantity in sandy soil until the seedlings were about two inches tall with four small leaves, from 9 to 15 weeks depending upon the season.

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Section: Discussionmentioning

confidence: 99%

Starch Formation in Tobacco Plants Deficient in Potassium1

Day

1940

Plant Physiology

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“…Each weekly average indicated represents 12 leaves from each of 8 trees on each of 6 days, or a total of 576 leaves. Figure 1 illustrates the increase in leaf weight occurring during the season.…”

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Seasonal and Diurnal Changes in the Water Contents and Water Deficits of Bartlett Pear Leaves

Ackley¹

1954

Plant Physiol.

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It is general knowledge that the water content of (leciduous leaves usually decreases as the season advances. It has also been noted that the water deficit fluctuations of such leaves are often more pronounced early in the growing season when these parts are young and succulent than later when they are older and harder. The seasonal changes in the actual weights of the water and dry matter components of leaves, however, are less commonly understood.Leaf samples are comparatively easy to pick, dry and weigh. For this reason, the water content of leaves is often used to indicate water changes within plants. Knight (5) found slight diurnal variations in water contents of leaves of the plants he tested in the area of southeastern England. Livingston and Brown (7) found large diurnal changes in the water contents of the desert plants with which they worked. Miller (9) made frequent periodic water content determinations on the leaves of corn and sorghums in his studies of the water relations of these crop plants.MIaximov (8), Stanescu (12), Kramer (6), and Wilson, Boggess, and Kramer (14) have also reported on the fluctuations in the water contents of plants.Stocker (13) devised a measurement of water deficits by which he related the amount of water needed to bring a leaf to full saturation, or zero deficit, to the total amount of water in the leaf at saturation. The resulting ratio figure was multiplied by 100 and expressed as a percentage. Stocker used such a measurement to obtain a comparison of the water deficits existing in the leaves taken at different periods of the day from plants growing in widely separated climatic zones. Oppenheimer and Mendel (10), Halma (3, 4), Compton (1), and Runyon (11) have reported on the use of similar measurements to determine changes in the water deficits of plants.During the past five years the Department of Horticulture of the State College of Washington has conducted a study of certain water relationships of Bartlett pear trees. A portion of this study included the measurement of the seasonal and diurnal fluctuations in the leaf water contents and water deficits and the weight changes of the leaf constituents responsible for these fluctuations.MATERIALS AND METHODS As a source of leaf materials, eight bearing Bartlett pear trees were selected for this study. These trees were located in one orchard block at the Tree Fruit Experiment Station, Wenatchee, Washington. The leaf samples were taken from non-bearing fruit spurs near the periphery of the trees. An effort was made to limit the number of leaves removed from In determining seasonal changes, the sampling dates covered six 6-day periods spaced at three-week intervals from May 15 to September 2, 1950. The samples were taken between 2:00 and 2:30 P.M. each day from four sides of each tree and at three levels-5, 10, and 15 feet from the ground. To determine diurnal changes, leaf samples were taken at 4-hour intervals during six 32-hour periods spaced throughout much of the 1950 growing season. Four leaves were selected from eac...

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“…One would expect the maximum leaf moisture content early in the morning just before transpiration begins to increase, but this does not seem to be true. Stanescu (1936) recently reported the maximum leaf moisture content in Ailanthus glandulosa to occur at 11 p.m. following a cloudy day and at 2 a.m. following a clear day. In Ampelopsis tricuspidata the maximum occurred at 1 a.m. following a clear day.…”

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The Relation Between Rate of Transpiration and Rate of Absorption of Water in Plants

Kramer

1937

American J of Botany

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shoots of course are not quantitatively comparable with those made on rooted shoots, but possibly may be useful for comparison between different species under the same conditions. Livingston and Brown (1912) reported that the leaf moisture content of a number of species showed a decrease during the day and an increase at night. Maximov and Krasnoselsky-Maximov (1924) determined the water content of leaves at various times of day and found that even in the cool, humid climate of Petrograd a considerable water deficit existed at mid-day. Both investigators interpreted their results as indicating that water was lost more rapidly than it was absorbed.'EXPERIMENTS ON PLANTS IN SOIL.-While it is comparatively easy to measure the rate of water loss, it is impossible to measure directly the rate of absorption of plants rooted in soil. However, by using auto-irrigators in the manner suggested by Transeau (1911) and later used by Livingston and Hawkins (1915), it is possible to measure the rate of absorption of the system plant-plus-soil and thus to obtain some idea of the rate of absorption during any desired period of time. Livingston and Hawkins studied the relation between rates of transpiration and absorption in Coleus, Pelarqonium, and Vicia. They found that the rate of absorption fell behind the rate of transpiration during the day, but exceeded it at night. The period of maximum absorption usually fell about two hours later than the period of maximum transpiration. The experiments to be described here were performed to determine whether or not the relations between absorption and transpiration are the same in woody, herbaceous, and succulent species. The species used were green ash (Fraxinus pennsylvanicum var. lanceolata Sarg.), yellow poplar (Liriodendron tulipijera L.), loblolly pine (Pinus taeda L.), black willow (Salix nigra Marsh.), cactus (Opuntia sp.), and sunflower (Helianthus annuus L.).The willow was grown from cuttings which were about 6 months old. The other woody species were grown from seed. The cacti were grown from single joints rooted in sand. Three months to a year before they were used, all plants were transferred to metal containers about 15 ern. in diameter and 20 cm. deep. Two plants were placed in each container on opposite sides of the centrally located auto-irrigator cone, and the containers were filled with fertile, sandy loam soil having a moisture equivalent of approximately 18 per cent. The sunflowers were grown from seed in the containers and were 6 to 8 weeks old at the time of the experiments. All plants were grown with the water level of the reservoir about 40 em. below the bottom of the containers, and no mercury barostats were used. The plants all made excellent growth. 10 THE Mos'r FUNDAMENTAL phase of plant water relations in respect to effect on growth is the internal water balance or degree of saturation of the tissues. This is determined by the relative rates of absorption and transpiration. The ratio of absorption to transpiration is therefore more important than the absol...

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Daily Variations in Products of Photosynthesis, Water Content, and Acidity of Leaves Toward End of Vegetative Period

Cited by 11 publications

References 5 publications

Starch Formation in Tobacco Plants Deficient in Potassium1

Starch Formation in Tobacco Plants Deficient in Potassium1

Seasonal and Diurnal Changes in the Water Contents and Water Deficits of Bartlett Pear Leaves

The Relation Between Rate of Transpiration and Rate of Absorption of Water in Plants

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