Behaviour Of Stomata Research Articles

A Method of Measurement for Transpiration of Sugar Beet Plant

Transpiration of sugar beet plant was measured as a loss in weight of detached leaf blade. A leaf blade (100-300 cm2) randomly sampled from the field plant was weighed by a top pan balance immediately after sampling. After direct exposure horizontally to the sun on the balance for five minutes, the leaf blade was weighed again. In preliminary experiments, it was ascertained that behavior of stomata and temparature of detached leaf were scarcely changed for about 20 minutes after detaching. The difference between the first and the second weight may be regarded as a loss mainly due to transpiration. Among several evironmental factors, the horizontal solar radiation seemed to have a predominant influence on transpiration. When thn loss in weight was plotted against the horizontal solar radiation, a linear relation was observed and the points were fitted by a regression line. The relation of transpiration to the horizontal solar radiation was by the following equation. t/dm-2. 5 minutes=(0.35x+0.02 where t=quantity of transpiration x=mean horizontal solar radiation (cal) for five minutes This equation was applied to estimate transpiration of a whole plant and of plants in unit field area. t/plant. 5 minutes=(0.35·x·R+0.02) L/plant t/unit field area·5 minutes=(0.35·x·R+0.02) L/unit field area where L=leaf area exposed to light R=mean solar radiation in all leaves exposed to light/horizontal solar radiation

Evaporation from Lucerne Under Advective Conditions in the Sudan I. Factors Affecting Water Losses and Their Measurement

SummaryIt is suggested that irrigation should ideally be based on two sets of measurements, i.e. of conditions in the leaf and of cumulative evaporation rates respectively, on the assumption that the question 'When to irrigate ? ’ can best be answered from a knowledge of leaf water potential and the daytime behaviour of stomata, and the question ‘How much water to apply?’ from a knowledge of the current soil water deficit. It is emphasized that there is no unique or fixed relation between leaf water potential and soil water deficit, and since neither can be deduced from the other it is advisable to measure both in critical experimental work on irrigation. Various methods of measuring leaf water potential and evaporation rates are discussed, and their value in experimental work assessed.

On a New Method for measuring the Stomatal Aperture of Leaves

SUMMARY A method is described of following the behaviour of stomata by utilizing a diffusion phenomenon, the Dufour effect. Hydrogen at laboratory temperature is blown on to one side of the leaf. As it diffuses through the leaf and out the other side it is accompanied by a rapid temperature wave of considerable magnitude. This is picked up by a fine thermocouple near the leaf and passed to a quick period galvanometer. The 'flick' of this measures the stomatal conductance. An experiment is described in which the behaviour of a wheat leaf was followed. The results agree well in broad outline with those obtained by other methods. Advantages claimed are that an approximation, at least, is obtained to the value of the important diffusive conductance of the stomata ; that the leaf does not have to be enclosed in any way, and that the instrument can easily be made automatic and recording. Ambient temperature changes are not troublesome. The purpose of this paper is to describe a new method for investigating the stomatal behaviour of leaves. The principle is, so far as is known, quite new and it has the advantage of depending on a diffusion phenomenon. To some extent therefore it gives information directly applicable to an analysis of the way in which stomata actually control the processes of carbon-dioxide supply and water loss. Before describing the method itself it will be helpful to make a few remarks on the physical principles underlying it. The Dufour effect. It is a phenomenon found very widely in the physical world in which two agencies of quite distinct nature often interfere with each other to produce additive results in the spheres of each. About 1872, Dufour discovered that when two gases at the same temperature are allowed to diffuse

The Effect on the Behaviour of Stomata of Alternating Periods of Light and Darkness of Short Duration

Journal Article The Effect on the Behaviour of Stomata of Alternating Periods of Light and Darkness of Short Duration Get access F. G. GREGORY, F. G. GREGORY From the Research Institute of Plant Physiology, Imperial College of Science and TechnologyLondon, S.W.7 Search for other works by this author on: Oxford Academic PubMed Google Scholar H. L. PEARSE H. L. PEARSE From the Research Institute of Plant Physiology, Imperial College of Science and TechnologyLondon, S.W.7 Search for other works by this author on: Oxford Academic PubMed Google Scholar Annals of Botany, Volume 1, Issue 1, January 1937, Pages 3–10, https://doi.org/10.1093/oxfordjournals.aob.a083458 Published: 01 January 1937

The resistance porometer and its application to the study of stomatal movement

The porometer is a convenient method of studying the behaviour of stomata since it automatically integrates the effect of a large number of stomata and the same group of stomata remain under continuous observation. The porometer was first described as a method for investigating stomatal movement by Darwin and Pertz (1911). In the apparatus described by these workers a glass chamber bearing a broad flange is cemented with glue to the stomata surface of tire leak; air is sucked through the stomata into the chamber by means of a water column, and the rate of fall of this column is measured at a known average pressure. This rate of fall is then taken as a measure of the degree of opening of the stomata. A modification of the method of direct observation has been described by Maskell (1928).

Certain water relations of the genusPrunus

Abstract does not appear. First page follows. This paper is based on a comparative study of stomatal behavior and moisture content of trees of the genus Prunus during the rainless summer months in California, where they are grown under conditions of both abundant and scanty soil moisture. The behavior of stomata in relation to transpiration has been a riddle to physiologists. Lloyd,(15)-(16) working with Fauquiera splendens in Arizona, first stated that the regulatory effect of stomata on transpiration was almost nil. Later he modified this view and showed that transpirational losses followed stomatal opening. Other physiologists thought that, except for the small water loss due to cuticular transpiration, the stomata controlled the transpirational losses. Francis Darwin,(3) Knight,(10)-(11) and others studied the action of stomata by means of the porometer. This device consisted of a hollow receptacle fastened to the leaf, through which a stream of air was drawn. From the amount of air which could be drawn through a leaf under carefully controlled conditions, these workers drew their conclusions regarding the transpiration of the plant. The value of this method was problematical and Darwin and Pertz(4) stated that “it is not certain that we shall ever be able to deduce the size of stomata from readings of the porometer.”

THE INFLUENCE OF LIGHT UPON THE ACTION OF STOMATA AND ITS RELATION TO THE TRANSPIRATION OF CERTAIN GRAINS

The stomata of leaves are the passages through which the necessary exchange of gases takes place between the interior of the land plant and its leaves and the outside world. They are the organs through which CO2 and 02 are taken from the air and given back to it. And it is through them that water vapor passes out into the air. The stomata are the exterior openings of intercellular spaces which may extend for great distances in the body of the plant. These openings are bounded by paired guard cells possessing in most plants a markedly greater degree of elasticity than the other epidermal cells. The mechanism and the behavior of stomata have been the object of study of many botanists for decades. For the older literature of the subject one may refer to Pfeffer (i). Only the few more recent papers bearing on the specific question which we asked ourselves will be referred to here. In general the behavior of the stomata of the Gramineae is as follows. When the opposite ends of the guard cells of a pair are in contact with each other the stoma is thereby closed. These opposed ends are thin-walled, the rest of the wall being thick and stiff. Opening begins with the expansion of the guard cells. This results in the separation of the guard cells, at first at the ends of the stoma, and later in the middle as well, the guard cells straightening and giving to the pore its familiar oblong shape and its uniform width for nearly its whole extent. Closing appears to be the reverse of this process. This action of the guard cells seems to be a mechanical process dependent upon the character of the environment in which the plant lives. The times, conditions, and significance of the opening and closing of stomata have interested many plant physiologists, and there are certain general conceptions current, as indicated by the concise statements of the textbooks. But the work of one of us in the field, in which the possible effect of sulphur dioxide fumes upon the stomata, as well as upon the other cells of the leaf, became a matter of importance, made it necessary to ascer-

Transpiration and Behaviour of Stomata in Halophytes

Transpiration and Behaviour of Stomata in Halophytes