Seasonal Study of Tissue Function and Organic Solute Movement in the Sunflower

Abstract

IntroductionStudies of seasonal changes of the nitrogenous and carbohydrate fractions of many plants have been made, but in few cases have the plants been sufficiently divided to show the functions of individual tissues. Usually when detailed work has been done, not all parts have been analyzed. Of course, many plants are constructed so as to make subdivision difficult and impractical. Hence, in this study it was decided to use the common cultivated sunflower (Helianthus annutus L.) as it fulfilled the requirement of being easily divided into anatomically distinct regions.Some work has already been done on various tissues of this plant over short periods. CLEMENTS (12) has dealt with the hourly variations of carbohydrates in the leaves. He has likewise studied seasonal changes in the sunflower, and although these data have not been published, they will be referred to from time to time in this paper.The purpose of this work was to determine the functions of plant tissues during various stages of growth and to obtain information of the synthesis and translocation of organic solutes.

Translocation of Carbohydrates in the Sugar Beet

“…If invertase activity is relatively low and the synthesizing system active, we may find, as in corn, mainly sucrose in the leaves; whereas, if invertase is active in the leaves, even though a sucrose-synthesizing system exists, as in the sugar beet, the sugars may be present mainly in the inverted state. This relationship is, likewise, correlated with the percentage of water in the tissue, as has been shown by the writer in work done on the sunflower (10). These relationships may explain the behavior of different plants in fluctuations of sucrose and reducing sugars during the day.…”

CARBOHYDRATE METABOLISM OF VITIS VINIFERA: HEMICELLULOSE

“…GARDNER, BRADFORD, and HOOKER (12) Still another type of finding that has led to an apparently erroneous conclusion is illustrated by the data of NELSON (25) and of LEUKEL (20) which show small decreases in hemicellulose in alfalfa roots that had undergone repeated top cutting-treatments, and of NIGHTINGALE (26) MURNEEK (24), LEONARD (19), and CLEMENTS (6) support the theory that hemicellulose serves as a reserve food in the plant. In their investigations, the observed variations of the hemicellulose content were irregular, and furthermore, are not correlated with the vegetative condition of the plant.…”

Carbohydrate Transformations in Leaf Blades, With Special Reference to Sucrose Synthesis

“…plants whose ears were predominately in the early milk stage, These blades were placed in quart jars containing 300 cc, of 6 per cent glucose solution in a semi-dark hallway in the basement of the botany building at Iowa State College, Ames, Iowa, Hartt (1937), Nurmia (1935), the author (Leonard, 1938), and others have found light not to be necessary for sucrose synthesis. The temperature of the hallway varied between 31°and 35°C.…”