Showing papers on "Plant physiology published in 1975"

The Growth of Maize (zea mays l.) under Field conditions as affected by its Water Relations.

Abstract: The growth potential of a plant is ultimately determined by its genetic make up. The environment, however, plays a major role. firing the extent to which the growth potential is expressed. Water, a major component of the environment, influences virtually all physiological processes, and constitutes one of the most important limiting factors in plant life . Much of the genetic expression for growth of a plant can be determined by the relative abundance of water in the growing medium.

Effect of calcium deficiency on the carbon metabolism in photosynthesis and respiration of tomato leaf

Abstract: Changes in carbon metabolism resulting from calcium deprivation of tomato leaf tissue were investigated employing C14O2 in photosynthesis and respiration and by comparing it with the control. By 8 to 10 days of calcium deprivation, the leaf tissue had only half as much chlorophyll, but excess of water soluble metabolites and dry matter. Its rate of apparent photosynthesis was lowered (30%) but not that of respiration. After 15 min photosynthesis in C14O2, the label was considerably low in the lipid fraction, sucrose and malic acid, to a smaller extent in aspartic acid and alanine, but was not altered in serine-glycine, sugar phosphates, and starch. During 6 hours respiration following 15 min photoassimilation of C14O2 the loss of radioactivity from starch, sucrose and sugar phosphates of the deficient leaf tissue was considerably low. Similarly, the gain in radio-activity occurring concurrently in citrate, malate, glutamate and cell wall residue was also low. Although the amount of CO2 given off by the deficient tissue in 6 hours was not significantly lower, the specific activity of the respired carbon dioxide was 10 to 15 times lower than that of the control. The results seem to indicate that in the calcium-deprived leaf tissue the early products of photosynthesis were much less available for the respiratory activities which occur outside the chloroplasts. A restriction in the movement or utilization of early products of photosynthesis outside the chloroplasts is therefore inferred as one of the possible effects of calcium deprivation. re]19740530

Iron uptake by sunflower plants under sterile and non-sterile conditions

Abstract: The possible involvement of micro-organisms in the iron nutrition of sun-flower plants grown in nutrient solutions with different sources of iron (— Fe; inorganic Fe3+; Fe EDTA) was investigated. It is shown that micro-organisms play no significant role since the ability of plants under iron stress, to decrease the pH of the nutrient solution and to release reducing substances and riboflavin and to make Fe3+ available for uptake and chlorophyll formation was similar under both sterile and non-sterile conditions.