| Popis: |
The essential nature of zinc as a micronutrient in plants has been known for a number of years and numerous studies of the zinc content of plant tissue have been made. However, relatively few investigations have been designed to determine its distribution in the plant cell components, and the data available are not conclusive. Whatley, Ordin, and Arnon (6) prepared chloroplast fragments of sugar beet and chard grown in nutrient solution and concluded that the zinc was not concentrated in the chloroplasts. They reported 65.3 micrograms zinc per gram of leaf tissue and 43.5 micrograms zinc per gram of chloroplast fragments on a dry weight basis. Wood and Sibly (7) found that leaves of oat plants contained 20 to 30 per cent of the total zinc in the plants. They found 16 to 20 per cent of the leaf zinc localized in the chloroplasts. In spinach 50 per cent of the total leaf zinc was found in the chloroplast fraction. Reynolds (3), in a study of zinc in alfalfa, concluded that the zinc was primarily associated with a water soluble constituent of the cytoplasm. Schrenk, Nauman and Hein (4) reported earlier on rate of uptake of radioactive zinc in alfalfa. The relatively slow rate of uptake was interpreted as indicating possible reaction of zinc with certain plant components. Although these and other investigations concerning the location of zinc in the plant cell have been conducted, it is evident that more data are needed relating to zinc and its distribution in plant cells. The following study was made in an effort to provide additional information concerning zinc distribution. Alfalfa was chosen as the plant for this study. |
