KIM, Joon Ho(Dept. of Biology, Kongju Teachers College, Kongju, Korea) Effects of urea nitrogen on the metabolism of plants. 1. studies on nitrogen absorption and metabolism by sunflower leaves sprayed with urea solution.
Kor. Jour. Bot. 4(2) 51~61 1961
In order to detect the way of absorption and metabolism of the urea it is sprayed on the surface of the leaves of sunflower. The sunflowers used in this study are grown in different conditions such that the one in nittogen aboundant and the other in nitrogen deficient soil, respectively . The area-N. ammonia-N, amide-N, and 80% alcohol soluble-N in the leaves were quantitatively determined. All of the nitrogenus components measured are generally tended to increased with rising the concentration of urea except only amide-N at 24 hours after sprayed. and these were highly significances. It seemed that hydrolizing of urea into ammonia and carbon dixide and the assimilation of ammonia into other organic nitrogenous constituent were rapid in the young leaves than in the mature. It is interest that the amide content, in the young leaves and nitrogen defieient one were enhanced with the increasing concentration of urea, althought in the mature ieaves it did not show any change in the urea treatment. It is presumed that the assimilation rate of ammonia and the urease activity were lower in the matture leaves than in the young and nitrogen deficient leaves.
No significance at 5% level showed all of the nitrog??nous components except total nitrogen between nitrogen abundant and deficent leaves. Urea content was a high peak at first 12 hours, ammonia at 48 hours, and amide and alcohol soluble nitrogen at 96 hours, whence decreased the content of these constituents gradually. The total nitrogen content is not increased obviously by only one time of urea spray in this study. When the concentration of urea was relatively high there appeared the wilting spots on the edge of leaves. As a whole, it seemd that sprayed urea was rapidly absorbed and taken part in nitrogen metabolism within relatively short period.
|