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KMID : 1041219830240020043
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Journal of Sericultural and Entomological Science
1983 Volume.24 No. 2 p.43 ~ p.54
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Effect of Nitrogen Rate on the Ionic Balance and the Variance with Leaf Sequance in Mulberry (Morus alba L.) Leaves
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Lee Won-Chu
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Abstract
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In a field trial, the influence was studied by measurement of growth and leaf yields and chemical composition (in organic cations and anions and total nitrogen) with two nitrogen dressings (lower nitrogen treatment 25kg and higher nitrogen treatment 75kg urea/10a as the summer fertilizer) after the summer cutting. The results were as follows; 1. With increasingn nitrogen dressing, branch length and weight were enchanced. The fresh weight of leaves was higher to be 273.6kg/10a in the higher nitrogen treatment than in the lower nitrogen treatment on 20 September. 2. The moisture content of leaves lasted above 73% until on 30 August. Afterward it decreased sharply upto 63% on 20 September. In higher nitrogen treatment it was higher about 0.1∼1.8% than in lower nitrogen treatment. The increasing nitrogen dressings combined with leaf condition led to be soft until on 10 October. 3. Dry matter weight of leaves started decreasing around on 10 September, whereas that of branches increased until around 30 September indicating that the dry matter moved to branch and root from leaves. 4. The increase in Ca2+/ content was particularly evident, whereas the K+/ and Mg2+/ decreased with growth. The Ca2+/ content was much higher in the high nitrogen treatment than in the low nitrogen treatment. 5. With rapid decrease in total nitrogen and water in the leaves around the end of August, the Ca2+/ and Cl-/ which were higher in the lower part moved up to the upper part. Whereas the K+/, HPO-/ and SO2-/ which were higher in the upper part moved down to the lower part. 6. Total nitrogen content decreased sharply 3,200me/kg DM to 2,000me/kg DM at the end of August changing the maxmium content of total nitrogen from upper to lower part in the low nitrogen treatment on 12 September and in the high nitrogen treatment on 22 September, and an apex of branches was died and fallen 10 days after respectively. 7. The sum of cation in leaves (∑C) increased from 1400me/kg DM to 1600me/kg DM with growth, wherease that of anions (∑A) was approximatly the same during the whole growing season. As the result, the ionic balance (C-A) increased from 1000me/kg DM to 1200me/kg DM. 8. ∑C, ∑A and (C-A) were higher in the high nitrogen treatment than in the low nitrogen treatment due to be much higher of Ca2+/ content and higher of NO-/, SO2-/ and HPO-/ content.
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KEYWORD
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