Influence of the forms of nitrogen supplied on the growth of vegetable crops. III.
Growth as influenced by variable cations and pH in the culture solution
1962 Volume 31 Issue 1 Pages 39-52
Details
1962 Volume 31 Issue 1 Pages 39-52
Experiments were carried out to compare the concentrations of cations and pH favorable for plant growth, in culture solution supplied with different forms of nitrogen. Several vegetable crops were cultivated in sand or solution under glass. Forms of nitrogen supplied were NO3-N, NO3+NH4 or NH4-N (10m.e. as N).
1. Cabbage plants supplied with NO3+NH4 or NH4-N required more calcium than plants supplied with NO3-N, for better growth. And in the NO3+ NH4 treatment, growth of plants which were given more calcium (6-18m.e.) caught up with growth of NO3 plants, but not in the case of NH4 plants. In turnip, however, growth of NO3+NH4 plants was also behind that of NO3 plants, notwithstanding higher calcium supply (4-12m.e.). On the other hand, in spinach, growth of plants supplied with any form of nitrogen did not increase so much, even when calcium level was raised up to 4-12m.e., and growh of both NO3+NH4 and NH4 plants were fairly below that of NO3 plants.
2. In cabbage, in spite of increased magnesium or potassium supply, growth of NO3+NH4 or NH4 plants was inferior to that of NO3 plants.
3. Calcium deficient symptoms of cabbage and turnip were rather severe in the plants supplied with NO3-N, but in spinach, severer symptoms emerged in the plants supplied with NO3+NH4 or NH4-N. Moreover in cabbage, there were some differences in the magnesium or potassium deficient symptoms among the forms of nitrogen supplied.
4. Total calcium coucentration in the leaves of turnip was fairly higher than that of spinach, its greater portions being in the soluble forms, and with increasing the calcium supply, the proportion of soluble calcium increased slightly in plants supplied, with any form of nitrogen. In the leaves of spinach also, the proportion of soluble calcium was fairly high in the lower calcium supply, but with increasing calcium supply, greater portions of calcium became insoluble, its tendency being most remarkable in the NO3 plants.
5. Growth of cabbage or bean plants which were given NO3-N showed no greater difference in the range between pH 4 and 7, but turnip plants developed chlorosis and lowered their growth at pH 7. In every test plant supplied with NO3+NH4 or NH4-N, its growth increased with rise of pH level, and at pH 7, NO3+NH4 supplied plants made equal growth to NO3 supplied plants, but, NH4 plants made less growth.
6. As for the interaction between pH and calcium, growth of cabbage plants supplied with NO3-N increased with increment of calcium supply in both solution mediums with pH adjusted at 4 and 7. On the other hand, growth of NO3+NH4 or NH4 plants did not increase in spite of calcium supply at pH 4, but at pH 7 their growth increaed with rise of calcium level, and growth of NO3+NH4 supplied plants came up with that of NO3 supplied plants.
