Year: 1958
Type: article
Abstract: Experiments were carried out to clarify the influ-ences of the forms of nitrogen supplied with vary-ing concentrations on the growth, yields and chemical compositions of turnip in sand culture under glass. In the first experiment, mixed nitrates (KNO3: Ca (NO3)2, ; Mg(NO3)2=5:5:4), NaNO3, NH2NO3, (NH4)2SO4 and (NH2)2 CO were used as nitrogen sources and nitrogen concentrations supplied were 5, 10, 20, 40, 80 and 120 m. e. for each nitrogen source, respectively. In the second experiment, nitrogen sources were NaNO3, NH4NO3 and (NH4)2SO4, and nitrogen concentrations supplied were 1, 3, 5, 10, 20, 40, 60, 80 and 120m. e. All known nutrients were provided for each treatment. Results of both experiments were summarized as follows. (1) In the mixed nitrates and NaNO3 treatments, leaves were light green and even-surfaced. On the contrary NH4NO3 plants produced deep green foliage, and with increased nitrogen concentration their leaves became darker green and uneven-surfaced. Further, in the later stage of growth, they developed symptoms similar to that of potassium deficiency. In the (NH4)2SO4 series, leaves were darker green at the lower concentrations, but at the higher concen-trations became dull to yellow green and developed injuries due to excessive ammoniacal nitrogen. Leaves of the (NH2)2CO plants were chlorotic. And leaf color was proportional to the chlorophyll contents in the leaves. (2) Among mixed nitrates, NaNO3 and NH4NO3 treatments, there was no great difference of their top growth up to 40m. e. (560ppm) nitrogen level. But beyond 40m. e., the decreasing of growth was most remarkable in the NH4NO3, and least in the mixed nitrates. The growth of plants supplied with (NH2)2CO, especially with (NH4)2SO4 were markedly inferior to the above 3 nitrogen forms at every concentration. And at higher concentrations of (NH4)2SO4 and of NH4NO2, the decreasing of fleshy root growth was more remarkable than other nitro-gen forms, and their fibrous roots were also injured. (3) Total nitrogen content of both leaves and roots increased with increment of nitrogen supplied, irrespective of nitrogen forms. And in the higher nitrogen concentrations supplied (beyond 40m. e.), increment of nitrogen content was remarkable for (NH4)2SO4 and NH4NO3 treatments, but gradual for mixed nitrates and NaNO3. (NH2)2CO plants at lower concentrations contained less nitrogen than other nitrogen forms, but at higher concentrati-ons absorbed fairly much nitrogen. And generally NaNO3 plants accumulated much of nitrate nitro-gen, but (NH4)2SO4 plants contained only trace, and NH4NO3 was intermediate. As to ammonium nitrogen, the relation of (NH4)2S04>NH4NO3>NaNO3 was found, but accumulation of ammonium nitrogen was much less compared with nitrate nitrogen. (4) In the NH4NO3, especially in the (NH4)2SO4 treatment, phosphorus content of leaves was higher and increased with increment of ammoniacal nitrogen supplied. As to potassium, plants supplied with mix-ed nitrates or (NH2)2CO contained much. Plants supplied with NaNO3, NH4NO3 or (NH4)2SO4, had less potassium than the above 2 nitrogen forms, and potassium content decreased against increased Na or NH4 supply
DOI: 10.2503/jjshs.27.21
Author: M. IWATA
Institution: The University of Tokyo
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: diamond
OpenAlex ID: W4205301484