- 日本土壌肥料學雜誌 (ISSN:00290610)
- vol.66, no.3, pp.238-246, 1995-06-05
Spinach and komatsuna were cultivated with 0,10,15 and 30g N m^<-2> applications in an Ando soil, and the changes of the contents of sugars, ascorbic acid, nitrate and oxalic acid which are the constituents related with the quality of the vegetables, and the relations between the growth (fresh weight), nitrogen status and the contents of these constituents were investigated. Ascorbic acid is contained both in spinach and komatsuna, but oxalic acid is contained at a high level in spinach and at trace levels in komatsuna. Nitrate nitrogen contents increased along with the increase of applied nitrogen, and reached 1.14g (kg FW)^<-1> in spinach leaf petiole and 1.26g (kg FW)^<-1> in komatsuna leaf petiole at harvest with the application of 30g N m^<-2>. In both crops, sucrose content was highest in the plot of 0g N m^<-2>, glucose content was highest in the plot of 10g N m^<-2>, and they were lowered with increased application of nitrogen. Total ascorbic acid (ASA+DHA) content was decreased by increasing the nitrogen application : from 0.74g (kg FW)^<-1> at the plot of 0g N m^<-2> to 0.51g (kg FW)^<-1> at the plot of 30g N m^<-2> in spinach and from 1.00g (kg FW)^<-1> at the plot of 0g N m^<-2> to 0.48g (kg FW)^<-1> at the plot of 30g N m^<-2> in komatsuna. In spinach, the total (water-soluble plus-insoluble) oxalic acid content was increased in the leaf blades and decreased in the leaf petioles along with the increase of nitrogen application, and there was no difference in the whole leaves with the treatments. The contents of sucrose and ascorbic acid were high in the plants in which yield and nitrogen content were low and dry matter content was high. In view of the quality of spinach and komatsuna, the low nitrogen application is better, but the amount of nitrogen application must be determined considering the maintenance of growth and yield.