ルビジウム/カリウム比法および相対ウレイド法による1993年の冷害におけるダイズの生育と窒素栄養の特徴

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In 1993,the amount of N accumulation and seed yield were the lowest in the past 4 experiment years (1990-1993) by cool-summer damage. The reason for the low seed yield in 1993 was studied in relation to N_2 fixation and N absorption. 1) In the Rb tracer experiment, we confirmed that the natural Rb was measurable in soybean shoots, and there was a tendency among the plant growth and the ratio of Rb/K. From the results, Rb/K ratio method was developed for estimating the root elongation to deep layer of soil. Rb/K ratio was became higher as the growth increased. The Rb/K ratio in 1993 was low and near the same as the restriction treatment of root systems at a 20-cm depth, and suggested that the distribution of root systems were restricted to a depth of 20 cm in 1993. 2) The relative ureide method was applied to estimate the amount of N_2 fixation. And the amount of N accumulation and N_2 fixation in 1993 were lower compared with the previous 3 years. 3) Although the concentration of ureide-N in xylem sap increased during R1 (Beginning bloom) and R3 (Beginning pod) in the normal growth conditions (1990 and 1992), the ureide-N concentration of xylem sap was depressed during vegetative and reproductive growth period in 1993. In 1993,the suppression of N_2 fixation and N absorption activity by cool-summer damage was confirmed throughout the growth period.
社団法人日本土壌肥料学会の論文
1995-04-05