フクシマダイイチゲンシリョクハツデンショジコゴニオケルタケオヨビモクザイノコンポストリヨウニカンスルケンキュウ

博士（農学)東京農工大

Comparative assessment of intensive tomato production in innovative non-circulating aquaponics vs. conventional hydroponics

New tendencies in farming techniques which include a composite agricultural production system have evolved as solutions for uninterrupted food supply. Production of high-yielding good-quality tomato (Solanum lycopersicum L.) is one of the leading challenges. This study aimed at evaluating the growth, yield, and fruit quality of hybrid tomato (Umagna), cultivated in non-circulating aquaponics and conventional hydroponics systems. A unique and innovative non-recirculating deep water culture aquaponics system (DWCAS) was developed as a prerequisite for high productivity comparable to current stand-alone fish/plant facilities. Including DWCAS, two other conventional hydroponics systems were compared during the study; the deep water culture hydroponics system (DWCHS) and the open bag system (OBS). The assessment of the production systems was based on the growth behavior, tomato yield, and quality. The maximum yield was observed for the DWCHS followed by DWCAS. The least yield was observed for the OBS. The results demonstrated the highest average fruit weight and marketable yield produced by DWCHS. There was no difference in plant dry matter content among production systems. The fertilizer use efficiency was increased by 11.7% and 85.86% in favor of the DWCHS and DWCAS, respectively.  The total rainwater use efficiency was also increased in DWCHS

Nutrient Status in Composts and Changes in Radioactive Cesium Following the Fukushima Daiichi Nuclear Power Plant Accident

Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the forests in the Fukushima area were highly contaminated with radiocesium (137Cs and 134Cs). Therefore, there is a need to develop strategies for remediation of the contaminated forests. We assessed changes in radioactive cesium (134Cs and 137Cs) contamination and nutrient status in composts derived from wood chip, bamboo leaf and bamboo powder using rice bran and wheat meal as sub-materials. Changes in soil properties and Komatsuna (Brassica rapa var. perviridis) growth were also investigated due the application of composts and initial materials at 0, 2.5, 5 and 10 kg·m−2 input levels. Mixing of sub-materials significantly reduced the concentration of radioactive Cs and improved compost quality. The effectiveness of three composts on soil quality improvement varied depending on their types and rates of applications. Amendments of bamboo leaf composts at 10 kg·m−2 resulted in the significantly highest soil inorganic N, available P and exchangeable K contents. Amendments of final composts also enhanced Komatsuna growth. Furthermore, radioactive Cs contaminations of the Komatsuna plants grown in these composts were below 0.1 Bq·kg−1. This study may help to remediate the forests contaminated with radiocesium in the Fukushima area while improving the soil organic matter content to enhance soil sustainability