HortJ

Among large-scale research projects for reconstruction of agriculture and fisheries of the area damaged by the Great East Japan Earthquake and Tsunami (2011), the results of field trials and research concerning field vegetables including cabbage and broccoli were reviewed. In Miyagi Prefecture, to reconstruct the agriculture of the Sendai Plain coastal area, a mechanized and labor-saving culture system of field vegetables, that can coexist with paddy rice production as the primary source, was chosen. In this article, from such a point of view, an integrated mechanical culture system of cabbage is introduced and discussed. In addition, in Fukushima Prefecture, the specific situation regarding the radioactive pollution soon after the disaster led to research trials on nursery production. For labor-saving in nurseries, broccoli plug seedlings were raised by a bottom watering system with application of NaCl solution to increase the drought-resistance of seedlings. In Iwate Prefecture, open-field cucumbers were cultured by a fertigation technique to maintain vigor and extend the harvest period.

The Great East Japan Earthquake heavily damaged horticultural production in the Tohoku Pacific Ocean coastal region of Japan. In this paper, we will describe the reconstruction support for strawberry production in Miyagi Prefecture that was damaged by the disaster. We have been involved in supporting horticultural reconstruction efforts in this region since the earthquake struck in 2011. In 2012, the Japanese Government began a research project to support reconstruction of the affected agricultural area (“A Scheme to Revitalize Agriculture and Fisheries in Disaster Area through Deploying Highly Advanced Technology”). The horticultural research station for the project, located in Yamamoto-town (Miyagi Prefecture), is a Venlo-type greenhouse 0.72 ha in area. Yamamoto-town and nearby Watari-town, together represent a major strawberry production region in Tohoku. Therefore, technical support to reconstruct the strawberry greenhouse facilities was a high priority of the research project. Since inception of the project, we have provided technical information to growers and the local extension service, and we have cooperated with them to solve technical problems. Due to the amount of salt accumulated in the soil after being flooded by the earthquake-related tsunami, we determined that an elevated growing-bed system was the best option to resume strawberry production. Therefore, we designed and proposed an elevated growing-bed system consisting of individual growing containers and a crown-temperature control system; this system should prevent the spread of soil-borne diseases from occurring frequently in connecting long beds. Separate containers also provide the drainage needed to keep the root zone (air and water contents) amenable for growing strawberries. The crown-temperature control system, established by the National Agriculture Research Organization (NARO), was added to increase yield and reduce fuel consumption. Large-scale, multi-span greenhouses were constructed by the local government (total 152 growers, 41 ha) and the first strawberry cultivation restarted in September 2013. In the research station greenhouse, we have continuously demonstrated or developed new technologies and provided information to the growers.

Agricultural lands in the Kesen area, which is located in the coastal area of Iwate Prefecture, were severely damaged by the Great East Japan Earthquake on March 11, 2011. Empirical research was undertaken to promote agricultural restoration and reconstruction. This project was conducted to realize low-cost protected horticulture utilizing local resources effectively. In this area, where forestry was popular, there was abundant unnecessarily thinned timber. Three types of low-cost greenhouses were developed, including a wooden frame house built using lumber derived from thinning. A stove to use thinned timber as a fuel was also developed. To establish protected horticulture at a low cost, greenhouses that could be constructed with accessible materials were developed along with a device for sterilizing nutrient solutions using charged plasma. An environmental control program was developed based on a “ubiquitous environment control system (UECS)” for small-scale facilities. Disease control using hot water for long-term cultivation was carried out. Strawberry and tomato production was conducted to demonstrate the use of these developed elements and resulted in yields significantly higher than those obtained for these crops before the disaster.

In blueberry culture, when sulfur and NH₄⁺ and K fertilizers are applied to soils, radiocesium in the soils may be released into the soil solution, absorbed by roots, and then translocated to fruit. We reanalyzed data from our previous experiment to evaluate soil factors affecting the concentration and total amount of natural stable Cs in blueberry organs and its translocation to fruit. During a 2-year pot experiment, 4-year-old rabbiteye blueberries (Vaccinium virgatum Aiton ‘Onslow’) were grown in three soils (Andosol, Cambisol, and Fluvisol) with or without soil treatment (acidification, NH₄⁺ and K fertilization, or combined acidification-fertilization treatment). We measured the concentrations of 13 elements (N, Na, Mg, Al, P, K, Ca, Mn, Fe, Cu, Zn, Rb, and Cs) in samples of the soil solution and the blueberry fruit, leaves, branches and stems, and roots, as well as the pH of the soil solution. Acidification, fertilization, and combined treatment increased the Cs concentration in the soil solution within each soil. On the other hand, the Cs concentration in the whole bush was not changed significantly by any soil treatment. The Cs concentration in fruit, leaves, and branches and stems was significantly negatively correlated with concentrations of Na, Mg, K, and Ca in the soil solution. Among the three soils, the concentrations of these basic cations were lowest in the soil solution of the Cambisol. The fruit Cs concentration in the Cambisol did not change significantly with any soil treatments. In contrast, in the Andosol and Fluvisol, the fruit Cs concentration was significantly decreased by both acidification and fertilization. The whole-bush Cs content did not differ significantly among the soil treatments, whereas the percentages of Cs in fruit and roots depended greatly on the soil treatment within each soil, although the distribution trends relative to the control were opposite for fruit and roots. Our results suggested that the soil treatments to increase the concentrations of soil basic cations could reduce the rate of transfer of Cs to fruit and thereby contribute to a reduction in the Cs concentration in fruit, but not the whole-bush Cs content.