@article{oai:repository.naro.go.jp:00001804,
 author = {木下, 貴文 and KINOSHITA, Takafumi},
 journal = {近畿中国四国農業研究センター研究報告, BULLETIN of THE NATIONAL AGRICULTURAL RESEARCH CENTER for WESTERN REGION},
 month = {Mar},
 note = {The root-proof capillary wick irrigation system, a type of sub-irrigation method, is expected to reduce environmental impact by eliminating drainage and save labor by eliminating the use of irrigation equipment. Application of controlled release fertilizers (CRF) by using this system has economic benefits because fertigation equipment is not requred. The purpose of this study was to establish a laborsaving and low-environmental-impact production system for forcing tomato culture by using a single basal application of CRF with this irrigation method. First, I investigated the effects of various substrates on growth and yield in relation to 3-phase distribution of substrates and inorganic nutrient solution in substrate solution in forcing tomato culture to determine an appropriate substrate for this culture method. These results suggested that liquid-phase distribution of substrates would be an indicator of suitable substrate selection in this culture ; the value was around 45-55%, including a substrate consisting of paddy soil : bark compost : peatmoss : perlite at a ratio of 2 : 4 : 1 : 1 (v/v). Secondly, a suitable level of CRF, which was applied by mixing the fertilizers with substrates in a conventional manner, for the forcing tomato culture was evaluated. Initially, 16.2 g N/plant appeared to be sufficient. I, then, investigated the effect of this concentration of CRF and liquid fertilizer (LF) on fruit productivity and nutrient dynamics. Marketable fruit weight was significantly lower with CRF than with LF, especially at the upper trusses, indicating that nutrient supply was lower in later phases of the plant growth cycle using CRF. Therefore, further investigations are required to determine the level of nutrients that is sufficient to increase fruit yield during the later period of cultivation. On the other hand, nutrient use efficiency for fruit production was higher with CRF than with LF. I, then, examined fruit production in plants treated with modified combinations of CRFs, compared CRF and LF with respect to nutrient uptake and transport in forcing tomato cultures. No significant difference was noted in marketable fruit yield between CRF- and LF-treated plants. The quantity of nutrient uptake per plant and per fruit yield was lower with CRF than with LF, indicating that nutrients were utilized more efficiently for fruit production in plants grown with CRF. Analysis of the volume and mineral concentrations of xylem exudates indicated that the amount of nutrients absorbed was greater with LF than with CRF, particularly after the 10th truss was harvested. Mineral concentrations in the substrate solution of CRF-treated plants were initially higher than those in the substrate solution of LF-treated plants, but were extremely low after the second truss was harvested ; mineral concentrations in the xylem exudates were similar in CRF- and LF-treated plants until the eighth truss was harvested. Thus, the difference in mineral concentrations between the xylem exudates and substrate solution was much larger for plants treated with CRF than for plants treated with LF, indicating that plants absorbed the bulk of the nutrients immediately after their release from the CRF surface. Therefore, CRF is suitable in this system because it combines high fruit production with high nutrient utilization efficiency. Finally, a tank-fertilization method (TF), in which CRF was supplied in the water reserve tank, was developed to simplify and reduce labor requirements for application of CRF and reutilization of substrate. In the TF method, efficient nitrification (production of NO_3-N) was achieved in the water tank by combining the addition of bark compost (substrate for nitrifying bacteria) with aeration of the water. Next, we compared 3 CRF fertilization methods : (1) completely mixed with the substrate ("mixed-fertilization" [MF]) ; (2) packed in bags and placed on the wick ("packed bag-fertilization" [PF]) ; and (3) TF in a short tomato-cultivation period. Fruit yield was lower under PF and TF than under MF, because a high incidence of blossom-end rot (BER) occurred in plants fertilized by PF and TF. However, promotion of nitrification under TF using the above-mentioned method increased fruit yield to the same level as that observed under MF, due to decreased incidence of BER. Thus, the use of CRF via "tank fertilization" for tomato production is effective by promoting nitrification in the water reserve tank. On the other hand, high incidence of BER probably was due to suppression of Ca uptake caused by high NH_4-N uptake. I, then, investigated the difference in the uptake ratio of NH_4-N/NO_3-N and nitrogen conversion of the supplied fertilizer, and attempted to determine the reason for the difference in BER rate among the different CRF-application methods. Based on nitrogen concentration in xylem exudates, the uptake ratio of NH_4-N/NO_3-N appeared to be lower under MF than under PF and TF. Therefore, the high NH4-N uptake under PF and TF could be the cause of Ca deficiency and increased incidence of BER. From these results, I finally investigated the applicability of the TF method to long-term forcing culture of tomato. Fruit yield under TF was similar to that under MF and LF. Furthermore, nutrient use efficiency for fruit production under TF was similar to that under MF and higher than LF. Moreover, substrates treated using TF may have high reusability. In conclusion, I demonstrated the effectiveness of a simplified, laborsaving, and low-environmentalimpact production system for long-term forcing tomato cultivation using a single basal application of CRF via root-proof capillary wick irrigation. Moreover, it was revealed that fertilizer use could be reduced by application of CRF in the system, because nutrients were utilized more efficiently for fruit production in plants grown with CRF than in those grown with LF. This finding is very important for environmental and resource conservation and for agricultural management. In addition, the tank-fertilization method of applying CRF, which was newly developed in this study, is important for other soilless culture systems because it is a laborsaving fertilization technique.},
 pages = {11--58},
 title = {防根給水ひも栽培に肥効調節型肥料を適用したトマトの省力・環境負荷低減型簡易生産システムの開発},
 volume = {13},
 year = {2014},
 yomi = {キノシタ, タカフミ}
}