巻号一覧
74 巻 (2018)
- 4 号 p. 129-
- 3 号 p. 97-
- 2 号 p. 63-
- 1 号 p. 1-
74 巻, 3 号
選択された号の論文の5件中1～5を表示しています
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Short Paper
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Tropospheric ozone reduces resistance of Japonica rice (Oryza sativa L., cv. Koshihikari) to lodgingMasahiro YAMAGUCHI, Yuriko NISHI, Sayaka KAWADA, Kentaro NAKASHIMA2018 年 74 巻 3 号 p. 97-101
発行日: 2018年
公開日: 2018/07/10
[早期公開] 公開日: 2018/05/30ジャーナル フリーTo clarify the effects of ozone (O3) on the resistance of Japonica rice (Oryza sativa L.) to root lodging, the Japanese major rice cultivar Koshihikari was exposed to four levels of O3 in open-top chambers (mean O3 concentration: 17.3, 32.4, 51.1, and 66.3 nl l-1). We evaluated the resistance to root lodging by measuring pushing resistance at 15 days after heading (DAH) and the dry masses of plant organs such as roots at harvest (35 DAH). Exposure to O3 significantly reduced pushing resistance per panicle, suggesting that the O3 reduced resistance to root lodging. Because the degree of O3-induced reduction in pushing resistance per panicle correlated with that of O3-induced reduction in root dry mass per panicle, the O3-induced reduction in the resistance to root lodging could be caused by O3-induced reduction in root development. There was a significant negative correlation between relative value of pushing resistance per panicle and O3 concentration or dose, indicating that resistance to root lodging decreases with increasing O3 concentration. In East Asia, because the O3 concentration is projected to increase in the near future, lodging issues in the rice cultivation could become serious.抄録全体を表示PDF形式でダウンロード (402K) -
Takafumi MIYAMA, Hiroyuki TOBITA, Kentaro UCHIYAMA, Kenichi YAZAKI, Sa ...2018 年 74 巻 3 号 p. 102-108
発行日: 2018年
公開日: 2018/07/10
[早期公開] 公開日: 2018/06/24ジャーナル フリーTropospheric ozone (O3) concentration has been increasing. The aim of this study was to compare the effect of O3 exposure on monoterpene emission rate and the components of Japanese cedar (Cryptomeria japonica) between three major gene pools identified by population genetic structure analysis. At the O3-FACE (Free-Air O3 and CO2 Enrichment) facility, 1-year saplings of three clones of Japanese cedar (Donden, Kawazu, and Yakushima) were exposed to ambient double concentrations of O3. After 15 months of O3 exposure experiment, monoterpene emission characteristics were evaluated by branch enclosure method using cutting samples of current-year leaves. Basal biogenic volatile organic compound emission rate (Es) was higher in the O3 exposure plots, and two-way analysis of variance revealed an effect of the O3 exposure (p<0.05) and an interaction between the O3 exposure and clone (p<0.05). Especially, high Es values were observed in the Yakushima after the O3 exposure. In addition, the coefficient β related to temperature sensitivity increased in the O3 exposure plots (p<0.05). Our findings supported the fact that there are large inter-clone variations in C. japonica. It is important to evaluate the differences in clones considering the genetic diversity and to clarify the mechanism of the differences after long-term moderate O3 exposure.抄録全体を表示PDF形式でダウンロード (457K) -
Kenta ITAKURA, Fumiki HOSOI2018 年 74 巻 3 号 p. 109-113
発行日: 2018年
公開日: 2018/07/10
ジャーナル フリーLidar (light detection and ranging) has been widely utilized for estimating the structural parameters of plants, such as tree height, leaf inclination angle, and biomass. However, individual trees have been primarily manually extracted from three-dimensional (3D) point cloud images. Automatically detecting each tree and analyzing its structural parameters is desirable. In this study, we propose a method to (1) detect each tree from 3D point cloud images obtained from ground-based lidar, (2) estimate the number of trees and diameter at breast height (DBH) from the detected 3D point cloud images of trees, and (3) segment each tree canopy. First, we focused on point clouds whose height ranged from 0.5 to 1.5 m and detected each cluster of tree trunks. Then, the clusters were expanded by classifying other points to the clusters that are located near the points and then repeating this process. The process assigns the points in the 3D point cloud image to each tree in the upward direction and separates not only tree trunks but also tree canopies. As a result, the trees in 3D point cloud images were detected with high accuracy, and the number of trees and DBH was estimated. Moreover, each tree canopy was segmented.抄録全体を表示PDF形式でダウンロード (987K) -
Zhi LI, Akira YANO, Marco COSSU, Hidekazu YOSHIOKA, Ichiro KITA, Yas ...2018 年 74 巻 3 号 p. 114-122
発行日: 2018年
公開日: 2018/07/10
ジャーナル フリーPhotovoltaic (PV) energy is emerging in the greenhouse industry to compensate energy demands for cultivation. Because both crops and PVs need sunlight, their compatibility on the same land unit often conflicts. To overcome this difficulty, we prototyped a venetian-blind-type shading system comprising semi-transparent bifacial PV modules that concurrently function for greenhouse shading control and electricity production. The PV blind installed in a test greenhouse was operated automatically according to the external solar irradiance. When the solar irradiance was higher than a predetermined threshold level, the PV modules were oriented parallel to the roof with sunlight shading of 42%. The PV modules were oriented to be perpendicular to the roof when the irradiance level was low, prioritizing the sunlight intake into the greenhouse. The blind system operations were managed completely by the electrical energy generated by the PV modules. Actually, the PV-produced electricity was surplus to the blind system operations, suggesting that additional greenhouse appliances can be operated by the PV-produced electricity. This system might be applicable to greenhouses in high-insolation regions as an energetically stand-alone dynamic shading system to produce a better light environment for crops.抄録全体を表示PDF形式でダウンロード (1290K)
Research Note
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Shin NAGAI, Taku M. SAITOH, Koji KAJIWARA, Shinpei YOSHITAKE, Yoshiak ...2018 年 74 巻 3 号 p. 123-127
発行日: 2018年
公開日: 2018/07/10
[早期公開] 公開日: 2018/05/10ジャーナル フリーForest disturbance by heavy snow seriously affects ecosystem functions and provision of ecosystem services. To evaluate the spatial distribution of this disturbance over large areas, it is necessary to develop a flexible, inexpensive, and generalizable method based on remote sensing. Here, we examined the ability of an unmanned drone to detect the disturbance caused by heavy snow in a Japanese cedar (Cryptomeria japonica) forest, which is a typical landscape species in Japan's mountainous areas. We obtained aerial photographs in late October 2016 using the drone in a research plot where many individuals were damaged by moist, heavy snow in mid-December 2014. The forest disturbance rate was estimated by visually inspecting the structure from motion (SfM) point clouds generated from the drone's aerial photographs. We detected 90 to 96% of healthy individuals, but many tilted trees and trees with broken stems but an intact canopy were misidentified as healthy individuals. The estimated forest disturbance rate (33%) obtained from the SfM point clouds coincided well with the actual forest disturbance rate (35%) obtained from tree surveys. Consequently, this approach can potentially be used to detect narrow and patchy disturbances in Japanese cedar forest, although further observations at multiple points will be required to develop the accuracy of this approach.抄録全体を表示PDF形式でダウンロード (1996K)
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