巻号一覧
78 巻 (2022)
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78 巻, 1 号
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Full Paper
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Ting-Wei CHANG, Yoshiko KOSUGI, Tomonori KUME, Ayumi KATAYAMA, Motono ...原稿種別: Full Paper
2022 年 78 巻 1 号 p. 1-7
発行日: 2022年
公開日: 2022/01/10
ジャーナル オープンアクセスIt is challenging to estimate isoprene emissions from plants and determine the basal isoprene emission rate (i.e., isoprene emission capacity under a specific light and leaf temperature) of plant species. Previous studies have investigated the effect of physiological factors on isoprene emission capacity; however, the effect of leaf morphology on isoprene emission capacity has seldom been mentioned. This study aims to clarify the relationship between the basal isoprene emission rate and leaf mass per area (LMA) of a woody bamboo (Phyllostachys pubescens). Since there was no observation of isoprene emission from low-LMA leaves of P. pubescens, we conducted measurements on culms exhibiting lower LMA (27.5-47.9 g m-2). By observing leaf-scale isoprene emission flux under a specific incident light (1000 μmol m-2 s-1) and temperature (30 °C) to represent basal isoprene emission fluxes, we found a series of varied area-based isoprene emission rate among leaves (1.4-32.2 nmol m-2 s-1) and a strong correlation between area-based isoprene emission rate and LMA without any distinction between culms. A further comparison with other studies demonstrated that even for the culms that exhibited larger LMA and isoprene emission flux, a generally consistent pattern in the relation of area-isoprene emission flux and LMA could be found across these sites. This result suggests the importance of detecting LMA in the determination of the basal isoprene emission rate, which can improve the current emission estimation method.抄録全体を表示PDF形式でダウンロード (342K) -
Yuanhao CHEN, Ryo MATSUDA, Kazuhiro FUJIWARA2022 年 78 巻 1 号 p. 8-18
発行日: 2022年
公開日: 2022/01/10
ジャーナル オープンアクセス
電子付録Phosphor-converted white LEDs (PCW-LEDs) of numerous types with different relative spectral photon-flux-density distributions (SPDs) are commercially available today. Some are regarded as promising light sources for use in plant factories with artificial lighting. The leaf net photosynthetic rate (Pn) measured under PCW-LED light is an important criterion for evaluating PCW-LEDs in terms of photosynthesis performance. To ascertain Pn rapidly under dozens of PCW-LED lights having different SPDs, we have developed a rapid and semi-automated Pn-quantification method. The method uses a modified LED-artificial sunlight source system (LASS system) and a Pn-measurement system. The modified LASS system can produce light with an SPD, which can accurately approximate that of any PCW-LED light at a photosynthetic photon flux density (PPFD) of 150 μmol m-2 s-1. First, PCW-LED lights of 30 types at a PPFD of 150 μmol m-2 s-1 were produced using the modified LASS system within 2.5 h. We then measured the Pn of cos lettuce, red-leaf lettuce, and green-leaf lettuce (Lactuca sativa L.) plants. In a 16-h Pn measurement repetition, the modified LASS system supplied all the produced lights automatically and successively to an identical leaf of a lettuce plant. A Pn-measurement system simultaneously measured Pn under the produced light. Results show that the mean Pn values of the cos lettuce, red-leaf lettuce, and green-leaf lettuce under the 30 produced lights at 20 days after sowing were, respectively, 7.11-8.02, 5.76-7.11, and 4.83-6.17 μmol m-2 s-1. A rapid and semi-automated method was developed for successive measurement of Pn under dozens of combined lights, of which each SPD approximated that of the selected PCW-LED lights, within days, which indicates that the method can determine the Pn quickly under numerous PCW-LED lights. Results show that the system contributes to rapid selection of PCW-LED lights performing high Pn.抄録全体を表示PDF形式でダウンロード (3339K) -
Taku YANO, Daisuke YASUTAKE, Yoshinobu KIYOSUE2022 年 78 巻 1 号 p. 19-30
発行日: 2022年
公開日: 2022/01/10
ジャーナル オープンアクセス
電子付録Under assuming that high-yield canopy structure would be simply explained by a given index, orchard productivity of greenhouse-grown early-flowering satsuma mandarins “Miyagawa wase” was assessed using conventional modified-open-center-training and trellis-training methods. This was done by using universal indices that assist with determining yield in relation to canopy structure. Leaf area index was the optimum index for determining fruit yield. Empirical extinction coefficients showed negative linear trends with yield. Either plant area index, estimated by using a plant canopy analyzer, and crown cover showed poor correlation with fruit yield. To effectively predict yield from leaf area index, a direct measurement is recommended rather than an indirect optical method. Trellis-trained trees were superior to modified-open-center-trained trees. This is because trellis-trained trees had higher fruit productivity up untill 10 yeas old, and because 15-year-olds had better canopy light distrubution patterns when compared with modified open-center-trained trees. Based on the costs associated with planting seedlings and the labor-efficiency due to width of free alley, trellis-training 2.2 m×1.0 m plots was optimum for planting. In this study, even when accounting for the measurement error of woody elements, empirical extinction coefficients was a good index to base yield productivity. This is because this index directly represents vertical canopy light distribution. Additionally, the clumping index, calculated by using direct measurement and indirect optical method, was suggested to relate to canopy light distribution, however, further study must be essential.抄録全体を表示PDF形式でダウンロード (1379K)
Short Paper
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Akira YANO, Ryo MATSUDA, Kazuhiro FUJIWARA2022 年 78 巻 1 号 p. 31-40
発行日: 2022年
公開日: 2022/01/10
ジャーナル オープンアクセスThis study investigated a light sensor function of light-emitting diodes (LEDs), the use of which is expanding in plant cultivations. Unimodal spectral LEDs of four types with respective emission peak wavelengths of 464, 501, 634, and 849 nm, and a white LED with a bimodal spectrum with 455-nm primary and 574-nm secondary peaks were used for this study. Open circuit voltage (VOC) of up to 1-2 V was induced in the LEDs when they were irradiated with sunlight. The VOC value of the 634 nm LED saturated with a low photon flux density can be used for binary discrimination between daylight and night. Each LED had a VOC inducible threshold wavelength of incident light. By virtue of the wavelength threshold feature, existence of a plant leaf between a light source and the LEDs is detectable by comparing the VOC values of blue-green range LEDs (464 nm, 501 nm) and near-infrared (NIR) LEDs (849 nm). Under leaf shadow, the NIR LED VOC exceeded those of the blue-green range LEDs. Under natural incident sunlight, the VOCs of the blue-green range LEDs were greater than that of the NIR LED. Another function of LEDs in agricultural use has been demonstrated.抄録全体を表示PDF形式でダウンロード (1695K)
Research Notes
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Masako KAJIURA, Takeshi TOKIDA2022 年 78 巻 1 号 p. 41-45
発行日: 2022年
公開日: 2022/01/10
ジャーナル オープンアクセス
電子付録A modified closed-chamber method for estimating total, plant-mediated, and bubbling (ebullition) emissions of CH4 from rice paddies has been developed to use high-time-resolution CH4 concentration data (~1 Hz) obtained by a spectroscopic mobile gas analyzer. Here we aimed at determining an appropriate minimum time length of chamber closure for accurate flux measurement by investigating 3255 datasets obtained from a 2-year field survey. To investigate the minimum time length for each chamber measurement, we generated a series of datasets from each measurement: by setting the hypothetical termination time of the chamber closure ahead in 1-min intervals, we obtained various chamber CH4 concentration time series with different durations of chamber closure, and separately estimated CH4 emissions via rice plants and bubbling from each. The estimated flux was sensitive to time length with short closure times, but became less sensitive with longer closure. We defined the minimum time length at which the difference in estimated flux between adjacent time windows was small enough (<10% of plant-mediated emission). The estimated minimum time length differed from one measurement to another, but 10 min was sufficient for >99% of cases. Detailed analysis showed a positive correlation between minimum time length and frequency of bubbling events; the time length needed to be longer as bubbling events became more frequent. From this relationship, we computed the appropriate chamber-duration time as a function of bubbling frequency. In the absence of ebullition, 4-5 min was sufficient, but as the bubbling frequency increased to 2.5 times per minute 15-20 min was necessary for accurate pathway-dependent flux measurements.抄録全体を表示PDF形式でダウンロード (721K)
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