The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Yutaka Maruyama - One of the best experts on this subject based on the ideXlab platform.
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Photosynthetic traits around Budbreak in pre-existing needles of Sakhalin spruce (Picea glehnii) seedlings grown under elevated CO2 concentration assessed by chlorophyll fluorescence measurements.
Tree physiology, 2012Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Hajime Utsugi, Masabumi Komatsu, Satoshi Kitaoka, Yutaka Maruyama, Takayoshi KoikeAbstract:To assess the effects of elevated CO2 concentration ([CO2]) on the photosynthetic properties around spring Budbreak, we monitored the total leaf sugar and starch content, and chlorophyll fluorescence in 1-year-old needles of Sakhalin spruce (Picea glehnii Masters) seedlings in relation to the timing of Budbreak, grown in a phytotron under natural daylight at two [CO2] levels (ambient: 360 µmol mol −1 and elevated: 720 µmol mol −1 ). Budbreak was accelerated by elevated [CO2] accompanied with earlier temporal declines in the quantum yield of PSII electron transport (ΦPSII) and photochemical quenching (qL). Plants grown under elevated [CO2] showed pre-Budbreak leaf starch content twice as high with no significant difference in ΦPSII from ambient-CO2-grown plants when compared at the same measurement [CO2], i.e., 360 or 720 µmol mol −1 , suggesting that the enhanced pre-Budbreak leaf starch accumulation might not cause down-regulation of photosynthesis in preexisting needles under elevated [CO2]. Conversely, lower excitation pressure adjusted for the efficiency of PSII photochemistry ((1 − qP) Fv′/Fm′) was observed in plants grown under elevated [CO2] around Budbreak when compared at their growth [CO2]
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Increased susceptibility to photoinhibition in pre-existing needles experiencing low temperature at spring Budbreak in Sakhalin spruce (Picea glehnii) seedlings
Physiologia Plantarum, 2004Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Takayoshi Koike, Yutaka MaruyamaAbstract:The seasonal changes in photosynthetic properties in 1-year-old needles of Sakhalin spruce (Picea glehnii) were measured using the chlorophyll fluorescence technique at various temperatures (5, 10, 20, 25 and 30°C). In the course of seasonal change, a temporary decrease in the quantum yield of PSII electron transport (Φ PSII ) was observed just before Budbreak. A decline in photochemical quenching (qp) was observed at the same time as that of Φ PSII but only at the two lowest temperatures (5 and 10°C). Photochemical efficiency of open PSII (F v '/F m ') also declined just before Budbreak at 25 and 30°C. An increase in thermal energy dissipation as indicated by a decrease in F v '/F m ' before Budbreak was not significant at lower temperatures (5 and 10°C) in spite of the declines in qp. This implies that thermal energy dissipation necessitated by the decline in Φ PSII might not be sufficiently strong to prevent a decline in qp at lower temperatures. On the other hand, at higher temperatures no decline was observed in qp because Φ PSII decreased to a relatively small extent, therefore thermal energy dissipation is sufficient in coping with the excessive energy accumulation in PSIL Seedlings of Sakhalin spruce exposed to ambient air temperature below 10°C before Budbreak exhibited photoinhibition indicated by a decrease in the maximal photochemical efficiency of PSII (F v /F m ) after an overnight dark adaptation. The present study suggests that 1-year-old shoots of Sakhalin spruce have an increased susceptibility to photoinhibition at low temperature just before Budbreak.
Takayoshi Koike - One of the best experts on this subject based on the ideXlab platform.
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Photosynthetic traits around Budbreak in pre-existing needles of Sakhalin spruce (Picea glehnii) seedlings grown under elevated CO2 concentration assessed by chlorophyll fluorescence measurements.
Tree physiology, 2012Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Hajime Utsugi, Masabumi Komatsu, Satoshi Kitaoka, Yutaka Maruyama, Takayoshi KoikeAbstract:To assess the effects of elevated CO2 concentration ([CO2]) on the photosynthetic properties around spring Budbreak, we monitored the total leaf sugar and starch content, and chlorophyll fluorescence in 1-year-old needles of Sakhalin spruce (Picea glehnii Masters) seedlings in relation to the timing of Budbreak, grown in a phytotron under natural daylight at two [CO2] levels (ambient: 360 µmol mol −1 and elevated: 720 µmol mol −1 ). Budbreak was accelerated by elevated [CO2] accompanied with earlier temporal declines in the quantum yield of PSII electron transport (ΦPSII) and photochemical quenching (qL). Plants grown under elevated [CO2] showed pre-Budbreak leaf starch content twice as high with no significant difference in ΦPSII from ambient-CO2-grown plants when compared at the same measurement [CO2], i.e., 360 or 720 µmol mol −1 , suggesting that the enhanced pre-Budbreak leaf starch accumulation might not cause down-regulation of photosynthesis in preexisting needles under elevated [CO2]. Conversely, lower excitation pressure adjusted for the efficiency of PSII photochemistry ((1 − qP) Fv′/Fm′) was observed in plants grown under elevated [CO2] around Budbreak when compared at their growth [CO2]
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Increased susceptibility to photoinhibition in pre-existing needles experiencing low temperature at spring Budbreak in Sakhalin spruce (Picea glehnii) seedlings
Physiologia Plantarum, 2004Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Takayoshi Koike, Yutaka MaruyamaAbstract:The seasonal changes in photosynthetic properties in 1-year-old needles of Sakhalin spruce (Picea glehnii) were measured using the chlorophyll fluorescence technique at various temperatures (5, 10, 20, 25 and 30°C). In the course of seasonal change, a temporary decrease in the quantum yield of PSII electron transport (Φ PSII ) was observed just before Budbreak. A decline in photochemical quenching (qp) was observed at the same time as that of Φ PSII but only at the two lowest temperatures (5 and 10°C). Photochemical efficiency of open PSII (F v '/F m ') also declined just before Budbreak at 25 and 30°C. An increase in thermal energy dissipation as indicated by a decrease in F v '/F m ' before Budbreak was not significant at lower temperatures (5 and 10°C) in spite of the declines in qp. This implies that thermal energy dissipation necessitated by the decline in Φ PSII might not be sufficiently strong to prevent a decline in qp at lower temperatures. On the other hand, at higher temperatures no decline was observed in qp because Φ PSII decreased to a relatively small extent, therefore thermal energy dissipation is sufficient in coping with the excessive energy accumulation in PSIL Seedlings of Sakhalin spruce exposed to ambient air temperature below 10°C before Budbreak exhibited photoinhibition indicated by a decrease in the maximal photochemical efficiency of PSII (F v /F m ) after an overnight dark adaptation. The present study suggests that 1-year-old shoots of Sakhalin spruce have an increased susceptibility to photoinhibition at low temperature just before Budbreak.
Mitsutoshi Kitao - One of the best experts on this subject based on the ideXlab platform.
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Photosynthetic traits around Budbreak in pre-existing needles of Sakhalin spruce (Picea glehnii) seedlings grown under elevated CO2 concentration assessed by chlorophyll fluorescence measurements.
Tree physiology, 2012Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Hajime Utsugi, Masabumi Komatsu, Satoshi Kitaoka, Yutaka Maruyama, Takayoshi KoikeAbstract:To assess the effects of elevated CO2 concentration ([CO2]) on the photosynthetic properties around spring Budbreak, we monitored the total leaf sugar and starch content, and chlorophyll fluorescence in 1-year-old needles of Sakhalin spruce (Picea glehnii Masters) seedlings in relation to the timing of Budbreak, grown in a phytotron under natural daylight at two [CO2] levels (ambient: 360 µmol mol −1 and elevated: 720 µmol mol −1 ). Budbreak was accelerated by elevated [CO2] accompanied with earlier temporal declines in the quantum yield of PSII electron transport (ΦPSII) and photochemical quenching (qL). Plants grown under elevated [CO2] showed pre-Budbreak leaf starch content twice as high with no significant difference in ΦPSII from ambient-CO2-grown plants when compared at the same measurement [CO2], i.e., 360 or 720 µmol mol −1 , suggesting that the enhanced pre-Budbreak leaf starch accumulation might not cause down-regulation of photosynthesis in preexisting needles under elevated [CO2]. Conversely, lower excitation pressure adjusted for the efficiency of PSII photochemistry ((1 − qP) Fv′/Fm′) was observed in plants grown under elevated [CO2] around Budbreak when compared at their growth [CO2]
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Increased susceptibility to photoinhibition in pre-existing needles experiencing low temperature at spring Budbreak in Sakhalin spruce (Picea glehnii) seedlings
Physiologia Plantarum, 2004Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Takayoshi Koike, Yutaka MaruyamaAbstract:The seasonal changes in photosynthetic properties in 1-year-old needles of Sakhalin spruce (Picea glehnii) were measured using the chlorophyll fluorescence technique at various temperatures (5, 10, 20, 25 and 30°C). In the course of seasonal change, a temporary decrease in the quantum yield of PSII electron transport (Φ PSII ) was observed just before Budbreak. A decline in photochemical quenching (qp) was observed at the same time as that of Φ PSII but only at the two lowest temperatures (5 and 10°C). Photochemical efficiency of open PSII (F v '/F m ') also declined just before Budbreak at 25 and 30°C. An increase in thermal energy dissipation as indicated by a decrease in F v '/F m ' before Budbreak was not significant at lower temperatures (5 and 10°C) in spite of the declines in qp. This implies that thermal energy dissipation necessitated by the decline in Φ PSII might not be sufficiently strong to prevent a decline in qp at lower temperatures. On the other hand, at higher temperatures no decline was observed in qp because Φ PSII decreased to a relatively small extent, therefore thermal energy dissipation is sufficient in coping with the excessive energy accumulation in PSIL Seedlings of Sakhalin spruce exposed to ambient air temperature below 10°C before Budbreak exhibited photoinhibition indicated by a decrease in the maximal photochemical efficiency of PSII (F v /F m ) after an overnight dark adaptation. The present study suggests that 1-year-old shoots of Sakhalin spruce have an increased susceptibility to photoinhibition at low temperature just before Budbreak.
Hiroyuki Tobita - One of the best experts on this subject based on the ideXlab platform.
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Photosynthetic traits around Budbreak in pre-existing needles of Sakhalin spruce (Picea glehnii) seedlings grown under elevated CO2 concentration assessed by chlorophyll fluorescence measurements.
Tree physiology, 2012Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Hajime Utsugi, Masabumi Komatsu, Satoshi Kitaoka, Yutaka Maruyama, Takayoshi KoikeAbstract:To assess the effects of elevated CO2 concentration ([CO2]) on the photosynthetic properties around spring Budbreak, we monitored the total leaf sugar and starch content, and chlorophyll fluorescence in 1-year-old needles of Sakhalin spruce (Picea glehnii Masters) seedlings in relation to the timing of Budbreak, grown in a phytotron under natural daylight at two [CO2] levels (ambient: 360 µmol mol −1 and elevated: 720 µmol mol −1 ). Budbreak was accelerated by elevated [CO2] accompanied with earlier temporal declines in the quantum yield of PSII electron transport (ΦPSII) and photochemical quenching (qL). Plants grown under elevated [CO2] showed pre-Budbreak leaf starch content twice as high with no significant difference in ΦPSII from ambient-CO2-grown plants when compared at the same measurement [CO2], i.e., 360 or 720 µmol mol −1 , suggesting that the enhanced pre-Budbreak leaf starch accumulation might not cause down-regulation of photosynthesis in preexisting needles under elevated [CO2]. Conversely, lower excitation pressure adjusted for the efficiency of PSII photochemistry ((1 − qP) Fv′/Fm′) was observed in plants grown under elevated [CO2] around Budbreak when compared at their growth [CO2]
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Increased susceptibility to photoinhibition in pre-existing needles experiencing low temperature at spring Budbreak in Sakhalin spruce (Picea glehnii) seedlings
Physiologia Plantarum, 2004Co-Authors: Mitsutoshi Kitao, Hiroyuki Tobita, Takayoshi Koike, Yutaka MaruyamaAbstract:The seasonal changes in photosynthetic properties in 1-year-old needles of Sakhalin spruce (Picea glehnii) were measured using the chlorophyll fluorescence technique at various temperatures (5, 10, 20, 25 and 30°C). In the course of seasonal change, a temporary decrease in the quantum yield of PSII electron transport (Φ PSII ) was observed just before Budbreak. A decline in photochemical quenching (qp) was observed at the same time as that of Φ PSII but only at the two lowest temperatures (5 and 10°C). Photochemical efficiency of open PSII (F v '/F m ') also declined just before Budbreak at 25 and 30°C. An increase in thermal energy dissipation as indicated by a decrease in F v '/F m ' before Budbreak was not significant at lower temperatures (5 and 10°C) in spite of the declines in qp. This implies that thermal energy dissipation necessitated by the decline in Φ PSII might not be sufficiently strong to prevent a decline in qp at lower temperatures. On the other hand, at higher temperatures no decline was observed in qp because Φ PSII decreased to a relatively small extent, therefore thermal energy dissipation is sufficient in coping with the excessive energy accumulation in PSIL Seedlings of Sakhalin spruce exposed to ambient air temperature below 10°C before Budbreak exhibited photoinhibition indicated by a decrease in the maximal photochemical efficiency of PSII (F v /F m ) after an overnight dark adaptation. The present study suggests that 1-year-old shoots of Sakhalin spruce have an increased susceptibility to photoinhibition at low temperature just before Budbreak.
Shinsuke Agehara - One of the best experts on this subject based on the ideXlab platform.
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Foliar application of defoliants after winter chill accumulation changes phytohormone dynamics and improves Budbreak in blackberry under subtropical climatic conditions
Plant Growth Regulation, 2021Co-Authors: Syuan-you Lin, Shinsuke AgeharaAbstract:Inadequate winter chill causes poor Budbreak in blackberry ( Rubus L. subgenus Rubus Watson), limiting the commercial production in the subtropics. In ‘Natchez’ blackberry, our previous study found that, under inadequate chilling conditions, urea and lime sulfur (LS) applied as defoliants before chill accumulation advanced Budbreak but did not improve final Budbreak. In this study, we applied the two defoliants at the end of chill accumulation and examined their effectiveness in breaking dormancy, with a hypothesis that it can be enhanced with increased exposure to chilling. Field experiments were conducted over two growing seasons under subtropical climatic conditions. ‘Natchez’ blackberry was sprayed with urea or LS at 10%. Both defoliants were effective in both advancing and maximizing Budbreak. Final Budbreak reached 42.6% to 76.8% in the defoliant treatments, compared with 27.1% to 31.6% in the control. Advanced Budbreak by defoliants increased early season yield by 35% to 88%. Although not statistically significant, defoliants increased total-season yield by 19% to 56%, compared with the control. Phytohormone profiling revealed no changes in abscisic acid and gibberellic acid 4, but increasing trends in jasmonic acid and indole-3-acetic acid (IAA) during Budbreak. The LS treatment increased IAA accumulation by up to 377% compared with the control. These results suggest that urea and LS are highly effective dormancy-breaking agents for blackberry when applied after winter chill accumulation. These defoliants could be an important adaptation tool for subtropical blackberry production. Furthermore, increased IAA accumulation appears to be, at least in part, the mode of action for LS-induced Budbreak.
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Foliar Application of Defoliants before Winter Chill Accumulation Advances Budbreak and Improves Fruit Earliness of Blackberry under Subtropical Climatic Conditions
HortScience, 2021Co-Authors: Syuan-you Lin, Shinsuke AgeharaAbstract:In subtropical blackberry (Rubus L. subgenus Rubus Watson) production, inadequate winter chill causes poor and erratic Budbreak, whereas high temperatures and heavy rainfall deteriorate late-season fruit quality. We examined the effects of four defoliants [zinc sulfate (ZS), potassium thiosulfate (KTS), urea, and lime sulfur (LS)] on defoliation, Budbreak, yield, and fruit quality of ‘Natchez’ blackberry grown under inadequate chilling conditions in two consecutive growing seasons. Plants were treated with defoliants at 187 kg·ha−1 via spray application (1870 L·ha−1) at the beginning of chill accumulation (late December). A nonionic surfactant (Agri-Dex) was added at 0.5% (v/v) to all treatments including the water control. Cumulative chilling hours (<7.2 °C) at the experiment site were 209 and 134 in the first and second growing seasons, respectively. Defoliation was only 40.2% to 55.5% in the control, but it was induced moderately by LS (69.7% to 84.7%) and severely by the other defoliants (81.7% to 94.7%). Budbreak was induced most rapidly by urea application, followed by LS, KTS, and ZS, advancing by 17 to 66 days compared with the control. Consequently, urea, KTS, LS, and ZS increased early season yield by 2.79, 2.55, 0.87, and 0.31 t·ha−1, respectively, compared with the control (0.12 t·ha−1). By contrast, the final percentage of Budbreak and total-season yield did not show significant treatment effects. KTS caused cane dieback and increased bud mortality, resulting in the lowest total-season yield among the treatments. Importantly, defoliants had no negative impact on berry size and soluble solids concentration. These results suggest that urea, LS, and ZS are effective bud dormancy-breaking agents for blackberry and that they could be an important adaptation tool for subtropical blackberry production. Among the three defoliants, urea appears to be the ideal chemical option because of its consistent efficacy, favorable safety profile, and low application cost.
