title: Determinants of water circulation in a woody bamboo species: afternoon use and night-time recharge of culm water storage.
abstract: To understand water-use strategies of woody bamboo species, sap flux density (Fd) in the culms of a woody bamboo (Bambusa vulgaris Schrader ex Wendland) was monitored using the thermal dissipation method. The daytime and night-time Fd were analyzed in the dry and rainy seasons. Additionally, diurnal changes in root pressure, culm circumference, and stomatal conductance (gs) were investigated to characterize the mechanisms used to maintain diurnal water balance of woody bamboos. Both in the dry and rainy seasons, daytime Fd responded to vapor pressure deficit (VPD) in an exponential fashion, with a fast initial increase in Fd when VPD increased from 0 to 1 kPa. The Fd and gs started to increase very fast as light intensity and VPD increased in the morning, but they decreased sharply once the maximum value was achieved. The Fd response of this woody bamboo to VPD was much faster than that of representative trees and palms growing in the same study site, suggesting its fast sap flow and stomatal responses to changes in ambient environmental factors. The Fd in the lower and higher culm positions started to increase at the same time in the morning, but the Fd in the higher culm position was higher than that of the lower culm in the afternoon. Consistently, distinct decreases in its culm circumference in the afternoon were detected. Therefore, unlike trees, water storage of bamboo culms was not used for its transpiration in the morning but in the afternoon. Nocturnal sap flow of this woody bamboo was also detected and related to root pressure. We conclude that this bamboo has fast sap flow/stomatal responses to irradiance and evaporative demands, and it uses substantial water storage for transpiration in the afternoon, while root pressure appears to be a mechanism resulting in culm water storage recharge during the night.
authors.affiliation: Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China yangshijian@mail.kib.ac.cn caokf@xtbg.ac.cn.
authors.forename: Shi-Jian
authors.initials: SJ
authors.lastname: Yang
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
authors.forename: Yong-Jiang
authors.initials: YJ
authors.lastname: Zhang
authors.affiliation: Department of Biology, University of Miami, PO Box 249118, Coral Gables, FL 33124, USA Departamento de Ecología Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. II 2°piso, C1428EHA Buenos Aires, Argentina.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Goldstein
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Sun
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China.
authors.forename: Ren-Yi
authors.initials: RY
authors.lastname: Ma
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China College of Forestry, Guangxi University, Nanning, Guangxi 530004, China yangshijian@mail.kib.ac.cn caokf@xtbg.ac.cn.
authors.forename: Kun-Fang
authors.initials: KF
authors.lastname: Cao
mesh_terms: D031723:Bambusa / Q000502:physiology*; D002940:Circadian Rhythm; D003624:Darkness; D017785:Photons; D010788:Photosynthesis; D053147:Plant Exudates; D018517:Plant Roots / Q000502:physiology; D018547:Plant Stems / Q000502:physiology*; D011891:Rain; D012621:Seasons; D013696:Temperature; D055548:Vapor Pressure; D014867:Water; D014934:Wood / Q000502:physiology*
chemical_list: D053147:Plant Exudates; D014867:Water
keywords: heat dissipation method; root pressure; sap flow; vapor pressure deficit; water recharge and balance