A survey of root pressure in 53 Asian species of bamboo Wang, Tian, Ding, Wan, M. Tyree To cite this version: Wang, Tian, Ding, Wan, M. Tyree. A survey of root pressure in 53 Asian species of bamboo. Annals of Forest Science, Springer Nature (since 2011)/EDP Science (until 2010), 2011, 68 (4), pp.783-791. 10.1007/s13595-011-0075-1. hal-00930808 HAL Id: hal-00930808 https://hal.archives-ouvertes.fr/hal-00930808 Submitted on 1 Jan 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Annals of Forest Science (2011) 68:783–791 DOI 10.1007/s13595-011-0075-1 ORIGINAL PAPER A survey of root pressure in 53 Asian species of bamboo Fusheng Wang & Xinli Tian & Yulong Ding & Xianchong Wan & M. T. Tyree Received: 4 October 2010 /Accepted: 4 January 2011 /Published online: 1 June 2011 # INRA and Springer Science+Business Media B.V. 2011 Abstract is comparatively rare. Xylem exudate and guttation fluid & Introduction Root pressure is a potentially important had an osmotic pressure greater than root pressure and this mechanism for dissolving embolisms in previously cavitat- can be explained in terms of a low reflection coefficient in ed vessels, but the occurrence of root pressure is not a context of how root pressure is generated according to the universal property in plants. composite membrane model of roots. & Material and methods We suggest that root pressure might & Conclusion We conclude that the next logical step is to be more common in monocots than dicots because in dicots, survey bamboo species to determine how common cavita- cambial growth can replace embolized vessels but monocots tion evens are and to determine if refilling of vessels occurs have no secondary growth and hence need mechanisms for by root pressure. repair of embolized vessels. In this paper, bubble manometers were used to investigate 53 bamboo species from 10 genera. Keywords Root pressure . Osmotic pressure . Asian species & Results A survey of root pressure in 53 Asian species of of bamboo bamboo revealed that all possessed root pressure and in some species root pressure was high enough to cause guttation of liquid from leaves at predawn. In contrast, in 1 Introduction woody vines were we might expect root pressure to be common because of reduced cambial growth, root pressure Bamboo is an important renewable resource of economic importance in the tropics and subtropics. Bamboo is a woody Handling Editor: Erwin Dreyer monocotyledonous perennial grass that can be used in : : furniture building and manufactured into laminate flooring F. Wang X. Tian Y. Ding which is claimed by retailers to be more durable than oak and Institute of Bamboo Research, Nanjing Forestry University, Nanjing 210037, China maple. Bamboos provide a sustainable wood resource because they can be grown to harvestable size and quality in 4–6years X. Wan (*) in subtropical climates versus 50–100 years for harvestable Institute of New Forest Technology, oak and maple in temperate climates. Chinese Academy of Forestry, Beijing 100091, China Bamboo, like all monocots, has no secondary growth; e-mail: [email protected] hence, the xylem vessels in bamboo stems have to remain water filled and functional for many years otherwise shoots M. T. Tyree or whole plants will die. Bamboo shoots can survive 5– Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2E3, Canada 20 years and regenerate asexually from rhizome which potentially could be much older; hence, the vessels must M. T. Tyree (*) remain functional for a rather long time. In contrast, trees United States Forest Service, with secondary growth can replace functional xylem Northern Research Station, 705 Spear St., – South Burlington, VT 05403, USA annually. Because water stress and freeze thaw events can e-mail: [email protected] embolize vessels (Tyree and Zimmermann 2002), many 784 F. Wang et al. people have wondered about the possible role of root 2 Material and methods pressure in refilling embolized vessels with water either on a daily basis or annually in early spring in temperate The observations were made at Nanjing, China (32.0°N, regions. Hence a number of people have surveyed trees and 118.5°E), which has a subtropic monsoon climate, annual woody vines for the occurrence of root pressure (Ewers et average temperature of 16°C, and annual precipitation of al. 1997; Fisher et al. 1997). So far, the only known report 1,106 mm. All bamboo species were cultivated in a bamboo of root pressure in bamboo was in a vine-like species botanical garden used for scientific research. The complete (Rhipidocladum racemiflorum, see Cochard et al. 1994). list of observed species is given in Table 1 with their Bamboos are much more common in tropical and growth habits and dimensions. There are two major types of subtropical ecosystems than in temperate ecosystems, but rhizome of bamboos based on the branching habit of the the reasons for this are unknown; however, it is possible rhizomes: leptomorph and pachymorph (McClure 1966). to speculate why. Wide xylem vessels are susceptible to While leptomorph and pachymorph rhizomes are species- freeze–thaw-induced embolism (Cochard et al. 1994; dependent, a few species of bamboos have both types of Sperry and Sullivan 1992;Sperryetal.1994)when rhizomes in the same species so McClure named them vessels are >40 μm diameter. When water freezes, the air metamorph rhizomes. Bamboos with leptomorph rhizomes dissolved in it comes out of solution and forms air pockets form groves or extensive tracts of rather evenly spaced between the ice crystals. The risk of embolism thus arises culms because of the running nature of the underground when the ice melts leaving many tiny air bubbles mixed system. In bamboos with pachymorph rhizomes, the culms with liquid water. These bubbles must dissolve before the are usually close together and form discrete clumps. water is again under tension due to renewed transpiration Rhizome types usually refer to their growth habit. Lep- otherwise the bubbles will seed an embolism. In large tomorph is common in bamboos of subtropic and temperate vessels (>40 μm), the small bubbles tend to combine into regions, such as Phyllostachys and Indosasa. Pachymorph larger bubbles that take longer to dissolve and are more rhizomes are common in bamboos of warm, tropic regions, likely to seed embolisms. Many bamboo species have such as Bambusa. vessels >40 μm and hence are likely to cavitate when they All measurements were made in August–September freeze/thaw. Hence, species that grow in temperate areas 2006, and March–April 2007. The late summer in Nanjing probably need root pressure to refill embolized vessels in is usually very hot and humid and is still high season for the same way as wild-grape vine, which has negligible plant growth. However, it is cool overnight and relatively secondary growth. In one study, wild grape was found to dry in the early spring. Both humidity and temperature in be fully embolized over winter but produced root the early spring had greater variation than in the late pressuresupto100kPatorefillinspring(Sperryetal. summer (see Table 2 for detail). 1987). The lumina of the bamboo vessels occupy only 6– Xylem pressure measurements were made with bubble 8% of a culm cross-section area, in comparison with about manometers which were made following the description 30% for rattans, 30% for diffuse–porous hardwoods, and and a diagram by Fisher et al. (1997). The manometers about 70% for softwoods (Liese and Kumar 2003). were made from glass micropipettes sealed at the distal end Another strategy for survival in cold climates might be by flame. The distal half was filled with air while water the propensity of bamboos to regrow from rhizomes filled the basal half. The base was connected to the cut stem following winter kill of shoots. Nevertheless, without or branch with a tight-fitting vinyl tube (using a hose clamp secondary growth, the vessel refilling after cavitation if necessary). could be crucial for the flora. Stems of all small bamboo species (diameters of the Root pressure may be quite common among bamboos. It culms of <2 cm at breast height) were cut near the base. For was reported that the stumps of bamboos exuded for days big bamboos (diameters of the culms of ≥2 cm at breast following harvest operations in the growing season. In old height), the first branches were used to measure the xylem Chinese literature, guttation of bamboos was described as pressure and to collect exudate. All cut surfaces were rain in bamboo forest when relative humidity is high in shaved with a new razor blade before bubble manometers warm spring mornings; therefore, bamboos could have very were attached to measure xylem pressure or vinyl tubes strong root pressure. Tyree and Cochard have personally sealed with Parafilm to collect exudate. All bubble experienced bamboo rain in Panama while working during manometers or collecting tubes were installed in the sunny early morning hours under the canopy of R. evening. After allowing the system to equilibrate overnight, racemiflorum, when root pressures typically reached the bubble length (Lpd) in the manometer was measured at 80 kPa overnight (Cochard et al. 1994). The purpose of pre-dawn. The vinyl tube was then cut and the bubble this study was to survey the occurrence of root pressure in length (Latm) was measured at atmospheric pressure.