This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/authorsrights Author's personal copy Flora 209 (2014) 279–284 Contents lists available at ScienceDirect Flora j ournal homepage: www.elsevier.com/locate/flora Morphological changes and resource allocation of Zizania latifolia (Griseb.) Stapf in response to different submergence depth and duration a,d a,b,d a c,e,∗ Qiulin Wang , Jingrui Chen , Fan Liu , Wei Li a Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, China b Institute of Soil and Fertilizer, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian 350013, China c Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, China d University of Chinese Academy of Sciences, Beijing 100039, China e Key Laboratory of Ecological Impacts of Hydraulic-Projects and Restoration of Aquatic Ecosystem of Ministry of Water Resources, Institute of Hydroecology, Ministry of Water Resources and Chinese Academy of Sciences, Wuhan 430079, China a r a t i b s c l e i n f o t r a c t Article history: Plants around ponds, rivers and lakes are subjected to long-term partial or complete submergence. When Received 1 June 2013 they are flooded, water level affects the plants simultaneously with duration of submergence. Separate Accepted 8 March 2014 and interactive effects of water level and duration on the growth of the herbaceous perennial Zizania Edited by R. Lösch latifolia (Poaceae) were investigated by exposing the plants in greenhouse water tanks to submergence Available online 27 March 2014 in different water depths and for different time-spans. The plants exhibited great shoot elongation upon submergence and prolonged flood duration, and the basal tiller number of the species decreased with Keywords: higher water levels. Submergence treatment advanced the flowering date and increased the inflorescence Growth elongation number. Plant total biomass did not differ among all the treatments, while the root:shoot ratio decreased Root:shoot ratio with increased water level, prolonged duration of submergence and their interaction. The high plasticity Submergence duration Water level in morphology and shifts in reproductive strategy and biomass allocation enabled the Zizania plants Zizania latifolia to survive the compound effect of flooding height and duration. This may explain the occurrence of this Wetland plants species in habitats subjected to long-term flooding. The results obtained in this experiment will contribute to understanding the impact of flooding dynamics on plants and the ways of adaptation responses to prolonged waterlogging. © 2014 Elsevier GmbH. All rights reserved. Introduction (Carter Johnson, 2000), decreased vegetation cover (Siebel, 1998), and eutrophication (Thoms, 2003). An essential habitat parameter in aquatic and emergent plant Coping with the harsh environmental conditions related to communities is the stress of flooding. High water level related to the flooding, wetland plant species are adapted to increase sur- excessive rainfall or discharge of melting snow and ice, and poor vival and reproduction. Morphological responses of some species land drainage can severely affect plant growth and survival (Blom to flooding are shoot elongation and formation of adventitious et al., 1994; Blom and Voesenek, 1996). Direct effects of flood- roots (Busch et al., 2004; Cooling et al., 2001; Kende et al., 1998). ing on plants include restricted oxygen exchange, hampered soil In contrast, other plants are able to tolerate complete submer- water movement (Hughes et al., 2001), and burial of individuals gence enduring with reduced or no growth the time until water by sediments (Karrenberg et al., 2003; Marigo et al., 2000). Indi- level drops (Bailey-Serres and Voesenek, 2008; Blom et al., 1994; rect effects are creation of bare substrates due to sedimentation Parolin, 2009). Physiologically, fluctuations of water level influ- ence the photosynthetic performance of the plants, leading to altered resource-allocation patterns and subsequent change of community productivity (Hogeland and Killingbeck, 1985; Junk and ∗ Piedade, 1993). Moreover, changes in reproductive strategies have Corresponding author at: Wuhan Botanical Garden, Chinese Academy of Sci- also been detected under flooding conditions, including increased ences, Wuhan, Hubei 430074, China. Tel.: +86 27 87510140; fax: +86 27 87510251. E-mail address: [email protected] (W. Li). flower number with prolonged inundation duration and decreased http://dx.doi.org/10.1016/j.flora.2014.03.006 0367-2530/© 2014 Elsevier GmbH. All rights reserved. Author's personal copy 280 Q. Wang et al. / Flora 209 (2014) 279–284 vegetative reproduction (Lowe et al., 2010; Mony et al., 2010). Such October 5th, 2010. All plants were designed to grow for 100 d and ecophysiological responses lead to individual survival, continued divided into 7 groups. In the control group, the rooting substrate growth and generative reproduction (Blom and Voesenek, 1996). was water-saturated to the soil surface of the pot during the entire The flooding regime is a major determinant of plant community experimental period (June 25th–October 5th). Other submergence development and of patterns of plant zonation in wetlands (Bunn treatments were as follows: (1) For the 100 d submergence treat- et al., 1997). With a gradually rising water level in the field, plants ment, two groups of shoots were submerged to the fixed water in the lower areas experience earlier, longer and deeper submer- level (50 cm, 100 cm) in a water tank during the entire experimen- gence, and vice versa. Parameters of the water regime itself (water tal period (June 25th–October 5th). (2) For the 70 d submergence depth, duration, timing, frequency, etc.) and its impact on the plants treatment, two groups of shoots were cultivated on soil water- (flooding depth and duration) exert impact on plant growth. Thus, saturated up to the soil surface for 15 d (June 25th–July 10th), plants in flood-prone habitats are interactively affected by water then submerged to the fixed water level (50 cm, 100 cm) from July depth and submergence duration. Much attention has been paid to 10th to September 20th, and thereafter readjusted to be emerged, the impact of water depth on the growth of plant species (Hussner growing on the water saturated substrate for another 15 d (Sep and Meyer, 2009; Lowe et al., 2010; Mony et al., 2010; Voesenek 20th–October 5th). (3) For the 40 d submergence treatment, two et al., 2006). Relatively little is known about plant survival and groups of shoots were cultivated on the water-saturated soil for growth in response to the combined effect of water depth and flood 30 d (June 25th–July 25th), then submerged to the fixed water level duration (Vreugdenhil et al., 2006). Relevant investigation may help (50 cm, 100 cm) between July 25th and September 5th, and read- to further explore the adaptive responses of plants to flooding. justed to be emerged, growing on water saturated substrate for In the present work, we investigated the combined effects of another 30 d (September 5th–October 5th). water depth and flood duration on an important macrophyte, Ziza- Every treatment was performed with six replicates and neces- nia latifolia, that is found at river banks and lake shore sites in East sary measures were taken to support the plants to prevent lodging Asia to address the following questions: (1) Does water depth work upon readjustment after submergence. The tank was filled with interactively with flood duration? (2) And if yes, how does the plant water from nearby Donghu Lake, and water level was monitored respond to their interaction? every 2 days. Water was added to the tank to keep the water levels constant. During the experiment, the blooming date of each inflorescence Materials and methods was recorded at the first sign of flowering and the inflorescence number of each plant was monitored till the end of the experi- Plant species description ment. After submergence treatment, plant height (from the soil surface to the tip of the longest leaf) and basal tiller number per Zizania latifolia (Griseb.) Stapf (Oryzeae/Poaceae), wild rice, is pot were determined. At the end of the experimental treatments all a perennial aquatic macrophyte with well-developed rhizomes. plants were harvested immediately and gently washed free of soil. The species is widely distributed in ponds, rivers and lakes of The plant biomass was separated into above-ground and below- the middle-lower reaches of the Yangtze River, China. In ponds ◦ ground parts and dried at 80 C for 48 h to constant weight. The or on river banks, the species grows to about 150–300 cm and its root:shoot ratio (below-ground biomass/above-ground biomass) usual rooting depth is about 20–30 cm. It reproduces sexually from was calculated for each plant. seedlings and/or asexually by rhizomes producing new tillers (Li, 1995). Z. latifolia has been historically domesticated and cultivated in China as an aquatic vegetable under infection by Ustilago escu- Statistical analysis lenta P. Henn (Guo et al., 2007). Its many elite varieties with high quality grain and resistance to sheath blight make it a potential Statistical analysis was conducted with SPSS (Version 13.0). valuable source of genetic material to improve the germplasm for Plant height, tiller number, total biomass and root:shoot ratio modern rice breeding (Shen et al., 2011).