Rhizome Diameter Research Articles

Effect of the Status of Planting Materials on Growth and Yield of Mango Ginger (Curcuma Amada Roxb.)

The influence of the status of planting materials such as mother rhizomes, primary fingers and secondary fingers on growth and yield of Curcuma amada Roxb. (Mango Ginger) was studied in detail. Out of sixteen characters observed, ten characters including yield per plant showed significant variation depending upon the status of planting materials used. Plants produced from mother rhizomes showed significantly higher plant height, leaf length, leaf breadth, leaf area, number of secondary fingers, length of primary and secondary fingers, diameter of mother rhizome and diameter of primary fingers. Yield per plant was 35 to 50 percent higher in the crop produced by mother rhizomes indicating the advantage of using mother rhizomes as planting material.

Adaptive Significance of and Factors Affecting Plasticity of Biomass Allocation and Rhizome Morphology: a Case Study of the Clonal PlantScirpus planiculmis(Cyperaceae)

ABSTRACT: In plants, biomass allocation and rhizome morphological plasticity reflect different strategies of adaptation to the environment. The aims of this study were to explore the patterns of allocation to different components of the belowground system, and to evaluate the effects of environmental factors on the plasticity of biomass allocation and rhizome morphology. We conducted a survey of the clonal plant, Scirpus planiculmis, in the Momoge wetland in northeastern China. Samples were collected at three sites. Site I is the washland of a seasonal lake. Site II is a permanent lake. Site III belongs to the bank of a recessive river. The average number of sampled plants was 686.25±91.61 per site. We determined the biomass of different plant parts (aboveground part, root, tuber, rhizome) and measured parameters of rhizome morphology (specific rhizome length, average rhizome diameter). Edaphic factors (soil moisture content, organic matter, available phosphorus, available potassium, pH, electrical conduc...

<I>Serpocaulon</I> × <I>manizalense</I>: a new hybrid between simple- and pinnate-leaved species of <I>Serpocaulon</I> (<I>Polypodiaceae</I>) from Colombia

During a revision of Serpocaulon from Colombia, a new hybrid was found between S. adnatum and S. levigatum near to Manizales city, which is described and illustrated herein. Qualitative and quantitative spore and macro-morphological characters were evaluated using principal component analyses to distinguish the new taxon. Our results suggest that the perispore with leasura, lamina width, rhizome diameter, blade dissection and number of pinnae are important characters to distinguish S. × manizalense. This is the first record of a hybrid between a simple and pinnate-leaved species in Serpocaulon, which is considered to be Critically Endangered (CR).

Symptoms of Fern Distortion Syndrome resulting from inoculation with opportunistic endophytic fluorescent Pseudomonas spp.

BackgroundFern Distortion Syndrome (FDS) is a serious disease of Leatherleaf fern (Rumohra adiantiformis). The main symptom of FDS is distortion of fronds, making them unmarketable. Additional symptoms include stunting, irregular sporulation, decreased rhizome diameter, and internal discoloration of rhizomes. We previously reported an association of symptoms with increased endophytic rhizome populations of fluorescent pseudomonads (FPs). The aim of the current study was to determine if FPs from ferns in Costa Rica with typical FDS symptoms would recreate symptoms of FDS.Methodology and FindingsGreenhouse tests were conducted over a 29-month period. Micro-propagated ferns derived from tissue culture were first grown one year to produce rhizomes. Then, using an 8×9 randomized complete block experimental design, 8 replicate rhizomes were inoculated by dipping into 9 different treatments before planting. Treatments included water without bacteria (control), and four different groups of FPs, each at a two concentrations. The four groups of FPs included one group from healthy ferns without symptoms (another control treatment), two groups isolated from inside rhizomes of symptomatic ferns, and one group isolated from inside roots of symptomatic ferns. Symptoms were assessed 12 and 17 months later, and populations of FPs inside newly formed rhizomes were determined after 17 months. Results showed that inoculation with mixtures of FPs from ferns with FDS symptoms, but not from healthy ferns, recreated the primary symptom of frond deformities and also the secondary symptoms of irregular sporulation, decreased rhizome diameter, and internal discoloration of rhizomes.ConclusionsThese results suggest a model of causation of FDS in which symptoms result from latent infections by multiple species of opportunistic endophytic bacteria containing virulence genes that are expressed when populations inside the plant reach a minimum level.

Patterns of morphological and genetic diversity of Valeriana jatamansi Jones in different habitats and altitudinal range of West Himalaya, India

Importance to know and understand diversity of Himalayan plants is increasingly recognized considering the fact that various natural and anthropogenic pressures might bring about serious influences to morphological and genetic diversity of the vegetation in the region. In this context, Valeriana jatamansi was investigated in detail, taking into account its importance in various Ayurvedic and modern medicines. Randomly selected mature plants from twenty five different populations (located between 1215m to 2775m asl) of V. jatamansi were analysed for their morphological attributes. Further, ISSR markers were used to detect genetic variation among 151 plants of selected 25 populations. Use of 20 primers yielded 125 reproducible polymorphic loci which were used to estimate different parameters of genetic diversity. These parameters were in turn applied to develop relationships with habitat types and altitude range. Significant variation (p<0.05) in above ground dry weight (AGDW) and below ground dry weight (BGDW) across the populations was observed. Nei's genetic diversity index (He) ranged from 0.25 to 0.37 across the populations, with a mean of 0.31. Genetic diversity exhibited a decreasing trend with increasing altitude, and maximum diversity (He=0.325) was observed in the range of 1201–1500m asl. Among the different habitat conditions, highest genetic diversity (He=0.334; Pp=84.38) was observed in grassland habitats while minimum in mixed forest habitats (He=0.285; Pp=72.433). The genetic diversity (He) had significant negative relationships with AGDW, BGDW and rhizome diameter (Pearson r=−0.359, −0.424 and −0.317, respectively; p<0.05). The genetic characterization of V. jatamansi from the western Himalaya by this study suggests influences of habitat types and the altitudinal range upon genetic diversity, and based on these proposals for conservation strategies in favour of the species are made.

Seagrass reproductive effort as an ecological indicator of disturbance

The available information on the changes in the reproductive effort (RE) of seagrasses in response to disturbances was reviewed and analysed to assess if seagrasses invest in RE when disturbed, and if this response is related to specific types of disturbance or seagrass traits. In 72% of the documented cases RE increased with disturbance, in 25% it decreased, and in 3% no changes were reported. Overall, seagrass RE increased 4-fold with disturbance. Anthropogenic disturbances had the highest impact on RE (a 13-fold increase); 3 times higher than the effect of natural disturbances. Mechanical and sedimentary/hydrodynamics disturbances caused the highest RE increase (9- and 5-fold, respectively). The positive RE response was significantly correlated with rhizome diameter of seagrasses, but not with shoot size (mass or length), suggesting that species with higher storage capacity have a higher capacity of investing in sexual reproduction when conditions deteriorate. Seagrasses showed a general trend of increasing RE under disturbance; this was evident regardless of the origin and type of disturbance, which suggests that changes in seagrass RE provide a valuable indicator of disturbance in coastal areas.

Effects of water depth on clonal characteristics and biomass allocation of Halophila ovalis (Hydrocharitaceae)

Halophila ovalis is a dioecious seagrass with a wide geographical and water depth range. The objective of this study was to understand its plasticity in clonal characteristics and biomass and also its allocation between above- and belowground in seagrass beds at different water depths. Four monospecific H. ovalis beds, Shabei, Xialongwei, Beimu and Yingluo, which have different water depths at maximum tide level (MTL) but otherwise similar environmental conditions, were studied. We measured main clonal characteristics, i.e. horizontal internodal length, branching angle, shoot height, leaf length and width, and rhizome diameter. Above- and belowground biomasses of H. ovalis were also estimated using a harvest method. We found no significant differences in coverage, leaf pair density or number of stem nodes per square meter between the four study sites. However, horizontal internodal length, leaf length, width, rhizome diameter and shoot height all increased significantly with the increases in water depth from 2- to 9-m MTL and decreased when the water depths were greater than 9-m MTL. No significant difference in above- or belowground biomass between the seagrass beds was found. However, the ratio of above- to belowground biomass was significantly higher in the shallowest site compared to the other three seagrass beds, indicating that more biomass was stored belowground in deeper water. The results demonstrated plastic responses in clonal characteristics and biomass allocation in H. ovalis across the water depth gradient.

Assessing establishment success of Zostera marina transplants through measurements of shoot morphology and growth

Since significant seagrass declines have been reported worldwide, numerous seagrass restoration projects through transplantation have been attempted in recent decades. In this study, Zostera marina shoots were transplanted into Jindong Bay on the southern coast of Korea in November 2006 to assess establishment success of the transplants to a new transplant environment. Shoot density, individual shoot weight, productivity, and morphological characteristics of transplants and reference plants in the vicinity of the planting site were monitored monthly for 13 months. Although shoot size of transplants was smaller than that of reference plants at the start of transplantation, individual shoot weight, leaf width, shoot height, and rhizome diameter of transplants increased rapidly, reaching even higher values than those of reference plants 5 months after transplantation. These results suggest that eelgrass transplants established morphologically 5 months after transplantation. Shoot productivity of transplants was lower than that of reference population during the first 5–6 months following transplantation, but became higher than that of reference population 6 months after transplantation. The higher transplant productivity was likely due to the lower shoot density at the transplant site than that at the reference population. Rapid changes in shoot morphology and growth of transplants indicated that eelgrass transplants had great morphological plasticity and established successfully in the new environment within 5–6 months. In addition to survival rates of transplants, monitoring of shoot morphology and growth appeared to be an effective approach for accurate assessment of the establishment success of eelgrass transplant.

Effect of FYM and GA3 on Growth and Yield of Sweet Flag (Acorus calamus L.) under Terai Zone of West Bengal

A field experiment was conducted during 2003 - 04 and 2004 - 05 at the Instructional Farm of Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal, to study the effect of different levels of Farm Yard Manure (FYM) (0, 12.5, 25, 37.5 and 50 t ha-1) and GA3 (0 and 100 ppm) on production in Sweet Flag. The experiment was laid out in Factorial Randomized Block Design with three replications. Farm Yard Manure significantly affected yield and vegetative characters. GA3 also showed similar effect, except, that rhizome diameter and dry-recovery percentage were found non-significant. Interaction effect between FYM and GA3 for growth and yield parameters was found nonsignificant. Plant height, number of leaves, rhizome length, rhizome diameter and yield increased with increase in dose of FYM from 0 to 50 t ha-1 but was reverse in the case of dry recovery. Similarly, these parameters increased with application of GA3 but showed non-significant relationship, except in rhizome yield. Maximum fresh and dry rhizome yield (3013.23 kg ha-1, 1389.15 kg ha-1 respectively) was recorded with 50 t ha-1 FYM supplemented with 100 ppm GA3-, followed by application of 50 t ha-1 FYM (2879.80 and 1342.65 kg ha-1, respectively).

CCC and Prohexadione-Ca Enhance Rhizome Growth and Lateral Bud Production in Rhubarb (Rheum rhabarbarum L.)

Accelerating rhizome growth is crucial to enhancing propagule production in rhubarb (Rheum rhabarbarum L.) because the crop is propagated through rhizome divisions. This can be achieved through manipulating source-sink activity. This study tested the hypothesis that synthetic plant growth retardants Prohexadione-Ca and CCC enhance rhizome growth in rhubarb. Two different concentrations of these plant growth retardants and GA3 (positive control) were foliarly applied on the cultivar German Wine at three stages of shoot growth under greenhouse conditions. Both Prohexadione-Ca and CCC favorably enhanced rhizome growth through suppressing shoot growth. CCC at 3000 mg L−1 produced the best results and the effect was apparent when applied at 12 weeks after shoot emergence. The rhizome diameter, fresh weight, and the number of viable buds were enhanced significantly in plants sprayed with CCC 3000 mg L−1. Both Prohexadione-Ca and CCC were equally effective in enhancing dry mass and starch allocation preferentially toward the rhizome. Prohexadione-Ca- and CCC-induced rhizome growth enhancement could possibly be due to their known role as GA biosynthesis inhibitors or through increasing photosynthetic efficiency and preferentially reallocating carbohydrates to the rhizome.

Linking clonal growth patterns and ecophysiology allows the prediction of meadow-scale dynamics of seagrass beds

Abstract Seagrasses are a group of 12 genera of monocotyledonous plants in four families that have successfully colonised shallow coastal seas, probably since the Cretaceous. Variations in light availability and water movement are prime environmental factors for the growth of these marine angiosperms. An overall similarity in growth form and modular clonal architecture allows the generalisation that small species have short-lived shoots with rapidly elongating rhizome axes, whilst the larger species have longer-lived shoots that do not expand rapidly with rhizomes. Annual rhizome elongation rates range between 2 cm and 4 m among species. This range in expansion capacity is correlated with rhizome diameter in an allometric fashion ( y =191 x −1.5 , r 2 =0.58, p n =150). Spatial complexity is highest in multi-species seagrass beds, such as those of the Indo-Pacific region and Australia. Seagrass beds function as important coastal filters for nutrients and pollutants and display high carbon sequestration rates. Due to the recalcitrant nature of seagrass detritus, it forms a disproportionally high contribution (12%, but only 1% of productivity) to the carbon stored in ocean sediments. The services provided by these ecosystems to human society range from water quality improvement via nursery and feeding grounds for economically important fish to storm buffering and recreative amenity.

Morphology, growth and carbohydrate storage of the plant Typha angustifolia at different water depths

Morphological characteristics, growth and carbohydrate storage dynamics of Typha angustifolia in relation to water depth were investigated. The study was based on observations carried out in two stands, namely Akigase and Teganuma, for two growth seasons. The latter stand was about two times deeper than the former. Teganuma stands exhibited significantly higher number of thick shoots compared to those of Akigase. Conversely, the difference in shoot heights between the two stands was insignificant. The same was true for rhizome lengths. Rhizome diameters were significantly bigger for Teganuma compared to Akigase. Furthermore, both the above and belowground biomass were significantly higher for Teganuma compared to those of Akigase. Teganuma stands allocated 55% of the total biomass to the aboveground parts, while Akigase stands allocated 60%. Similarly, Teganuma exhibited significantly higher stocks of total non-structural carbohydrates (TNC) compared to Akigase. The higher number of thick shoots and the relatively bigger rhizome diameters in Teganuma are seemingly important tolerance strategies in maintaining effective aeration into the rhizosphere, by reducing internal resistance. In addition, the higher TNC stocks and biomass help not only to enhance survival under anoxia for longer durations, they also provide firm substrate anchorage in the deeper Teganuma stands.

Effect of water depth on the rhizome dynamics of Typha angustifolia

The rhizome dynamics of Typha angustifolia in relation to water depth were investigated. Observations were made in two different stands, namely Akigase from April 2002 to December 2003, and Teganuma from April 2003 to December 2004. The mean rhizome length in the two stands was not significantly different but the mean rhizome diameter and biomass showed a significant difference. The larger rhizome diameter in Teganuma is seemingly an important adaptation to maintain effective aeration of the rhizome by reducing the internal resistance; while larger biomass helps survival under anoxia for longer periods of time, it also provides strong anchorage to the substrate.

CLONAL GROWTH OF FARGESIA NITIDA UNDER DIFFERENT CANOPY CONDITIONS IN A SUBALPINE DARK CONIFEROUS FOREST IN WOLONG NATURE RESERVE, CHINA

Aims Fargesia nitida, one of the Giant Panda's main food sources, is adapted to varied canopy conditions through changes in morphology and/or biomass allocation. We hypothesized that changes in clonal regeneration may be another way for this plant to be adapted to different canopy conditions. Methods From August to September 2005, we measured the number, size and rhizome size of new shoots and the age and size of the parent ramet in four canopy conditions: forest understory (FU), moderate gap (MG), large gap (LG) and forest edge wilderness (FEW) in an Abies faxoniana forest in Wolong Nature Reserve in the western Sichuan, China. The data were analyzed by One-Way ANOVA, independent-sample t-test and regression. Important findings The density of surviving new shoots was lower in the FU than that in the other three canopy conditions. With decreasing canopy cover (i.e., from FU to MG to LG), the number of surviving new shoots per genet increased. At the ramet level, the mean height, basal diameter, and biomass of surviving new shoots and parent ramet were significantly different (p0.01) and increased as canopy cover decreased. In the different canopy conditions, the number of new shoots cloned by two-year-old primary parent ramets was the largest, but mean ages of parent ramets were not significantly different. There were no significant differences in average number and basal diameter of surviving new shoots reproduced by primary parent ramets with different ages in the same environment. In each canopy condition, the basal diameter of primary and secondary parent ramets were both positively correlated with basal diameter of surviving new shoots, but the effect of the primary parent ramets on surviving new shoots was stronger than that of the secondary parent ramets. The rhizome diameter of new shoots was positively correlated with the basal diameter of new shoots and primary parent ramet, but the rhizome length of surviving new shoots was not significantly correlated with basal diameter of the primary parent ramet. These results indicated that the clonal growth features exhibited significant differences strongly correlated with canopy conditions.

Resource translocation within seagrass clones: allometric scaling to plant size and productivity

The allometric scaling of resource demand and translocation within seagrass clones to plant size (i.e. shoot mass and rhizome diameter), shoot production and leaf turnover was examined in situ in eight seagrass species (Cymodocea nodosa, Cymodocea serrulata, Halophila stipulacea, Halodule uninervis, Posidonia oceanica, Thalassodendron ciliatum, Thalassia hemprichii and Zostera noltii), encompassing most of the size range present in seagrass flora. One fully developed shoot on each experimental rhizome was incubated for 2-3 h with a pulse of NaH(13)CO(3) (235 micromol) and (15)NH(4)Cl (40 micromol). The mobilisation of incorporated tracers across the clone was examined 4 days later. Carbon and nitrogen demand for shoot production across seagrass species scaled at half of the shoot mass, whereas seagrass leaves incorporated tracers ((13)C and (15)N) at rates proportional to the shoot mass. The shoots of all seagrass species shared resources with neighbours, particularly with younger ones. The time scales of physiological integration and the absolute amount of resources shared by seagrass ramets scaled at 2.5 power of the rhizome diameter. Hence, the ramets of larger species were physiologically connected for longer time scales and share larger absolute amounts of resources with neighbours than those of smaller species. The different pattern of resource translocation exhibited by seagrasses helps explain the ecological role displayed by these species and the success of large seagrasses colonising nutrient-poor coastal areas, where they often dominate.

EFFECT OF NITROGEN AND POTASSIUM ON GROWTH AND DEVELOPMENT OF CURCUMA ALISMATIFOLIA GAGNEP.

Stubbed rhizomes (without storage root) of Curcuma alismatifolia Gagnep. were planted in soilless medium using sand + rice husk charcoal at the ratio 1:1 (v:v). After shoot sprouting, plants were fertilized with different nutrient solutions three times a week. Three levels of N (50, 100 and 200 mg l -1 ) combined with three levels of K (50, 100 and 200 mg l -1 ) were investigated. The results showed that the nitrogen concentration at 200 mg l -1 gave the highest results in plant height, number of plants/cluster, diameter of new rhizome, number of new rhizomes, the length of storage root and flower quality. The different levels of potassium tested did not affect these parameters excepted for the number of green bracts and vase life. The optimal levels of nitrogen and potassium for Curcuma alismatifolia Gagnep. growing in the soilless medium was each at 200 mg l -1 .

Contrasting responses in two populations of Zostera noltii Hornem. to experimental photoperiod manipulation at two salinities

Zostera noltii plants from two contrasting habitats (the intertidal Zandkreek in the SW Netherlands and a quiet cove Cala Jonquet on the Mediterrranean coast of Catalonia, NE Spain) were grown for 28 weeks in a common garden experiment. In this experiment the plants were exposed to two salinities (15 and 35‰S) and two seasonal daylength regimes (one representing 22°Northern Latitude or the southern limit of this species in Mauretania and the other of 55°NL or northern Denmark, close to the northern limit). Plants from both populations suffered considerable mortality at the high salinity (25% survival for the Dutch and 60% for the Catalonian population) but survival was good at the low salinity. Dutch plants realised similar shoot production as in the field only in the treatment combination of 15‰S–55°NL. Surviving Catalonian shoots produced comparable numbers of shoots as in the field in all four treatments and hence were less sensitive to daylength seasonality. Although the differences between populations had decreased during the experiment, observed variation in leaf width and rhizome diameter at the end of the experiment was explained largely by the factor source population (contributed 73 and 83%, respectively, to total variation in a threeway ANOVA comparing effects of source population, daylength regime and salinity). For total biomass produced, shoot length and weight, root length as well as rhizome internode length, the experimental salinities and daylength regimes often also explained comparable proportions of variance. It is concluded that: (a) the observed quantitative differences between the two populations of Z. noltii must have a considerable genetic basis, (b) plants from both populations were not well equipped to survive at worldwide average seawater salinity of 35‰S, and (c) the Dutch population responded more vigorously to the more pronounced daylength seasonality of northern latitudes, which is coupled to its higher photosynthetic light requirements.

Structural response of marine and estuarine plants of Halophila ovalis (R. Br.) Hook. f. to long-term hyposalinity

An unusual double membrane structure, or `annulus' located within leaf blade epidermal cells of the euryhaline seagrass Halophila ovalis may be an important site for ion transport and storage during osmotic adjustment. Cuttings of marine and estuarine H. ovalis were cultured for 4 weeks in enriched seawater at 35‰ and 25‰, respectively (the salinities in which they were growing at the time of collection) and 15‰ below these habitat salinities. In a second experiment, plants growing at low salinity were returned to their habitat salinities. Paradermal sections of severed leaves revealed that the double membrane structure was in fact tonoplast encircled by protoplast and present only in the cells of marine plants. Cell responses differed between marine and estuarine plants. Marine H. ovalis plants were intolerant of prolonged exposure to low salinity (20‰). Plant mortality reached 75% within 3 weeks, and plants continued to deteriorate following their return to marine salinity (35‰). Estuarine H. ovalis were healthy at 20‰ and plants grew well at 10‰, but appeared stressed after 4 weeks. Chloroplasts were swollen and few in number, while the number of cells with visible vacuoles increased under low salinity conditions. Leaf senescence was accelerated by approximately 1 week when compared to control plants grown at habitat salinities. Cell surface area, leaf and internode length and rhizome diameter decreased with prolonged exposure to low salinity. These structural changes were reversed when estuarine plants were returned to 25‰ salinity. Differences in the salinity tolerance of marine and estuarine H. ovalis may result from acclimation or the emergence of ecotypes, as occurs in algae with wide salinity distributions.

Rhizome elongation and seagrass clonal growth

A compilation of published and original data on rhizome morphometry, horizontal and vertical elongation rates and branching patterns for 27 seagrass species developing in 192 seagrass stands allowed an examination of the variability of seagrass rhizome and clonal growth programmes across and within species. Seagrass horizontal rhizomes extend at rates ranging between 1.2 and 574 cm yr(-1), develop a branch, with an angle from 19 to 72 degrees, for every 6 to 1800 horizontal internodes, and add a new shoot for every 1.1 to 7.5 cm of rhizome produced. Vertical rhizomes elongate at rates between 0.1 and 34 cm yr(-1) and the probability that they will branch varies over 3 orders of magnitude. Much (between 40 and 173%) of the variability of seagrass horizontal rhizome and clonal growth programmes is species-specific, largely (21 to 63% of the variance) associated with differences in size among species, although seagrasses also show important intraspecific variability. The broad repertoire of seagrass rhizome and clonal growth programmes explains the different rates and efficiency at which the species occupy space. The implications of specific growth programmes for space occupation were examined by simulating the development of seagrass rhizome networks of 3 seagrass species encompassing the range of horizontal rhizome growth (Halophila ovalis, Thalassodendron ciliatum, Posidonia oceanica). This exercice showed that small, fast-growing species achieve a much lower spread efficiency (m(2) of ground covered m(-1) of rhizome produced) than the large, slow-growing species. Differences in rhizome branching angles greatly constrained the form of rhizome networks. The results show that clonal growth patterns are a primary component of seagrass productivity and, therefore, the key to the development and maintenance of seagrass meadows. [KEYWORDS: seagrasses; clonal growth; plant allometry; rhizome diameter; spacer length; rhizome elongation; branching rate and angle Herb glechoma-hederacea; nodosa ucria ascherson; cymodocea- nodosa; thalassia-testudinum; posidonia-oceanica; syringodium- filiforme; population-dynamics; experimental burial; branching patterns; vertical growth]

Leaf growth response to simulated herbivory: a comparison among seagrass species

We examined in seven seagrass species the response of the leaf growth rate per shoot (mg DW shoot −1 day −1) to a gradient of herbivory simulated by leaf clipping. The clipping procedure was intended to mimic the removal by herbivores which only consume the leaves of a single shoot at every feeding attack and which do not feed over the same shoots selectively (i.e., most poikilotherm vertebrate and invertebrate herbivores). We tested whether (1) this defoliation procedure does not normally depress shoot leaf growth rates (i.e., the occurrence of compensatory leaf growth), and (2) whether leaf nutrient content, relative leaf growth rate, average distance between consecutive short shoots and rhizome diameter influence the response of the leaf growth rate per shoot to a gradient of defoliation. The leaf growth rate per shoot varied among clipping treatments in nine of the 15 populations treated (ANOVA, p<0.05) and meta-analyses techniques revealed a significant overall variation ( χ 2 test, p<0.001) when all the populations were considered in concert. The leaf growth rate per shoot was persistently depressed in all the clipping treatments only in one of the 15 populations treated, with only three more populations showing depressed leaf growth under some treatments (Tukey HSD test, p<0.05). The response of the leaf growth rate to clipping intensity, which was analysed on a per shoot basis (i.e. relationship between the leaf growth rate per shoot and clipping intensity on the shoot) was significant only for four populations, although meta-analyses revealed a tendency towards a general significance. None of the seagrass properties considered was related to the response of leaf growth to clipping intensity. Our results stress the remarkable variability seagrass leaf growth may exhibit under single events of defoliation on scattered shoots. Furthermore, because leaf growth rates are rarely depressed, these results suggest that most poikilotherm vertebrate and invertebrate herbivores, which typically remove <30% of leaf production, have a modest impact on the depression of leaf growth rates through removal of photosynthetic tissue.