Rate Of Leaf Production Research Articles

Shifts in plant functional strategies over the course of wheat domestication

Abstract Human selection, changes in environmental conditions and management practices drove the phenotypic trajectory of crops during domestication. The characterization of the crop domestication syndrome lies mostly on reproductive characters. However, biophysical and ecophysiological constraints during vegetative growth are also at play and can strongly impact crop phenotypes. It has been argued that a broadened examination of crop phenotypes through a functional trait‐based lens should improve our understanding of the domestication syndrome. We used a collection of 39 genotypes representative of key steps during tetraploid wheat domestication and grew them in a common garden experiment. We quantified the vegetative phenotype of each genotype through the measurements of 13 functional traits related to root, leaf and whole‐plant dimensions. In modern cultivars, compared to ancestral forms, leaf longevity was shorter, while net photosynthetic rate, leaf production rate and nitrogen content were higher. Modern cultivars had a shallower root system and exhibited a larger proportion of fine roots, preferring to invest biomass above‐rather than below‐ground. We found ancestral forms to be integrated phenotypes characterized by coordination between above‐ and below‐ground functioning. Conversely, in modern forms, human selection appeared to have broken this coordination and to have generated a new type of network of trait covariations. Synthesis and applications. The examination of leaf, root and whole‐plant traits of wheat accessions indicated a strong shift in plant functional strategies over the course of domestication. Elite genotypes tended to better optimize resource‐use acquisition strategies than ancestral ones. The characterization of the crop phenotype based on vegetative traits thus suggests a much more complete domestication syndrome. Our findings highlight the benefits of using a functional trait‐based characterization of crop phenotypes to document the extent of domestication syndrome and to further advance the agroecological management of cereals.

Initial performance of ten oil palm cross combinations under three agro-climatic conditions in India

<p>High yielding hybrids can play an important role in increasing the productivity of oil in the oil palm. With a view to evaluate high yielding new oil palm cross combinations, a field experiment was conducted in different agro-climatic regions of India <em>viz</em>., Zone No-10 Southern Plateau and Hills (Gangavathi, Karnataka), Zone No-12 Western Coastal Plains and Ghats (Mulde, Maharashtra) and Zone No-11 Eastern Coastal Plains and Hills (Vijayarai, Andhra Pradesh) involving ten cross combinations of tenera oil palm (NRCOP 1-10). The data from three locations over two years indicated that, significantly higher annual rate of leaf production per palm was recorded in NRCOP-6 (21.7) compared to NRCOP-3 and it was on par with other hybrid combinations. Significantly higher sex ratio was recorded with NRCOP-4 (63.1%) compared to NRCOP-1 (54.6%) and NRCOP-6 (54.8%) and was on par with other hybrid combinations.The hybrid cross combination, NRCOP-4 recorded significantly higher fresh fruit bunches (FFBs) yield 12.5 t ha-1 compared to NRCOP-1, NRCOP-3, NRCOP-7 and NRCOP-9 and it was on par with remaining hybrids and a similar result in bunch weight and number of bunches per palm was recorded. Pooled data on FFB yield for 2013-15 indicated that the hybrid combination NRCOP-4 which recorded higher FFB yield (12.6 t ha-1) at Gangavathi and at Vijayarai (22.6 t ha-1) have better prospects for adaptation under Tungabhadra command area and coastal region of Andhra Pradesh. For Konkan region of Maharashtra, the hybrid NRCOP-8 recorded the highest FFB yield.</p>

Gibberellin-Regulation and Genetic Variations in Leaf Elongation for Tall Fescue in Association with Differential Gene Expression Controlling Cell Expansion.

Leaf elongation rate (LER) is an important factor controlling plant growth and productivity. The objective of this study was to determine whether genetic variation in LER for a fast-growing (‘K-31’), and a dwarf cultivar (‘Bonsai’) of tall fescue (Festuca arundinacea) and gibberellic acid (GA) regulation of LER were associated with differential expression of cell-expansion genes. Plants were treated with GA3, trinexapac-ethyl (TE) (GA inhibitor), or water (untreated control) in a hydroponic system. LER of ‘K-31’ was 63% greater than that of ‘Bonsai’, which corresponded with 32% higher endogenous GA4 content in leaf and greater cell elongation and production rates under the untreated control condition. Exogenous application of GA3 significantly enhanced LER while TE treatment inhibited leaf elongation due to GA3-stimulation or TE-inhibition of cell elongation and production rate in leaves for both cultivars. Real-time quantitative polymerase chain reaction analysis revealed that three α-expansins, one β-expansin, and three xyloglucan endotransglycosylase (XET) genes were associated with GA-stimulation of leaf elongation, of which, the differential expression of EXPA4 and EXPA7 was related to the genotypic variation in LER of two cultivars. Those differentially-expressed expansin and XET genes could play major roles in genetic variation and GA-regulated leaf elongation in tall fescue.

Xylem conductivity of petioles and primary stem tissues at stem terminals of herbaceous plant species1

Abstract Shoot apical meristems produce stem tissues, produce leaves, and produce flowers. Cell proliferation characteristics of meristems are dependent upon cell maturation processes and the functions of newly formed cells. Cells of stem terminals depend upon water availability from other plant portions. Inadequate moisture availability to stem terminals reduces shoot growth rates and leaf production rates. Xylem conductivity measurements of terminal shoot meristems and small leaves were approximated using the Hagen-Poiseuille equation to determine relationships between xylem contributions to leaves versus xylem conductivity within stems. Analyses of petiole and stem xylem conductivities for the 23 herbaceous plant species were confined to stem terminals that only had primary xylem cells in stems and only five leaves or leaf pairs. Among stem segments (10 mm to 64 mm in length) among species, the largest leaf areas ranged from 2.34 cm2 to 54 cm2, stem diameters ranged from 0.82 mm to 3.83 mm, and maximum...

Leaf appearance of annual clovers responds to photoperiod at emergence

Abstract Leaf appearance rate and time to canopy expansion of four annual clover species (arrowleaf, balansa, gland and Persian) were quantified in field and controlled environment studies. Crops sown in autumn, which experienced shortening daylengths at emergence, had a slower rate of leaf production and consequently took a longer time to initiate branching, than spring-sown crops. When autumn-sown ‘Bolta’ balansa clover emerged on the shortest day in winter (21 June), the rate of leaf appearance was lengthened by 4 °C d/leaf/h. When the same species emerged after the shortest day, into an increasing photoperiod, the phyllochron was shortened by 5 °C d/leaf/h. This influence of photoperiod on the phyllochron consequently altered the time to axillary leaf production (branching). Throughout all sowing dates, phyllochron was the fastest for ‘Prima’ gland (33–91 °C d/leaf) and slowest for ‘Cefalu’ arrowleaf (53–116 °C d/leaf) clovers. ‘Bolta’ balansa was 44–82 °C d/leaf and ‘Mihi’ Persian 61–93 °C d/leaf. The response of phyllochron to photoperiod suggests these annual clovers should be sown in late summer or early autumn to initiate axillary leaf production as soon as possible to ensure maximize dry matter for early spring.

A grazing height target to minimize tiller stem elongation rate in annual ryegrass swards

ABSTRACT: Italian ryegrass (Lolium multiflorum Lam) is one of the most cultivated temperate annual forage crop around the world. Despite that, there is little information about the process of stem elongation during its vegetative growth. This information would be useful for grazing management purposes. Thus, the aim of this study was to assess the herbage accumulation and stem elongation rates in annual ryegrass pastures submitted to intermittent stocking. The experimental design used was a completely randomized 2x2 factorial with three replications. The treatments were defined by the combination of two pre-grazing heights (15 and 25cm) associated with two post-grazing heights (4 and 8cm). The herbage accumulation rates were higher in pastures with 25cm pre-grazing associated with post-grazing heights of 8cm. However, leaf production rate was only affected by post-grazing height, with higher values being recorded for stubbles heights of 8cm, regardless of pre-grazing height. Stem elongation rates in annual ryegrass tillers increased rapidly when pastures reached around 18cm, a condition where there was a relatively low competition for light, suggesting that; 1) pre-grazing heights of 18 to 20cm in annual ryegrass could be used as a upper limit for grazing management purposes whether the objective is to minimize stem contribution in accumulated herbage and 2) It seems that stem elongation is as inevitable process (independently of competition for light) and that this could be related to the necessary strength of stems, pseudostems and sheaths to support larger and heavier leaves.

Morphoanatomy and ecophysiology of tree seedlings in semideciduous forest during high-light acclimation in nursery

The recomposition of deforested environments demands the acclimation of seedlings in nurseries. This process induces changes in physiological, anatomical, and morphological traits of plants, favouring their establishment after transplantation to the field. The present study aimed to verify the influence of full-sun acclimation on seedling hardiness. For the purpose, leaf gas-exchange, plant anatomical and morphological parameters of three tree species [Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae), Croton floribundus Spreng. (Euphorbiaceae), and Cecropia pachystachya Trecul (Urticaceae)], which are used for reforestation in the Brazilian Atlantic biome, were evaluated. Seedlings were grown under 40% of total PPFD (shaded control) and under full sun (acclimated) for 168 days. The acclimation process induced a higher leaf production rate in C. speciosa and C. floribundus, whereas C. pachystachya seedlings replaced their leaves quickly, irrespective of the light conditions. The newly developed leaves of all three species presented a lower area and thicker palisade parenchyma, resulting in a reduced specific leaf area. The seedlings of C. speciosa and C. pachystachya showed increases in light-saturated net photosynthesis and transpiration rates, whereas water-use efficiency generally remained unchanged in all three species. The full-sun acclimated seedlings of C. pachystachya showed a reduced relative growth rate, lower height/stem diameter (H/D) and shoot to root dry mass ratios, characteristics that may result in greater physical resistance and ability for water and nutrient uptake to support the higher transpiratory demand under full sun. The reduction of the H/D ratio also occurred in the acclimated seedlings of C. speciosa. The seedlings of C. floribundus showed few changes during acclimation, but they did not seem to be affected by excessive light. In spite of the observed differences among the three species, all of them developed hardiness characteristics, mainly related to leaf anatomy, which should favour their establishment after transplantation to the field.

Poblaciones de Copernicia tectorum (Arecaceae) en las tierras bajas del Caribe de Colombia: una palma pionera expuesta a la dinámica de un río

<p><em>Copernicia tectorum</em> is a palm that grows in large populations on seasonally flooded savannas in the Caribbean region of Colombia, where its stems and expanded leaves are used in construction, and its unexpanded leaves are used to make handicrafts. We studied abundance and population structure in 34 plots of 20×10m (0.68 ha) of three localities (Plato, Córdoba and Magangué) at the Mompox Depression, an inner delta formed by the confluence of four large rivers. We recorded growth and mortality of 164 palms of different size classes over 13 months, and additionally we estimated seedling and juvenile mortality in two 10x10m plots within the same sites. Data analysis using Kolgomorov-Smirnov (KS), Kruskal-Wallis and Mann-Whitney tests were made on Statgraphics Plus and SPSS.<em> </em>We related the structure and dynamics of the palm stands to flood intensity. <em>Copernicia tectorum </em>has the fastest leaf production rate recorded for any palm (19-23 leaves/year in subadults and adults), and a short life span of ca. 46 years. The abundance, density and high leaf production rate of this palm offers a great potential for the sustainable use of its unexpanded leaves (especially at Plato, where there are ca. 480ha of palm stands with 300-1 000 individuals/ha), as leaf harvest from subadult and adult individuals does not appear to affect population structure. The palm is a pioneer of the flood plain, and the palm stands at particular sites appear to wax and wane following sedimentation dynamics, in which the species plays in important role. Current population structure and the scarce recruitment of juveniles at the study site suggest that the population is waning in that site. Management actions should be taken to reestablish natural river dynamics at the lagoon complex where the palm grows. Appropriate management of palm stands may contribute to minimize any negative effects of river dynamics.</p><p> </p>

Contrasting growth phenology of native and invasive forest shrubs mediated by genome size.

Examination of the significance of genome size to plant invasions has been largely restricted to its association with growth rate. We investigated the novel hypothesis that genome size is related to forest invasions through its association with growth phenology, as a result of the ability of large-genome species to grow more effectively through cell expansion at cool temperatures. We monitored the spring leaf phenology of 54 species of eastern USA deciduous forests, including native and invasive shrubs of six common genera. We used new measurements of genome size to evaluate its association with spring budbreak, cell size, summer leaf production rate, and photosynthetic capacity. In a phylogenetic hierarchical model that differentiated native and invasive species as a function of summer growth rate and spring budbreak timing, species with smaller genomes exhibited both faster growth and delayed budbreak compared with those with larger nuclear DNA content. Growth rate, but not budbreak timing, was associated with whether a species was native or invasive. Our results support genome size as a broad indicator of the growth behavior of woody species. Surprisingly, invaders of deciduous forests show the same small-genome tendencies of invaders of more open habitats, supporting genome size as a robust indicator of invasiveness.

Management of the palm Astrocaryum chambira Burret (Arecaceae) in northwest Amazon

We studied the management of the fiber-producing chambira palm Astrocaryum chambira by indigenous people in the Colombian Amazon. Between 2009 and 2012, we visited four communities and two marketing centers, where we interviewed 12 people. In addition, we specifically observed A. chambira harvesting, processing, and commercialization; studied palm populations at five localities; measured leaf production rate; and integrated secondary data. At least 21 aboriginal groups in the Colombian Amazon use chambira fiber. The palm grows in association with human communities, and it has been widely used and managed in past agroforestry systems. The fiber is obtained from the unexpanded leaves of juvenile or adult palms, and harvesting is often unsustainable because of overharvesting acaulescent palms or of cutting down adult palms. This is leading to a depletion of palm population. Annual leaf production rate was 1.59-2.89 leaves/palm year−1, which is lower than that reported in other studies. Based in our results, we recommended a harvest of 1 leaf/palm year−1 in acaulescent palms, and 1-2 leaves/palm year−1 in stemmed palms. Chambira-derived products are mostly handicrafts for marketing, and their trade represents 40%-100% of artisan household cash income. Improving the management of chambira palms requires the introduction of non-destructive harvest techniques and a wider use of the palm in agroforestry systems. An analysis of traditional management practices and of the role of chambira among Amerindian people indicates that A. chambira was an incipient domesticate at the time of the European conquest.

Ethnoecology of the palm Brahea dulcis (Kunth) Mart. in central Mexico.

BackgroundThere have been few studies on the sustainable use of non-timber forest products in arid and semi-arid zones. The palm Brahea dulcis has been one of the most important resources in semi-arid Mesoamerica, since pre-Hispanic times. Currently, some populations grow within protected natural areas, representing both a challenge and an opportunity for local development. This ethnoecological study of B. dulcis in central Mexico aimed to evaluate their uses, harvesting context, and potential for exploitation, in order to give practical advice on their best use and management.MethodsEthnographic and ecological information was obtained in Barranca de Metztitlán Biosphere Reserve and Valle del Mezquital, Mexico. We studied the population structure and density; additionally, we evaluated the rate of leaf production, leaf renewal rate, percent survival of new leaves, the development of reproductive structures and performed a one-year defoliation experiment (involving a control and four treatments including a mix of semiannual and annual frequency of harvest and removal of two new leaves and/or two mature leaves).ResultsTwenty uses of the palm were recorded in the study area. Religious/symbolic and handicraft uses are highlighted. The population density of this species was the highest reported for the genus (1244 ± 231.7 ind/ha). The leaf production rate was the highest reported for arborescent palms of the Americas (11.83 ± 0.036 leaves/individual/year). The sexual reproductive cycle was 2.3 years long. A one-year defoliation experiment did not show statistically significant differences. Recommendations include: 1) implement management focused on increasing the abundance and quality of this useful resource in Metztitlán; 2) employ a strategy of focusing on ethnicity and gender in promoting their exploitation; 3) learn from theoretical frameworks of other non timber forest product studies.ConclusionsWe propose that Brahea dulcis is the palm with the highest potential for sustainable use in the arid and semi-arid zones of Mexico. The challenge to improving management includes simplifying the legal protection framework, promoting uses and developing a market strategy. Collaborations to share experiences with peasant farmers from Guerrero is recommended. We further recommend the development of a governmental strategy to enhance and reassess this important resource.Electronic supplementary materialThe online version of this article (doi:10.1186/1746-4269-11-1) contains supplementary material, which is available to authorized users.

Relationships between biomass allocation, axis organogenesis and organ expansion under shading and water deficit conditions in grapevine.

The relationships between whole-plant growth and morphogenetic processes under abiotic stresses are still partly unknown. Whole-plant biomass growth can be decreased by many abiotic stresses, including water deficit and shading. Two experiments were performed on potted plants of one grapevine cultivar (Vitis vinifera L. cv. Syrah) subjected to watering and shading treatments. Under water stress, plants reduced their primary and secondary axis leaf production rate, whereas secondary axis budburst was relatively unaffected. Individual leaf area was reduced and a strong decrease in leaf expansion rate was observed. Under shading, primary axis organogenesis was maintained, both secondary axis budburst rate and phytomer appearance rate were decreased, and individual leaf area slightly increased. Specific leaf area did not change under soil water deficit, whereas it increased under shading. These results confirm the existence of dynamic changes in organ sink strength and biomass allocation patterns to favour plant leaf area growth under shading, and to reduce plant leaf area and water losses by transpiration under water stress. From a modelling point of view, this study shows that functional structural models based on a C balance are not fully relevant for simulating plant growth under abiotic constraints if they do not include non-trophic relationships (hormonal signalling or plant hydraulic properties) that modify organ sink strength according to abiotic constraints.

Effect of rainfall seasonality on the growth of Cecropia sciadophylla: intra-annual variation in leaf production and node length

Abstract:Patterns of leaf production and leaf fall directly influence leaf area index and forest productivity. Here, we focused on Cecropia sciadophylla individuals inhabiting the extremes of the gradient in seasonality in rainfall at which C. sciadophylla occurs. In Colombia and French Guiana we compared the intra-annual variation in leaf production as well as the intra-annual fluctuation in internode length on a total of 69 saplings ranging in size from 1 to 2 m. The mean rate of leaf production was ~2 leaves mo−1 in both populations, and the rate of leaf production was constant throughout the year. Our results showed monthly variation in internode length and the number of live leaves per sapling in the seasonal habitat and variation only in internode length in the everwet habitat. Because the rate of leaf production is constant at both localities, the difference in number of live leaves per sapling at the seasonal site must reflect seasonal variation in leaf life span. We show that in Cecropia, internode length can serve as an indicator of precipitation seasonality. Finally an open question is whether leaf production in other pioneer species is also independent of climatic seasonal cues. This information could allow us to link growth and climate of secondary forest species and better understand how past and future climate can affect plant growth trajectories.

Changes in leaf size and in the rate of leaf production contribute to cytokinin-mediated growth promotion in Epipremnum aureum L. cuttings.

SummaryThe growth of ornamental foliage plants is often limited by pot size, which exerts a restriction on root growth and, therefore, on the production of root-synthesised cytokinins which play key regulatory roles in the development and growth of the shoot. We studied the effect of exogenous 6-benzylaminopurine (BAP) on plant growth and on the development of leaf area in Epipremnum aureum L. plants grown in pots. The hypothesis was that increasing the concentration of shoot cytokinins by foliar spraying of BAP would promote plant growth by overcoming the effects of root restriction on whole plant development. Three glasshouse experiments were conducted using (i) different concentrations of BAP, (ii) different numbers of spray applications, and (iii) different light environments. The results showed that a single spray application of BAP at 5 mg l–1 significantly (P ≤ 0.05) increased leaf area (by 20 – 40%) and biomass [fresh weight (FW)] accumulation (by 30 – 35%), while higher BAP concentrations, or repeated spray applications had less effect. The maximum effect of BAP was observed under intermediate levels of irradiance. The increased development of leaf area in BAP-sprayed plants resulted from increases in both individual average leaf areas (by 100 – 150% cf. the controls) and the rate of leaf initiation (by 30 – 120% cf. the controls). The latter could be attributed to a shortening of the phyllochron, since no branching was observed under any BAP spray treatment. Alternative physiological explanations, as well as possible commercial applications of these BAP-elicited responses are discussed.

Black leaf streak disease and plantain fruit characteristics as affected by tree density and biomass management in a tropical agroforestry system

Black leaf streak disease (BLSD) affects both bananas and plantains. Anecdotal evidence suggests that when plantain is grown under shade in agroforestry systems, there is less damage from BLSD. In this study, BLSD severity and agronomic fruit characteristics of plantain were compared under high and low timber stand densities (TSD), and also under different crop management systems (mulching, burning, intercropping). By 11 months after planting, in high TSDs, plants had 1.2 more standing leaves, 1.5 more symptom-free leaves and a lower percentage of total leaf area attacked than in low TSDs. At harvest, plants in high TSDs had, on average, 1.4 more standing leaves than those in low TSDs. Percentage leaf area attacked by BLSD was 43.0 % in high TSD treatments, significantly lower than the 57.2 % in low TSD treatments. There was a significant and positive relationship between the number of leaves at flowering and dry fruit bunch mass for plantains grown under low TSD. However, there was no correlation between the number of leaves and fruit mass for the high TSD. The beneficial effects of shade in the high TSD, such as reduced severity of BLSD, were established. However, as there was bunch mass loss associated with reduced leaf production rates under the high TSD, a reduction in BLSD only partially compensated for this yield loss. Thus overall, at the high TSD, there was no yield gain from reduced BLSD.

Herbivory, growth rates, and habitat specialization in tropical tree lineages: implications for Amazonian beta‐diversity

Tropical plant diversity is extraordinarily high at both local and regional scales. Many studies have demonstrated that natural enemies maintain local diversity via negative density dependence, but we know little about how natural enemies influence beta‐diversity across habitats and/or regions. One way herbivores could influence plant beta‐diversity is by driving allocation trade‐offs that promote habitat specialization across resource gradients. We therefore predicted that increasing resource availability should be accompanied by increasing herbivory rates and decreasing plant allocation to defense. Second, relative abundances within plant lineages are predicted to reflect patterns of habitat specialization and allocation trade‐offs. A phylogenetic context is vital not only to compare homologous plant traits (including defense strategies) across habitat types, but also to connect evolutionary trade‐offs to patterns of species diversification in each phylogenetic lineage.We tested these predictions for trees in white‐sand, clay terra firme, and seasonally flooded forests in Peru and French Guiana that represent the range of soil fertility, forest structure, and floristic compositions found throughout the Amazon region. We established 74 0.5‐ha plots in these habitats and sampled all trees. Within 12 representative plots we marked newly expanding leaves of 394 saplings representing 68 species, including the most abundant species in each plot in addition to species from five focal lineages: Swartzia and Inga (Fabaceae), Protieae (Burseracaeae), Bombacoideae (Malvaceae), and Micropholis (Sapotaceae). We measured total leaf production rates for each sapling and calculated relative herbivory impact as the ratio between herbivory rate and leaf production rate.Herbivory rates averaged 2.1% per month, did not correlate with leaf production rate, and were similar across habitats. Relative herbivore impacts exceeded leaf production rates for most species. Leaf production rate averaged 2.8%, was significantly higher in seasonally flooded forests than the other two habitats, and exhibited significant correlations with specific leaf area. Species with high herbivory rates exhibited significantly lower relative abundances in terra firme forests. Overall, focal species within lineages present contrasting patterns regarding their herbivory rates and leaf production rate within habitats. These results highlight why a lineage‐based approach is necessary when attempting to connect hypotheses regarding evolutionary trade‐offs to community assembly patterns.

Different genotypes of Phragmites australis show distinct phenotypic plasticity in response to nutrient availability and temperature

We studied the phenotypic plasticity of physiological and growth traits in two distinct clones of common reed (Phragmites australis (Cav.) Trin. Ex Steud.). Replicates of a clone from Denmark (DK clone) belonging to the European temperate P. australis and a clone from Algeria (ALG clone) belonging to the African-Mediterranean gene pool of P. australis were grown in phytotrons in a factorial block design at 15°C or 25°C daytime temperature and high or low fertilization level. Plant growth, tissue nutrient concentrations, photosynthetic pigments and photosynthetic characteristics were measured. Phenotypic plasticity was quantified for the measured traits as plasticity indices in relation to temperature and fertilization. The plasticity index was calculated as the difference between the maximum and the minimum mean value divided by the maximum mean value of a parameter within a treatment. The functional significance of the plasticity and its contribution to plant fitness was assessed by correlation of the plant traits to plant biomass as a proxy for fitness.The DK clone responded much more to temperature than the ALG clone, which responded more to fertilization, and both clones responded to high fertilization with lower allocation of biomass to roots and rhizomes. The ALG clone had a higher nutrient demand due to its large and fast biomass development. Hence, for most traits, the calculated plasticity indices for fertilization were highest for the ALG clone, especially within photosynthetic parameters and pigments, and the plasticity indices for temperature were highest for the DK clone, especially within growth parameters. In both clones, photosynthetic pigments, biomass allocation to leaf blades and rhizomes, the shoot:root ratio as well as leaf and shoot production rates were highly correlated to fitness. These traits also had a relatively high degree of plasticity, indicating a functional significance of plasticity, but several traits that showed high plasticity did not correlate with fitness (e.g. Pmax). We conclude that the responses of the two contrasting P. australis genotypes to temperature and fertilization are genetically determined and related to the climatic conditions at the site of their origin. Although phenotypic plasticity per se is not a precondition for plant fitness, the genetically determined differences in the degree of phenotypic plasticity of distinct P. australis genotypes to temperature and nutrient availability affect fitness and may influence how the genotypes will respond to global environmental change.

Strong persistent growth differences govern individual performance and population dynamics in a tropical forest understorey palm

Summary Persistent variation in growth rate between individual plants can have strong effects on population dynamics as fast growers reach the reproductive size at an earlier age and thus potentially contribute more to population growth than slow growers. In tropical forests, such persistent growth differences have so far been documented for canopy tree species, where they are primarily associated with forest gap dynamics, but not for forest understorey species which are less responsive to gaps. Here, we study persistent growth differences and their demographic consequences for a tropical forest understorey palm, Chamaedorea elegans. We measured internodes along stems and annual leaf production rates to reconstruct lifetime growth trajectories. Using regression analysis, we determined the relative effect of stem length and past growth rate on vital rates (survival, growth and reproduction). We then simulated population dynamics using integral projection models (IPMs), in which individuals were categorized by both stem length and lifetime past growth rate. Stem growth differences among individual palms persisted over most of their lifetime. Past growth rate averaged over the palm's lifetime proved to be a very good predictor of growth, reproduction probability and seed production, often much better than stem length or age. The effects of past growth rate were positive, indicating that fast growers maintain high rates of growth and reproduction. Projected population growth rate (λ) was 1.056, and stable stage distributions closely resembled observed population structures. Separating individuals with above‐median and below‐median past growth rates in IPMs revealed substantial differences in elasticity values. The 50% fastest growers had a 1.8 times higher elasticity, and thus a 1.8 times higher contribution to population growth, compared to slow growers. Synthesis. Strong and persistent growth differences that are probably associated with environmental (edaphic) and/or genetic factors govern individual performance and population dynamics of a tropical forest understorey palm. Overall, our study shows that strong inter‐individual growth variation is not limited to canopy trees and that it can be generated by other factors than canopy dynamics. It is likely that persistently fast‐growing ‘super performers’ govern population growth of many long‐lived species.

Germinación y crecimiento inicial en Abarco Cariniana pyriformis: una alternativa para su conservación

We evaluated the germination and early growth of Abarco Cariniana pyriformis on several substrates as land of ant, poultry manure (gallinacea) and sand, in Salero, Union Panamericana municipality, Choco, Colombia. They were built five beds germination with dimensions of 1mx1.50mx0.20 m, semi-protected solarization, in with 30 seeds were sown for each substrate pretaration or treatment: T1: gallinacean-ant land of sand- 1:1:1 ratio, T2: gallinaceanant of priority 1:1, T3: land of ant-sand ratio 2.1; T4: gallinacean- sand ratio of 2:1; T5: sand the variables evaluated were: percentage germination, height, leaf production, vigor, health status and survival rate of seedlings. The highest percentage of germination was introcuce to the treatments T5 and T4, whit 75 and 745 respectively. While the greater height and seedlins leaf production were the T4 y T1 and subsequently seedlings had atraght stems, leaves and foliage of good color well formed. The survival rate was low, presenting T4 and T5 treatments highest percentage with 68% and 62%. According to the results it is concluded that, you can use gallinacea manure and sand as substrates for germination and growth or Abarco C. pyriformis .

Resilience to chronic defoliation in a dioecious understorey tropical rain forest palm

Summary1. Perennial plants often endure chronic loss of leaf area due to recurrent physical damage, herbivory and, for species used as non‐timber forest products, due to leaf harvesting. However, little is known about functional and demographic resilience (extent and speed of recovery) of plants subjected to varying levels of chronic defoliation.2. We used a dioecious, understorey palm (Chamaedorea elegans) to evaluate temporal trajectories and rates of recovery of leaf functional traits and vital rates (survival, growth and reproduction) after being subjected to experimental chronic defoliation regimes.3. Pristine populations of mature C. elegans, categorized by gender (male and female), were subjected to five defoliation levels (0%, 33%, 50%, 66% or 100% of newly produced leaves) every 6 months over a period of 3 years (1997–2000). To evaluate recovery from defoliation, surviving palms were monitored for 3 years after the cessation of the defoliation treatment (2000–2003). We recorded leaf functional traits (leaf persistence, leaf production rate, leaf size and leaf area) and annual rates of mortality, growth and reproduction.4. Cumulative effects of chronic defoliation concomitantly reduced leaf traits, survival, growth and reproduction, and this effect was stronger in female than in male palms, independent of plant size. Recovery from defoliation was faster in males than in females, but proceeded gradually overall. Survival increased first, followed by growth, while reproductive traits showed the slowest recovery rate. Recovery was independent of plant size. Notably, 3 years after defoliation treatment, the standing leaf area and probability of reproduction had not recovered to pre‐defoliation levels. Additionally, we found that the occurrence of a severe drought in the first year (2000) after defoliation ceased led to decreased survival, growth and reproduction and the ability of plants to recover from defoliation.5. Synthesis. Chronic defoliation reduces fitness components of C. elegans palms differentially between genders. Recovery is gradual and is slower and less complete in females compared with males. The lower level of resilience to chronic defoliation shown by female plants may have profound consequences for the dynamics and genetic variability of populations of tropical understorey plants undergoing prolonged defoliation. Such effects may be aggravated by severe drought episodes that are expected to increase in frequency according to global climate change predictions.