Higher Leaf Area Ratio Research Articles

Bioinoculation Strategies for Enhanced Growth and Development of Economically Important Dalbergia latifolia Roxb

The present experiment was conducted to evaluate the plant growth properties of the native rhizospheric microflora of Dalbergia latifolia, an important medicinal, timber and biofuel plant. A systemic isolation, characterization and identification of rhizospheric soil, collected indigenously, initially produced 45 numbers of fungi and 3 numbers of bacteria. Both groups of organisms were characterized for their extracellular useful activity, especially phosphate solubilisation potential, and presented in terms of solubilisation index and solubilisation efficiency. Two fungi and two bacteria with good phosphate solubilization activity, along with NPK and organic manure, were selected and used in a pot culture experiment to promote the growth and development of Dalbergia latifolia under nursery conditions. Data recorded on 90 Days of plant growth exhibited the growth promotion of inoculated plants over control uninoculated experimental set. Results obtained on morphological and physiological growth parameters exhibited that the application of Aspergillus flavus followed by Burkholderia territorii + org. manure showed maximum shoot height and inoculation of Burkholderia anthina + Aspergillus sp. + NPK was significantly higher leaf area. Significantly longer root has been observed in Burkholderia territorii. However, a difference was observed in the number of leaves in Aspergillus flavus. + Org. manure and higher numbers of branches were observed in Aspergillus flavus only as compared to uninoculated control. Coinoculation of Aspergillus flavus + Penicillium simplicissimum showed better performance in fresh and dry shoot biomass as compared to other treatments. Burkholderia territorii + Org.manure produced higher fresh biomass of roots and coinoculation of bacteria Burkholderia territorii + Burkholderia anthina helped in enhancing root dry biomass. Dual inoculation of Aspergillus flavus + Penicillium simplicissimum gives better result in both fresh biomass of leaves and dry biomass of leaves. Application of Aspergillus flavus + Penicillium simplicissimum enhanced the total fresh biomass of the seedlings whereas supplementation of Burkholderia anthina + Penicillium simplicissimum enhanced the total dry biomass. Coinoculation of Aspergillus flavus + Penicillium simplicissimum showed higher RGR and coinoculation of Burkholderia anthina + Aspergillus flavus + NPK showed quite higher Leaf area ratio (LAR cm2gm-1). Co inoculation of Burkholderia territorii + Burkholderia anthina + Organic Manure showed highest root-shoot ratio and Coinoculation of Penicillium simplicissimum + Org. manure showed higher Net assimilation rate (NAR). However, Bacterial and fungal inoculants were also used as potent bioinoculants for the growth and establishment of crops of forest tree species.

Growth analysis of Kentucky bluegrass cultivars from six classification groups

AbstractKentucky bluegrass (Poa pratensis L.) cultivars are diverse in their phenotype with a common classification system used to describe their growth habit but it is unclear why their growth differs. Growth analysis measurements have been used to explain growth rate differences among grass species and cultivars. The objective of this experiment was to study the growth of six commercially available Kentucky bluegrass cultivars from different growth habit classifications using classical growth analysis. Kentucky bluegrass seed was germinated and transplanted into cone‐tainers and transferred to a growth chamber maintained at 25/15°C (day/night) and a 12‐h photoperiod. Thirty plants per cultivar were used with six whole plants of each cultivar harvested 8 weeks after transplanting and once per week for the next 4 weeks for a total of five harvests. Barvette HGT produced the largest plants, and Moonlight SLT produced the smallest plants by the end of the experiment, although the relative growth rate and absolute growth rate did not vary between the cultivars. Results from the growth analysis revealed that Moonlight SLT had the highest leaf area ratio (89.4 cm2 g−1), specific leaf area (200.1 cm2 g−1), and rhizome weight ratio (0.101 g g−1), but the lowest stem weight ratio (0.120 g g−1) and root weight ratio (0.338 g g−1). Final plant weights and leaf area measurements were closely aligned with Kentucky bluegrass classification information. Unfortunately, classical growth analysis provided little insight into why some cultivars possess more aggressive growth characteristics or compact growth habits.

Linking soil nutrients and traits to seedling growth: A test of the plant economics spectrum

Investigating the link among plant growth rates, traits and local environmental heterogeneity is necessary for understanding forest dynamics and community assembly. Although recent results showed that aboveground traits are key for determining organism’s performance and main resource-use strategies, it is clear that organism performance is influenced by both above- and below-ground traits. However, we have limited understanding about how belowground strategies change in response to soil fertility and determine plant performance. We hypothesize that belowground traits have significant effects on plant performance and that shifts in soil nutrient variability are associated to shifts belowground traits. We tested these hypotheses by surveying plant communities including 3969 seedlings represented by 49 common species over a 10-year period, measured soil nutrients, including total nitrogen (TN), phosphorus (TP) and potassium (TK), and leaf and root traits to examine the links among soil nutrients, traits and growth. We first examined the coordination of leaf and root traits of community level, then used traits to predict individual and species mean height growth rate (RGRh). Finally, we tested for shifts in traits in response to gradients of soil nutrients. We found that community-level traits tended to be multidimensional. Species with acquisitive leaf traits, e.g., high leaf area ratio (LAR), phosphorus content (LP), specific leaf area (SLA) and low leaf dry matter content (LDMC), exhibited high growth rates. However, root traits were weak predictors of RGRh, all root traits were not significantly correlated to RGRh of species, only root tissue density (RTD), specific root area (SRA) and length (SRL) was significantly correlated with RGRh of individuals. Community-weighted mean traits only significantly changed along the gradients of limiting soil nutrients, especially for TK and TP. Species with high LN, SLA, root nitrogen content, SRA and SRL, and low tissue density associated with high TK and TP. Ultimately, multidimensional trait variations, and weak links between root traits and growth only partly support the plant economics spectrum (correlation among traits along one axis), but emphasizes that, beyond root traits, other resource uptake processes of roots should be linked to plant performances. Our findings provide further insights into the understanding of how ecological strategies regulate plant performances and shape potential responses of plant communities to environmental change.

Grow slowly, persist, dominate-Explaining beech dominance in a primeval forest.

Being able to persist in deep shade is an important characteristic of juvenile trees, often leading to a strong dominance of shade‐tolerant species in forests with low canopy turnover and a low disturbance rate. While leaf, growth, and storage traits are known to be key components of shade tolerance, their interplay during regeneration development and their influence on juveniles' survival time remains unclear. We assessed the ontogenetic effects of these three traits on the survival time of beech (Fagus sylvatica), and Norway and sycamore maples (Acer pseudoplatanus, Acer platanoides) in a primeval beech forest. Biomass allocation, age, and content of nonstructural carbohydrates (NSC) were measured in the stems and roots of 289 seedlings and saplings in high‐ and low‐vitality classes. Saplings experienced a trade‐off between absolute growth rate (AGR) and storage (NSC) as the leaf area ratio (LAR) decreases with biomass development. High LAR but low AGR and low NSC corresponded to beech with a marked ability to persist in deep shade while awaiting canopy release. In turn, a comparably small LAR in combination with a high AGR and higher storage (NSC), as observed in Norway maple and sycamore maple, reduced sapling survival time, thus offering an explanation for beech dominance and maple disappearance in the undergrowth of old‐growth beech forests.

Relating leaf traits to seedling performance in a tropical forest: building a hierarchical functional framework.

Trait-based approaches have been extensively used in community ecology to provide a mechanistic understanding of the drivers of community assembly. However, a foundational assumption of the trait framework, traits relate to performance, has been mainly examined through univariate relationships that simplify the complex phenotypic integration of organisms. We evaluate a conceptual framework in which traits are organized hierarchically combining trait information at the individual- and species-level from biomass allocation and organ-level traits. We focus on photosynthetic traits and predict that the positive effects of increasing plant leaf mass on growth depend on species-level leaf traits. We modeled growth data on more than 1,500 seedlings from 97 seedling species from a tropical forest in China. We found that seedling growth increases with allocation to leaves (high leaf area ratio and leaf mass fraction) and this effect is accentuated for species with high specific leaf area and leaf area. Also, we found that light has a significant effect on growth, and this effect is additive with leaf allocation traits. Our work offers an approach to gain further understanding of the effects of traits on the whole plant-level growth via a hierarchical framework including organ-level and biomass allocation traits at species and individual levels.

Growth of canola hybrids resistant and sensitive to herbicides

Plant growth analysis is useful for determining adequate management practices and exploring the maximum yield potential of cultivars or hybrids. Canola hybrids with resistance to herbicides have been studied and registered for Brazilian conditions, as they improve weed management in canola crops. This study evaluated the growth of canola hybrids resistant to triazine or imidazolinone herbicides compared to a sensitive hybrid. The experiment was conducted using a completely randomized design, with four replications, in a bifactorial scheme using three hybrids and six sampling times. The canola hybrids used were Hyola 571CL (resistant to imidazolinones), Hyola 555TT (resistant to triazines), and Hyola 61 (sensitive to both herbicides). Height, leaf area, and dry matter of roots, leaves, stems, and shoots of the plants were evaluated at 14, 28, 42, 56, 70, and 119 days after emergence (DAE). The physiological indices absolute growth rate, leaf area ratio, specific leaf area, and net assimilation rate were calculated, and yield indices evaluated. Compared to Hyola 61, the Hyola 555TT hybrid showed lower values of leaf dry matter at 70 DAE, absolute growth rate up to 56 DAE, and net assimilation rate at 14 and 28 DAE, and a higher leaf area ratio at 56 DAE, whereas the hybrid Hyola 571CL presented lower leaf area and lower leaf dry matter at 70 DAE. At flowering, compared to Hyola 61, the hybrid Hyola 571CL presents lower leaf area, and the hybrids Hyola 555TT and Hyola 571CL have lower leaf dry matter accumulation. Differences in the growth of canola hybrids Hyola 555TT, Hyola 571CL and Hyola 61 do not cause differences in their grain yield.

Differential growth response of green and variegated Ficus benjamina to exogenous cytokinin and shade

Abstract Benjamin fig (Ficus benjamina) is an important foliage and landscape crop species comprising green and variegated genotypes. The latter develop leaves with yellow and white leaf areas which may impose lower photosynthetic activity, thus resulting in slower growth than green genotypes. In many species, the exogenous supply of cytokinin to pot-grown plants promotes growth, mainly due to enhanced carbon fixation. In this work, we analyze the effect of spraying the cytokinin 6-benzylaminopurine (BAP) on growth and development of green and variegated Ficus benjamina genotypes. Two experiments were carried out in a greenhouse, in which either different number of BAP applications (Experiment 1) or different BAP concentrations (Experiment 2) were tested. In Experiment 2, plants were grown under three different light intensities. BAP sprays promoted rate of leaf appearance, leaf expansion and whole-plant growth, and the effect was stronger in variegated than in green plants. The relative growth rate promotion by BAP was associated with increased net assimilation rate rather than with variation in the leaf area ratio. On the other hand, shading had a more negative impact on growth and development of variegated plants than in green ones. Variegated plants, unlike green ones, developed leaves with high specific leaf area under the lowest light intensity. This led to high leaf area ratio values, which helped to maintain relative growth rates close to those of plants under moderate shading.

Expression of seed vigor and initial growth of red clover under fungicide influence

The objective of this study was to evaluate the expression of seeds vigor and physiological performance of initial growth of red clover plants under the influence of fungicide doses of carboxin + thiram. Three lots of seeds were used (high; medium and low vigor) treated with 0; 150; 250 fungicide doses and 350 mL i.a./100 kg of seeds. Germination, first count, emergence and speed index of seedling emergence, length and dry matter of shoot and root, leaf area and shoot/root ratio were evaluated. The experimental design was completely randomized in a factorial 3 x 3 (three lots - high, medium and low vigor x three fungicide doses of carboxin + thiram). Data were submitted to analysis of variance and if significant at 5% probability, adjusted for orthogonal polynomials. According to the data observed in Figures 1, 2 and 3, it was possible to observe that there were significant differences for the means of the variables germination, first germination count, emergency, emergency speed index, shoot length, root length, aerial part dry mass, root dry mass, leaf area, leaf area ratio and shoot and root ratio. The fungicide doses of 150 mL to 350 mL i.a./100 kg of seeds result in greater seedling emergence, higher leaf area ratio and increased shoot/root ratio in plants from lots of medium vigor seeds. The fungicide consisted of carboxin + thiram enhances the expression of seed vigor and physiological performance of plant growth derived from lots of medium vigor seeds.

Titanium dioxide nanoparticles model growth kinetic traits of some wheat cultivars under different water regimes

Deficit irrigation affected drastically growth kinetics and leaves traits with variant degrees drawing the tolerance or sensitivity of four wheat cultivars which recorded from pre- to post-anthesis stage. The main susceptibility characters of hypersensitive cultivar Sohag 3 were reduction of photosynthetic efficiency (chlorophyll and photosynthetic rate), leaf greenness (low leaf area index; LAI), accelerated leaf aging (low biomass duration; BMD and leaf area duration; LAD), thinner and lighter leaves (high specific leaf area; SLA and high leaf area ratio; LAR) which dramatically reflected on low net assimilation rate; NAR and unit leaf rate; ULR, hence diminished absolute growth rate; AGR and relative growth rate; RGR, the vice versa was displayed by the most tolerant cultivar Seds 12. Intermediated response was manifested by cultivars Benisuif 5 and Sakha 93, since the former was close in response to cultivar Seds 12 and the latter showed the main characters of cultivar Sohag 3 but in lower degree. The photo-catalytic property of TiO2-NPs seemingly accomplished improvement of leaves and growth kinetics traits by fertigation the soil of wheat cultivars growing at different water regimes. TiO2-NPs fertigation promoted leaf characteristics through production of thicker and heavier leaves as well as promoting leaf longevity by enhancement of BMD and LAD. Thus, TiO2-NPs activated production of vigor and well-constructed leaves with higher chlorophyll and photosynthetic rate thereby, high LAI, hence higher values of RGR, AGR, ULR and NAR.

Recruitment Niches of Enterolobium contortisiliquum (Vell.) Morong: Functional Acclimations to Light

Adjustments that a tree species displays in acclimating to light conditions may explain its fate in different forest successional stages. Enterolobium contortisiliquum (Vell.) Morong is a tree found in contrasting light environments and used in reforestation programs because of its rapid growth. This study analyzed the performance of tamboril seedlings grown in three light environments: FS—full sun (100% of photosynthetically active radiation (PAR) and a red/far-red ratio (R/FR) of 1.66), S—shade net (38% of PAR and a R/FR of 1.54) and I—Insulfilm® (Insulfilm, São Paulo, Brazil) shade cloth (24% of PAR and a R/FR of 0.69). Greater net assimilation, higher root/shoot ratio, higher stomatal density, and reduced leaf area are some of the functional traits developed by tamboril to acclimate to full sun. On the other hand, a larger leaf area associated with a greater specific leaf area, higher leaf area ratio, higher leaf number and leafing intensity, as well as higher chlorophyll and carotenoid contents are among the most important traits for tamboril to acclimate to shade. The seedlings growing in FS displayed the best quality index. However, the traits developed in the nursery under each light condition could promote the successful installation and survival of tamboril seedlings under similar conditions in the field.

Growth attributes of rapeseed varieties (Brassica campestris l.) in relation to sowing dates and weedings treatments

Context: To analyze the effect of sowing dates and weeding treatments on growth attributes such as total dry matter (TDM), leaf area index (LAI), net assimilation rate (NAR), crop growth rate (CGR), leaf area ratio (LAR) of three rapeseed (Brassica campestris L.) Objectives: The objective of the study was to identify the growth in relation to sowing dates and weed competition and identify the weeding number for better growth of rapeseed. Materials and Methods: This investigation was arranged as factorial experiment based on the split-split plot design with three replications. Four sowing dates were including 18 October (S1), 12 November (S2), 17 November (S3) and 3 December (S4) and three weeding treatments were no weeding (W0), one hand weeding (W1) and two hand weeding (W2) and three varieties viz., BINA Sarisha-5, BINA Sarisha-6 and BARI Sarisha-14 were investigated. Results: The results showed that, TDM, LAI, CGR, NAR and LAR were affected by sowing date and weeding treatments. The highest TDM, LAI and CGR were obtained in the first sowing and two weedings treatment. The highest NAR was found in S2 plants and W0 treatment. The highest LAR was found in S2 plants and W1 treatment. Conclusion: The results obtained in this study suggest that the first sowing and two weeding treatments are superior for the production of rapeseed. DOI: http://dx.doi.org/10.3329/jbs.v21i0.22519 J. bio-sci. 21: 51-59, 2013

Influence of Biophysical Priming on Seed Germination and Yield on Two Landraces of Lemon-Balm (Melissa officinalis L.)

The aim is to study the effects of physical seed priming on germination and yield of lemon balm. Laboratory and pots experiments were conducted as factorial based on completely randomized design. The treatments are magnetic field with 75 mT for 10 and 15 min durations; laser light with 2 mw.cm-2 for 20 min; ultrasonic wave with physiotrapy device for 20 min; cs-gamma ray for one hour in lead cell, and control that were applied on two landraces of lemon balm (‘Karaj’, ‘Esfahan’). Then in laboratory with use of special paper and pure water the seeds were cultured in petri-dishes and were putt in germinator with 19°C temperature for 8 days and were counted daily. Some parts of primed seeds were stored in normal condition for 6 months and were cultured in laboratory condition. All the primed seeds were farmed in pots. Three months later the plants were harvested in first blooming level and dry weight and essential oil percentage were measured. Results showed that the influence of various treatments on germination percentage and germination rate were significant. Magnetic field treatment (15 min) showed the highest positive effect on percentage (86%), and rate. The length and weight of seedling in magnetic field treatment were the highest in comparison with other ones. Considering physiological characteristics, the higher Leaf Area Ratio and Leaf Area Index were seen in magnetic field. Effect of different treatments on plant height, biomass dry weight and essential oil concentration was significant.

Plant traits in relation to the performance and distribution of woody species in wet and dry tropical forest types in Panama

Summary Understanding the factors that limit species distributions along environmental gradients is a central question of ecology. Here, we evaluate the hypothesis that the traits that result in performance trade‐offs between habitats contribute to the turnover of woody species along a rainfall gradient in the Isthmus of Panama. We studied 24 plant species with contrasting distributions along this rainfall gradient. We measured 18 morphological and physiological traits, and three performance variables in seedlings planted in common garden experiments in two contrasting sites across the Isthmus. We found evidence for a trade‐off suggesting that better survival during the dry season corresponded to a lower growth rate in the forest understorey. This trade‐off correlated well with the distribution of the species along the rainfall gradient and was explained mostly by variation in photosynthetic capacity. While not all species fit into this trade‐off, most dry‐distribution species, which we had previously reported to have higher drought survival, were associated with higher stem hydraulic conductance and higher capacity for CO2 assimilation. Our interpretation is that this combination of traits may be associated mostly with desiccation avoidance (deep roots) or desiccation delay (deciduousness) rather than desiccation tolerance. Despite their higher photosynthetic capacity, these species had lower growth in the low‐light understorey, probably because of higher maintenance costs (dark respiration rates). Wet‐distribution species, on the other hand, had lower photosynthetic capacity and higher leaf area ratio. This strategy is typical of shade‐tolerant species and may explain their higher growth rates in the low‐light understorey. In conclusion, our results suggest that habitat associations along the rainfall gradient in the Isthmus of Panama may result in part from a trade‐off between traits that are favourable to species that avoid or delay desiccation but that otherwise limit shade tolerance. This trade‐off may limit the capacity of some dry‐distribution species to colonize wet forests.

Plastic responses of Populus yunnanensis and Abies faxoniana to elevated atmospheric CO2 and warming

To examine whether deciduous and evergreen tree species differ in their performance and plastic responses to elevated atmospheric CO2 and temperature, we investigated growth, leaf area ratio (LAR), specific root length (SRL), nitrogen uptake efficiency (NUpE) and nitrogen use efficiency (NUE) of Populus yunnanensis and Abies faxoniana grown in environment-controlled chambers. Our results showed that temperature stimulated growth more than did CO2 in both species. The magnitude of temperature and CO2 effects varied between the species, as greater stimulation was detected in A. faxoniana than in P. yunnanensis. Greater responses of A. faxoniana were associated with higher LAR and higher NUE. However, NUpE did not differ between species and could not explain this advantage. On the other hand, the studied species did not differ in their mean overall plasticity (calculated for each species by averaging the indices of plasticity obtained for each of the 17 variables), which, however, was achieved in different ways. Across CO2 and temperature treatments, A. faxoniana exhibited greater plasticity in stomatal conductance, LAR, SRL and NUE, whereas P. yunnanensis exhibited greater plasticity in net photosynthesis rate, leaf respiration and root/shoot ratio. Our results suggested that plasticity of key traits, such as LAR, SRL and NUE, may have important implications for the superiority of A. faxoniana in the response to climate change. Our results highlight the importance of exploring the functional significance of traits rather than the extent of plasticity as potential determinants of interspecific differences in responses to climate change.

Leaf nitrogen allocation and partitioning in three groundwater-dependent herbaceous species in a hyper-arid desert region of north-western China

Groundwater-dependent vegetation (GDV) is useful as an indicator of watertable depth and water availability in north-western China. Nitrogen (N) is an essential limiting resource for growth of GDV. To elucidate how leaf N allocation and partitioning influence photosynthesis and photosynthetic N-use efficiency (PNUE), three typical GDV species were selected, and their photosynthesis, leaf N allocation and partitioning were investigated in the Taklamakan Desert. The results showed that Karelinia caspica (Pall.) Less. and Peganum harmala L. had lower leaf N content, and allocated a lower fraction of leaf N to photosynthesis. However, they were more efficient in photosynthetic N partitioning among photosynthetic components. They partitioned a higher fraction of the photosynthetic N to carboxylation and showed higher PNUE, whereas Alhagi sparsifolia Shap. partitioned a higher fraction of the photosynthetic N to light-harvesting components. For K. caspica and P. harmala, the higher fraction of leaf N was allocated to carboxylation and bioenergetics, which led to a higher maximum net photosynthetic rate, and therefore to a higher PNUE, water-use efficiency (WUE), respiration efficiency (RE) and so on. In the desert, N and water are limiting resources; K. caspica and P. harmala can benefit from the increased PNUE and WUE. These physiological advantages and their higher leaf-area ratio (LAR) may contribute to their higher resource-capture ability.

Invasive Eupatorium adenophorum has ecophysiological advantages over native congeners but similar responses to CO(2) enrichment.

Both global change and biological invasions threaten biodiversity worldwide. However, their interactions and related mechanisms are still not well elucidated. To elucidate potential traits contributing to invasiveness and whether ongoing increase in CO(2) aggravates invasions, noxious invasive Eupatorium adenophorum and native E. japonicum and E. chinensis were compared under ambient and doubled atmospheric CO(2) concentrations in terms of growth, biomass allocation, morphology, and physiology. The invader had consistently higher leaf mass fraction and specific leaf area than the natives, contributing to a higher leaf area ratio, and therefore to faster growth and invasiveness. The higher leaf mass fraction of the invader was associated with lower total root mass fraction. The invader allocated a higher fraction of leaf nitrogen (N) to photosynthesis, contributing to higher area-based N content in photosynthetic apparatus, photosynthetic rate, nitrogen- and water-use efficiencies, and invasiveness. CO(2) enrichment increased growth of all studied plants by increasing actual photosynthesis, although it decreased photosynthetic capacities due to decreased area-based leaf and photosynthetic N contents. Responses of the invasive and native plants to elevated CO(2) were not significantly different, indicating that the ongoing increase in CO(2) may not exacerbate biological invasions, inconsistent with the prevailing results in references. The difference may be associated with the fact that almost all previous studies compared phylogenetically unrelated invasive and native plants. More comparative studies of sympatric, related invasive and native plants are needed to elucidate whether CO(2) enrichment facilitates invasions.

Innate and evolutionarily increased advantages of invasive Eupatorium adenophorum over native E. japonicum under ambient and doubled atmospheric CO2 concentrations

Both innate and evolutionarily increased ecophysiological advantages can contribute to vigorous growth, and eventually to invasiveness of alien plants. Little effort has been made to explore the roles of innate factors of alien plants in invasiveness and the effects of CO2 enrichment on alien plant invasions. To address these problems, we compared invasive Eupatorium adenophorum, its native conspecific, and a native congener (E. japonicum) under ambient and doubled atmospheric CO2 concentrations. Native E. adenophorum from Mexico grew slower than invasive E. adenophorum but faster than native E. japonicum under both CO2 concentrations. The faster growth rate of invasive E. adenophorum was associated with higher photosynthetic capacity and leaf area ratio. For invasive E. adenophorum, the higher photosynthetic capacity was associated with higher nitrogen (N) allocation to photosynthesis, which was related to lower leaf mass per area; the higher leaf area ratio was due to lower leaf mass per area and higher leaf mass fraction. Tradeoff between N allocations to photosynthesis versus defenses was found. CO2 enrichment significantly increased relative growth rate and biomass accumulation by increasing actual photosynthetic rate for all studied materials. However, the relative increase in growth was not significantly different among them. CO2 enrichment did not influence N allocation to photosynthesis, but increased N allocation to cell walls. The reduced leaf N content decreased N content in photosynthesis, explaining the down-regulation of photosynthetic capacity under prolonged elevated CO2 concentration. Our results indicate that both innate and evolutionary advantages in growth and related ecophysiological traits contribute to invasiveness of invasive E. adenophorum, and CO2 enrichment may not aggravate E. adenophroum’s invasion in the future.

Morphological traits and allocation patterns related to stress-tolerance and seed-yield in wild and domesticated evening primrose ( Oenothera L. Onagraceae)

Wild evening primrose species ( Oenothera spp.) native to Argentina, have been suggested as a new crop for irrigated valleys of semi-arid Patagonia. This paper describes patterns of biomass allocation, morphological traits related to stress-tolerance and seed-yield in four species of Oenothera grown in a common garden at three plant densities. Wild and domesticated species are compared. The effect of resource availability on those traits during three phenological stages (vegetative, reproductive and maturity) is described. Native species were characterized by traits related to stress-tolerance (high root allocation and low specific leaf area) during the vegetative stage. This suite of traits resulted in low biomass accumulation and low seed-yield. The domesticated O. biennis was characterized by a combination of traits related to stress-tolerance (low specific leaf area) and high productivity (high leaf allocation and leaf area ratio and low root allocation). Domesticated species accumulated more biomass than natives. Total biomass and total non-structural carbohydrates present in roots were positively correlated to seed-yield. Oenothera biennis showed the highest seed-yield, although this species showed yield instability in response to changes in the environmental quality. No changes in seed-yield in response to plant density were recorded for either O. lamarckiana or native species. Oenothera biennis showed an optimum density of 20 plants m −2 and yielded 260 g m −2, a seed-yield similar to that reported in other countries. Low seed-yield of native species is major drawback that must be overcome. Improving seed-yield in these species could be possible by selection oriented to increase total biomass. Since no detrimental effect of density was found in O. lamarckiana and natives, a higher plant density might increase yield production per unit area.

Inter-clonal variation in functional traits in response to drought for a genetically homogeneous Mediterranean conifer

Mediterranean trees are expected to be exposed to an increased aridity in the near future. The lack of genetic variability of stone pine ( Pinus pinea L.) could limit the adaptation potential of the species to more severe droughts. However, information on intra-specific variability in adaptive traits that might confer potential drought tolerance is scant for stone pine. In this study, we explored the adaptation potential of stone pine to water deficit through variability of key functional traits. In particular, inter-clonal variation in whole plant performance in response to water deficit was studied. The role of inter-clonal variation in functional traits and phenotypic plasticity as determinants of whole plant performance under water deficit were also assessed. Relative growth rate (RGR) and key morphological and physiological traits were studied in ramets of 20 different clones of stone pine from a wide range of populations in the Iberian Peninsula. The plants were grown in climatic chamber under controlled environmental conditions and were submitted to an experimental water deficit of 20 days. The results showed significant inter-clonal variation in total dry mass, RGR, biomass partitioning specific leaf area (SLA), leaf area ratio (LAR), net photosynthetic rate ( A n), stomatal conductance ( g s) and intrinsic water use efficiency (WUE i). Significant phenotypic plasticity in response to drought was found for A n, g s and WUE i but it did not differ among clones. The clones could be clustered into different groups according to the variability of the studied traits in a principal components analysis. LAR, SLA and net photosynthetic rates explained most of the variation. A combination of traits (high LAR and low WUE i) agreeing with a water spending strategy rather than with a water saving strategy seemed to underlie enhanced RGR under water deficit. Stone pine showed high phenotypic plasticity and significant intra-specific variation in functional traits in response to water deficit. The pattern of variation found in morphological and physiological traits might allow adaptation to short term water deficit in this species.

Influence of rootstock on vegetative growth, fruit yield and quality in ‘Cuore di Bue’, an heirloom tomato

SummaryHeirloom tomatoes (Solanum lycopersicum L.) such as ‘Cuore di Bue’ are highly appreciated by consumers for their outstanding quality and flavour. Nowadays, they are often grafted onto vigorous rootstocks in order to overcome several soil-borne diseases. The present study was conducted in 2007 and 2008 in Southern Italy. Plants of ‘Cuore di Bue’, an heirloom ‘oxheart’ tomato, were grown in a greenhouse either as non-grafted plants, or grafted onto two inter-specific (S. lycopersicum S. habrochaites) rootstocks (‘Beaufort F1’ and ‘Maxifort F1’) in order to evaluate their effects on vegetative growth, marketable yield, fruit quality, and the sensory properties of ‘Cuore di Bue’ tomato fruit. Growth analysis revealed that ‘Maxifort F1’ enhanced plant growth, particularly in terms of leaf area and leaf fresh weight. Grafted plants had higher leaf area ratios (by 13%) and higher leaf dry weight fractions (by 18%) compared to non-grafted ‘Cuore di Bue’ plants. Marketable yields increased by 20 – 25% in grafted plants in both years. However, total soluble solids (TSS) contents, titratable acidity (TA), and TSS/TA ratios were not significantly affected by grafting.Vitamin C contents decreased by 14 – 20% in both years in the fruit of plants grafted onto either rootstock. The sensory profiles of fruit were not modified by grafting, although taste panelists expressed a higher preference for purchasing fruit from plants grafted onto ‘Maxifort F1’. These results confirm that, when using the appropriate rootstock/scion combination, grafting can improve plant growth and the marketable yield of heirloom tomato fruit without reducing the sensory quality of the fruit or its biochemical parameters. However, grafting can reduce vitamin C contents and, thus, nutritional quality.