Biomass Allocation Strategies Research Articles

The influence of phosphorus on leaf function, cadmium accumulation and stress tolerance of poplar leaves under cadmium exposure

A pot experiment was conducted to evaluate the effect of phosphorus (P) availability on leaf function, cadmium accumulation and stress tolerance of poplar leaves under cadmium exposure. The pot experiment consisted of two-factors including three Cd treatments and two P treatments, and a clone of Populus × euramericana was used as plant material. Leaf development and gas exchange were less inhibited by Cd exposure than that by P deficiency. Under different P levels, Cd accumulation increased with the increasing intensity and duration of Cd exposure, while Cd accumulation in leaves was inhibited by P deficiency. With sufficient P nutrition, Cd content and Cd concentration of leaves reached 300 μg plant -1 and 32 μg g -1 DW, respectively. Cd was preferentially enriched in leaf veins to avoid Cd poisoning in photosynthetic apparatus. In the absence of Cd exposure, P promoted WUE i via increasing photosynthesis rate . In contrast, P nutrition promoted WUE i under Cd exposure via regulating stomata aperture and reducing water loss via transpiration. The activities of antioxidants including GR and CAT were enhanced by P addition, as a result of the elevated expression of related genes ( Gr chl , Gr cyt , Cat2 , Cat3 ). The mechanisms underlying the promotive effect of P on leaf function and Cd tolerance are elucidated. Phosphorus promotes leaf function and Cd tolerance of poplar by enhancing photosynthetic process, stomatal regulation and antioxidant defense. Phosphorus shortage reduced the levels of phytohormones, while P addition contributes to stress tolerance via promoting the levels of phytohormones including ABA, JA and IAA. Salicylic acid (SA) promotes stress tolerance under Cd exposure via affecting the inducement of antioxidant enzymes. The improved Cd tolerance of leaves facilitates leaf carbohydrate production, promotes Cd bio-extraction and benefits xylem development of poplars growing under Cd exposure. • Cd stress changed the biomass allocation strategy of poplar among different organs. • The promotion mechanism of P on WUE i was different under different Cd treatments. • P promoted the accumulation of Cd in leaves and preferentially stored Cd in the veins. • P deficiency reduced the levels of antioxidant enzymes and hormones and decreased the accumulation of Cd. • P enhanced antioxidant defense and photosynthetic carbon assimilation and thus promoted xylem development.

Precipitation predictability affects intra- and trans-generational plasticity and causes differential selection on root traits of Papaver rhoeas.

Climate forecasts show that in many regions the temporal distribution of precipitation events will become less predictable. Root traits may play key roles in dealing with changes in precipitation predictability, but their functional plastic responses, including transgenerational processes, are scarcely known. We investigated root trait plasticity of Papaver rhoeas with respect to higher versus lower intra-seasonal and inter-seasonal precipitation predictability (i.e., the degree of temporal autocorrelation among precipitation events) during a four-year outdoor multi-generation experiment. We first tested how the simulated predictability regimes affected intra-generational plasticity of root traits and allocation strategies of the ancestors, and investigated the selective forces acting on them. Second, we exposed three descendant generations to the same predictability regime experienced by their mothers or to a different one. We then investigated whether high inter-generational predictability causes root trait differentiation, whether transgenerational root plasticity existed and whether it was affected by the different predictability treatments. We found that the number of secondary roots, root biomass and root allocation strategies of ancestors were affected by changes in precipitation predictability, in line with intra-generational plasticity. Lower predictability induced a root response, possibly reflecting a fast-acquisitive strategy that increases water absorbance from shallow soil layers. Ancestors' root traits were generally under selection, and the predictability treatments did neither affect the strength nor the direction of selection. Transgenerational effects were detected in root biomass and root weight ratio (RWR). In presence of lower predictability, descendants significantly reduced RWR compared to ancestors, leading to an increase in performance. This points to a change in root allocation in order to maintain or increase the descendants' fitness. Moreover, transgenerational plasticity existed in maximum rooting depth and root biomass, and the less predictable treatment promoted the lowest coefficient of variation among descendants' treatments in five out of six root traits. This shows that the level of maternal predictability determines the variation in the descendants' responses, and suggests that lower phenotypic plasticity evolves in less predictable environments. Overall, our findings show that roots are functional plastic traits that rapidly respond to differences in precipitation predictability, and that the plasticity and adaptation of root traits may crucially determine how climate change will affect plants.

Global systematic review with meta-analysis shows that warming effects on terrestrial plant biomass allocation are influenced by precipitation and mycorrhizal association

Biomass allocation in plants is fundamental for understanding and predicting terrestrial carbon storage. Yet, our knowledge regarding warming effects on root: shoot ratio (R/S) remains limited. Here, we present a meta-analysis encompassing more than 300 studies and including angiosperms and gymnosperms as well as different biomes (cropland, desert, forest, grassland, tundra, and wetland). The meta-analysis shows that average warming of 2.50 °C (median = 2 °C) significantly increases biomass allocation to roots with a mean increase of 8.1% in R/S. Two factors associate significantly with this response to warming: mean annual precipitation and the type of mycorrhizal fungi associated with plants. Warming-induced allocation to roots is greater in drier habitats when compared to shoots (+15.1% in R/S), while lower in wetter habitats (+4.9% in R/S). This R/S pattern is more frequent in plants associated with arbuscular mycorrhizal fungi, compared to ectomycorrhizal fungi. These results show that precipitation variability and mycorrhizal association can affect terrestrial carbon dynamics by influencing biomass allocation strategies in a warmer world, suggesting that climate change could influence belowground C sequestration.

Differentiation in seed mass and seedling biomass allocation in Prosopis laevigata throughout its distribution range in Mexico is associated to water availability

Background: Seedling establishment depends on the quality of the seeds and environmental conditions. Differential biomass allocation in emergent seedlings probably constitutes a relevant adaptive response of populations along environmental gradients.
 Questions: Are there differences in seed mass and biomass allocation in seedlings among Prosopis laevigata populations? Is this variation correlated with environmental variables?
 Studied species: Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C.Johnst (Fabaceae).
 Study site and dates: Thirteen localities along the distribution of P. laevigata in México. From 2016 to 2020.
 Methods: Seeds were collected from four or five mother trees per locality. Seed mass (SM) was obtained in ten seeds per mother and six functional traits indicative of biomass allocation were measured in the seedlings after 10 days of germination. Population mean values were obtained for the six traits plus SM and subjected to a principal component analysis (PCA). Population scores on the first two axis of the PCA were regressed against environmental variables from the collection localities using a stepwise regression model.
 Results: Populations displayed functional variation congruent with alternative biomass allocation strategies. The conservative strategy was characterized by larger seeds and seedlings with denser tissues and a higher investment in root biomass, while the opposite characterized the acquisitive strategy. Actual evapotranspiration in May, isothermality and soil water content in February were environmental variables that significantly predicted population scores on the first two axes of the PCA.
 Conclusion: Water availability gradients influence seed mass and seedling biomass allocation variation among P. laevigata populations.

Environment and plant traits explain shrub biomass allocation and species composition across ecoregions in North China

AbstractQuestionsInterspecific differences in plant biomass allocation reflect plant nutrient use strategy, determining species fitness under different environmental conditions. However, plant biomass allocation may be affected by both habitat and plant traits. We asked how environmental conditions and plant traits jointly affect shrub biomass allocation. Specifically, how they further play roles in understanding community species composition as ecoregion changes.LocationShaanxi province, North China.MethodsPlant biomass, plant traits and community composition were surveyed for 48 shrub sites distributed in five ecoregions. Species‐specific allocation parameters (allometric constants and scaling exponents) and plant traits were weighted with species abundance to calculate the community biomass allocation and community traits. Linear mixed models were used to assess relative contributions of plant traits and environmental factors in explaining biomass allocation pattern. Their roles in explaining species composition were analyzed by canonical correspondence analysis (CCA).ResultsWe reported that shrub biomass allocation parameters of stems vs leaves and roots vs shoots varied significantly among ecoregions. Plant traits explained more variation in stem vs leaf biomass allocation than soil and climate factors, while climate factors played important roles in variation of root vs shoot biomass allocation. Combined with plant traits and environmental conditions, biomass allocation showed a synergistic role in explaining community species composition.ConclusionsEnvironment and plant traits explain different aspects of shrub biomass allocation, and species‐specific biomass allocation strategy have the potential to predict community species composition and distribution across ecoregions. Our study sheds light on the biomass allocations significance in understanding species turnover and community distribution.

Divergent responses of plant biomass and its allocation to the altered precipitation regimes among different degraded grasslands in China

Climate models predict shifts in precipitation patterns characterized by increased precipitation amount and decreased frequency for semi-arid grasslands in northeast China. However, under these novel climatic conditions, potential differences in plant biomass and its allocation among different degraded grasslands remain unclear. We conducted a mesocosm experiment to test the effects of higher precipitation amount (increased by 50% from the long-term mean) and lower frequency (decreased by 50%) on plant biomass and allocation in the lightly, moderately, and severely degraded grasslands. Lower precipitation frequency promoted belowground biomass but reduced aboveground biomass through enhancing soil water variability. Higher precipitation amount enhanced aboveground biomass in the lightly and moderately degraded grasslands, but not in the severely degraded grassland due to lower soil nitrogen availability. Lower precipitation frequency weakened or ended the positive effects of higher precipitation amount on aboveground and belowground biomass, and higher precipitation amount suppressed the enhancement of lower precipitation frequency on belowground biomass, which could be attributed to temporary waterlogging. Plants in the moderately degraded grassland preferred to adjust root vertical distribution, which was impacted by the changes in plant community composition. However, adjustment of aboveground biomass vs. belowground biomass was the primary biomass allocation strategy in the other two grasslands. Our findings emphasized the importance of considering the degradation level of grasslands when predicting responses of ecosystem functions to the projected changes in precipitation regimes. These findings are critical for making feasible decisions for the sustainable management of degraded grasslands. Legend: + and − indicate positive and negative relationships, respectively LDG, MDG and SDG-lightly degraded, moderately degraded and severely degraded grasslands, respectively DPF-decreased precipitation frequency treatment, IPA-increased precipitation amount treatment SWC and CVSWC-mean and variation of soil water content, respectively SINC-soil inorganic nitrogen content AGB and BGB-aboveground and belowground biomass, respectively fAGB-AGB / total biomass BGB0–10 (%)-belowground biomass proportion in the 0–10 cm soil layer, $${{{\text{BGB}}_{{0 - 10}} } \mathord{\left/ {\vphantom {{{\text{BGB}}_{{0 - 10}} } {{\text{BGB}}_{{0 - 30}} {\text{~}} \times 100}}} \right. \kern-\nulldelimiterspace} {{\text{BGB}}_{{0 - 30}} \times 100}}$$ RAGB-relative aboveground biomass

Hybridization With an Invasive Plant of Xanthium strumarium Improves the Tolerance of Its Native Congener X. sibiricum to Cadmium.

Hybridization is one of the important factors influencing the adaptive evolution of invasive plants. According to previous studies, hybridization with an invasive plant reduces the adaptability of its native congener to environment. However, in this study, the hybridization with an invasive plant of Xanthium strumarium (LT) improves the tolerance and accumulation of its native congener Xanthium sibiricum (CR) to cadmium (Cd). Under Cd stress, X. sibiricum♀ × X. strumarium♂ (ZCR) showed higher biomass and Cd accumulation. Compared with CR, ZCR has longer vegetative and reproductive growth time. Moreover, ZCR adopted more reasonable biomass allocation strategy. ZCR increased the proportion of reproductive allocation and ensured its own survival with the increase of Cd stress. Furthermore, ZCR increased the translocation of Cd to aboveground parts and changed the distribution of Cd. A large amount of Cd is stored in senescent leaves and eliminated from the plant when the leaves fall off, which not only reduces the Cd content in the plant, but also reduces the toxicity of Cd in the normal leaves. Transcriptome analysis shows a total of 2055 (1060 up and 995 down) differentially expressed genes (DEGs) were detected in the leaves of Cd-stressed ZCR compared with CR, while only 792 (521 up and 271 down) were detected in X. strumarium♀ × X. sibiricum♂ (ZLT) compared with LT. A large number of DGEs in ZCR and ZLT are involved in abscisic acid (ABA) synthesis and signal transduction. The genes induced by ABA in ZCR, including CNGC5/20, CPK1/28, CML, PTI1-like tyrosine-protein kinase 3, respiratory burst oxidase homolog protein C, and WRKY transcription factor 33 were found differentially expressed compared CR. carotenoid cleavage dioxygenase 4, NCED1/2, phytoene synthase 2, and CYP707A involved in ABA synthesis and decomposition in ZLT were found differentially expressed compared LT. We speculated that ABA played an important role in Cd transportation of hybrids and Cd distribution in senescent and normal leaves. The results demonstrate that hybridization with an invasive plant improves the adaptability of the hybrid to Cd stress and may enhance the extinction risk of native congener in pollution environment.

Variation in resource allocation strategies and environmental driving factors for different life‐forms of aquatic plants in cold temperate zones

Abstract Resource allocation, including biomass allocation and nutrient allocation between different organs in a plant, reflects the trade‐off in partitioning between above‐ground and below‐ground organs and the growth and adaptation strategies of plants in a changing environment. Although varied resource allocation patterns among different organs in different functional groups of terrestrial plants have been found, few studies have focused on freshwater ecosystems. In this study, to clarify biomass and nutrient allocation strategies and their responses to environmental factors, we collected and analysed 2,162 samples from 262 aquatic plant communities (including emergent plants, floating‐leaved plants and submerged plants) in various aquatic habitats in north‐eastern China. The results showed that the root/shoot (R/S) ratios of the three aquatic plant life‐forms were significantly different, and the trend showed that the ratio values for the three plant life‐forms occurred in the following order: emergent plants > floating‐leaved plants > submerged plants. There were obvious scaling relationships between above‐ground biomass, N (or P or N:P ratios) and below‐ground biomass, N (or P or N:P ratios), but their scaling exponents changed among different aquatic plant life‐forms. The allocation of biomass and nutrients between different organ responses to environmental factors was not consistent for the different life‐forms of aquatic plants. The partial least squares path model revealed that plant stoichiometric characteristics are important direct drivers of biomass production. Climate conditions, water properties and soil nutrients indirectly affect biomass through effects on plant stoichiometric characteristics. Synthesis. Our study demonstrates that global climate change may affect water properties and soil nutrients, influence plant stoichiometric characteristics and affect aquatic plant growth, further altering aquatic plant community structure and biogeochemical cycles.

The relationship of the main root-shoot morphological characteristics and biomass allocation of Saussurea salsa under different habitat conditions in Sugan lake wetland on the northern margin of the Qinghai-Tibet Plateau

The response analysis of plant morphological characteristics and biomass allocation in salt marsh wetland to heterogeneous habitats is helpful to explore the internal correlation between plant morphological plasticity mechanism and biomass allocation, which is of great significance for the in-depth understanding of habitat stress tolerance strategies of salt marsh plants. However, the relationship between the main root-shoot morphological indexes and biomass allocation of inland alpine arid area salt marsh plant is still unclear. According to the difference of the habitat conditions of Saussurea salsa, 3 test sample were set up, plot I (the Inland salt marsh area, 200–500 m from the lakeshore), plot II (the Oasis Wetland area, 500–1000 m from the lakeshore), plot III (the Seasonal river wetland area, 1000–1500 m from the lakeshore). The relationship between the main root-shoot morphological characteristics and biomass allocation of Saussurea salsa in the Sugan Lake salt marsh was studied in response to heterogeneous habitats. The results showed that Saussurea salsa tended to form the large and thick leaf pattern, the root morphological construction pattern with moderate root diameter (RD) and specific root length (SRL), and the root-shoot ratio (RSR) with minimum biomass allocation strategy in plot I. In plot II, the thin-leaf pattern with the largest specific leaf area (SLA) and the smallest thickness (LT) was formed. Meanwhile, the slender root morphology pattern with the smallest RD, the largest SRL and the moderate RSR was preferred. In plot III, a lobular pattern with minimum leaf area (LA) and SLA, and moderate thickness was formed. At the same time, a thick root pattern with maximum RD and minimum root length, and a maximum RSR were formed. Moreover, there was a highly significant negative correlation (p < 0.01) between SLA and RD at three plots. Besides, there appeared a less significant positive correlation (p < 0.05) between LA and LT, shoot biomass at three plots. Through the synergistic changes of morphological characteristics of aboveground and underground organs and biomass allocation strategies, the inland salt marsh plant population can maintain normal survival, growth and reproduction under harsh environment, which reflects its morphological plasticity and stress resistance mechanism under heterogeneous environment.

Effects of succession stages and altitudinal gradient on leaf surface area and biomass allocation of typical plants in the subalpine of Eastern Tibetan Plateau

Leaves are the main organs of plants for photosynthesis. The scaling relationship between leaf mass (LM) and leaf area (LA) can reflect the capabilities of plants to capture light energy, obtain net carbon benefits, and adapt to environmental changes. The LA-LM relationship is intimately associated with the water and carbon economics of plants. The scaling relationship between LA and LM is important to reveal the strategies of plant biomass allocation with changes of environmental stresses. Previous studies primarily focused on relatively close plants within the same taxon (e.g., a family or a genus), different plants in different altitude gratient, or special groups such as epiphytes. However, it is still unknown about whether and how the scaling relationship between LM and LA varies across succession stages and altitudinal gratient. We measured LA, leaf fresh weight (LFW) and leaf dry weight (LDW) of 201 plant species with 603 individuals in nine plots in Zhouqu County of China to study the strategy of allometry relationships of LA and LM among different plant life forms, succession stages and altitudinal gratient. We found that the quotient of LDW and LFW for woody plants was significantly higher than that for herbaceous plants. In the process of adapting to changes of life forms, succession stages and altitudes, the scaling exponent of LFW vs. LA was more sensitive than that of LDW vs. LA. Most scaling relationships of LFW vs. LA conformed to the law of diminishing returns, but the scaling relationship between LDW and LA appeared more complicated. The scaling relationships between LDW and LFW mainly exhibited an increasing returns. Increasing returns were more obvious in life forms, middle altitude and mid-succession. In addition, no matter at which level, the coefficient of determination (i.e. R2) of LA vs. LFW was greater than that of LA vs. LDW. It might be more convincing to predict the relationship between LA and LM by using the data of LA vs. LFW. Most of (17 of 24, 70.83%) the R2 of PGLS (Phylogenetic Generalized Least Squares) regression were higher than those of SMA (Standardized Major Axis) regression, which showed that the influence of phylogeny should not be ignored in the study of multi-species traits relationships. In general, the trade off or allometry between LA and LM varied among plants life forms or environmental changes including succession stages and elevation variability. This pattern can be explained by different leaf strategies in response to environmental pressure and constrains.

Modeling biomass allocation strategy of young planted Zelkova serrata trees in Taiwan with component ratio method and seemingly unrelated regressions

Trees accumulate biomass by sequestrating atmospheric carbon and allocate it to different tree components. A biomass component ratio is the ratio of biomass in a tree component to total tree biomass. Modeling the ratios for Zelkova serrata, an important native reforestation tree species in Taiwan, helps in understanding its biomass allocation strategy to design effective silvicultural treatments. In this study, we applied Component Ratio Method (CRM) to relate biomass component ratios of main stem, large branch, twig, and foliage to tree attributes of Z. serrata from a 9-year-old plantation. Nonlinear and linear CRM models were fitted with Seemingly Unrelated Regression to account for model correlations. Linear CRM models with dbh as the predictor had the best fit with model correlations as high as 80%. About 46% and 40% of total tree biomass was allocated to main stem and large branch, respectively. However, main stem biomass decreased by 1.9% with every 1-cm increase in dbh, but large branch biomass increased by 2.2% instead. Results suggest that dominant Z. serrata trees tend to branch and fork, while smaller trees invest in larger main stem. An early pruning treatment should focus on dominant trees to maintain crown ratio and ensure wood quality.

Models to estimate the above and below ground carbon stocks from a subtropical scrub forest of Pakistan

Despite an increased number of studies on carbon stock estimates from tropical and temperate forests, little information is available for subtropical forests, although they constitute a significant proportion of global forest cover. In this present study, we aimed to assess the above- and below ground biomass allocation strategies and carbon stocks of Acacia modesta and Olea ferruginea, which co-dominate a subtropical dry forest in Pakistan covering approximately 1.6 Mha. This scrub forest has been subjected to mining, overgrazing, and other anthropogenic activities resulting in the loss of trees and habitat degradation. For the assessment of biomass and carbon stock, 11 trees of each species representing the diameter range of 10–52 cm at 1.3 m height were harvested. The harvested A. modesta and O. ferruginea trees showed 80% and 82% of biomass in the above-ground parts and 20% and 18% to below ground parts respectively. We developed power models from the destructive harvest data for both the above- and below-ground biomass components to assess the tree-level carbon. Furthermore, we also estimated the carbon content in the leaves, roots, and shoots of both species by using a carbon analyzer, which ranged from 43.42% to 46.50%. Using the developed models, we found that the total carbon stock was 49.82 t ha−1 in the studied forest with a basal area of 27 m2 ha−1, consisting of 568 trees ha−1. This study provides useful information about the tissue carbon content, on-site models for estimating the above- and below ground biomass and carbon stock in two dominant species from a subtropical dry forest, which can be applied to estimate the carbon stock of forests in arid climate.

Early Selection of Tree Species for Regeneration in Degraded Woodland of Southeastern Congo Basin

Miombo woodland (MW) has several multi-purpose forest species, which are over-exploited for agriculture, charcoal and logging. Industrial plantations are among the promising solutions for sustainable management of MW, but high-yielding MW species are still lacking in the forestry sector. In this context, the present study assessed the growth of MW species, with respect to their early (ES) or late (LS) successional status. Seedling development was assessed for eight tree species, which were ES (Combretum collinum, Pterocarpus tinctorius) and LS (Brachystegia boehmii, B. longifolia, B. spiciformis, B. wangermeana, Julbernardia globiflora, J. paniculata), 1, 2 and 4 years after planting. Germination and survival varied in relation to ontogenetic traits of the species, but not the successional status, as was the case for growth and productivity. Seed germination was 60% to 88% for all species (except C. collinum). Seedling survivorship was greater than 70% for most species, except for J. paniculata (36%). ES species have greater growth compared to LS, due to the allocation of biomass to diameter and the length of the root, respectively, from the early stage of seedling development. These two strategies of biomass allocation are positively correlated with height. We further observed two distinct phases of seedling development (0–2 and 2–4 years) for all species. Growth differences among LS species were identified 4 years after planting. Based on seedling biomass, B. spiciformis, C. collinum and P. tinctorius are the most productive potential candidates for reforestation of degraded MW. We concluded that seedling growth and productivity varied according to strategies of biomass allocation that were related to successional status (ES (Chipya group) versus LS (Miombo group)) and to age following planting.

不同密度猪毛菜形态结构性状及生物量分配策略的异速关系

植物的生长特性随环境条件的变化具有可塑性，而不同的环境因素对植物可塑性的影响也不尽相同。利用异速分析的方法，通过模拟退化草地恢复过程中猪毛菜（Salsola collina）的不同种群密度（16、44、100、400株/m²），研究其形态结构性状及生物量分配策略的异速关系在种群密度间的差异。结果表明，种群密度增大能抑制猪毛菜的生长，而且对猪毛菜的株高、根长、一级分枝数、二级分枝数、三级分枝数以及总分枝长均产生了极显著的影响，表明种群密度的变化使得植物的高生长和侧向生长发生了显著变化。种群密度的变化也引起了植物生物量的变化，其中植物根、茎、叶间的生物关系是一种表观可塑性，植物的生长策略未发生改变，只是植物个体大小发生改变引起的生物量分配的变化。植物株高、总分枝长、一级分枝数及繁殖分配的变化，是由种群密度变化引起的，植物的适应策略发生了改变，是真正的可塑性。种群密度改变了植物的繁殖分配策略，而未改变植物叶的分配策略，说明当环境发生变化时，植物调整了其繁殖策略以适应环境因素的改变，以保证种群的生存繁衍。;Plant growth characteristics have plasticity in response to changes of environmental conditions, and different environmental factors have different effects on plant plasticity. The allometric method was used to analyze the morphological-structural traits and biomass allocation strategies by simulating population densities of S. collina (16, 44, 100 and 400 plants/m²) during the restoration of degraded grassland. The results showed that the increased population density could inhibit the growth of S. collina. population density had significant effects on plant height, root length, primary branch number, second-level branch number, third-level branch number, and total branch length, indicating that population density changes have caused significant changes in vertical and lateral growth of S. collina. Population density changes also influenced on the biomass of plant. The biological relationships between roots, stems, and leaves are an apparent plasticity, and the growth strategy has not changed at all, only the variation of biomass allocation were caused by the change of individual plant size. Changes in plant height, total branch length, primary branch number and reproductive biomass allocation were significantly influenced by population density, representing true plasticity. The results showed that variation of population density caused the strategy change of the reproductive allocation rather than the leaf allocation, indicating that when environment changes, plant would adjust the reproductive strategy to adapt to surrounding environmental factors, to ensure the survival and reproduction of the population.

Morphological, anatomical and photosynthetic consequences of artificial allopolyploidization in Cucumis

Studies have shown that polyploidy has pronounced effects on plants in multiple aspects, including genome structure, gene expression, metabolism and so on, which finally induce changes in phenotype. Many of these changes occurred immediately after polyploidization and retained or lost later. Therefore, it is meaningful for crop breeders to gain knowledge of these changes when it is relatively stable. In this study, we investigated the phenotypes of a highly self-pollinated synthesized allotetraploid in Cucumis, named with Cucumis × hytivus J. F. Chen & J. H. Kirkbr. (C. ×hytivus for short). Results showed that although many phenotypes of C. ×hytivus were intermediate between its parents, total leaf area and cell size exhibited parent-of-origin and dosage effect, respectively. Additionally, C. ×hytivus exhibited divergent biomass allocation strategy compared to the parents, developing more leaves. Beside the commonalities across different polyploid systems, the combination of hybridity and genome duplication in allopolyploids may lead to a diverse possibility of phenotypic changes. In spite of the reduced light absorption by less photosynthetic pigments in young leaves, allopolyploidy caused limited adverse effect on the photosynthesis of C. ×hytivus, which may benefit from the increased leaf thickness and potentially facilitated the survival and speciation of this novel species. The present study offers novel insights into the varied phenotypic effects of polyploidy and is a valuable reference for the crop improvement through polyploidization.

What lies beneath: Predicting seagrass below-ground biomass from above-ground biomass, environmental conditions and seagrass community composition

Seagrass condition, resilience and ecosystem services are affected by the below-ground tissues (BGr) but these are rarely monitored. In this study we compiled historical data across northern Australia to investigate biomass allocation strategies in 13 tropical seagrass species. There was sufficient data to undertake statistical analysis for five species: Cymodocea serrulata, Halophila ovalis, Halodule uninervis, Thalassia hemprichii, and Zostera muelleri. The response of below-ground biomass (BGr) to above-ground biomass (AGr) and other environmental and seagrass community composition predictor variables were assessed using Generalized Linear Models. Environmental data included: region, season, sediment type, water depth, proximity to land-based sources of pollution, and a light stress index. Seagrass community data included: species diversity and dominant species class (colonising, opportunistic or persistant) based on biomass. The predictor variables explained 84–97% of variance in BGr on the log-scale depending on the species. Multi-species meadows showed a greater investment into BGr than mono-specific meadows and when dominated by opportunistic or persistent seagrass species. This greater investment into BGr is likely to enhance their resistance to disturbances if carbohydrate storage reserves also increase with biomass. Region was very important for the estimation of BGr from AGr in four species (not in C. serrulata). No temporally changing environmental features were included in the models, therefore, they cannot be used to predict local-scale responses of BGr to environmental change. We used a case study for Cairns Harbour to predict BGr by applying the models to AGr measured at 362 sites in 2017. This case study demonstrates how the model can be used to estimate BGr when only AGr is measured. However, the general approach can be applied broadly with suitable calibration data for model development providing a more complete assessment of seagrass resources and their potential to provide ecosystem services.

Biomass allocation strategies and Pb-enrichment characteristics of six dwarf bamboos under soil Pb stress

Dwarf bamboos are clonal plants with potential applications in the remediation of heavy metal-polluted soils, although their pollution adaptation strategies are unknown. This study examined the biomass allocation strategies and lead (Pb) enrichment characteristics of various dwarf bamboo tissues by the end of the growing season and explored their potential for phytoremediation of Pb stress in the soils. Six dwarf bamboo genotypes were treated with three levels (0, 300, and 1500 mg kg–1) of soil Pb stress. The majority of the bamboos adopted two biomass allocation strategies to adapt to Pb stress, namely, “reducing biomass allocation into new bamboo growth” and “increasing/stabilizing biomass allocation into rhizomes”. Pb accumulation was highest in the roots, rhizomes, and old stems and showed the following trend: rhizomes/old stems> new roots/old roots> old leaves> new leaves> new stems among various tissues. Moreover, the six bamboos used three different Pb-enrichment strategies, as follows: (i) “rhizome domination and old stem synergy” (Sasaella glabra (Nakai) f. albo-striata Muroi, Sasa auricoma (Mitford) E.G. Camus, Sasa fortunei (Van Houtte) Fiori, and Shibataea lanceifolia C.H. Hu); (ii) “old stem domination and rhizome synergy” (Indocalamus decorus Q.H. Dai); and (iii) “old stem domination and new root synergy” (Sasa argenteostriata (Regel) E.G. Camus). In Pb-contaminated soils, genotypes with TFs greater than 1 were Sasa fortunei (Van Houtte) Fiori, Sasa argenteostriata (Regel) E.G. Camus, and Indocalamus decorus Q.H. Dai; in addition, only S. argenteostriata had BCF values greater than 1. Furthermore, this study provides the first evidence that S. argenteostriata can extract 0.22 and 0.58 mgplant−1 of Pb ions in soil polluted with 300 and 1500 mg kg−1 Pb, respectively. S. argenteostriata showed the greatest potential for phytoremediation among the bamboo genotypes in both Pb-contaminated urban and mining sites.

Nitrogen application mitigates drought-induced metabolic changes in Alhagi sparsifolia seedlings by regulating nutrient and biomass allocation patterns

Groundwater and its associated nutrients sustain the establishment and persistence of phreatophytes. Rapid root elongation immediately after germination is vital for desert species to access deep water sources to avoid water-deficit stress. However, the growth strategy and responses to nutrients and water of young phreatophyte seedlings before their roots reach the water table are poorly understood, especially in the scenarios of nitrogen (N) deposition and drought. We investigated how simulated N deposition and drought affect the plasticity of Alhagi sparsifolia seedlings by multiple eco-physiological mechanisms. Seedlings were planted under drought-stressed or well-watered conditions and subjected to various levels of N addition (0, 3.0, 6.0, or 9.0 gN·m−2 yr−1). The amounts of N and water independently or interactively affected the photosynthetic traits, drought tolerance characteristics, morphological traits, biomass allocation strategy, and nutrient distribution patterns among the plant organs. Moreover, changes mediated by N addition at the leaf level reflected the drought acclimation of the seedlings, which may be related to biomass and nutrient partitioning between organs. The roots were found to be more sensitive to variation of the N:phosphorus (P) ratio, and greater proportions of biomass, N, and P were allocated to resource-acquiring organs (i.e., leaves and fine roots) than to other tissues. A. sparsifolia adopts numerous strategies to tolerate drought, and additional N input was crucial to enhance the growth of drought-stressed A. sparsifolia, which was mainly attributable to its positive impact on the N and P uptake capacity mediated by increased biomass allocation to the roots.

The impacts of warming and nitrogen addition on competitive ability of native and invasive populations of Plantago virginica

Abstract Aims Global change factors (e.g. warming and nitrogen deposition) may influence biological invasions, but how these factors may influence the performance of invasive species and further mediate the interactions with native competitors remain still unknown. Methods Here, we conducted a 5-month greenhouse experiment to examine the effects of warming (using open-top chambers, +0.62°C) and N addition (adding NH4NO3 at a rate of 4.2 g m−2) on the performance of the native and invasive populations of an invasive species Plantago virginica in competition with a native Plantago asiatica. Important Findings Under warming treatment and its interaction with nitrogen addition treatment (W × N), invasive and native populations of P. virginica had different biomass allocation strategies to compete with native competitor P. asiatica. Native population of P. virginica (PV-Na) increased more below-ground biomass, whereas those from the invasive population (PV-In) increased more above-ground biomass. We also found that invasive species P. virginica had stronger responses to warming and N addition than the native species P. asiatica. The competitive ability of the invasive plants was significantly reduced by warming which indicated that the invasive plant were much stronger sensitivity to elevated temperature than native plant. Similarly, N addition and W × N reduced the competitive response of PV-In in below-ground biomass, but increased the competitive response of PV-Na in above-ground and total biomass when they grew with the P. asiatica. The results show that P. virginica have occurred differential biomass allocation strategies during its invasions and invasive population exhibit flexible competition ability to adapt to environmental changes (especially warming). These findings may potentially help to predict plant invasions and make management strategies in a world with changing climate.

Traits controlling shade tolerance in tropical montane trees.

Tropical canopies are complex, with multiple canopy layers and pronounced gap dynamics contributing to their high species diversity and productivity. An important reason for this complexity is the large variation in shade tolerance among different tree species. At present, we lack a clear understanding of which plant traits control this variation, e.g., regarding the relative contributions of whole-plant versus leaf traits or structural versus physiological traits. We investigated a broad range of traits in six tropical montane rainforest tree species with different degrees of shade tolerance, grown under three different radiation regimes (under the open sky or beneath sparse or dense canopies). The two distinct shade-tolerant species had higher fractional biomass in leaves and branches while shade-intolerant species invested more into stems, and these differences were greater under low radiation. Leaf respiration and photosynthetic light compensation point did not vary with species shade tolerance, regardless of radiation regime. Leaf temperatures in open plots were markedly higher in shade-tolerant species due to their low transpiration rates and large leaf sizes. Our results suggest that interspecific variation in shade tolerance of tropical montane trees is controlled by species differences in whole-plant biomass allocation strategy rather than by difference in physiological leaf traits determining leaf carbon balance at low radiation.