Tropical dry forests (TDF) are one of the most threatened and poorly protected ecosystems in the Americas. Although there are international efforts for the restoration of TDF, how stress factors such as herbivory or water limitation due to changes in precipitation, impact the regeneration dynamics of these forests is poorly understood. Specifically, how seedlings of key tree species for TDF restoration cope with current abiotic pressures such as the intensification of climatic events, and biotic factors like herbivory, is not yet fully understood. Here, we compared seedling performance, and allocation of biomass, and water to roots vs. shoots for three legume, and one non-legume TDF tree species, as a response to water limitation and herbivory in an 8-month greenhouse experiment. Contrary to our expectations, we found that the non-legume species, G. ulmifolia, had the best performance compared to legumes, while N-fixing and non-fixing legumes showed similar performance. Based on our findings, we suggest the use of G. ulmifolia in TDF restoration projects due to its high performance despite abiotic and biotic stress factors, its allocation of biomass and water to belowground structures. We also recommend the use of N-fixing legume species owing to their ability to fix nitrogen, which guarantees an N input to the soil, important in the first stages of succession. However, the legume species used in this experiment do not appear to resist the abiotic and biotic stressors studied. Thus, more studies exploring the response of dry forest plant species to stress factors are key for informing and assuring more effective TDF restoration efforts.

Differential tree seedling recruitment across forest-savanna ecotones is poorly understood, but hypothesized to be influenced by vegetation cover and associated factors. In a 3-y-long field transplant experiment in the forest-savanna ecotone of Ghana, we assessed performance and root allocation of 864 seedlings for two forest (Khaya ivorensis and Terminalia superba) and two savanna (Khaya senegalensis and Terminalia macroptera) species in savanna woodland, closed-woodland and forest. Herbaceous vegetation biomass was significantly higher in savanna woodland (1.0 ± 0.4 kg m−2 vs 0.2 ± 0.1 kg m−2 in forest) and hence expected fire intensities, while some soil properties were improved in forest. Regardless, seedling survival declined significantly in the first-year dry-season for all species with huge declines for the forest species (50% vs 6% for Khaya and 16% vs 2% for Terminalia) by year 2. After 3 y, only savanna species survived in savanna woodland. However, best performance for savanna Khaya was in forest, but in savanna woodland for savanna Terminalia which also had the highest biomass fraction (0.8 ± 0.1 g g−1 vs 0.6 ± 0.1 g g−1 and 0.4 ± 0.1 g g−1) and starch concentration (27% ± 10% vs 15% ± 7% and 10% ± 4%) in roots relative to savanna and forest Khaya respectively. Our results demonstrate that tree cover variation has species-specific effects on tree seedling recruitment which is related to root storage functions.

Field horsetail was grown from rhizome segments for 28 and 52 d under 35, 60, 120, 170, and 320 μmol m–2 s–1 photosynthetic photon flux (PPF) and four continuous nitrogen (N) supply rates corresponding to a total of 1 to 6 kg N ha–1 28 d after planting (DAP) and 6 to 41 kg N ha–1 52 DAP. There was no response to the supply of N in the first growth period, probably due to the mobilization of nitrogen available in the planted rhizomes, and only dry weight (DW) of new belowground production, mostly roots, responded to increased light. Rhizomes were produced during the latter part of the 52-d period. Requirements for light and N during the 52-d period were low, because total new tissue production was only reduced at the lowest levels of light (35 μmol m–2 s–1 PPF) and the two lowest N supply rates (6 and 18 kg N ha–1). The ratio of shoot DW to belowground organ DW increased only as the N supply increased. Shoot height response to an increased N supply was also small. Field horsetail can therefore be considered tolerant of low levels of N but will be overtopped by fast-growing species when competing for increased supplies of N. Both an increase in N supply and a reduction in light increased the reduction of DW of the planted rhizomes, whereas tuber production was favored by low N supply and high light intensities. Field horsetail can tolerate low levels of N but is not likely to be competitive in a dense crop stand.

Field horsetail shoots were severed from the rhizomes and grown hydroponically with and without shade (40 and 190 μmol m–2 s–1 photosynthetic photon flux) under six different nutrient regimes, by using nutrient solutions with different amounts of nitrogen (N) and potassium (K) (6/42 mmol L–1 N; 7/15/24 mmol L–1 K). Nutrients were supplied daily with the same volumes for the six different nutrient solutions at exponentially increasing rates corresponding to a maximum relative growth rate (RGR) of 12.5% from days 0 to 31 and 6% from days 32 to 48. RGR was calculated for the highest N and K rate. Photosynthetic rate and stomatal conductance to water vapor were determined on day 48, then the plants were harvested. The fresh weight (FW) and dry weight (DW) of different plant components were determined. Shade completely inhibited growth of tubers and fertile shoots and drastically reduced RGR, average aerial shoot height, and DW of shoots and rhizomes. N supplied at the high rate to unshaded plants increased the growth of all parts or the plant except fertile shoots and tubers. No effects of K were detected at the low N rate, whereas at the high N rate, K significantly increased total DW and belowsurface DW. RGR never exceeded 10% d–1. In the unshaded treatments, the K concentration was higher in aerial shoots, 150 to 240 μmol g–1 FW, than in belowsurface organs, 30 to 90 μmol g–1 FW. Shoot growth was significantly reduced at shoot K concentrations below 150 to 210 μmol g–1 FW, and root growth was significantly reduced at root K concentrations below 30 to 50 μmol g–1 FW. K significantly increased maximum net photosynthetic rate, 10 μmol CO2 m–2 s–1, at light saturation, 1,300 μmol m–2 s–1, in unshaded plants, whereas it reduced the light compensation point and respiratory losses of CO2 in darkness. It is concluded that field horsetail is a typical sunny habitat species with a rather high K demand.

The development of optimal weed management strategies that rely, in part, on crop interference will require an understanding of how weeds compensate for limitations in above- and belowground resources. Trade-offs in the leaf morphology and biomass partitioning of rice and late watergrass were investigated under glasshouse conditions in 1999 and 2000. Both species responded to shade with increased height, reduced biomass, greater partitioning of biomass to leaves, and greater leaf area ratios. At the lowest light level (18% sunlight), plants of both species showed little response to nitrogen (N). However, height, tillers, biomass, and leaf area increased for plants grown at 50% and full sunlight as N increased from 0 to 224 kg N ha−1. Late watergrass exhibited more plasticity in specific leaf area and root weight ratio than rice in response to shade. This plasticity contributed to the ability of late watergrass to maintain a higher percent of its tillers and total dry weight than rice when sunlight was reduced by 50%. These results support the hypothesis that except at low light levels, limited N further reduces the growth of shaded late watergrass plants. Thus, weed management strategies that limit the plasticity of late watergrass by manipulating light and N availability are likely to be more effective than strategies that rely on manipulating a single resource.

Twenty-day cohorts of corn poppy were grown in the presence or absence of barley, and seedling survival, biomass accumulation and allocation, plant reproduction, and seed dormancy were measured. Seedling survivorship and biomass accumulation differed strongly among cohorts and were influenced by crop competition. In the absence of crop competition, plants from the first three cohorts (emerging October to January) had 900% higher biomass and 160% more seeds per plant than later cohorts (emerging January to April). Crop competition reduced cohort fitness; for example, in 2003 to 2004, corn poppy biomass was reduced 57 to 96%, and seed production 77 to 97%. Seeds collected from plants that had emerged in spring were less dormant, and thus, germination and emergence of these seeds were higher (25% higher and 200 to 600% higher, respectively) than those for seeds collected from other cohorts. Environmental factors at the time of seed formation may be responsible for the observed differences in dormancy. Cohort-dependent emergence, growth, reproduction, and dormancy have relevant implications for corn poppy management and demography in agricultural systems in northeastern Spain. The dormant seeds produced by autumn to winter cohorts will be the main contributors to the seed bank and weed population shift in subsequent generations. For efficient corn poppy management, the control of cohorts emerging before or with the crop in a cereal field is essential.

The Asian grass Miscanthus sinensis (Poaceae) is being considered for use as a bioenergy crop in the U.S. Corn Belt. Originally introduced to the United States for ornamental plantings, it escaped, forming invasive populations. The concern is that naturalized M. sinensis populations have evolved shade tolerance. We tested the hypothesis that seedlings from within the invasive U.S. range of M. sinensis would display traits associated with shade tolerance, namely increased area for light capture and phenotypic plasticity, compared with seedlings from the native Japanese populations. In a common garden experiment, seedlings of 80 half-sib maternal lines were grown from the native range (Japan) and 60 half-sib maternal lines from the invasive range (U.S.) under four light levels. Seedling leaf area, leaf size, growth, and biomass allocation were measured on the resulting seedlings after 12 wk. Seedlings from both regions responded strongly to the light gradient. High light conditions resulted in seedlings with greater leaf area, larger leaves, and a shift to greater belowground biomass investment, compared with shaded seedlings. Japanese seedlings produced more biomass and total leaf area than U.S. seedlings across all light levels. Generally, U.S. and Japanese seedlings allocated a similar amount of biomass to foliage and equal leaf area per leaf mass. Subtle differences in light response by region were observed for total leaf area, mass, growth, and leaf size. U.S. seedlings had slightly higher plasticity for total mass and leaf area but lower plasticity for measures of biomass allocation and leaf traits compared with Japanese seedlings. Our results do not provide general support for the hypothesis of increased M. sinensis shade tolerance within its introduced U.S. range compared with native Japanese populations.

The Detroit Lakes chain of lakes consists of five basins in northwest Minnesota adjacent to the town of Detroit Lakes. Flowering rush has been established in these basins since the 1960s. We evaluated the distribution of flowering rush in the five basins using a point intercept method, with 830 points distributed in a grid with points 150 m apart. These data were analyzed to determine whether invasive and native species frequencies were different between 2010 and 2011. We also assessed co-occurrence of flowering rush with native hardstem bulrush. The distribution of both flowering rush and hardstem bulrush was unchanged from 2010 to 2011. Flowering rush is invading areas with native plants and not establishing in unvegetated areas. Although flowering rush is found as deep as 4.5 m, it is most frequent at a depth of 1.3 m. We also examined the distribution of biomass and growth across a depth gradient from 0.3 to 3.0 m in 0.3-m intervals. At each 0.3-m interval, three biomass samples were collected at each of 10 transects for a total of 30 samples per depth interval or 300 biomass samples. At each point, leaf height, emergent leaf height, water depth, number of ramets, and number of rhizome buds were counted. Biomass samples were collected in a 0.018-m2 core sampler, sorted to shoots and belowground biomass. We found that flowering rush height and biomass peaked at 1.3 m and declined with greater depth. Bud density was negatively related to water depth. Bud density averaged 300 buds m–2, which was three times the average ramet density (100 ramets m–2).

Sheep sorrel is an invasive, creeping perennial weed of lowbush blueberry fields that decreases yields and hinders harvest. Much of the basic phenology of sheep sorrel in blueberry fields is unknown and not documented in peer-reviewed journals. Three levels of fertilizer (0, 20, and 40 kg N ha−1) and two levels of hexazinone (0 and 1.92 kg ai ha−1) were applied to three vegetative-year blueberry fields to determine their effects on root and shoot growth, biomass allocation, and seed production of sheep sorrel plants. Hexazinone efficacy varied widely between sites, but suppressed shoot biomass, achene number and weight, and reproductive biomass, as well as the reproductive : shoot biomass ratio. Fertilizer tended to increase achene number and increased sheep sorrel shoot biomass in the absence of hexazinone, but had no effect on achene weight, root biomass, or reproductive biomass. When fertilizer was applied, sheep sorrel allocated resources to sexual reproduction at the expense of vegetative growth.

Some species-rich secondary forests in New Caledonia have a monodominant canopy. Here we investigate growth and biomass allocation traits that might explain single-species’ dominance of these post-disturbance stands, and their later decline in the absence of large-scale disturbance. Seedlings of 20 rain-forest trees were grown in two light treatments in a nursery house. In the sun treatment, monodominants grew faster (56.7 ± 1.4 mg g−1 wk−1) than subordinates (40.2 ± 2.6 mg g−1 wk−1). However, some episodically regenerating (ER) subordinates had high growth rates similar to those of monodominants. In the shade treatment, monodominants and subordinates had similar growth rates (33.7 ± 2.6 and 34.0 ± 1.9 mg g−1 wk−1 respectively). Notably, monodominants in both sun and shade treatments had lower root mass fraction (0.29 ± 0.02 and 0.27 ± 0.02 g g−1 respectively) than subordinates (0.39 ± 0.02 and 0.37 ± 0.02 g g−1). Fast growth in sunny conditions is probably imperative for these relatively shade-intolerant ER monodominants. In field conditions, high shoot mass fraction combined with efficient root performance may facilitate faster growth in monodominants competing with other ER species in sunlit sites. Slower growth in shade may contribute to loss of dominance over time in undisturbed forests.

In this study, we tested the hypothesis that functional traits associated with nutrient impoverishment contribute to enhancing shade-tolerance (survival at low light) for the juveniles of canopy tree species in Bornean rain forests. To test the hypothesis, survival and functional traits (biomass allocation, leaf dynamics and foliar nutrient concentration) were investigated as a function of light conditions for saplings of 13 species in three forests with different levels of nutrient availability. As predicted by the hypothesis, the species in the severely nutrient-poor site (a tropical heath forest on nutrient-poor soils) showed greater shade-tolerance (>91% survival for 8 mo at 5% global site factor) than in the other two sites (mixed dipterocarp forests) (54–87% survival). Across the species, greater shade-tolerance was associated with a higher biomass allocation to roots, a slower leaf production and a higher foliar C concentration, which are considered as C-conservation traits under nutrient impoverishment. These results suggest that the juveniles of the canopy species occurring on nutrient-poor soils can enhance shade-tolerance by the same mechanisms as the adaptation to nutrient impoverishments. Tree species in nutrient-poor environments may be selected for surviving also in shaded conditions.

We performed a pot experiment in which 540 seedlings of nine non-pioneer light-demanding tree species were grown for 12 months in shade houses at three light levels, 46% daylight, 13% daylight and 2% daylight, to examine the mechanisms contributing to the coexistence of seedlings of non-pioneer light-demanding tree species in secondary successional tropical rain forest in Hainan, China. Growth and survival of tree seedlings were compared at different light levels, and the morphological and physiological correlates of high-light seedling growth and low-light survival across species were determined. For all species, mortality was very low in the 46% daylight and 13% daylight treatment but increased significantly in the 2% daylight treatment. Seedling survival in 2% daylight treatment was positively related to seed mass. Trade-off between high-light growth and low-light survival was more evident in the relationship with 2% daylight treatment as compared with 13% daylight treatment. Relative growth rate in the 2% daylight treatment was not significantly related to relative growth rate in the 13% daylight or 46% daylight treatment; although a slight negative correlation was apparent. Interspecific variation in RGRm was only closely correlated with net assimilation rate (NAR). The results provide some support for the niche-partitioning hypothesis.

Precise estimation of root biomass is important for understanding carbon stocks and dynamics in tropical rain forests. However, limited information is available on individual root masses, especially large trees. We excavated 121 root systems of various species (78) and sizes (up to 116 cm in dbh), and estimated both above- and below-ground biomass in a lowland primary dipterocarp forest in the Pasoh Forest Reserve, Peninsular Malaysia. A tree census was conducted in four research plots (each 0.2 ha) and stand-level biomass was estimated. We examined relationships between tree size parameters and masses of coarse roots (roots ≥5 mm in diameter) and derived a dbh-based allometric equation. The amounts of coarse roots that were lost during excavation were corrected. Coarse-root biomass before and after correction for lost roots was estimated to be 63.8 and 82.7 Mg ha−1, indicating that significant amounts of roots (23%) were lost during the sampling. We also estimated the biomass of small root (<5 mm) by applying pipe-model theory. The estimate, 13.3 Mg ha−1, was similar to another estimate of small roots, 16.4 Mg ha−1, which was obtained directly by the soil-pit sampling method. Total below-ground (BGB) and above-ground biomass (AGB) was estimated to be 95.9 and 536 Mg ha−1, respectively. The biomass-partitioning ratio (BGB/AGB) was about 0.18. In conclusion, the dbh-based allometric equation for coarse roots developed in this study, which kept good linearity even including the data of larger trees, might be useful for evaluating below-ground carbon stocks in other stands of similar forest (old-growth dipterocarp) in South-East Asia.

A comparison is made of the light acclimation potential of seedlings of three canopy species of the tropical rain forest of Los Tuxtlas, Mexico: Cordia megalantha, Lonchocarpus guatemalensis, and Omphalea oleifera. These species showed similar growth rates in a range of microhabitats. Gap dynamics were simulated by transferring plants between three environments: beneath a closed canopy, a small gap, and a large gap. Plants of all three species were able to adjust their morphology and growth rates in response to changes in light availability. Growth rates increased when plants were moved to a (larger) gap, and decreased when plants were moved to a more shaded environment. Shade-grown plants were able to acclimate faster to increasing light availability than sun-grown plants to decreasing light availability. Also, plants moved from shady to sunny conditions showed higher relative growth rates than sun control plants, whereas sun-grown plants when moved to the shade showed lower relative growth rates than shade control plants. Species differed in their response to gap dynamics. Omphalea could not acclimate morphologically to shading, but reacted faster than the other species in response to the occurrence of a large gap. Acclimation potential seemed to be related to plasticity in physiological rather than in morphological traits. Suppressed seedlings of all three species performed well in the shade, and were able to acclimate rapidly to gap-conditions.

Twelve native woody species were studied to investigate the influences of soil fertility and root morphology on colonization by arbuscular mycorrhizal (AM) fungi during seedling establishment and growth. Seedlings were grown in soils of low and high natural fertility, uninoculated or inoculated with AM fungi, under greenhouse conditions. The mycorrhizal root colonization and plant responsiveness were higher among early successional species than late successional ones. Among early successional species, in both soils, mycorrhizal colonization provided significant increase in total dry mass, growth rates of shoot and root, root length, density of root tissues, root surface area and P concentration and content in the shoot. Early successional species grown with AM fungi displayed significant decreases in carbon allocation to roots, specific root length and the length and incidence of root hairs. Mycorrhizal colonization did not affect the root morphology of the late successional species in either soil. The growth of these woody species was influenced by differences in soil fertility. There was positive correlation between the degree of plant responses to AM inoculation with the percentage of root colonized by AM fungi. In both soils, plant responsiveness and mycorrhizal root colonization correlated positively to root-hair incidence and root-hair length and correlated negatively to fine-root diameter. The results suggest that during the establishment of seedlings, the large responses to the inoculation and colonization of roots by AM fungi are related to both the successional status and root morphological plasticity of the host plant, regardless of soil fertility.

Although the potential contribution to tropical tree species coexistence of niche differentiation along light gradients has received much attention, the degree to which species perform differentially along soil resource gradients remains unclear. To examine differential growth response to soil resources, we grew seedlings of nine tropical tree species at 6.0% of full sun for 12 mo in a factorial design of two soil types (clay and white sand), two phosphate fertilization treatments (control and addition of 100 mg P kg−1) and two watering treatments (field capacity and water limitation to one-third field capacity). Species differed markedly in biomass growth rate, but this hierarchy was almost completely conserved across all eight treatments. All species grew more slowly in sand than clay soils, and no species grew faster with phosphate additions. Only Eperua grandiflora and E. falcata showed significant growth increases in the absence of water limitation. Faster-growing species were characterized by high specific leaf area, high leaf allocation and high net assimilation rate but not lower root allocation. Slower-growing species exhibited greater plasticity in net assimilation rate, suggesting that tolerance of edaphic stress in these species is related more to stomatal control than to whole-plant carbon allocation. Although relative growth rate for biomass was correlated with both its physiological and morphological components, interspecific differences were best explained by differences in net assimilation rate across six of the eight treatments. A suite of traits including high assimilation and high specific leaf area maintains rapid growth rate of faster-growing species across a wide gradient of soil resources, but the lack of plasticity they exhibit may compromise their survival in the poorest soil environments.

The study of size and its biological consequences – called allometry – has fascinated biologists for centuries. Recent advances in this area of study have stimulated a renewed interest in these scaling phenomena, especially in terms of the search for mechanistic explanations that transcend mere descriptive phenomenology. These advances are reviewed in the context of plant biology. Allometric derivations are presented that predict how annual growth in total body biomass is partitioned to construct new leaf, stem, and root tissues at the level of an individual plant. Derivations are also presented to predict annual reproductive effort and to predict how the biomass of body parts changes as a function of the number of plants per unit area in communities. The predictions emerging from these derivations are then examined empirically by comparing predicted and observed scaling exponents for each relationship using a world-wide data compendium gathered from the primary literature. These comparisons provide strong statistical support for each of the allometric predictions. This support is taken as evidence that a general unifying allometric theory for plant biology is near at hand. Nevertheless, the validation of this theory requires much additional work and raises a number of procedural and conceptual concerns that must be resolved before a single ‘global’ theory is accepted.

Predictions of root architecture have been tested using only a narrow set of environmental conditions and species. There is little information on root architecture of plants growing on semi-arid grasslands where soil nutrient heterogeneity and defoliation might impose particular restrictions on root growth. We conducted a split-root study to evaluate the effect of nonuniform nutrient supply and clipping on root architecture and biomass allocation of three range grasses found in the Intermountain West of the USA: ‘Whitmar’, a cultivar of Pseudoroegneria spicata, Bromus tectorum (cheatgrass), and ‘Hycrest’, a hybrid between Agropyron desertorum and A. cristatum. Root systems of individual seedlings were equally divided between the two divisions of a partitioned 10-l pot, and each of the divisions was independently supplied with ‘high or ‘low’ nutrient solution. Plants were either clipped or not. Characteristics of root architecture (topology and link length), root size (root length and number of root tips), and biomass distribution (specific root length and root mass[ratio ]root volume ratio) were evaluated. Root topology (branching distribution) changed with nutrient treatments and defoliation in all three species. Length of links (a segment of root between two branches, or between a node and a root tip) responded to nutrient treatment only in defoliated plants of ‘Whitmar’, in which relative growth rate was associated with changes in architectural traits (external–external and internal–internal link length), while biomass accumulation and relative growth rate in cheatgrass and ‘Hycrest’ maintained allometric relationships with root length. Our results suggest that large plasticity in root architecture, together with inherently low relative growth rate are adaptations that allow ‘Whitmar’ to grow well in heterogeneous and poor soil-nutrient conditions. Cheatgrass and ‘Hycrest’ exhibited characteristics suggesting capability for rapid exploitation of nutrient patches.

Floerkea proserpinacoides (Limnanthaceae) is a spring ephemeral annual species that grows in deciduous forests throughout eastern North America. Seeds germinate from late November to December, although the first leaf emerges only from late March to early April. Growth begins in early April at the onset of favourable temperatures, following snowmelt, and continues through mid-June. Senescence coincides with increasing air temperature and decreasing light level as a result of canopy closure. In this paper, we present the results of a growth chamber study designed to determine the effect of light level on growth, biomass allocation and reproduction of F. proserpinacoides. The study consists of two parts: in a first experiment, plants were grown at five constant photosynthetic photon fluence rates (PPFR: 90, 180, 360, 540 or 900 μmol m−2 s−1), and in a second experiment, PPFR was reduced from 900 μmol m−2 s−1 to 180 μmol m−2 s−1 after 0, 14, 21, 28 or 35 d of growth. Relative humidity, temperature, nutrient and water supply were kept constant in a hydroponic sand culture experiment. Total biomass, leaf mass and leaf area increased with increasing PPFR up to 540 μmol m−2 s−1. Plants grown at the highest (900 μmol m−2 s−1) and the lowest (90 μmol m−2 s−1) PPFR had a substantially lower biomass by the end of the 35-d growth period than plants grown at intermediate PPFRs (360 or 540 μmol m−2 s−1). Despite differences in total biomass, there were no significant differences in seed production among treatments. The mean relative growth rate (RGR) increased with increasing light levels between 90–540 μmol m−2 s−1, and it was reduced at 900 μmol m−2 s−1. However, differences in RGR were not significant among treatments. Specific leaf area did not vary consistently as a function of light level, whereas leaf area ratio and leaf mass ratio tended to increase with increasing PPFR, reaching maximum values at 360–540 μmol m−2 s−1. However, none of these growth variables differed significantly across the range of PPFR levels. The transfer of plants to lower PPFR had no significant effect on any of the growth components. Biomass production for the species appeared to be optimized at PPFR of 360–540 μmol m−2 s−1. Growth might be restricted by an insufficient supply of photosynthates at low PPFR and by photoinhibitory processes at higher PPFRs.

This paper analyses relationships between relative growth rate (rgr), seed mass, biomass allocation, photosynthetic rate and other plant traits as well as habitat factors (rainfall and altitude) in 20 wild species of Aegilops L. and one closely related species of Amblyopyrum (Jaub. & Spach) Eig., which differ in ploidy level (diploid, tetraploid and hexaploid). The plants were grown hydroponically for 20 d in a growth chamber. The relationships between parameters were calculated either using the phylogenetic information (phylogenetically independent contrasts, PIC) or without using the phylogenetic information (trait values of taxa, TIP). The results using the two approaches were very similar, but there were a few exceptions in which the results were different (e.g. rgr vs. seed mass). Specific leaf area (sla) was positively correlated with leaf area ratio (lar) and negatively correlated with net assimilation rate (nar), which together resulted in the absence of a correlation between sla and rgr. Leaf photosynthetic rates (expressed on a mass or area basis) showed no correlation with rgr. rgr was positively correlated with the stem mass ratio and negatively with root mass ratio. Species with a lower d. wt percentage have a higher rgr. Aegilops species from locations with higher annual rainfall invested less biomass in roots and more in shoots (leaves and stems) and had a higher rgr. Diploid species had a lower seed mass and initial mass than the hybrids (tetraploid and hexaploid species), but there was no correlation of rgr with ploidy level. Polyploid species, which have higher seed mass, occur at a higher altitude than diploid species. Our results show that variation in rgr in Aegilops and Amblyopyrum spp. is associated mainly with variation in biomass allocation (proportion of biomass in stems and roots) and d. wt percentage, and not with variation in sla, leaf photosynthetic rates or seed mass.