Southern Ecotypes Research Articles

Photosynthetic responses to temperature-mediated dormancy induction in contrasting ecotypes of red-osier dogwood (Cornus sericea L.)

Dormancy development in plants is synchronized with the cessation of environmental conditions that favour plant growth. The timing of this response is important in trees for growth and survival. Woody plants, such as dogwood (Cornus sericea L.) have evolved different ecotypes that are closely adapted to local climatic conditions, which are differentiated by irradiance, photoperiod and/or temperature. While short photoperiods are well known to play a key role in dormancy induction in northern ecotypes, low temperatures alone can by-pass the photoperiodic requirement. It is well established that the combination of low temperature and even low to moderate light intensities predispose plants to photoinhibition of photosynthesis. However, plants possess numerous photoprotective mechanisms to minimize photoinhibition including increased rates of photosynthesis as well as non-photochemical dissipation of excess excitation energy, a process involving xanthophyll cycle carotenoids. We used two ecotypes of dogwood, the northern ecotype of Northwest Territories (NWT 62°N latitude) and the southern Utah, U.S.A. (42°N latitude) ecotype, which exhibit differential responses to photoperiodic- and temperature-induced dormancy. These ecotypes were exposed to various combinations of photoperiod and low temperature treatments and monitored for photosynthetic and photoprotective processes as the plants entered dormancy. Our results demonstrate differential long- and short-term responses to photoinhibition at low temperatures between the two ecotypes. The northern ecotype was more tolerant to photoinhibition of photosynthesis than the southern ecotype potentially through a zeaxanthin-independent mechanism of photoprotection. Furthermore, anthocyanin accumulation may be involved in the LD-Cold treatment through putative sugar sensing mechanisms to trigger dormancy.

Ecotypes of European grass species respond differently to warming and extreme drought

Summary 1. Climate extremes are expected to increase in frequency and magnitude as a consequence of global warming. 2. Managed permanent grasslands cover a large surface in Europe and contribute substantially to agricultural production. These managed plant communities are dominated by perennial clonal species. Their capacity to adapt to rapidly changing environmental conditions may be limited. 3. We hypothesize that those plant populations that have already been exposed to conditions that are expected to occur due to future climate change, particularly conditions that would be ‘extreme’ in the target area, are able to cope better with these conditions. 4. For a common‐garden experiment we selected ecotypes (provenances as supported by accessions in seed banks) of important European grass species: Arrhenatherum elatius, Festuca pratensis, Holcus lanatus and Alopecurus pratensis. Southern target locations of ecotypes (populations) were identified based on climate model projections for the local site in Northern Bavaria, Germany. 5. In a controlled experiment, the plants were exposed to warming and extreme drought. Drought conditions(16–19 days, depending on the species) were imposed starting from the end of May in combination with and without an increase in the average temperature from May to September 2009 (+1.5 K compared with control; +2.5 K compared with ambient conditions outside of the experimental units). 6. Ecotypes and drought manipulation had significant impacts on biomass production and tissue die‐back. Significant interactions between ecotype and drought indicated a different drought tolerance of the ecotypes in some cases. The warming treatment yielded a less significant response. The local ecotype generally did not perform significantly worse than the presumably better‐adapted southern ecotypes. 7. Synthesis. The selection of ecotypes that are adapted to more extreme climatic conditions could be an option for maintaining future ecosystem functioning in temperate managed grasslands, as was indicated by the clear differences between ecotypes in our experiment. Based on our data, however, performance cannot be predicted from climatic origin. Therefore, we recommend enhancing the genetic variability within populations of species in general.

Seed Germination of Habenaria repens (Orchidaceae) in situ Beyond its Range, and its Potential for Assisted Migration Imposed by Climate Change

All orchids require free-living, mycorrhizal fungi to complete their life cycles in nature and consequently, orchid conservation must take into account both organisms. In light of climate change now underway, orchids and other plants must be capable of migrating to higher latitudes, either on their own or with human intervention ( = assisted migration). In this paper, we describe the symbiotic germination of a common terrestrial orchid, Habenaria repens, in situ using seeds from a southern ecotype (Florida) placed at latitudes at and above the species' current natural range. To recover fungi in situ, 500 nylon packets containing 25,000–50,000 seeds were buried at 5 field sites within the Atlantic coastal plain in North Carolina, Maryland, and Virginia. After ca. 5 months, a total of 10 leafless seedlings (protocorms) were recovered from two North Carolina sites, one harboring an extant H. repens population, the other an extirpated population. These protocorms yielded mycorrhizal fungi assignable to the anamorphic genus Epulorhiza. The physiological significance of each isolate was confirmed after H. repens seeds germinated in vitro following fungal inoculation ( = symbiotic germination). This study demonstrates that seeds of H. repens from a southern ecotype (Florida) are indeed capable of germinating at higher latitudes where fungi already persist. Consequently, the mycotrophic demands of orchids like H. repens might be met by assisted migration involving seed release alone.

Seasonal Adaptations to Day Length in Ecotypes ofDiorhabdaspp. (Coleoptera: Chrysomelidae) Inform Selection of Agents Against Saltcedars (Tamarixspp.)

Seasonal adaptations to daylength often limit the effective range of insects used in biological control of weeds. The leaf beetle Diorhabda carinulata (Desbrochers) was introduced into North America from Fukang, China (latitude 44° N) to control saltcedars (Tamarix spp.), but failed to establish south of 38° N latitude because of a mismatched critical daylength response for diapause induction. The daylength response caused beetles to enter diapause too early in the season to survive the duration of winter at southern latitudes. Using climate chambers, we characterized the critical daylength response for diapause induction (CDL) in three ecotypes of Diorhabda beetles originating from 36, 38, and 43° N latitudes in Eurasia. In a field experiment, the timing of reproductive diapause and voltinism were compared among ecotypes by rearing the insects on plants in the field. CDL declined with latitude of origin among Diorhabda ecotypes. Moreover, CDL in southern (<39° N latitude) ecotypes was shortened by more than an hour when the insects were reared under a fluctuating 35-15°C thermoperiod than at a constant 25°C. In the northern (>42° N latitude) ecotypes, however, CDL was relatively insensitive to temperature. The southern ecotypes produced up to four generations when reared on plants in the field at sites south of 38° N, whereas northern ecotypes produced only one or two generations. The study reveals latitudinal variation in how Diorhabda ecotypes respond to daylength for diapause induction and how these responses affect insect voltinism across the introduced range.

Temperature-driven plasticity in growth cessation and dormancy development in deciduous woody plants: a working hypothesis suggesting how molecular and cellular function is affected by temperature during dormancy induction

The role of temperature during dormancy development is being reconsidered as more research emerges demonstrating that temperature can significantly influence growth cessation and dormancy development in woody plants. However, there are seemingly contradictory responses to warm and low temperature in the literature. This research/review paper aims to address this contradiction. The impact of temperature was examined in four poplar clones and two dogwood ecotypes with contrasting dormancy induction patterns. Under short day (SD) conditions, warm night temperature (WT) strongly accelerated timing of growth cessation leading to greater dormancy development and cold hardiness in poplar hybrids. In contrast, under long day (LD) conditions, low night temperature (LT) can completely bypass the short photoperiod requirement in northern but not southern dogwood ecotypes. These findings are in fact consistent with the literature in which both coniferous and deciduous woody plant species' growth cessation, bud set or dormancy induction are accelerated by temperature. The contradictions are addressed when photoperiod and ecotypes are taken into account in which the combination of either SD/WT (northern and southern ecotypes) or LD/LT (northern ecotypes only) are separated. Photoperiod insensitive types are driven to growth cessation by LT. Also consistent is the importance of night temperature in regulating these warm and cool temperature responses. However, the physiological basis for these temperature effects remain unclear. Changes in water content, binding and mobility are factors known to be associated with dormancy induction in woody plants. These were measured using non-destructive magnetic resonance micro-imaging (MRMI) in specific regions within lateral buds of poplar under SD/WT dormancing inducing conditions. Under SD/WT, dormancy was associated with restrictions in inter- or intracellular water movement between plant cells that reduces water mobility during dormancy development. Northern ecotypes of dogwood may be more tolerant to photoinhibition under the dormancy inducing LD/LT conditions compared to southern ecotypes. In this paper, we propose the existence of two separate, but temporally connected processes that contribute to dormancy development in some deciduous woody plant: one driven by photoperiod and influenced by moderate temperatures; the other driven by abiotic stresses, such as low temperature in combination with long photoperiods. The molecular changes corresponding to these two related but distinct responses to temperature during dormancy development in woody plants remains an investigative challenge.

Effect of Ecotype and Latitude on Growth, Frost Hardiness, and Oxidative Stress of South to North Transplanted Scots Pine Seedlings

Ecotypes of Pinus sylvestris seedlings from Kuhmo (64°N) and Ranua (66°N) were transplanted to 0 (control), 1, 2, and 3°N higher latitude in Northern Finland in 1997. Sampling was carried out twice per year (spring/autumn) during 1998–2000. Shoot elongation, total nitrogen concentration, frost hardiness and oxidative stress state (lipid peroxidation, glutathione reductase activity, and protein oxidation) in the needles were analyzed. Comparison between the seasonal sampling times indicated that total nitrogen, lipid peroxidation, glutathione reductase activity, and protein oxidation were lower in autumn, during which the frost hardiness was higher. The above suggests that the stress conditions were higher in spring. Comparison between the origins of the seedlings demonstrated that shoot elongation of the northern origin were minor, while their total nitrogen concentrations and frost hardiness were more pronounced. Effect of latitude on elongation of Scots pine is most probably a result of a combination of temperature and light quality. No delay in frost hardening due to higher latitude was observed during the autumnal equinox. No marked stress caused by transplantation to the north was either observed. It is concluded that southern ecotypes of Scots pine have the potential to adapt to migration driven by a warming climate.

Genetic Improvement of Local Chickens by Crossing with the Label Rouge (T55*SA51): Carcass Characteristic, Organoleptic Qualities and Heterosis Effects

The aim of this study was to evaluate the carcass characteristic and the organoleptic qualities of Label Rouge, North and South Local Chicken and their crossbreed MnFl (females Label Rouge x males of North ecotype), MlFn (North females ecotype x males Label Rouge) and MsFl (Label Rouge females x males of the South ecotype). This study was carried out on the Experimentation Farm of the Polytechnic School of Abomey-Calavi, from August 2007 to may 2008. Ten chicken of each genotype were slaughtered at 24 weeks age. The local chickens of the North ecotype had a live weight at the slaughter significantly higher than that of the Southern ecotype and lower compared to the cross and the Label Rouge; the same tendency was observed for the noble carcass cuts. The carcass yield was similar for the six genetic types. The meats of Label Rouge chickens, the local chickens and the Cross MsFl were less tender (p<0.05) than those of North chickens and the Cross containing the "North blood" (MnFl and MlFn). No significant differences were observed in other hand on the juiciness and the flavor for the six genetic types. For each type of crossing, the heterosis effect of the live weight, the hot carcass weight and the wet carcass weight had a close values. In general, the different heterosis rates of the crossing male of North ecotype x female Label was superior than those of the other crossings.

산지별 국내산 마늘종의 항산화 성분과 항산화 활성 비교

마늘의 재배 부산물인 마늘종을 산지별로 나누어 항산화 관련 물질을 측정하고 용매 추출물의 항산화력 및 아질산염 소거능을 조사하여 마늘종의 소비 확대를 장려할 수 있는 기초자료를 마련하고자 하였다. 항산화 성분 중 클로로필, 카로티노이드, 페놀화합물, allicin 함량은 한지형 마늘종이 많았고, 비타민 C 함량은 난지형 마늘종이 조금 많았다. 마늘은 마늘종에 비해 클로로필, 카로티노이드, 비타민 C 함량은 유의적으로 크게 낮았으나 페놀화합물과 allicin 함량은 유의적으로 높았다. 항산화 효능은 추출용매나 재배지역의 기후에 따라 영향을 받는 것으로 ethanol 추출물보다 methanol 추출물이, 난지형 마늘종보다 한지형 마늘종이 더 높았다. 마늘종은 마늘에 비해서 전자공여능, linoleic acid system에서의 항산화능, 아질산염 소거능이 낮았지만 마늘 항산화 효능의 50% 이상을 보였으며, SOD 유사활성은 마늘보다 유의적으로 높게 나타났다. 본 연구결과들로 마늘종도 마늘과 마찬가지로 항산화 효능이 있고 한지형이 난지형보다 더 높은 항산화 효능을 가지는 것으로 밝혀졌다. 따라서 마늘종도 기능성 식품소재로서 충분히 활용가치가 있다고 보이므로 이를 다양한 제품 개발에 이용할 수 있는 방법들도 추후 연구되어야 할 것이다.

COLD HARDINESS OF SOUTHERN AND NORTHERN SALTGRASS ECOTYPES

COLD HARDINESS OF SOUTHERN AND NORTHERN SALTGRASS ECOTYPES

Genetic Properties of Milk Thistle Ecotypes from Iran for Morphological and Flavonolignans Characters

The aim of present study was to investigate the genetic variation within and between 32 milk thistle ecotypes collected from northern (23 accessions) and southern (9 accessions) regions of Iran along with two introduced varieties, CN seeds and Budakalaszi, for morphological and flavonolignans properties. The two collections were assessed at separate field experiments. MANOVA for all the morphological traits showed significant difference between ecotypes. Univariate ANOVA verified these differences for most of the traits in the northern ecotypes (first collection) while for southern ecotypes no significant differences were obtained for the studied traits except seed yield. Among and within ecotypes genotypic coefficient of variation indicated higher level of variation among ecotypes than within ecotypes. In both of the experiments, there was a large genetic variation for silybin and silymarin quality and quantity. Cluster analysis of 34 accessions was performed for morphological traits and silymarin and silybin characteristics, separately. The resulting dendrogram based on silybin and silymarin characteristics revealed that the native accessions such as Dezfoul, Fereydounkenar and Nour, had highest flavonolignans and they were better than the foreign varieties. Also, there was no clear relationship between clustering based on morphological traits and flavonolignan compounds.

Critical night length for bud set and its variation in two photoperiodic ecotypes of Betula pendula

We studied the variation in critical night length for bud set in two photoperiodic ecotypes (two latitudinally distant stands) of silver birch (Betula pendula Roth) in three phytotron experiments. Seeds from 21 open-pollinated mother trees in a southern (Tuusula, 60 degrees N) and a northern (Kittilä, 67 degrees N) Finnish stand were germinated and grown for 4 weeks in a 24-h photoperiod in a greenhouse and then moved to different night length treatments at 18 degrees C for 4 to 6 weeks. Night lengths from 5 to 8.5 h were used for southern origin seedlings and from 1 to 4.5 h for northern origin seedlings. At the end of the treatments, apical bud set was observed and the percentage of seedlings with bud set calculated for each treatment and tree progeny. The critical night lengths (CNL) for 50% bud set were determined separately for seedlings from each mother tree by regression analysis. In both ecotypes, the mean percentage of seedlings with bud set was lowest for the shortest night lengths and increased rapidly as night lengths increased. Mean CNL with its 95% confidence interval for the southern and northern ecotypes was 6.3 +/- 0.2 and 3.1 +/- 0.3 h, respectively. The CNL of the two ecotypes differed significantly in three experiments. Within-ecotype variance of the CNL was significantly higher in the northern ecotype (0.484) than in the southern ecotype (0.150). Significant differences in CNL were detected between individual mother trees of the southern ecotype, but not between mother trees of the northern ecotype. The ranking of individual mother trees, based on CNL, differed in the three experiments.

Fingerprints of environmental change on the rare mediterranean flora: a 115‐year study

AbstractWe empirically assessed the long‐term changes in the rare species assemblage of a Mediterranean flora, in terms of species life history traits, niche and biogeographic features, and taxonomic groups. We used a 115‐year historical record of ca. 2100 plant species occurrences in a 6250 km2 region in Mediterranean France. Species were assigned to two classes of regional abundance for the years 1886 and 2001 (rare species, i.e. exhibiting one or two occurrences vs. nonrare species), and to three classes of abundance changes during 1886–2001 (decreasing/extinct, stable, increasing/immigrant). Then, we tested whether species regional abundance and species abundance change were related to their morphological and life‐history traits (life form, perenniality, height, dispersal agent, pollination mode), niche and biogeographic features (habitat specialization, level of endemism, biogeographic origin) and taxonomic group. The regional assemblage of rare species was not biologically random and significantly changed between 1886 and 2001. Species classified as rare in 1886 had a significantly higher rate of extinction in the study region during 1886–2001. The highest rate of regression/extinction was found among hydrophyte and/or water‐dispersed rare species, and among annual rare species. However, herbaceous perennial, tree and wind‐dispersed rare species significantly increased in abundance during 1886–2001. Rare species with Eurosiberian distributions, occurring at the southern margin of their range in the study region, dramatically declined or went extinct in the region during 1886–2001; whereas rare species with Mediterranean affinities remained significantly stable. We also found strong evidence for taxonomic patterns in species abundance and abundance changes from 1886 to 2001. The long‐term biological changes documented here in the rare species assemblage of a Mediterranean flora are consistent with the predicted consequences of climate and land use changes currently occurring in the Mediterranean Basin. With the potential decline or even extinction of entire taxa and the loss of southern ecotypes of widespread Eurosiberian species, both evolutionary history and speciation potential of the Mediterranean Region could be strongly altered in future decades.

Genetic Diversity of Chinese Cultivated Soybean Revealed by SSR Markers

ABSTRACTChina is the center of origin of soybean [Glycine max (L.) Merr.] and is therefore expected to represent a primary source of germplasm for this crop. Genetic diversity assessments among Chinese soybean accessions should provide useful information for local and international soybean researchers to more effectively utilize this material. A sample of 129 accessions were selected to represent phenotypic variability for 14 agronomic and morphological traits in the Chinese soybean collection. These accessions were analyzed with 60 mapped simple sequence repeats (SSRs) to determine the genetic diversity represented. In total, 732 alleles were detected (12.2 alleles per locus) and the polymorphic information content (PIC) among accessions varied from 0.5 to 0.92 with a mean of 0.78. Pairwise coefficients of genetic distance among all accessions ranged from 0.05 to 0.91 (mean 0.23). Unweighted pair‐group method arithmetic average (UPGMA) analysis showed that the accessions formed five major clusters; two contained primarily Northern ecotypes, one contained primarily Yellow River Valley ecotypes, and one contained Southern ecotypes. The fifth cluster contained a mixture of Northern and Yellow River Valley ecotypes. Accessions from the lower regions of the Yellow River Valley possessed the greatest allelic richness, had the lowest pair‐wise genetic diversity estimates, and were dispersed throughout the five clusters, suggesting that the Yellow River Valley may be center of diversity for Chinese cultivated soybean. The results indicated that stratified sampling based on seven primary ecotypes may represent an optimal strategy for assembling a representative core collection of Chinese soybean.

The influence of root-zone temperature on growth of Betula pendula Roth.

We have examined shoot and root growth and the concentration of carbohydrates in seedlings of a northern (67°N) and a southern (61°N) ecotype of Betula pendula Roth. cultivated at root-zone temperatures of 2, 6, 12 and 17°C. Three hydroponic experiments were conducted in controlled environments. We used three different pretreatments before seedlings were subjected to the experimental temperature treatments. Actively growing seedlings that were acclimated to the hydroponic solution for 3 weeks at a root temperature of 17°C, continued to grow at all the experimental temperatures, with an expected increase in growth from 2 to 17°C. However, if we started with ecodormant cold stored plants or used seedlings grown actively in perlite, no growth was observed at 2°C and only minor growth was found at 6°C. The highest root temperature always produced the best growth. The concentration of nonstructural carbohydrates was higher in seedlings grown at 2°C than at 17°C, and this is probably due to extensive incorporation of carbohydrates into cell walls and other structural elements at 17°C. We found no evidence for differences between the two ecotypes in root growth, in timing of bud burst, but shoot growth terminated in the northern ecotype in the first experiment because the natural photoperiod was below the critical value. Our study highlights the importance of post-transplantation stress (planting check) related to root growth, and that root threshold temperatures may change according to the way plants are pretreated.

Differential responses of silver birch (Betula pendula) ecotypes to short-day photoperiod and low temperature

We investigated interrelations of dormancy and freezing tolerance and the role of endogenous abscisic acid (ABA) in the development of silver birch (Betula pendula Roth) ecotypes in controlled environments. Short-day treatment induced growth cessation, bud set and dormancy development, as well as initiation of cold acclimation and an increase in freezing tolerance. Subsequent low temperature and short days (12-h photoperiod) resulted in a significant increase in freezing tolerance, whereas bud dormancy was gradually released. The concentration of ABA increased in response to short days and then remained high, but ABA concentrations fluctuated irregularly when the dormant plants were subsequently exposed to low temperature during short days. Although there was a parallel development of freezing tolerance and bud dormancy in response to short days, subsequent exposure to low temperature had opposite effects on these processes, enhancing freezing tolerance and releasing dormancy. Compared with the southern ecotype, the northern ecotype was more responsive to short days and low temperature, exhibiting earlier initiation of cold acclimation, growth cessation and an increase in ABA concentrations in short days, and higher freezing tolerance, faster dormancy release and greater alteration in ABA concentrations when subsequently exposed to low temperature during short days. The rates and extent of the increases in ABA concentration may be related to increases in freezing tolerance and dormancy development during short days, whereas the extent of the fluctuations in ABA concentration may play an important role in enhancing freezing tolerance and releasing dormancy during a subsequent exposure to low temperature during short days.

Metabolism of [14C]GA19 and [14C]GA53 by ecotypes of Betula pendula: the role of photoperiod

In many temperate woody species, short days (SDs) induced growth cessation has been shown to be prevented by the application of gibberellins (GAs). Evidence has also been forwarded for the influence of photoperiod on the metabolism of applied GAs. Continuing with this line of research, we studied the metabolism of 14C-labelled GA19 and GA53. [14C]GA19 and [14C] A53 were applied to the apices of the northern ecotype (67º N) and to the leaves of the southern ecotype (64º N) of Betula pendula Roth. under different photoperiods and at different times in order to compare metabolism during day and night periods. Assay of metabolites was made 10 h after application. Less than half of each applied GA was taken in by the plants and most of the activity was recovered from the application points. There was no clear effect of photoperiod on uptake of the GAs. After the HPLC analysis, most of the absorbed radiolabelled GAs were eluted as unmetabolised forms. However, significant levels of gibberellins A20, A29, A1, and A8 were recovered as metabolites of [14C]GA19 both in apical stems and leaves. In 1SD and 4SD-treated plants, there was less metabolism of [14C]GA19 compared to LD-treated plants. The difference was due to reduced metabolism of 14C]GA19 by SD-treated plants during the night period. On the other hand, metabolism of [14C]GA53 was very limited in all day-length treatments and during both, day and night periods. The most abundant metabolite was [14C]GA19 (10% of the activity in the samples). Key words/phrases: Conjugation, ecotype, gibberellins, metabolism, radioactivity SINET: Ethiopian Journal of Science Vol. 28 (1) 2005: 33–40

Phenology of temperate trees in tropical climates

Several North American broad-leaved tree species range from the northern United States at approximately 47 degrees N to moist tropical montane forests in Mexico and Central America at 15-20 degrees N. Along this gradient the average minimum temperatures of the coldest month (T (Jan)), which characterize annual variation in temperature, increase from -10 to 12 degrees C and tree phenology changes from deciduous to leaf-exchanging or evergreen in the southern range with a year-long growing season. Between 30 and 45 degrees N, the time of bud break is highly correlated with T (Jan) and bud break can be reliably predicted for the week in which mean minimum temperature rises to 7 degrees C. Temperature-dependent deciduous phenology-and hence the validity of temperature-driven phenology models-terminates in southern North America near 30 degrees N, where T (Jan)>7 degrees C enables growth of tropical trees and cultivation of frost-sensitive citrus fruits. In tropical climates most temperate broad-leaved species exchange old for new leaves within a few weeks in January-February, i.e., their phenology becomes similar to that of tropical leaf-exchanging species. Leaf buds of the southern ecotypes of these temperate species are therefore not winter-dormant and have no chilling requirement. As in many tropical trees, bud break of Celtis, Quercus and Fagus growing in warm climates is induced in early spring by increasing daylength. In tropical climates vegetative phenology is determined mainly by leaf longevity, seasonal variation in water stress and day length. As water stress during the dry season varies widely with soil water storage, climate-driven models cannot predict tree phenology in the tropics and tropical tree phenology does not constitute a useful indicator of global warming.

Biofuel Component Concentrations and Yields of Switchgrass in South Central U.S. Environments

Optimizing biofuel production and quality from switchgrass (Panicum virgatum L.) may require matching of ecotype and morphological type to environments, particularly in southern regions. Nine genotypes from four combinations of ecotype and morphological switchgrass type were harvested from 1998 to 2000 in five sites across Texas, Arkansas, and Louisiana that varied in latitude and precipitation. An additive main effects and multiplicative interaction (AMMI) method was used to evaluate genotype × environment interaction (G × E) patterns for traits important to biofuel production. Compared with upland genotypes across all site‐years, lowland genotypes had greater lignocellulose yields (3.26 vs. 7.40 Mg ha−1), greater removal rates of soil N (41 vs. 83 kg ha−1) and P (6 vs. 12 kg ha−1), greater concentrations of moisture (394 vs. 452 g kg−1) and cellulose (388 vs. 394 g kg−1), and lower concentrations of N (6.3 vs. 5.7 g kg−1) and ash (48 vs. 40 g kg−1). Compared with northern ecotypes, southern ecotypes had greater lignocellulose yields (4.95 vs. 6.85 Mg ha−1), greater removal rates of soil N (60 vs. 76 kg ha−1) and P (8 vs. 11 kg ha−1), greater moisture concentrations (417 vs. 445 g kg−1), and lower ash concentrations (45 vs. 40 g kg−1). Lignocellulose yield paralleled dry matter yield (DMY) patterns. Switchgrass biofuel production efforts in the south‐central USA should focus on improving DMY of southern lowland genotypes to maximize lignocellulose yields, but management factors may be more effective in optimizing moisture, ash, and mineral concentrations for combustion.

Sexual differences in cold acclimation and freezing tolerance development in sea buckthorn ( Hippophae rhamnoides L.) ecotypes

Sexual differences in cold acclimation and freezing tolerance development of two contrasting sea buckthorn ( Hippophae rhamnoides L.) ecotypes from northern and southern regions in China were recorded after exposure to short day photoperiod (SD) and low temperature (LT). The results demonstrated that cold acclimation could be triggered by exposing the plants to SD or LT alone, and that a combination of both treatments had an additive effect on freezing tolerance in all plants tested. However, development of freezing tolerance was dependent on the sex of plants under SD and LT, the males were clearly more responsive to SD and LT than the females in both ecotypes studied. On the other hand, development of freezing tolerance was also ecotype-dependent, the northern ecotype was more responsive to SD and LT than the southern ecotype, resulting in earlier cold acclimation under SD and higher freezing tolerance under LT. Moreover, development of freezing tolerance induced by SD and LT was accompanied by changes in ABA levels. These alterations in ABA levels were different in different treatments, ecotypes and sexes. Therefore, the differences in SD and LT-induced physiological responses showed that the different ecotypes and the different sexes might employ different survival strategies under environmental stress.

Population variability of triple symbiotic system: Paramecium bursaria-zoochlorella-and algophages

The triple symbiotic system (TSS): P. bursaria-Chlorella-Chlorovirus, was studied. In Eurasia we found only 2 forms TSS, named N, northern and S, southern ecotypes. Each ecotype manifested at 32°C ts (N)-or tr (S)-phenotypes. In northeren parts of P. bursaria areals, from Karelia up to Kamchatka, near Baikal and in Armenia highlands, we find only ts-viruses, in Central Asia - only tr-types. Two types of genome characters were shown by PCR of 18 S RNA-genes. According all this characters populations of zoochlorella in P. bursaria - 2 clones of obligate symbionts