Total Nonstructural Carbohydrate Concentration Research Articles

Climate Change and Bemisia tabaci (Hemiptera: Aleyrodidae): Impacts of Temperature and Carbon Dioxide on Life History

Abstract Climate change is relevant to life around the globe. A rise in ambient temperature and carbon dioxide (CO2) may have various impacts on arthropods such as altered life cycles, modified reproductive patterns, and changes in distribution. The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a global pest responsible for significant losses of agricultural yields annually. This study was conducted to determine the impacts of changing temperature and CO2 levels on selected life history parameters of B. tabaci biotype B. Populations were established at three temperature regimes (25,28, and 33°C), and each population was evaluated in all three environments. Collard, Brassica oleracea ssp. acephala de Condolle (Brassicaceae), was used as the host. These results were based on data from 5 to ≈30 generations. Oviposition, nymphal survival, and reproduction were significantly affected by temperature, with net reproductive success declining to 36.4% at 33°C. Overall, 28°C was most favorable for whitefly fitness. However, the optimal temperature for B. tabaci reproduction may be between 28 and 33°C. There were no temperature effects on total nonstructural carbohydrate concentrations in collard, and impacts of the host plant on whitefly development in the different environments were determined to be minimal. An environment of enriched CO2 (750 ppm) was not observed to have an adverse effect on whitefly reproduction. Temperature was negatively correlated with adult body size. Length and width of males and females were affected by temperature. Data regarding population dynamics of B. tabaci in response to climate change are important for accurate predictions and improving management practices.

Pushing toward Cogongrass (Imperata cylindrica) Patch Eradication: The Influence of Herbicide Treatment and Application Timing on Cogongrass Rhizome Elimination

AbstractCogongrass, an invasive grass native to Asia, has infested thousands of hectares in the southeastern United States. Although numerous studies have examined cogongrass control, no published studies, to our knowledge, have tested strategies for cogongrass eradication. Cogongrass has a persistent, thick rhizome mat but an ephemeral seedbank; therefore, successful eradication methods must largely focus on the rhizomes. A field study to evaluate specific herbicide treatments and application timings for cogongrass patch eradication was conducted at two locations in southwestern Alabama. Herbicide treatments included glyphosate at 4.48 kg ai ha−1, imazapyr at 0.84 kg ai ha−1, and a tank mix of glyphosate and imazapyr at the same rates. Treatments were applied in May, August, or October for 3 consecutive yr, and the May glyphosate treatment included a second annual application each October. Cogongrass visual control, shoot biomass, rhizome biomass, rhizome depth, and total nonstructural carbohydrate (TNC) content were sampled during the course of the study. Cogongrass response to treatments varied by location but by 36 mo after initial treatment (MAIT), complete elimination of cogongrass shoot and rhizome biomass and 100% visual control was achieved in several herbicide treatment–timing combinations at both locations. These included glyphosate plus imazapyr at any application timing, imazapyr in August or October, and glyphosate applied in May and October each year. TNC levels of surviving healthy rhizomes were not affected by herbicide treatments, but a seasonal pattern was observed. The maximum live-rhizome depth was not influenced by any treatment, indicating that herbicides were not preferentially leaving deeper, surviving rhizomes. These results demonstrate, for the first time, that the entire rhizome layer of cogongrass can be eliminated within 3 yr with multiple treatment options and that cogongrass patch eradication is possible for many land managers.

Plant maturity and nitrogen fertilization affected fructan metabolism in harvestable tissues of timothy (Phleum pratense L.)

Timothy (Phleum pratense L.) is an important grass forage used for pasture, hay, and silage in regions with cool and humid growth seasons. One of the factors affecting the nutritive value of this grass is the concentration of non-structural carbohydrates (NSC), mainly represented by fructans. NSC concentration depends on multiple factors, making it hardly predictable. To provide a better understanding of NSC metabolism in timothy, the effects of maturity stage and nitrogen (N) fertilization level on biomass, NSC and N-compound concentrations were investigated in the tissues used for forage (leaf blades and stems surrounded by leaf sheaths) of hydroponically grown plants. Moreover, activities and relative expression level of enzymes involved in fructan metabolism were measured in the same tissues. Forage biomass was not altered by the fertilization level but was strongly modified by the stage of development. It increased from vegetative to heading stages while leaf-to-stem biomass ratio decreased. Total NSC concentration, which was not altered by N fertilization level, increased between heading and anthesis due to an accumulation of fructans in leaf blades. Fructan metabolizing enzyme activities (fructosyltransferase—FT and fructan exohydrolase—FEH) were not or only slightly altered by both maturity stage and N fertilization level. Conversely, the relative transcript levels of genes coding for enzymes involved in fructan metabolism were modified by N supply (PpFT1 and Pp6-FEH1) or maturity stage (PpFT2). The relative transcript level of PpFT1 was the highest in low N plants while that of Pp6-FEH1 was the highest in high N plants. Morevoer, transcript level of PpFT1 was negatively correlated with nitrate concentration while that of PpFT2 was positively correlated with sucrose concentration. This distinct regulation of the two genes coding for 6-sucrose:fructan fructosyltransferase (6-SFT) may allow a fine adequation of C allocation towards fructan synthesis in response to carbon and N availability. Contrary to fructans, starch content increased in low N plants, suggesting different regulatory mechanisms and/or sensitivity of starch and fructan metabolism in relation to the N status.

Photoperiodic phytochrome-mediated vegetative growth responses of container-grown citrus nursery trees

In Florida, most citrus trees are grown on rootstocks with trifoliate orange parentage. Nurserymen have long noted that these rootstocks exhibit much slower growth during the winter than their non-trifoliate counterparts (e.g., ‘Volkamer’ lemon, ‘Sour Orange’). Since 2007 citrus nursery trees in Florida must be grown in greenhouses to protect them from the Asian citrus psyllid, the vector of huanglongbing (citrus greening). Greenhouse production of citrus nursery trees has greatly increased production costs and, thus, the desire to determine why trifoliate-type rootstocks grow poorly during the winter. We hypothesized that trifoliate-type rootstocks, because of their deciduous habit, respond to photoperiod and exhibit slow growth under short days (photoperiods <12h). Our objective was to determine the effect of photoperiod on the growth of container-grown trees of the two most common trifoliate-type rootstocks, ‘Carrizo’ citrange and ‘Swingle’ citrumelo with and without ‘Hamlin’ sweet orange scions. Three weeks after budding, all trees were placed in growth chambers under three different photoperiods: short days (SD – 10h photoperiod), long days (LD – 14h) and short days+night interrupt (SD-NI – 10h photoperiod+1h night interrupt) for 14 weeks, and maintained at 28/21°C day/night temperature. All trees, regardless of being budded or not, had reduced growth under SD conditions, whereas the trees under SD-NI grew similar to those under LD. Average tree growth during the 14-weeks was 19, 52 and 55cm, across all rootstock-scion combinations for SD, LD and SD-NI treatments, respectively. The difference in growth between budded and non-budded trees in the SD treatment was not significant, but was highly significant in LD and SD-NI. Across rootstock-scion combinations, the average numbers of new nodes produced per tree were 13, 30 and 32 nodes in the SD, LD and SD-NI treatments, respectively, indicating that the increased growth under LD and SD-NI conditions was not simply a result of internode elongation. Net CO2 assimilation was higher under the SD and SD-NI treatments compared with LD, but there were no significant differences in whole-plant total nonstructural carbohydrate concentrations as a result. The ability of a 1-h night interrupt to overcome the SD response indicates that the photoperiod effect observed is a phytochrome-mediated response.

Growth, plant quality and leaf damage patterns in a dioecious tree species: is gender important?

Frequently, female plants allocate more resources to reproductive structures and defense-related secondary compounds in comparison with male plants that invest more resources to growth, reflecting trade-offs between reproduction, growth and defense. Therefore, differences in herbivory can be expected between genders. In this study, over two years, we analyzed the differences in plant chemical defense, nutritional quality, plant size and herbivory between genders in the dioecious tree, Spondias purpurea in a Mexican tropical dry forest. We estimated the total leaf area and the area consumed by folivory using a digital image of each leaf. The nutritional quality was estimated as water content, and the concentration of chlorophyll and total nonstructural carbohydrates. The secondary metabolites analyzed were total content of soluble phenolics, flavonoids, protein precipitation capacity of tannins, gallotannins, soluble proanthocyanidins, hydrolyzable tannins and ellagitannins. Our results differ from most of studies that analyze the differential herbivory patterns in dioecious plants. We found that female trees had higher levels of herbivory than male trees of S. purpurea. In the same way, female trees showed higher size and nutritional quality than males, while chemical defense was higher in male trees. The higher percentage of folivory in female trees of S. purpurea is associated with greater nutritional quality and lower chemical defenses. Our results show that male-biased herbivory might not be universal in dioecious species. Therefore, studies of fitness components affected by herbivory are necessary to understand the evolution of dioecy and the importance of herbivores as selective agents on breeding system features.

Drought Resistance Strategies of Seashore Paspalum Cultivars at Different Mowing Heights

Understanding how mowing height and soil moisture influence drought resistance mechanisms may lead to better management of seashore paspalum. This research was conducted to evaluate the effect of mowing height and soil moisture replacement on drought tolerance strategies in three seashore paspalum cultivars. In a greenhouse, clear polyvinyl chloride (PVC) root tubes were placed in a black PVC sleeve with a bottom cap drilled with holes for drainage. Sod pieces (10 cm in diameter) of seashore paspalum (Paspalum vaginatum Swartz) cultivars Salam, Excalibur, and Adalayd were planted into these tubes after roots were trimmed. In a split-split experimental design, water regimes applied included control [100% of the total evapotranspiration (ET)] as well as 75%, 50%, and 25% of the total ET. Mowing heights were 45.0, 35, and 25 mm. Visual turf quality, maximum root extension (MRE), root length densities (RLD), total nonstructural carbohydrate content (TNC), shoot reducing sugar content (RSC), and proline content were determined. Turf quality decreased linearly with the decrease in irrigation water applied under the three mowing heights with higher slope at 25.0 mm than at either 35.0 or 45.0 mm. ‘Salam’ turf quality declined only to the unacceptable rating of 5.5 and 4.5 when mowed to 35 and 25 mm, respectively, whereas quality was 6.5 at the mowing height of 45 mm under the water regime of 25% of total ET. ‘Excalibur’ did not show acceptable turf quality at the 25% treatment, whereas ‘Adalayd’ did not show such quality at both 50% and 25% water regimes under all mowing heights. Regression analysis indicated a significant negative association between RLD and drought levels at all mowing heights and soil depths. In ‘Salam’, as drought levels increased from control to 25%, average RLD decreased by 76%, 75%, and 76% at 25-, 35-, and 45-mm mowing heights, respectively, at the top 30 cm of soil in the column. The change was 93%, 85%, and 83% at 25-, 35-, and 45-mm mowing heights, respectively, at the deeper soil (90 to 120 cm). In ‘Salam’, on average overall water regimes, MRE at 45 mm was ≈10% to 17% greater than that of 35-mm mowing height and 28% to 36% greater than that of 25-mm mowing height. The highest root mass (810 mg) was obtained when ‘Salam’ was mowed to 45 mm and subjected to the drought level of 50% of the total ET. The lowest root mass (320 mg) was obtained when ‘Salam’ was mowed to 25 mm and the water regime was not limiting. In ‘Salam’, as drought increased from control to 25% of the total ET, average TNC decreased by 43.5%, 26.0%, and 29.0% and the average TNC decrease in ‘Excalibur’ shoots was 48.0%, 30.0%, and 32.0%, whereas the decrease in ‘Adalayd’ was 51.3%, 42.3%, and 35.4% at 25-, 35-, and 45-mm mowing heights, respectively. As drought levels increased from control to 25% of the total ET, average RSC increased by 57.3%, 57.1%, and 53.0% in ‘Salam’ and by 59.4%, 57.0%, and 51.5% in ‘Excalibur’ and 61.2%, 58.1%, and 61.0% in ‘Adalayd’ at 25-, 35-, and 45-mm mowing height, respectively. When drought increased to 25%, average proline content in shoots increased by 435%, 432%, and 431% in ‘Salam’; 404%, 376%, and 324% in ‘Excalibur’; and 257%, 278%, and 302% in ‘Adalayd’, at 25-, 35-, and 45-mm mowing heights. The resistance of paspalum cultivars to moderate to high drought stress can be enhanced by increasing the mowing height that may be related to increased carbon fixation, which favors increased root production. Proline accumulation could add to the drought tolerance through osmoregulation or by acting as a carbon and nitrogen sink for stress recovery.

Drought tolerance in citrus trees is enhanced by rootstock-dependent changes in root growth and carbohydrate availability

Valencia orange scions grafted on Rangpur lime or Swingle citrumelo were grown under water deficit to evaluate how those rootstocks modulate the non-structural carbohydrate (NSC) availability and the drought tolerance of citrus trees. Additionally, the importance of young mature leaves as possible sources of carbon in citrus trees was studied. Herein, young mature leaves are those ones fully expanded and developed during water deficit. After 30 days under water limiting conditions, plant growth, leaf water status, photosynthetic rate and carbohydrate availability in old mature and young mature leaves, branches and roots were evaluated. Water deficit reduced the leaf water potential and caused diffusive limitation of photosynthesis in both rootstocks. Drought-induced decrease in total NSC content occurred only in plants grafted on Swingle. While plant growth on Swingle citrumelo was severely reduced by water deficit, plants grafted on Rangpur did not exhibited impairment of dry matter accumulation. The lower sensitivity of plant growth on Rangpur lime was associated with the enhanced root growth, the maintenance of the total carbohydrate pool and to a large shift in the carbohydrate partitioning, with the roots accumulating carbohydrates under water deficit. Regarding the young mature leaves, they exhibited higher photosynthetic rates than the old mature leaves after 30 days of treatment, regardless of the water conditions. As possible sources of carbohydrates, young mature leaves have equal importance as compared to branches under well-watered conditions.

干旱对兴安落叶松枝叶非结构性碳水化合物的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱对兴安落叶松枝叶非结构性碳水化合物的影响 DOI: 10.5846/stxb201401260198 作者: 作者单位: 东北林业大学,东北林业大学生态研究中心,东北林业大学生态研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家"十二五"科技支撑项目(2011BAD37B01); 长江学者和创新团队发展计划(IRT1054) The influence of drought on non-structural carbohydrates in the needles and twigs of Larix gmelinii Author: Affiliation: Northeast Forestry University,Northeast Forestry University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:降水格局的变化以及极端干旱的频繁发生是全球气候变化的重要特征之一.为了揭示干旱对树木碳代谢的影响,通过控雨试验研究兴安落叶松(Larix gmelinii Rupr.)枝叶的非结构性碳水化合物(NSC)及其组分(可溶性糖和淀粉)的浓度对降水减少的响应,探索枝叶NSC浓度与土壤含水率的关系.控雨试验包括减雨100% (100%RE)、减雨50% (50%RE)和对照 (CK) 3个处理;控雨时期为2012年生长季(6月至8月).结果表明,叶NSC浓度对干旱处理的响应比枝更显著.控雨处理对枝叶总NSC浓度影响不显著(P > 0.05),试验期间叶总NSC平均浓度变化在9.45-14.12 mg/g范围内;枝总NSC平均浓度变化在7.72-9.26 mg/g之间.然而,不同处理之间的叶片可溶性糖浓度差异显著.100%RE最高(8.98±0.31)mg/g、50%RE次之(8.45±0.13)mg/g、CK最低(7.73±0.32)mg/g.相反,叶淀粉浓度以CK最高(2.99±0.22)mg/g、50%RE次之(2.68±0.32)mg/g、100%RE最低(2.63±0.17)mg/g.叶可溶性糖与淀粉浓度的比值的大小顺序为:CK (2.27) < 50%RE (2.51) < 100%RE (3.70).叶可溶性糖浓度、可溶性糖浓度和淀粉浓度的比值与土壤含水率呈显著的负相关关系(P < 0.05),而叶淀粉浓度有随土壤含水率升高而增高趋势,但相关关系不显著(P > 0.05).叶NSC总浓度、枝NSC及其组分浓度与土壤含水率的关系均不显著(P > 0.05).研究表明,短期干旱对兴安落叶松树体内总NSC浓度的影响不显著,树木可以通过将淀粉转化成可溶性糖的方式维持其正常的呼吸作用等生理活动. Abstract:Global climate change is characterized by variations in precipitation patterns and frequency of drought events. Extreme drought events may lead to large-area tree death and thus changes in the geographical distribution of vegetation, of which the underlying mechanisms are still unclear. It has been postulated that carbon starvation may be responsible for the drought-induced tree death, which, however, needs to be tested with a well-designed controlled experiment. In this study, we conducted a rainfall exclusion experiment on Dahurian larch (Larix gmelinii Rupr.) plantation during the growing season of 2012 and examined the concentrations of non-structural carbohydrates (NSC) in twigs and needles of the larch. The experiment included three treatments: 100% rainfall exclusion (100% RE), 50% rainfall exclusion (50% RE) and control (CK, i.e., ambient rainfall). Our objectives were to (1) compare the concentration of NSC components in the needles and twigs among the treatments; and (2) explore relationships between NSC concentrations in needles or twigs and soil moisture. Three trees were randomly selected for each treatment. The twigs and needles from upper, mid and lower crowns in the southern direction were monthly sampled and mixed, respectively, for each tree from early June to late August of 2012. A modified phenol-sulphuric method was used to determine the concentrations of soluble sugars and starch. For a specific sample, the total concentration of NSC was obtained by by summing the concentrations of the sugars and starch. There was no significant effect of the treatments on the total NSC concentrations in both needles and twigs (P > 0.005). The mean concentrations of total NSC in needles varied from 9.45 mg/g to 14.12 mg/g, and those in twigs ranged between 7.72 mg/g and 9.26 mg/g. However, the concentration of soluble sugars in needles differed significantly among the treatments (P < 0.05). The sugar concentration in needles was highest for the 100% RE treatment (8.98±0.31)mg/g, followed by the 50% RE treatment (8.45±0.13)mg/g, and the lowest for the CK (7.73±0.32)mg/g. In contrary, the starch concentration in needles ranked as the CK (2.99±0.22)mg/g > 50% RE (2.68±0.32)mg/g > 100% RE (2.63±0.17)mg/g. The ratio of soluble sugars to starch in the needles ranked as the CK (2.27) < 50% RE (2.51) < 100% RE (3.70). There was a significant negative relationship between soil moisture and concentration of soluble sugars or ratio of sugar to starch in needles (P < 0.05). The concentration of starch in needles tended to increase with soil moisture increasing, but their correlation was insignificant (P > 0.05). There were no significant correlations between soil moisture and the total NSC concentration in needles, and between soil moisture and the concentrations of total NSC or component concentrations in twigs (P > 0.05). This study illustrated that the short-term drought stress had no significant effect on the total NSC concentration, but resulted in a transfer of starch into soluble sugar that maintained tree metabolic activities and survival during the drought event. 参考文献 相似文献 引证文献

Increase and Decrease in Milk Production is affected by Pasture intake

Quality pasture reduces input costs and increases net returns, increases yield and quality of forage, decreases purchased feed, decreases equipment and fuel, decreases manure handling and bedding, better animal health and, reduces labor to feed or harvest the forage. Successes at maintaining good milk yield are generally due to an ability to optimize pasture yield and quality; supplement rations to meet energy requirements; and balance diets for undegradable protein in livestock rearing. Yields of high quality pasture forage can be similar to yields obtained on most farms that mechanically harvest forage for hay or silage. Quality pastures can achieve 4- 6 ton of dry matter per acre and can be grazed 6-9 times each season in the temperate and all year round in the tropical countries.An experiment was conducted to determine the Total Non-structural carbohydrates (TNC) of three napier grass (Pennisetumpurpurem) harvested at vegetative and reproductive phases. The cultivars tested were Taiwan (Gt), King (Gk), and Mott (Gm) and arranged in a 3 x 2 of treatments with four replicates following nested designed. The results showed that the highest sugar content (P<0.01) was found in Gt cultivar and the lowest was in Gm cultivar. The highest starch content (P<0.01) was found in in Gk cultivar and the lowest was in Gt cultivar. TNC content of Gt and Gk cultivars were not significantly different, but both were not significantly higher (P<0.01) compared with the Gm cultivar. It can be concluded from the study done that there were differences in TNC between cultivars, however, the TNC content in Gk cultivar was not different with Gt cultivar, while Gm cultivar have the lowest (P<0.01)TNC content. At reproductive phase all cultivars have higher (P<0.01) TNC and starch content than at vegetative phase. Napier grass (PennisetumPurpureumSchum) is a perennial grass, famous throughout the wet tropics because of its high production capability. Several cultivars have been developed and were introduced to Indonesia, Malaysia, Philippines and South East Asian Countries. Such as cultivars of Africa, Hawaii, Trinidad, Merkeri, King, Taiwan and Mott are closely related. There are differences between cultivars morphology, growth rate and response to farming practices that lead to differences in production and non-structural carbohydrate content.

Responses of soybean lodging and lodging-related traits to potassium under shading by maize in relay strip intercropping system

The relay strip intercropping system of maize-soybean is dominant in southwest China. Compared to monoculture, the productivity of soybean is unstable in this system, since soybean seedling grow under shading by maize, which beget elongated plants and prone to lodging. Therefore, a 3-year study was conducted to determine the influence of K on lodging and lodging-related traits of soybean, and to identify the key traits associated with lodging resistance in relay strip intercropping system in Sichuan Province, China during 2008-2010. The results showed that K application significantly affected basal stem diameter, stem breaking strength, total nonstructural carbohydrate (TNC) concentration, concentration of K and lignin, while differences in plant height and weight of basal internode were not significantly. The K-fertilized treatments had higher seed yield and seed ratio than treatment without K application. The lodging had significantly negative correlation with grain yield, seed ratio, basal stem diameter, weight of basal internode, stem breaking strength, concentration of lignin and K, but no correlation was observed between lodging and TNC in both pot and field trial. The plant height was positively correlated with lodging only in field trial. Thus, these results suggested that K application could alter the lodging-related traits in soybean for greater lodging resistance, and it may be worthwhile to focus on basal stem diameter, stem breaking strength, and lignin concentration.

The effects of bagging and debagging on external fruit quality, metabolites, and the expression of anthocyanin biosynthetic genes in ‘Jonagold’ apple (Malus domestica Borkh.)

‘Jonagold’ apple (Malus domestica Borkh.) was used to determine the effects of bagging and debagging on fruit external and internal qualities, as well as transcript levels for key genes involved in anthocyanin synthesis. Fruits from three treatments – control (never bagged), always bagged, or debagged – were harvested at 0h, 6h, 30h, 3 d, 7 d, and 14 d after certain bags were removed. Peel and flesh tissues were sampled separately. Compared with the control, bagged fruit were yellowish, and had higher scores for lightness and hue angle, lower values for chroma, and the lowest concentration of anthocyanins. Fruit firmness was slightly increased by bagging treatment, whereas soluble solids content (SSC) was decreased. Compared with the control, bagged fruit had more starch, glucose, and galactose, but less of the other sugars and sugar alcohols. The concentrations of fructose and total non-structural carbohydrates were not obviously affected by bagging. Although the malic acid concentration was not influenced by bagging, other acids were either increased (quinic, shikimic, and citric) or decreased (ascorbic). The concentration of total organic acids did not show large difference among three treatments except that it tended to be lower at 14 DABR (days after bag removal). Phenolic compounds, especially flavonols in the peel, were severely inhibited, but their concentrations were increased by re-exposure to sunlight after bag removal. The debagging treatment led to up-regulation of the expression of MdMYB10 and seven structural genes involved in anthocyanin biosynthesis, and subsequent accumulation of anthocysnins. However, the peel of debagged fruit still have lower levels of anthocyanins and other phenolic compounds at harvest, although bag removal made up for the loss of total phenolics in the flesh.

The invasive wetland plant Alternanthera philoxeroides shows a higher tolerance to waterlogging than its native Congener Alternanthera sessilis.

Plant invasion is one of the major threats to natural ecosystems. Phenotypic plasticity is considered to be important for promoting plant invasiveness. High tolerance of stress can also increase survival of invasive plants in adverse habitats. Limited growth and conservation of carbohydrate are considered to increase tolerance of flooding in plants. However, few studies have examined whether invasive species shows a higher phenotypic plasticity in response to waterlogging or a higher tolerance of waterlogging (lower plasticity) than native species. We conducted a greenhouse experiment to compare the growth and morphological and physiological responses to waterlogging of the invasive, clonal, wetland species Alternanthera philoxeroides with those of its co-occurring, native, congeneric, clonal species Alternanthera sessilis. Plants of A. philoxeroides and A. sessilis were subjected to three treatments (control, 0 and 60 cm waterlogging). Both A. philoxeroides and A. sessilis survived all treatments. Overall growth was lower in A. philoxeroides than in A. sessilis, but waterlogging negatively affected the growth of A. philoxeroides less strongly than that of A. sessilis. Alternanthera philoxeroides thus showed less sensitivity of growth traits (lower plasticity) and higher waterlogging tolerance. Moreover, the photosynthetic capacity of A. philoxeroides was higher than that of A. sessilis during waterlogging. Alternanthera philoxeroides also had higher total non-structural and non-soluble carbohydrate concentrations than A. sessilis at the end of treatments. Our results suggest that higher tolerance to waterlogging and higher photosynthetic capacity may partly explain the invasion success of A. philoxeroides in wetlands.

Carbohydrate reserve status of Malbec grapevines after several years of regulated deficit irrigation and crop load regulation

Background and Aims Regulated deficit irrigation (RDI) and bunch thinning are two viticultural practices applied worldwide. There is limited knowledge, however, about their combined effects on carbohydrate dynamics and accumulation. We evaluated during year 3 and 4 of the experiment the effect of 4 consecutive years of RDI and bunch thinning on carbohydrate status, vegetative and reproductive variables. Methods and Results From 2006/07 to 2009/10, we imposed four levels of water supply [100, 60, 38 and 25% of reference evapotranspiration (ETo)] and two crop loads (100 and 50% of the bunches). We compared shoot length, flowers per inflorescence and yield in 2009/10. We also measured pruning mass and the concentration of non-structural carbohydrates in dormant wood in the winters of 2009 and 2010. Starch concentration in the trunk was reduced by severe water deficit (25 and 38% ETo) and improved by bunch thinning. Pruning mass, shoot length, flowers per inflorescence and yield were affected in vines with water applied at 25 and 38% of ETo. Conclusions Severe water stress and high crop load reduced trunk starch concentration with no interaction between both factors, whereas the concentration of total non-structural carbohydrate was not affected. Vegetative growth and yield were reduced after 4 years of severe water stress. Significance of the Study We provide evidence that starch concentration and carbon partitioning can be manipulated through common viticultural practices, such as irrigation and crop load.

Season and light affect constitutive defenses of understory shrub species against folivorous insects

Understory shrubs contribute to overall species diversity, providing habitat and forage for animals, influence soil chemistry and forest microclimate. However, very little is known about the chemical defense of various shrub species against folivorous insects. Using six shrub species, we tested how seasonal changes and light conditions affect their constitutive defense to insect damage. We monitored leaf perforation, concentrations of total phenols, condensed tannins, nitrogen (N), and total nonstructural carbohydrates (TNC). Leaf damage caused by insects was low in Sambucus nigra, Cornus sanguinea, and Frangula alnus, intermediate in Corylus avellana and Prunus serotina, and high in Prunus padus. Leaves of all the species, when growing in high light conditions, had high concentrations of defense metabolites. Except for C. avellana, leaves of the other shrub species growing in full sun were less injured than those in shade. This may be due to higher concentrations of defense metabolites and lower concentrations of nitrogen. Similar patterns of the effects of light on metabolites studied and N were observed for leaves with varying location within the crown of individual shrubs (from the top of the south direction to the bottom of the north), as for leaves from shrubs growing in full sun and shrubs in the shade of canopy trees. A probable cause of the greater damage of more sunlit leaves of C. avellana was the fact that they were herbivorized mostly by Altica brevicollis, a specialist insect that prefers plant tissues with a high TNC level and is not very sensitive to a high level of phenolic compounds.

Spatial variations in non-structural carbohydrates in stems of twelve temperate tree species

The radial, axial and inter-specific variations in concentrations and contents of non-structural carbohydrates (NSC) in stems were investigated for 12 Chinese temperate tree species. These species had contrasting leaf phenology (evergreen and deciduous) and wood types (non-, ring- and diffuse-porous wood). For each species, we sampled bark (periderm and phloem), outer wood (light-colored) and inner wood (dark-colored) at four heights along the stem (stump, breast height, crown base and mid-crown). Concentrations of total NSC (TNC, sum of sugars and starch), sugars and starch were much higher in bark than those in wood. On average, contents of sugars and starch accounted for 48 and 52 % of the TNC, respectively, and contents of TNC in bark, outer wood, and inner wood accounted for 34, 38, and 28 % of the stem total, respectively. Bark was the major pool of sugars in the stem (accounting for 50 % of the stem total on average), while outer wood was the major pool of starch (41 %). The concentration of sugars varied axially for all the conifers but did not for the broadleaved species. Mean concentrations of TNC, sugars and starch in stem varied by more than twofold among the species. However, there were no significant differences in these values for the species groups with different leaf phenology or wood types. Ignoring the radial, axial and inter-specific variations in NSC in stem would introduce large bias in estimating NSC storage at tree or ecosystem levels.

Wild‐boar disturbance increases nutrient and C stores of geophytes in subalpine grasslands

Wild-boar soil disturbance (i.e., rooting) increases the abundance of some species of geophytes (i.e., plants with underground renewal buds) in upland meadows. However, the mechanisms that could lead to such enhanced prevalence remain unexplored. • We analyzed the effects of wild-boar disturbance on the size, nutrient (N, P, K, C, and total ash), and nonstructural carbohydrate (soluble sugars, starch plus fructans, and total nonstructural carbohydrate) content of the storage organs of five taxa of upland geophytes. Results were explored in relation to the nutrient availability (total N, available P, and K) in the soil. • Wild-boar rooting increased the size and the nutrient content of the storage organs of geophytes. Such enhanced storage was further promoted by rooting recurrence and intensity. Although we could not detect a direct impact of rooting on soil nutrient concentrations, plants were clearly N limited and such limitation was ameliorated in areas rooted by wild boar. Furthermore, plant-soil interactions for N were different in rooted areas, where plant N-concentrations responded positively to soil N. • Geophytes growing in rooted areas have an increased nutrient value, which may promote the revisit of wild boars to previously rooted areas, with further positive feed-back effects on plant quality. This plant-animal interaction may shape upland geophyte communities.

Carbon dynamics of eucalypt seedlings exposed to progressive drought in elevated [CO2] and elevated temperature

Elevated [CO2] and temperature may alter the drought responses of tree seedling growth, photosynthesis, respiration and total non-structural carbohydrate (TNC) status depending on drought intensity and duration. Few studies have addressed these important climatic interactions or their consequences. We grew Eucalyptus globulus Labill. seedlings in two [CO2] concentrations (400 and 640 μl l(-1)) and two temperatures (28/17 and 32/21 °C) (day/night) in a sun-lit glasshouse, and grew them in well-watered conditions or exposed them to two drought treatments having undergone different previous water conditions (i.e., rewatered drought and sustained drought). Progressive drought in both drought treatments led to similar limitations in growth, photosynthesis and respiration, but reductions in TNC concentration were not observed. Elevated [CO2] ameliorated the impact of the drought during the moderate drought phase (i.e., Day 63 to Day 79) by increasing photosynthesis and enhancing leaf and whole-plant TNC content. In contrast, elevated temperature exacerbated the impact of the drought during the moderate drought phase by reducing photosynthesis, increasing leaf respiration and decreasing whole-plant TNC content. Extreme drought (i.e., Day 79 to Day 103) eliminated [CO2] and temperature effects on plant growth, photosynthesis and respiration. The combined effects of elevated [CO2] and elevated temperature on moderate drought stressed seedlings were reduced with progressive drought, with no sustained effects on growth despite greater whole-plant TNC content.

Do elevations in temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated silver birch seedlings?

Climate warming increases the risk of insect defoliation in boreal forests. Losses in photosynthetically active surfaces cause reduction in net primary productivity and often compromise carbon reserves of trees. The concurrent effects of climate change and removal of foliage on root growth responses and carbohydrate dynamics are poorly understood, especially in tree seedlings. We investigated if exposures to different combinations of elevated temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated 1-year-old silver birches (Betula pendula). We quantified nonstructural carbohydrates (insoluble starch as a storage compound; soluble sucrose, fructose, and glucose) singly and in combination in fine roots of plants under winter dormancy. Also the total mass, fine root proportion, water content, and length of roots were defined. We hypothesized that the measured properties are lower in defoliated birch seedlings that grow with ample resources than with scarce resources. On average, fertilization markedly decreased both the proportion and the carbohydrate concentrations of fine roots in all seedlings, whereas the effect of fertilization on root water content and dry mass was the opposite. However, defoliation mitigated the effect of fertilization on the root water content, as well as on the proportion of fine roots and their carbohydrate concentrations by reversing the outcomes. Elevation in temperature decreased and elevation in CO2 increased the absolute contents of total nonstructural carbohydrates, whereas fertilization alleviated both these effects. Also the root length and mass increased by CO2 elevation. This confirms that surplus carbon in birch tissues is used as a substrate for storage compounds and for cell wall synthesis. To conclude, our results indicate that some, but not all elements of climate change alter belowground carbon gain and root morphology in defoliated silver birch seedlings.

Biomass and Stored Carbohydrate Compensation after Above-Ground Biomass Removal in a Perennial Herb: Does Environmental Productivity Play a Role?

Many plant species are able to tolerate severe disturbance leading to removal of a substantial portion of the body by resprouting from intact or fragmented organs. Resprouting enables plants to compensate for biomass loss and complete their life cycles. The degree of disturbance tolerance, and hence the ecological advantage of damage tolerance (in contrast to alternative strategies), has been reported to be affected by environmental productivity. In our study, we examined the influence of soil nutrients (as an indicator of environmental productivity) on biomass and stored carbohydrate compensation after removal of aboveground parts in the perennial resprouter Plantago lanceolata. Specifically, we tested and compared the effects of nutrient availability on biomass and carbon storage in damaged and undamaged individuals. Damaged plants of P. lanceolata compensated neither in terms of biomass nor overall carbon storage. However, whereas in the nutrient-poor environment, root total non-structural carbohydrate concentrations (TNC) were similar for damaged and undamaged plants, in the nutrient-rich environment, damaged plants had remarkably higher TNC than undamaged plants. Based on TNC allocation patterns, we conclude that tolerance to disturbance is promoted in more productive environments, where higher photosynthetic efficiency allows for successful replenishment of carbohydrates. Although plants under nutrient-rich conditions did not compensate in terms of biomass or seed production, they entered winter with higher content of carbohydrates, which might result in better performance in the next growing season. This otherwise overlooked compensation mechanism might be responsible for inconsistent results reported from other studies.

Relationships between root respiration rate and root morphology, chemistry and anatomy in Larix gmelinii and Fraxinus mandshurica

Tree roots are highly heterogeneous in form and function. Previous studies revealed that fine root respiration was related to root morphology, tissue nitrogen (N) concentration and temperature, and varied with both soil depth and season. The underlying mechanisms governing the relationship between root respiration and root morphology, chemistry and anatomy along the root branch order have not been addressed. Here, we examined these relationships of the first- to fifth-order roots for near surface roots (0-10 cm) of 22-year-old larch (Larix gmelinii L.) and ash (Fraxinus mandshurica L.) plantations. Root respiration rate at 18 °C was measured by gas phase O2 electrodes across the first five branching order roots (the distal roots numbered as first order) at three times of the year. Root parameters of root diameter, specific root length (SRL), tissue N concentration, total non-structural carbohydrates (starch and soluble sugar) concentration (TNC), cortical thickness and stele diameter were also measured concurrently. With increasing root order, root diameter, TNC and the ratio of root TNC to tissue N concentration increased, while the SRL, tissue N concentration and cortical proportion decreased. Root respiration rate also monotonically decreased with increasing root order in both species. Cortical tissue (including exodermis, cortical parenchyma and endodermis) was present in the first three order roots, and cross sections of the cortex for the first-order root accounted for 68% (larch) and 86% (ash) of the total cross section of the root. Root respiration was closely related to root traits such as diameter, SRL, tissue N concentration, root TNC : tissue N ratio and stele-to-root diameter proportion among the first five orders, which explained up to 81-94% of variation in the rate of root respiration for larch and up to 83-93% for ash. These results suggest that the systematic variations of root respiration rate within tree fine root system are possibly due to the changes of tissue N concentration and anatomical structure along root branch orders in both tree species, which provide deeper understanding in the mechanism of how root traits affect root respiration in woody plants.