Root Carbohydrate Content Research Articles

Effectual Role of Plant Growth-Promoting Fungi and Fosthiazate in Controlling Tomato Root-Knot Nematode Infection: In Vivo and In Vitro Studies

Plant growth-promoting fungi (PGPF) are known to induce systemic resistance in plant diseases caused by microbial pathogens. However, the induced resistance by PGPF has not yet been elucidated in plant diseases caused by root-knot nematodes (RKNs, Meloidogyne spp.). Meloidogyne incognita can severely damage tomato plants, causing considerable losses in world yields. This study aimed to isolate and evaluate the potential of PGPF through enhancing systemic resistance, possibly through activating defense-related pathways in tomato plants, comparing to the commercial chemical nematicide, Melithorin® (fosthiazate 90%). The most potent PGPF (K7, K13, K14) were identified morphologically and molecularly as Alternaria photistica, Penicillium buchwaldii, and Aspergillus niger, respectively. We tested the efficacy of these fungi against RKN (M. incognita) both in vitro and in vivo. The results demonstrated that the commercial nematicide fosthiazate (90%) was the most effective treatment for controlling RKN J2 larvae, achieving a mortality rate of 94% after 96 hours. This was followed by the PGPF treatments, with A. niger at 92.6%, P. buchwaldii at 87.7%, Verticillium lecanii at 73.3%, and A. photistica at 47.4%. Additionally, applying A. photistica, A. niger, P. buchwaldii, and V. lecanii significantly enhanced the levels of photosynthetic pigments, total carbohydrates, and proteins in both healthy and RKN-infected plants. Notably, Melithorin® (fosthiazate 90%), A. niger, and V. lecanii led to substantial increases in root carbohydrate content, with increases of 97%, 63%, and 58%, respectively. Furthermore, Melithorin®, A. photistica, and A. niger significantly boosted shoot protein content by 68%, 65%, and 49%, respectively, compared to the infected control group. These findings indicate that both nematicide and fungal treatments effectively reduce nematode populations and improve overall plant health and nutrient composition. At the same time, the results appeared that infected plants treated with PGPF or Melithorin® showed variation in number and molecular weight of protein bands. SDS-PAGE results indicated that, the highest number of bands (twelve) was recorded in the infected plants treated with Melithorin® followed by P. buchwaldii (11 bands), A. photistica (10 bands), V. lecanii (8 bands), and A. niger (7 bands), respectively. Also, the application of Melithorin®, A. niger, and V. lecanii resulted in a significant increase in the number and weight of fruits, respectively, compared to healthy control plants. Our results suggested that A. photistica, A. niger, P. buchwaldii, and V. lecanii could be used as effective and safe nematicides against RKNs.

Phosphorus application under continuous wheat-cotton straw retention enhanced cotton root productivity and seedcotton yield by improving the carbohydrate metabolism of root

ContextStraw retention could reduce phosphorus (P) application without decreasing seedcotton yield but related physiological mechanisms were unclear. Cotton root is the first organ to sense the changes in soil environment, and its growth and development, especially carbohydrate metabolism, significantly affected the formation of seedcotton yield. Therefore, it is necessary to explore the responses of cotton root carbohydrate metabolism to straw retention combined with P application. ObjectiveThis study was to investigate the effects of straw retention combined with P application on root carbohydrate metabolism and its relationship with seedcotton yield. MethodsA field experiment (2020–2022) was conducted to evaluate the changes in seedcotton yield, cotton canopy apparent photosynthesis rate (CAP), biomass, root productivity, root carbohydrate contents and related enzyme activities under different straw management [removal (S0), retention (S1)] and P rates (0, 100, 200 kg P2O5 ha−1). ResultsStraw retention and P application both increased seedcotton yield and had a significant interaction effect on it. In the 5th-7th year of straw retention, straw retention reduced 24 %-26 % P application to reach a similar yield of S0 with 100 kg P2O5 ha−1. Analyzing the reasons: (1) Straw retention combined with P application increased cotton CAP, providing adequate assimilates for cotton development; (2) Straw retention combined with P application promoted the utilization of root carbohydrates, thereby increasing root productivity and seedcotton yield. Specifically, compared with S0 without P, S1 combined with P application increased the enzyme activities related to carbohydrate metabolism, especially sucrose synthase (7.6 %-59.4 %) and acid invertase (3.9 %-58.6 %), which reduced sucrose (3.3 %-32.2 %) and starch (4.3 %-28.7 %) contents at the peak boll setting stage. Efficient utilization of sucrose and starch enhanced root productivity, the ratio of root to shoot (R/S) reduced by 2.7 %-21.6 %, while the boll loading of root system (BLR) and boll capacity of root system (BCR) increased by 0.6 %-39.2 % and 3.1 %-50.6 % at the boll opening stage, respectively, favoring the formation of seedcotton yield. Furthermore, when the R/S, BLR, and BCR reached 0.12, 0.81 boll g−1, and 4.33 g g−1, cotton harvested the maximum theoretical yield of 3780, 3774, and 4069 kg ha−1, respectively. ConclusionsStraw retention combined with P application increased root productivity and seedcotton yield by promoting the utilization of root carbohydrates. ImplicationsThis study revealed the internal mechanism for straw retention combined with P application to affect seedcotton yield from the angle of root carbohydrate metabolism and provided a theoretical basis for rationally reducing P fertilizer under straw retention.

Impacts of long-term application of best management practices on yields and root carbohydrate content in asparagus (Asparagus officinalis) (UK)

Yield physiology of asparagus (Asparagus officinalis L.) is strongly influenced by biotic factors such as crown and root rot caused by Fusarium spp. and by abiotic conditions such as precipitation or temperatures, duration of each harvest, and field management practices. Asparagus yields are linked to the availability of soluble carbohydrates (CHO) in the storage root system which is considered a key factor in asparagus productivity. The aim of this study was to quantify the impacts of the long-term application of a range of potential Best Management Practices (BMPs) on yield and storage root carbohydrate content in green asparagus in a long-term field trial. The trial was established in 2016 with the asparagus ‘Gijnlim’ variety. Commercial yields were collected in 2018, 2019 and 2020. Root carbohydrate content was determined in 2019 and 2020. BMPs included (1) companion crops - Rye (Secale cereale L.), Mustard (Sinapis alba L.), (2) interrow surface mulch applications of either straw mulch or PAS 100 compost (Publicly available specification) in combination with shallow soil disturbance (SSD), (3) the conventional practice and modifications of the conventional tillage practice by applying SSD or not applying SSD and (4) a zero-tillage option. Annual re-ridging (R) and not ridging (NR) were applied to BMP options 1–3. SSD had no significant impact on asparagus yields while annual re-ridging negatively affected total yields of treatments with bare soil interrows, which were managed without SSD. Conventional practice was associated with a 22% yield reduction and ∼€4250 ha−1 annual loss in potential revenue as compared to the Zero-tillage treatment. Companion cropping with mustard did not have a significant impact on asparagus yields. Rye without annual re-ridging was however associated with yield reductions of > 20% as compared to the Conventional practice. PAS 100 Compost applied in asparagus interrows (at 25 t ha−1 per year) in combination with SSD without annual re-ridging resulted in improvements to yields of 20%, 10% and 34% in 2018, 2019 and 2020, respectively, as compared to the Conventional practice. No correlation was observed between storage root soluble carbohydrate content and asparagus yields. The results of this study confirmed that asparagus yield, and thus total farm income can be significantly improved through implementation of several of the BMPs investigated.

A 6-yr evaluation of prescribed-fire timing on yearling cattle growth performance and plant community dynamics on native tallgrass prairie in the Kansas Flint Hills

Abstract A 6-yr experiment was conducted to determine the effects of prescribed-fire season on stocker cattle growth performance and rangeland plant community characteristics in the Kansas Flint Hills. Eighteen pastures were grouped by watershed and each watershed was randomly assigned to 1 of 3 prescribed-fire treatments: spring (11 April ± 5.7 d), summer (25 August ± 6.2 d), or autumn (2 October ± 9.0 d). All burns were applied prior to grazing in years 1, 2, 3, and 5; however, no burns were applied in year 4 because of unfavorable burn conditions. Over 5 consecutive grazing seasons, 1,939 yearling stocker calves (initial BW = 281 ± 58.9 kg) were grazed from May to August at a targeted stocking density of 280 kg live-weight + ha−1. Beginning in June of 2018 (pretreatment), a permanent 100-m transect was established in each pasture and was used to determine plant-species composition using a modified step-point method. Forage biomass accumulation and root carbohydrate concentrations of 4 native tallgrass plant species were also measured. All data were analyzed as a completely randomized design using a mixed model. Average daily gain (ADG) was 0.05 to 0.07 kg greater (P = 0.02) for calves grazing spring-burned pastures compared with calves grazing summer- or autumn-burned pastures; however, ADG did not differ (P ≥ 0.55) between calves assigned to the summer or autumn prescribed-fire treatments. Basal cover of all graminoids and all forbs did not differ (P ≥ 0.30) among prescribed-fire treatments; however, basal cover of C3 grasses tended (P = 0.06) to be greater while basal cover of C4 grasses tended (P = 0.08) to be less in autumn-burned pastures compared with spring-burned pastures. Forage biomass accumulation did not differ (P = 0.58) among treatments. In addition, root starch or root water-soluble carbohydrate concentrations in big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), Indiangrass (Sorghastrum nutans), or purple prairieclover (Dalea purpurea) did not differ (P ≥ 0.26) among prescribed-fire treatments. Overall, we interpreted these data to suggest that prescribed-fire timing had small influences on yearling stocker cattle growth performance and rangeland plant composition but did not influence forage biomass accumulation or root carbohydrate concentrations of key native tallgrass plant species in the Kansas Flint Hills.

Interactive effect between tree ageing and trunk-boring pest reduces hydraulics and carbon metabolism in Hippophae rhamnoides.

Sea-buckthorn (Hippophae rhamnoides) is widely distributed across the Eurasian continent. Recently sea-buckthorn has shown premature ageing and decline when confronted with water deficiency and Holcocerus hippophaecolus damage in northwest China and the Loess Plateau region. However, the physiological process of sea-buckthorn senescence in response to drought and pest damage is still unknown. In this study, 4-year-old (4y), 15-year-old normal growth (15yN) and 15-year-old seriously moth-damaged sea-buckthorn plants (15yH) were used as the research objects. The growth of branches and roots, branch water potential and percentage loss of conductivity (PLC), branch vulnerability to embolism (quantified by P50, xylem water potential at 50 % of PLC), branch xylem parenchyma cell viability, photosynthesis and the non-structural carbohydrate (NSC) content in branches and roots in dry and wet seasons were measured. The results showed that the length, basal diameter of 1-year-old branches and the leaf area of 4y trees were significantly larger than that of 15yN and 15yH trees, and the fine root density of 15yH trees was significantly lower than that of 15yN trees in all measured areas. The branch-specific hydraulic conductivity of 15yN and 15yH trees was only 50.2 % and 12.3 % of that of 4y trees, and the P50 of 4y, 15yH and 15yN trees was -3.69 MPa, -2.71 MPa and -1.15 MPa, respectively. The midday water potential and photosynthetic rate were highest in 4y trees, followed by 15yN and then 15yH trees in both the dry season and wet seasons, while branch PLC declined in the opposite direction (15yH trees highest, 4y trees lowest). The degree of PLC repair within a day was highest in 4y trees, followed by 15yN and then 15yH trees, and the viability of xylem cells was consistent with this pattern. The branch xylem starch and NSC content of 4y and 15yN trees were significantly higher than that of 15yH trees in the dry season, and the root starch and NSC content of 4y trees were significantly higher than that of 15yH trees in the two seasons. The above results suggest that the hydraulic properties of the normal elderly and seriously pest-damaged sea-buckthorn were significantly worse than in juvenile plants. Narrower early wood width and vessel density, high embolism vulnerability and weak embolism repair capacity led to the decline in water-conducting ability, and similarly further affected photosynthesis and the root NSC content. The decline in xylem parenchyma cell viability was the main reason for the limited embolism repair in the branches.

Response of the fine root morphological and chemical traits of Tamarix chinensis to water and salt changes in coastal wetlands of the Yellow River Delta.

To explore the adaptation of the fine root morphology and chemical characteristics of Tamarix chinensis to water–salt heterogeneity in the groundwater–soil system of a coastal wetland zone, T. chinensis forests at different groundwater levels (high: GW1 0.54 m and GW2 0.83 m; medium: GW3 1.18 m; low: GW4 1.62 m and GW5 2.04 m) in the coastal wetland of the Yellow River Delta were researched, and the fine roots of T. chinensis standard trees were excavated. The fine roots were classified by the Pregitzer method, and the morphology, nutrients, and nonstructural carbohydrate characteristics of each order were determined. The results showed that the groundwater level had a significant indigenous effect on the soil water and salt conditions and affected the fine roots of T. chinensis. At high groundwater levels, the specific root length and specific surface area of fine roots were small, the root tissue density was high, the fine root growth rate was slow, the nutrient use efficiency was higher than at low groundwater levels, and the absorption of water increased with increasing specific surface area. With decreasing groundwater level, the N content and C/N ratio of fine roots first decreased and then increased, and the soluble sugar, starch, and nonstructural carbohydrate content of fine roots first increased and then decreased. At high and low groundwater levels, the metabolism of fine roots of T. chinensis was enhanced, and their adaptability to high salt content and low water content soil environments improved. The first- and second-order fine roots of T. chinensis were mainly responsible for water and nutrient absorption, while the higher-order (from the third to fifth orders) fine roots were primarily responsible for the transportation and storage of carbohydrates. The fine root morphology, nutrients, nonstructural carbohydrate characteristics, and other aspects of the water and salt environment heterogeneity cooperated in a synergistic response and trade-off adjustment.

Effect of early cane pruning on yield components, grape composition, carbohydrates storage and phenology in <i>Vitis vinifera</i> L. cv. Merlot

Dormant cane pruning has a great impact on vineyard management both in terms of labour costs and the time required to complete this field operation in the absence of mechanisation. In this study, we investigated over three seasons the influence of five pruning dates on yield components, grape composition, phenology and carbohydrate reserves in the variety Merlot, grown in a warm climate area. Pruning was conducted soon after harvest, at the end of leaf fall, two bud dormancy stages and vine bleeding. Early pruning, carried out a few days after the grape harvest, did not significantly affect vine productivity or grape composition in the next season compared to full winter pruning. Similarly, non-structural carbohydrate concentration in trunk and roots showed no difference just before budburst, no matter the timing of pruning. Late winter pruning at vine bleeding slightly postponed budburst and flowering; it also delayed veraison in one out of two years of observation without affecting grape maturity. Our findings suggested that, in a warm-climate area where leaf fall occurs within a ten-week period after harvest, early pruning had no detrimental effects on reserve accumulation in storage organs and, therefore, in vine yield and grape composition in the next harvest, thus allowing viticulturists to operate winter pruning over an extended interval of time.

Belowground carbon dynamics in Scots pine stands

Boreal forest soils are globally one of the most extensive carbon storages, whereas soil respiration (CO2 efflux) forms the largest carbon flux from the ecosystem to the atmosphere. Current changes in the world climate may have unpredictable effects on belowground carbon processes, and thereby, on the carbon balance of boreal forests. To better understand the various processes in soil and to quantify the potential changes in the carbon cycle, forest-floor respiration (RFF) was partitioned into five different components, and tree-root respiration (RR) was estimated, using four different methods in a mature boreal Scots pine (Pinus sylvestris L.) stand in southern Finland. Non-structural carbohydrate (NSC) concentrations in tree roots were determined, and carbon allocation to belowground by trees was estimated with the whole-tree carbon model ‘CASSIA’. In addition, RR and heterotrophic soil respiration (RH) were separated using root exclusion in seven coniferous forests along a latitudinal gradient in Northern and Central Europe. The RR comprised almost half of the RFF, the RH almost a third, and ground vegetation and respiration of mycorrhizal hyphae the remaining fifth in the boreal Scots pine stand. While the annual RR decreased throughout the first three study years, the RH increased when the mycorrhizal roots were excluded from the treatments. The RR and most of the NSC concentrations were higher in the warmer years and lower in the cooler, as estimated with most of the methods. Three methods resulted in rather similar RR estimations, while the RR estimated with root incubation was significantly lower. The RR was over 50% of the annual photosynthesis in the northernmost forest stand, whereas in the southernmost stand it was only up to 15%. Carbon allocation to the belowground, as modelled with CASSIA was a third of the annual photosynthesis on average and almost 5% for the symbiotic mycorrhizae.

Same Season and Carry-Over Effects of Source-Sink Adjustments on Grapevine Yields and Non-structural Carbohydrates

The grapevine (Vitis vinifera L.) is managed to balance the ratio of leaf area (source) to fruit mass (sink). Over cropping in the grapevine may reveal itself as spontaneous fruit abortion, delayed ripening, or as alternate bearing. The aim of this work was to study the same season and carry-over effects of manipulating source to sink ratios on grapevine phenology, leaf gas exchange, yield components, berry soluble solids accumulation, and reserve carbohydrate and soluble sugar concentration in roots. Cabernet Sauvignon grapevines were subjected to defoliation (33, 66, and 100% of the leaves retained) and fruit removal treatments (33, 66, and 100% of clusters retained) arranged in a factorial design. Results from two seasons of source-sink manipulations were substantially different. In both seasons defoliation treatments affected season-long net carbon assimilation (AN) and stomatal conductance (gs) where the less leaves were retained, the greater the AN and gs, and fruit removal had no impact on leaf gas exchange. In the first season, leaf area to fruit mass was hardly related to berry soluble solids and in the second season they were strongly correlated, suggesting a degree of acclimation. Defoliation treatments had great impacts on berry size, berries per cluster, and total soluble solids in both years. Fruit removal treatments only had effects on berry mass and berries per cluster in the first season, and only on berry soluble solids in the second. The predominant effect of defoliation (carbon starvation) cascaded onto reducing root starch content, root mass and delaying of veraison and leaf senescence, as well as harvest which was delayed up to 9 weeks with 33% of the leaves retained. In a third season, where grapevines grew without treatments, defoliation treatments had resultant carryover effects, including reduced leaf area, number of berries per cluster, clusters per vine, and yield, but not on leaf gas exchange dependent on previous seasons' severity of defoliation. Balancing source-to-sink ratio is crucial to obtain an adequate speed of ripening. However, this was the culmination of a more complex whole-plant regulation where the number of leaves (source strength) outweighed the effects of fruits (sink strength).

Root Growth and Carbohydrate Content of <i>Phalaenopsis</i> ‘KS Little Gem’ Young Plantlets as Influenced by Temperature and Fertilizer Application

Root Growth and Carbohydrate Content of <i>Phalaenopsis</i> ‘KS Little Gem’ Young Plantlets as Influenced by Temperature and Fertilizer Application

Nonstructural carbohydrates, carbon and nitrogen concentrations in fine roots of Quercus variabilis secondary forests after two different periods of regeneration

Aim of study: Quercus variabilis is a sclerophyllous oak with strong resprouting capabilities and whose regeneration is facilitated by the development of stump shoots following disturbance. During secondary forest regeneration, fine roots are important organs relative to changes in stand characteristics. Here, we aimed to provide novel insights into the chemical composition variations in roots with seasonality and root order hierarchy in a Q. variabilis forest at different periods of regeneration.Area of study: The forest is located next to the Baxianshan National Reserve in the southern part of the Yanshan Mountains, Tianjin, China.Materials and methods: Six plots were established in stands with either eight or 40 years of regeneration for the repeated sampling of fine roots during the growing season of 2019. All roots were classified by branch order. The first three root orders were collected to analyse the concentrations of nonstructural carbohydrate, carbon, and nitrogen.Main results: Short-term regeneration stands showed a reduction in soil moisture and an increase in soil temperature because of the lower canopy cover, compared to long-term stands. Soluble sugar and starch were lower in roots of short-term stands than in those of long-term stands, and the decreasing ratio of both parameters was observed in short-term stands. Less carbon and greater nitrogen concentrations of fine roots were found in short-term stands than in long-term stands, which resulted in weaker C/N ratio values. Nonstructural carbohydrate was stored more in higher order roots than terminal roots and presented greater sensitivity to forest regeneration. Redundancy discriminate analysis demonstrated that the nonstructural carbohydrate concentrations in roots were affected positively by canopy cover and negatively by soil temperature.Research highlights: The seasonal dynamics and branch allocation of chemical reserves in fine roots varied in the different periods of forest regeneration because of the discrepancy between the canopy cover and soil traits. Less nonstructural carbohydrate and a lower C/N ratio at the onset of forest regeneration may elevate the risk of root death.Keywords: soluble sugar; starch; forest regeneration; root order; C/N ratio; redundancy discriminate analysis.

Effects of prescribed fire timing on grazing performance of yearling beef cattle, forage biomass accumulation, and plant community characteristics on native tallgrass prairie in the Kansas Flint Hills.

Recent research demonstrated that mid- or late-summer prescribed fires can be employed to manage sericea lespedeza (Lespedeza cuneata) infestations in the Kansas Flint Hills. The effects of prescribed fire applied during the growing season (i.e., August to October) on grazing performance of yearling cattle have not been evaluated. Native pastures (n = 18; 22 ± 4.0 ha) were grouped by watershed and assigned randomly to one of three prescribed-fire treatments: spring (7 April ± 2.1 d), summer (21 August ± 5.7 d), or autumn (2 October ± 9.9 d). Yearling beef cattle were grazed from May to August at a targeted stocking density of 280 kg live-weight/ha following prescribed-fire application. Forage biomass accumulations, soil cover, plant species composition, and root carbohydrate concentrations in four native plant species were evaluated. Total body weight (BW) gains and average daily gain were greater (P = 0.01) for cattle that grazed the spring and summer prescribed-fire treatments compared with those that grazed the autumn prescribed-fire treatment. As a result, final BW were greater (P = 0.04) in the spring and summer treatments than the autumn treatment. Conversely, forage biomass accumulations did not differ (P = 0.91) between fire regimes. Proportions of bare soil were greater (P < 0.01) in the spring treatment compared with the summer and autumn treatments, whereas proportions of litter on the soil surface were greater (P < 0.01) in summer- and autumn-burned pastures compared with spring-burned pastures. Total basal cover of graminoids and forbs did not differ (P ≤ 0.15) between prescribed fire treatments. Likewise, total basal cover of C3 or C4 perennial grasses did not differ (P ≥ 0.23) between prescribed-fire treatments. No treatment differences (P = 0.24) in root starch or root water-soluble carbohydrate concentrations in big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), Indiangrass (Sorghastrum nutans), or purple prairieclover (Dalea purpurea) were detected. These data were interpreted to suggest that summer or autumn prescribed fire can be applied without reducing forage biomass accumulations, root carbohydrate concentrations in key native plant species, or considerably altering native plant populations compared with conventional spring-season prescribed fire; however, summer prescribed fire could be favored over spring or autumn prescribed fire both to maintain stocker cattle growth performance and to achieve control over sericea lespedeza.

Characterization of Eucalyptus camaldulensis clones with contrasting response to short-term water stress response

The intra-specific diversity of adaptive traits in tree species is a key factor determining their survivability under stress conditions. In vitro screening under controlled environmental conditions to evaluate the whole-tree response to drought condition is routinely employed to select tolerant genotypes for breeding and conservation programs. The present study demonstrates the response of two Eucalyptus camaldulensis clones to progressive short-term water stress condition at morphological, physiological, biochemical, molecular and metabolite levels. Distinct differential response was recorded in root: shoot, specific leaf area, relative water content and leaf phenol content across the clones. The biochemical changes were significant in root tissues of both genotypes after stress imposition when compared to leaf. Metabolite profiling revealed accumulation of α-limonene, fenchyl alcohol, borneol, 4-terpineol, 4-thujanol, aromadendrene, α-eudesmol and eicosyl acetate in tolerant clone under water stress condition. Molecular profiling documented up-regulation of germin (GER3) in leaf and several transcription factors like DREB, CBF2 and CBF1c in root tissues of tolerant clone. This study has presented several parameters with distinct variation across the tolerant and susceptible clone like root carbohydrate content, stomatal density and root phytohormone level, which can be used for nursery screening of Eucalyptus clones for water stress tolerance.

Root Response of Moso Bamboo (Phyllostachys edulis (Carrière) J. Houz.) Seedlings to Drought with Different Intensities and Durations

The root of Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) develops extremely rapidly at seedling phase and is highly sensitive to water content in soil, but its response patterns and adaptation strategies of its root to drought are little known. The aim of this study was to investigate the response of root morphology and architecture of Moso bamboo to drought at seedling phase and then to explore the drought adaptation strategies of its root. One-year-old potted seedlings of Moso bamboo were planted under three drought treatments (control, moderate drought and severe drought) for three months. Seedling growth, specific root length (SRL), root architecture (fractal dimension (FD), root branching angle (RBA) and root topological index (TI)) and non-structural carbohydrate (NSC) concentrations in roots were measured every month. The results are as follows: (i) The dry weight of root and shoot decreased significantly under drought stress. (ii) The SRL decreased under drought stress in the early duration (the first month), and then increased in the late duration (the third month). Both FD and RBA decreased, while TI and the concentrations of NSCs increased under drought stress. (iii) The NSC concentrations were positively correlated with SRL and TI, but exhibited an inverse relationship to FD and RBA. Our results indicated that Moso bamboo seedlings formed a “steeper, simpler, expensive (low SRL and high TI)” root architecture to adapt to a short-term drought (one month), and formed a “cheaper (high SRL)” root to adapt to a long-term drought (three months). Increase of NSC concentrations supported the root architecture plasticity to some extent.

Growth and respiratory metabolic adaptation strategies of riparian plant Distylium chinense to submergence by the field study and controlled experiments

Submergence tolerance is crucial when thinking in promising species for restoration of ecosystems prone to suffer extreme flooding events. In this study, two-year-old seedlings of Distylium chinense were subjected to one field study and five controlled experiments: unsubmerged and watered daily as controls (CK) and completely submerged for 30, 60, 90 and 120 days, respectively followed by a 60-day recovery period to test the submergence tolerance. The results showed that the survival decreased with the increasing flooding duration. Different submergence duration treatments affected dry mass accumulation and carbohydrate content of roots, stems and leaves. Flooding stress affected the activities of pyruvate decarboxylase (PDC), ethanol dehydrogenase (ADH) and lactic dehydrogenase (LDH) enzymes, which indicated the roots and leaves adapt to long-term flooding by reinforcing their anaerobic respiration and activities of ADH were higher than those of LDH for roots and leaves with stronger alcoholic fermentation mainly. After de-submergence, the recovery patterns of carbohydrate were coincided with those of dry mass accumulation of the roots, stems and leaves. A significant regression equation analysis showed root starch content and dry mass accumulation were the major factors affecting the seedling survival. And D. chinense accumulated substantial amounts of carbohydrate before submergence and invested more in roots and stems than in leaves, which enhances long-term survival under submergence. Carbohydrate storage is a key functional trait that can explain high survival under submergence. D. chinense may have adopted a suite of growth and respiratory metabolic adaptation strategies to survive long-term submergence.

Seedling regeneration techniques affect root systems and the response of Quercus robur seedlings to water shortages

Regenerating oak seedlings by different methods impacts taproot architecture, root-to-shoot allometry and, potentially, soil water use and plant growth under water limitations. In the present study, Quercus robur (L.) seedlings regenerated by four different methods – sowing (acorn-sown seedlings), sowing followed by shoot clipping (coppiced), sowing followed by root-pruning (root-pruned), and container planting with the root plug intact (containerized) – were subjected to four water-shortage regimes – full watering and 75, 50, and 25% of full watering. These treatments were used to test the hypotheses that root morphology, anatomy and biochemistry varied among regeneration methods, and, thus, differentially affected plant responses to water-shortages. For most traits, the response to water shortage of acorn-sown and containerized seedlings was similar, and opposite to that of coppiced and root-pruned seedlings. Water shortage did not change tree allocation to total root biomass among regeneration methods but altered the partitioning between absorptive and structural roots within the root system. Acorn-sown and containerized seedlings produced more pioneer roots, and coppiced and root–pruned seedlings more highly-branched fine roots with greater specific root length and specific root surface area under greater water shortage. Thus, acorn-sown and containerized oaks appeared to be primed for water foraging, and coppiced and root-pruned oaks for water absorption efficiency in response to water shortage. Water shortage caused a reduction in nonstructural carbohydrate concentrations in fine roots of acorn-sown and containerized seedlings and in the taproot of coppiced and root-pruned seedlings. Results generally indicated that seedling response to water limitation depended on the regeneration method, highlighting the importance of root–to–shoot allometry, taproot development, and carbon reserve mobilization for plant functioning under water shortage. Acorn-sown and containerized oaks seedlings might be more suitable for forest regeneration in sites characterized by severe water shortage periods. The reduction of taproot starch reserves under strong water shortage may render root-pruned oak trees more susceptible to topsoil water deficit than acorn-sown trees. This work contributes to understand drought acclimation and to identify the most adequate forestry regeneration practices to adapt forest ecosystems to ongoing climatic changes.

Response of Fine Root Carbohydrate Content to Soil Nitrogen Addition and Its Relationship with Soil Factors in a Schrenk (Picea schrenkiana) Forest

Fine roots are vital for water and nutrient uptake in plants. Understanding the responses of metabolic traits to changing environmental conditions is critical, but little is known. In this study, the carbohydrate content of fine roots was characterized for six soil layers and three diameter classes in a Schrenk spruce (Picea schrenkiana) forest on the Tianshan Mountains of China. Soil nitrogen addition can influence carbohydrate content, but the degree is related to soil layer and fine root diameter. Specifically, as nitrogen (N) levels increased, the soluble sugar, cellulose, lignin and structural carbohydrate content (SC) all increased and then decreased; the starch and non-structural carbohydrate content (NSC) decreased gradually. In addition, N addition had significant effects on starch and cellulose content, as well as total carbohydrates. The interaction between root diameter and N addition also influenced soluble sugars, cellulose and NSC, while the three-way interaction among N addition, soil layer and diameter only affected cellulose content and NSC/SC. In the control treatment (no nitrogen addition), the following soil factors influenced fine root metabolism in order of decreasing importance: C:N, C:P, N:P, C, N, water content, bulk density, pH, conductivity, and P. In the N addition treatments, the soil conductivity, pH, and N content were strongly correlated with root metabolic characteristics.

Non-structural carbohydrate concentrations of Fagus sylvatica and Pinus sylvestris fine roots are linked to ectomycorrhizal enzymatic activity during spring reactivation

We evaluated whether changes in fine root non-structural carbohydrate reserves of Fagus sylvatica and Pinus sylvestris trees influence potential enzymatic activities of their ectomycorrhizal symbionts from winter towards spring reactivation, and whether these changes influence potential soil enzymatic activities. We analyzed sugar and starch concentrations in the fine roots of Fagus sylvatica and Pinus sylvestris and potential activities of ß-glucosidase, ß-xylosidase, and cellobiohydrolase (as proxies for carbon-degrading enzymes) as well as leucine aminopeptidase and chitinase (as proxies for nitrogen-degrading enzymes) of their dominant ectomycorrhizal symbionts as well as in the soil. Sugar concentrations in the fine roots were significantly positively correlated with enzymatic activities of the ectomycorrhizal symbionts. In Pinus sylvestris, both carbon- and nitrogen-degrading enzyme activities showed significant positive correlations with fine root sugar concentrations. In Fagus sylvatica, fine root sugar concentrations were explicitly positively correlated with the activity of nitrogen-degrading enzymes. The chitinase activity in the soil was found to be strongly positively correlated with the enzymatic activity of the ectomycorrhizal symbionts as well as with fine root sugar concentrations. Fine root carbohydrate concentrations of Fagus sylvatica and Pinus sylvestris trees and enzymatic activities of their associated ectomycorrhizal fungi are connected. The specific nutrient demand of the tree species during spring reactivation may affect ectomycorrhizal enzymatic activity via carbon mobilization in the fine roots of Fagus sylvatica and Pinus sylvestris. Moreover, our results suggest that trees indirectly contribute to the degradation of fungal necromass by stimulating ectomycorrhizal chitinase activity in the soil.

Correlation between growth characteristics and quality of rhizomes of Notopterygium incisum under wild tending

Study the growth and development process of rhizomes(bamboo-like part) of Notopterygium incisum and the changes of carbohydrate, endogenous hormones and secondary metabolites, and provide theoretical guidance for the formation of high-quality N. incisum medicinal commodities under artificial cultivation. The One-year-old seedlings were transplanted to the original habitat,and the growth and physiological characteristics of N. incisum were dynamically monitored. The results showed that: ① Seedlings transplanted to the original habitat in spring could form rhizomes(bamboo-like part) in the same year. ② After 60 days of transplantation, the root length and root diameter of underground part of N. incisum had increased rapidly, and carbohydrate content in roots and rhizomes had accumulated rapidly. After 120 days of transplantation, the roots and rhizomes of underground part had grown slowly, and starch content in roots and rhizomes increased continuously, while sucrose and total soluble sugar content decreased gradually. ③ The content of abscisic acid(ABA) in rhizomes decreased firstly and then increased, while the indole acetic acid(IAA) content stabilized firstly and then increased rapidly, and the contents of gibberellin(GA_3) and zeatin riboside(ZR) continued to increase. ④ The content of notopterol in rhizomes was higher than that in roots, while the content of isoimperatorin was lower than that in roots, but the total content of the both in rhizomes was higher than that in roots. Therefore, N. incisum can form rhizomes with high content of secondary metabolites under wild tending, and the growth and development of rhizomes are closely related to changes in carbohydrates and are regulated by related endogenous hormones.

Influence of Regulated Deficit Irrigation and Environmental Conditions on Reproductive Response of Sweet Cherry Trees.

The reproductive response of fifteen year old sweet cherry trees (Prunus avium L.) combination ‘Prime Giant’/SL64 under Mediterranean climate to deficit irrigation was studied in a commercial orchard in south-eastern Spain for four seasons. Three irrigation treatments were assayed: (i) control treatment, irrigated without restrictions at 110% of seasonal crop evapotranspiration; (ii) sustained deficit irrigation treatment, irrigated at 85% ETc during pre-harvest and post-harvest periods, and at 100% ETc during floral differentiation, and (iii) regulated deficit irrigation treatment, irrigated at 100% ETc during pre-harvest and floral differentiation and at 55% ETc during post-harvest. The duration and intensity of the phenological phases of sweet cherry trees, including cold accumulation, flowering, fruit set or fruit and vegetative growth, were assessed to ascertain whether the different irrigation strategies imposed affect the trees’ reproductive response (fruit yield, fruit size, leaf area, fruit physiological disturbances, and starch and soluble carbohydrates stock) in the same season or have a negative effect in the next season. Deficit irrigation did not advance, enhance or penalize flowering, fruit set or fruit growth. Neither did it diminish carbohydrate concentration in roots or cause an increase in the number of double fruits, which was more linked to high temperatures after harvest. However, deficit irrigation decreased vegetative growth and consequently the leaf area/fruit ratio, which, when it fell below 180 cm2 fruit−1, affected cherry size.