Non-structural Carbohydrate Levels Research Articles

Effect of nonstructural carbohydrates on production performance, rumen metabolism and rumen health in lambs fed with isocaloric and isonitrogenous complete diets.

Nonstructural carbohydrates (NSC) are readily fermentable in the rumen and, are a critical factor while preparing protracted feed for higher animal performance. Four isocaloric and isonitrogenous complete feeds were prepared for this investigation to contain varying levels of nonstructural carbohydrates viz., 40.13 (NSC1), 45.21 (NSC2), 50.00 (NSC3) and 55.85 (NSC4) per cent, respectively. The four isocaloric and isonitrogenous complete feeds were tested in 32 Mecheri ram lambs (around three months of age) in a completely randomised block design (n = 8), and the lambs were fed their respective feed for six months. The study revealed that the increased NSC level in the complete diet increased the body weight and weight gain linearly (P < 0.05). The dietary NSC level affected the dry matter consumption in a quadratic manner (P < 0.05) and the lambs of the NSC4 group consumed significantly (P < 0.05) less DM compared to other dietary groups. The overall average feed conversion efficiency differed significantly (P < 0.05) among dietary groups. The correlation between dietary NSC level and faecal score was quadratic (r2 = 62.7, P < 0.05). The rumen pH, total nitrogen and NH3-N concentration were linearly decreased (P < 0.05) and the molar proportion of total short-chain fatty acids and propionic acid were increased (P < 0.05). The energy loss expressed as methane production was significantly (P < 0.01) lower for the high NSC diet-fed lambs. The lambs fed on a low NSC diet had significantly (P < 0.05) lower carcass weights, dressing percentage and loin eye area. The per cent share of rumen weight in the total fore stomach and the rumen papillae measurements length, width and surface area were significantly (P < 0.05) higher in high NSC diet-fed lambs. Increased levels of NSC in the diet increased (P < 0.05) fat deposition in the internal organs. The saturated fatty acids content in the meat was significantly (P < 0.05) lowered, whereas, the oleic acid and linoleic acid were increased (P < 0.05) as the NSC level increased in the diet. The study revealed that as the level of NSC increased in the complete diet there was a concomitant improvement in the final body weight, ADG and feed efficiency of post-weaned Mecheri lambs. It can therefore be recommended that the complete feed with 50 per cent NSC levels would be optimum to reap maximum returns from fattening Mecheri lambs.

MiR408 balances plant growth and heat response in rice

MicroRNAs are small noncoding RNAs that regulate gene expression by targeting complementary mRNA molecules. Among them, microRNA408 (miR408) is an ancient microRNA influencing plant growth and aiding in abiotic stress adaptation. We proved that miR408 sliced uclacyanin7 (UCL7) directly by degradome sequencing. However, the mechanisms underlying the balance between growth and stress response of rice (Oryza sativa L.) controlled by miR408 remain unclear. We conducted a study comparing Nipponbare (wild-type, WT) plants with miR408–3p-overexpression (miR408–3p-OX) and UCL7-overexpression (UCL7-OX) plants under normal and heat stress conditions. Through RNA-sequencing, physiological measurements, and phenotype examination, we observed that miR408 overexpression resulted in increased dry weight and grain yield, higher levels of ATP and non-structural carbohydrates (NSC), improved photosynthesis, and reduced H2O2 content, antioxidant enzyme activity, and ATPase activity in seedling plants compared to UCL7-OX plants. Additionally, the application of H2O2 scavengers, such as ascorbic acid (ASA) and dimethylthiourea (DMTU), further enhanced dry weight and photosynthesis by reducing H2O2 levels. Under heat stress conditions, miR408 overexpression sharply increased H2O2 content, antioxidant enzyme activity, ATP levels, and ATPase activity compared to UCL7-OX plants, thereby enhancing heat tolerance in rice seedlings. These findings suggest that miR408 and its target gene UCL7 participate in regulating energy homeostasis to achieve a balance between growth and heat response. This regulation involves modulating H2O2 levels and optimizing the relationship between the target of rapamycin (TOR) and SNF1-related protein kinase 1 (SnRK1) in rice.

Marine heatwaves recurrence aggravates thermal stress in the surfgrass Phyllospadix scouleri

The surfgrass Phyllospadix scouleri grows in highly productive meadows along the Pacific coast of North America. This region has experienced increasingly severe marine heatwaves (MHWs) in recent years. Our study evaluated the impact of consecutive MHWs, simulated in mesocosms, on essential ecophysiological features of P. scouleri. Overall, our findings show that the plants' overall physiological status has been progressively declining. Interestingly, the indicators of physiological stress in photosynthesis only showed up once the initial heat exposure stopped (i.e., during the recovery period). The warming caused increased oxidative damage and a decrease in nitrate uptake rates. However, the levels of non-structural carbohydrates and relative growth rates were not affected. Our findings emphasize the significance of incorporating recovery periods in this type of study as they expose delayed stress responses. Furthermore, experiencing consecutive intense MHWs can harm surfgrasses over time, compromising the health of their meadows and the services they offer to the ecosystem.

The metabolism of nonstructural carbohydrates, lipids, and energy in two Cycas species with differential tolerance to unexpected freezing stress.

With the climate warming, the occurrence of freezing events is projected to increase in late spring and early autumn in the Northern Hemisphere. Observation of morphological traits showed that Cycas panzhihuaensis was more tolerant to unexpected freezing stress than C. bifida. Energy balance is crucial for plant tolerance to stress. Here, we aimed to determine whether the different responses of the two species to the unpredicted freezing stress were associated with the metabolism of energy and related substances. The effects of unexpected freezing temperatures on C. panzhihuaensis and C. bifida were studied by measuring chlorophyll fluorescence parameters, energy charge and the profile of nonstructural carbohydrates (NSC) and lipids. C. panzhihuaensis exhibited higher stability of photosynthetic machinery than C. bifida under unpredicted freezing events. Significant interaction between species and treatments were observed in the energy charge, the level of NSC and its most components and the amount of most lipid categories and lipid classes. The decrease of soluble sugar and the increase of neutral glycerolipids at the early freezing stage, the accumulation of membrane glycerolipids at the late freezing stage and the continuous decrease of energy charge during the freezing period were the characteristics of C. panzhihuaensis responding to unexpected freezing stress. The degradation of membrane glycerolipids and the continuous decrease of soluble sugar during the freezing period and the accumulation of neutral glycerolipids and energy charge at the late freezing stage represented the characteristics of C. bifida responses. The different freezing sensitivity between C. panzhihuaensis and C. bifida might be associated with the differential patterns of the metabolism of energy, NSC and lipids. C. panzhihuaensis possesses the potential to be introduced to the areas of higher latitudes and altitudes.

Nutrient and Rumen Fermentation Studies of Indian Pasture Legumes for Sustainable Animal Feed Utilisation in Semiarid Areas

This study evaluated 5 annual and 11 perennial Indian pasture legumes species for their nutritive value, dry matter and mineral contents and in vitro fermentation parameters. Legume species differed significantly (p &lt; 0.05) in various nutritional aspects such as organic matter, crude protein (CP), ether extract, fibres and protein fractions. Perennial Clitoria ternateaa had higher (p &lt; 0.05) buffer soluble protein (477), while neutral detergent soluble protein was highest in annually grown Lablab purpureus (420 g/kg CP). Atylosia scarabaeoides (AS) had higher levels of nonstructural carbohydrates (NSCs) (392 g/kg dry matter (DM)) than structural carbohydrates (SC) (367 g/kg DM). Its rapidly degradable fraction (51.7 g/kg (total carbohydrate) tCHO) was lower (p &lt; 0.05) than other fractions of carbohydrates. Total digestible nutrients, digestible energy and metabolisable energy varied, with Desmodium virgatus (DV) having higher values and Stylosanthas seabrana (SSe) having the lowest. Predicted dry matter intake, digestible dry matter and relative feed value also showed significant differences (p &lt; 0.05). Annual grasses such as Dolichos biflorus, Macroptilium atropurpureum, Rhynchosia minima (RM) were found to be better balanced with micro minerals. In vitro dry matter degradability, partition factor, short-chain fatty acids and microbial protein production of legumes varied significantly (p &lt; 0.05). Gas and CH4 production (mL/g and mL/g (digestible DM) DDM) also varied, with Clitoria ternatea-blue having the highest gas production and C. ternatea -white (CT-w) and AS having lower CH4 production. Methane in total gas was low for DV, RM and CT-w (8.99%, 9.72% and 9.51%). Loss of DE and ME as CH4 varied (p &lt; 0.05) among the legumes. Each legume offers unique benefits, potentially allowing for tailored combinations of annual and perennial legumes to optimize rumen feed efficiency.

Chitosan nanoparticles upregulate C and N metabolism in soybean plants grown under elevated levels of atmospheric carbon dioxide

Despite the wide utilization of chitosan nanoparticles (CSNPs) as a promising approach for sustainable agriculture, their efficiency under elevated CO2 (eCO2), has not been evaluated. The interactive effects of CSNPs and eCO2 were evaluated on the growth and C and N metabolism of soybean plants. Plants were treated with CSNPs and grown under ambient CO2 (410 ppm, aCO2) or eCO2 (645 ppm). Regardless of CO2 level, CSNPs improved the net photosynthetic rate. CSNPs aggravated the effect of eCO2 treatment on the levels of non-structural carbohydrates (i.e., glucose, fructose, sucrose, and starch), especially in shoots, which was inconsistence with the upregulation of carbohydrates metabolizing enzymes. Being the most pivotal energetic and signaling organic compounds in higher plants, the synergistic action of CSNPs and eCO2 on the accumulation of soluble sugars upregulated the N metabolism as indicated by induced activities of nitrate reductase, arginase, glutamate dehydrogenase, glutamine synthetase, and glutamine oxoglutarate aminotransferase which was manifested finally as increased shoot and root total nitrogen content as well as proline and aspartate in roots. At the hormonal level, the coexistence of eCO2 with CSNPs further supports their positive impact on the contents of IAA and, to a lesser extent, GAs. The present data prove that the biofertilization capacity of CSNPs is even more potent under futuristic eCO2 levels and could even further improve the growth and resilience of plants.

Intrinsic morphology and spatial distribution of non-structural carbohydrates contribute to drought resistance of two mulberry cultivars.

Drought is one of the most adverse environmental stresses limiting plant growth and productivity. However, the underlying mechanisms regarding non-structural carbohydrates (NSCs) metabolism in source and sink organs are still not fully elucidated in woody trees. Saplings of mulberry cultivars Zhongshen1 and Wubu were subjected to a 15-day progressive drought stress. NSCs levels and gene expressions involved in NSCs metabolism were investigated in roots and leaves. The growth performance and photosynthesis, leaf stomatal morphology, and other physiological parameters were also analyzed. Under well-watered conditions, Wubu had higher root-to-shoot ratio (R/S) with higher NSCs in leaves than roots, while Zhongshen1 exhibited lower R/S with higher NSCs in roots than leaves. Under drought stress, Zhongshen1 showed decreased productivity and increased concentrations of proline, abscisic acid, reactive oxygen species and activities of antioxidant enzymes, while Wubu sustained comparable productivity and photosynthesis. Interestingly, drought resulted in decreased levels of starch and slightly increased soluble sugars in leaves of Wubu, accompanied by notable downregulation of starch-synthesizing genes and upregulation of starch-degrading genes. The similar patterns in NSCs levels and relevant gene expressions were also observed in roots of Zhongshen1. Concurrently decreased soluble sugars and unchanged starch in roots of Wubu and leaves of Zhongshen1 were found. However, the gene expressions of starch metabolism in roots of Wubu were unaltered, but in leaves of Zhongshen1 the starch metabolism was largely activated. These findings revealed that intrinsic R/S and the spatial distribution of NSCs in roots and leaves concomitantly contributed to drought resistance in mulberry.

Effects of NSC in different organs and at different growth stages on the yield of oil peony Fengdan with different ages.

Non-structural carbohydrates (NSC) as resource reserves of plants play important roles in energy supply for normal growth and reproduction under environmental stress. The yield of perennial crops is mainly determined by the carbohydrate production and allocation in the current growth season, as well as the re-allocation of NSC reserves. However, the contribution of NSC to crop yield has not been fully determined. Fengdan (Paeonia ostii) is a variety of oil Peony that is newly developed in China. The effects of tree age and NSC on yield were examined by investigated the variations of biomass, soluble sugars, starch, and NSC in the organ and whole tree levels in the dormant and ripening stages of Fengdan populations with 4-, 6-, and 8-year-old in 2020 and 5-, 7-, and 9- year old in 2021. Results showed that the biomass, yield (seed biomass), soluble sugars, starch, and NSC reserve of Fengdan at the whole tree level increased with the increase in age. Although consistent correlations were observed between soluble sugars, starch and NSC storage, and yield among the plants with different ages, Fengdan showed allometric growth relationships between the accumulation of soluble sugars, starch, and NSC and yield and biomass (standardized major axis analyses slope b ≠ 1). Tree age significantly affected biomass and its allocation and NSC levels, especially the yield of Fengdan plants. The results of the investigation of the variations in the relationships between the yield and seasonal fluctuations of NSC and biomass indicate that roots is the key storage structure, whereas stems both serve as sink and/or source functions for the adult (7-9a) plants. NSC level, particularly the concentration of soluble sugars, in stems mainly influences Fengdan yield. These findings together provide new insights into the mechanisms underlying the yield formation of Fengdan and have implications for manipulating sink-source relationship to achieve high yield.

Iso-osmotic calcium nitrate and sodium chloride stresses have differential effects on growth and photosynthetic capacity in tomato

Calcium nitrate [Ca(NO3)2] and sodium chloride (NaCl) are among the main salts used in cultivation and present in salinized soil, respectively. These salts at high levels would reduce photosynthetic capacity and eventually cause a reduction in tomato growth. To better understand the growth disruption caused by Ca(NO3)2 salt (from the fertilizer) and the other predominant salt NaCl in salinized soils, tomato plants were grown in half-strength Hoagland's nutrient solution with three treatments. Through 7 days of salt stress and later 7 days of recovery, we investigated tomato seedling growth, nonstructural carbohydrates accumulation, antioxidant capacity, photosynthetic gas exchange, and chlorophyll fluorescence parameters. We found that Ca(NO3)2 and NaCl stresses increased the levels of nonstructural carbohydrates, reactive oxygen species (ROS), and various antioxidant enzyme activities in tomatoes while lowering foliar photosynthetic capacity. Under iso-osmotic salt stress conditions, the disruption of photosynthesis by NaCl was greater than that brought about by the Ca(NO3)2 treatment, which was attributed to Na+ accumulation. Interestingly, Na+ increased the levels of nonstructural carbohydrates and disrupted the feedback inhibition of photosynthesis. In addition, Na+ inhibited the activities of antioxidant enzymes, leading to more ROS production that would disrupt the processes within various photosynthetic apparatus. Our study further revealed that foliar nonstructural carbohydrates played an important role in delaying the onset of photoinhibition and rapid recovery of photosystem damage after Na+stress.

Identifying possible thresholds for nonstructural carbohydrates in the insulin dysregulated horse.

Identifying intake levels of nonstructural carbohydrates (NSCs) that limit the postprandial insulinaemic response in the insulin dysregulated (ID) horse may help reduce hyperinsulinaemia-associated laminitis (HAL) risk. To determine if ID horses have thresholds for pure sources of starch and sugar, above which there is an augmented insulin response. Randomised crossover experiment. Fourteen adult horses (6 ID and 8 noninsulin dysregulated, NID; matched for bodyweight) were randomly fed eight dietary treatments. Dietary treatments were formulated using a base of low-nonstructural carbohydrate pellet (LNSC; 0.04 g of water-soluble carbohydrates (WSCs)/kg bwt and 0.01 g of starch/kg bwt), to which pure sugar (dextrose) or starch (50:50 mix of waxy-maize and oat starch powder) sources were titrated to create diets with increasing amounts of either WSC (0.06-0.17 g WSC/kg bwt), or starch (0.03-0.1g starch/kg bwt). Horses were fed each dietary treatment at a rate of 1g/kg bwt once over 12 weeks. Serial blood samples were collected pre- and up to 240 min postprandially. Insulin was determined via RIA and diet analytes were determined via wet chemistry. Statistical analysis was performed with a mixed effect model. Positive incremental area under the curve for insulin (IAUCi) was calculated for all horses and dietary treatments. There was no significant effect of diet in NID horses but diets with NSC >0.1g/kg bwt produced an augmented response in ID horses compared with the LNSC (p < 0.05). ID horses IAUCi were also significantly different to all NID IAUCi for diets with NSC >0.1g/kg (p < 0.04). Apparent thresholds for sugar and starch addition varied. Based on this study, using supplemental pure starch and sugar sources, ID horses seem to have an apparent threshold for NSC of around 0.1g/kg bwt/meal, above which significantly increased insulin responses are seen compared with NID horses.

Unraveling the Effects of Pruning Frequency on Biomass Productivity, Nonstructural Carbohydrates and Nitrogen Fixation Rates of Sesbania sesban

Tree pruning is a management tool in agroforestry systems for reducing shade, enhancing nutrient cycling or providing fodder. However, little information is available on the effect of pruning management on plant growth, nonstructural carbohydrate (NSC) levels in the roots and N2 fixation of Sesbania sesban. A glasshouse experiment was conducted to assess the effect of pruning frequency on biomass production, NSC levels and N2 fixation of Sesbania sesban. Pruning treatments consisted of a control (PF0), one pruning at 3 months after transplanting (MAT) (PF1), two successive prunings at 3 and 6 MAT (PF2), and three successive prunings at 3, 6 and 9 MAT (PF3), with each pruning removing shoot biomass above 50% of the initial height. The experiment was laid out in a completely randomized design (CRD) with four replications. Results showed that increasing pruning frequency resulted in decreased nodulation and nonstructural carbohydrate levels in the roots. Above and below ground biomass, root length, percentage N derived from the atmosphere and amount of N2 fixed were decreased in a similar manner whether plants were successively pruned twice or thrice. It can be concluded that two or three successive prunings in nine months significantly reduce nonstructural carbohydrates, DM productivity and N2 fixation of S. sesban, and might result in supply of insufficient biomass required for improving soil N fertility and livestock production.

Regulating carbon and water balance as a strategy to cope with warming and drought climate in Cunninghamia lanceolata in southern China.

Human activities have increased the possibility of simultaneous warming and drought, which will lead to different carbon (C) allocation and water use strategies in plants. However, there is no conclusive information from previous studies. To explore C and water balance strategies of plants in response to warming and drought, we designed a 4-year experiment that included control (CT), warming (W, with a 5°C increase in temperature), drought (D, with a 50% decrease in precipitation), and warming and drought conditions (WD) to investigate the non-structural carbohydrate (NSC), C and nitrogen (N) stoichiometry, and intrinsic water use efficiency (iWUE) of leaves, roots, and litter of Cunninghamia lanceolata, a major tree species in southern China. We found that W significantly increased NSC and starch in the leaves, and increased NSC and soluble sugar is one of the components of NSC in the roots. D significantly increased leaves' NSC and starch, and increased litter soluble sugar. The NSC of the WD did not change significantly, but the soluble sugar was significantly reduced. The iWUE of leaves increased under D, and surprisingly, W and D significantly increased the iWUE of litter. The iWUE was positively correlated with NSC and soluble sugar. In addition, D significantly increased N at the roots and litter, resulting in a significant decrease in the C/N ratio. The principal component analysis showed that NSC, iWUE, N, and C/N ratio can be used as identifying indicators for C. lanceolata in both warming and drought periods. This study stated that under warming or drought, C. lanceolata would decline in growth to maintain high NSC levels and reduce water loss. Leaves would store starch to improve the resiliency of the aboveground parts, and the roots would increase soluble sugar and N accumulation to conserve water and to help C sequestration in the underground part. At the same time, defoliation was potentially beneficial for maintaining C and water balance. However, when combined with warming and drought, C. lanceolata growth will be limited by C, resulting in decreased NSC. This study provides a new insight into the coping strategies of plants in adapting to warming and drought environments.

The effects of previous summer drought and fertilization on winter non-structural carbon reserves and spring leaf development of downy oak saplings.

It is still unknown whether the previous summer season drought and fertilization will affect the winter non-structural carbohydrate (NSC) reserves, spring leaf development, and mortality of trees in the next year. We, therefore, conducted an experiment with Quercus pubescens (downy oaks) saplings grown under four drought levels from field capacity (well-watered; ~25% volumetric water content) to wilting point (extreme drought; ~6%), in combination with two fertilizer treatments (0 vs. 50kg/ha/year blended) for one growing season to answer this question. We measured the pre- and post-winter NSC, and calculated the over-winter NSC consumption in storage tissues (i.e. shoots and roots) following drought and fertilization treatment, and recorded the spring leaf phenology, leaf biomass, and mortality next year. The results showed that, irrespective of drought intensity, carbon reserves were abundant in storage tissues, especially in roots. Extreme drought did not significantly alter NSC levels in tissues, but delayed the spring leaf expansion and reduced the leaf biomass. Previous season fertilization promoted shoot NSC use in extreme drought-stressed saplings over winter (showing reduced carbon reserves in shoots after winter), but it also showed positive effects on survival next year. We conclude that: (1) drought-stressed downy oak saplings seem to be able to maintain sufficient mobile carbohydrates for survival, (2) fertilization can alleviate the negative effects of extreme drought on survival and recovery growth of tree saplings.

Effect of selenium supplementation on mycorrhizal onion (Allium cepa L.) plants

ABSTRACT Selenium (Se) is a beneficial element for higher plants; however, its involvement in improving the plants availability to soil nutrients has not been adequately addressed. Onion (Allium cepa L.) plants were grown under the sufficient (2 mM) and deficient (0.05 mM) phosphorus (P) supply and inoculated with an arbuscular mycorrhizal fungus (AMF, Diversispora versiformis) in the absence or presence of 20 or 80 µg Se L–1 applied as Na2SeO4 under greenhouse conditions. Phosphorus deficiency impaired both shoot and root growth, while mycorrhisation increased plants biomass and root length by up to two times, accompanied by increased potassium uptake, levels of non-structural carbohydrates, protein and amino acids in the leaves and roots. AMF’s impact on biomass production was enhanced by Se supplementation, and the rates of photosynthesis and nitrogen assimilation were also boosted. Besides, AMF effects on the root activity of phosphatase, the acidification of rhizosphere and the mobilisation of insoluble P in the substrate were significantly exacerbated by Se. Our results showed a strong synergistic effect between Se and AMF in improving the plants performance on P-impoverished soils via enhanced ability to solubilise non-labile P fractions in the substrate and stimulation of carbon and nitrogen metabolism.

The effect of hydrological regimes on the concentrations of nonstructural carbohydrates and organic acids in the roots of Salix matsudana in the Three Gorges Reservoir, China

Hydrological fluctuations accelerate biodiversity loss and damage riparian ecosystems surrounding dams and reservoirs. Restoration of vegetation is urgently required in such highly impacted buffer zones. However, it is not known how the nonstructural carbohydrate (NSC) and organic acid concentrations of prominent woody plants such as Salix matsudana would alter under the hydrological regime described in the literature. The study aims to investigate the tap and lateral roots of S. matsudana in the Three Gorges Reservoir, as well as the NSC and organic acid metabolism of these roots. Three groups of two-year-old S. matsudana saplings were planted in this experiment: control (SS), moderate submergence (MS), and deep submergence (DS) at altitudes of 175 m, 170 m, and 165 m, respectively. The results indicated that hydrological regimes restrained the height of S. matsudana with less impact on diameter at P < 0.05 compared with SS but showed a 100 % survival rate throughout the experiment. Meanwhile, root starch concentrations of 108.46 ± 9.18 mg/g (mean ± standard error) were higher than those of soluble sugars (86.81 ± 12.98 mg/g) after hydrological stress. Moreover, the levels of soluble sugar, starch, and NSC in MS were higher than those of SS1 (1stphase of control). However, soluble sugar, starch, and NSC content in DS were lower than in SS2 (2ndphase of control), where lateral root starch and NSC content were more significant than those in the taproot. After 205 days of submersion (DS), oxalic acid, tartaric acid, and malic acid content were higher than after 135 days (MS). They followed the pattern of malic acid > tartaric acid > oxalic acid. The tartaric acid content of the lateral roots and the total roots was significantly higher in MS than in SS1. Conversely, the oxalic acid and malic acid levels in tap roots, lateral roots, and total roots were higher in DS than in SS2. There were strong Pearson's correlations between root starch and NSC with tartaric and malic acids; these correlations ranged from −0.898 < r < 0.981. These data indicate that S. matsudana can maintain certain levels of starch, malic acid, and tartaric acid to enable it to better adapt to its environment under in-situ flooding stress.

Edaphic factors as genetic selection agents and adaptation drivers of native plant species in harsh environments of the Brazilian savanna

BackgroundThe highly diversified flora in the Brazilian Cerrado (savanna) region is attributed to several factors, including the high concentrations of metals in soils, especially Al in widespread Ferralsols and Ni in soils derived from ultramafic rocks. We hypothesized that adaptation mechanisms are responsible for the genetic diversity of the following native plant species that are found in the abovementioned environments: Euploca salicoides (ES), Justicia lanstyakii (JL), and Oxalis hirsutissima (OH).ObjectivesWe aimed to analyse the main edaphic factors that differentiate ultramafic from Al-rich environments, and act as drivers of the evolution of physiological mechanisms underlying plant adaptation to these harsh environments.MethodsWe analysed the chemical attributes of four ultramafic soils (SAP5, SAP7, SAP9, LAT) and an Al-rich soil (CAM), and the elemental composition and DNA of the three species growing in both environments. ES was used as a model species to analyse changes in the levels of non-structural carbohydrates (NSCs) and Ni localization in plant leaves.ResultsThe soil types presented significant differences in available nutrients and heavy metals. The DNA sampled from the same species from ultramafic sites was genetically closer, but different from that in the Al-rich sites. In ultramafic soils, ES accessions had high levels of NSCs and Ni accumulated in trichomes.ConclusionsThe genetic diversity observed in plants growing in both areas is probably related to plant adaptation to the contrasting edaphic conditions of these environments. The raffinose production and Ni allocation to trichomes are mechanisms employed by ES to overcome metal toxification in ultramafic environments.

Root Carbon Resources Determine Survival and Growth of Young Trees Under Long Drought in Combination With Fertilization.

Current increases in not only the intensity and frequency but also the duration of drought events could affect the growth, physiology, and mortality of trees. We experimentally studied the effects of drought duration in combination with fertilization on leaf water potential, gas exchange, growth, tissue levels of non-structural carbohydrates (NSCs), tissue NSC consumption over-winter, and recovery after drought release in oak (Quercus petraea) and beech (Fagus sylvatica) saplings. Long drought duration (>1 month) decreased leaf water potential, photosynthesis, and NSC concentrations in both oak and beech saplings. Nitrogen fertilization did not mitigate the negative drought effects on both species. The photosynthesis and relative height increment recovered in the following rewetting year. Height growth in the rewetting year was significantly positively correlated with both pre- and post-winter root NSC levels. Root carbon reserve is critical for tree growth and survival under long-lasting drought. Our results indicate that beech is more sensitive to drought and fertilization than oak. The present study, in a physiological perspective, experimentally confirmed the view that the European beech, compared to oak, may be more strongly affected by future environmental changes.

The genotype does not influence the establishment of elephantgrass (Pennisetum purpureum Schum.)

This study investigated whether genotype influences the establishment of Pennisetum purpureum Schumach. The experimental design was a randomized complete blocks with four treatments and eight replications (n=8). The treatments were four genotypes of P. purpureum, two classified as tall sizes: P. purpureum cv. Elephant B and cv. IRI 381; and two as dwarf types: P. purpureum cv. Mott and Taiwan A-146 2.37. They were planted in a tropical wet and dry region of Brazil. Tall genotypes showed superior field sprouting rates (p &lt; 0.05), ranging between 95-99%, while dwarfs varied between 88-90%, however, Elephant B and IRI 381 produced a much lower average number of tillers (31 and 32 linear m-1, respectively), than Taiwan A-146 2.37 and Mott (56 and 41 linear m-1, respectively) (p &lt; 0.05). Dwarf genotypes produced lower biomass yields (p &lt; 0.05), but this was genotype-dependent and did not impact on their establishment. The levels of non-structural carbohydrates (NSC) (&gt;10%) in the planted stems were associated with satisfactory field sprouting of the elephantgrass genotypes. Despite some variations between the genotypes in terms of sprouting, tillering, and growth rates, the kind of genotype had no major significance on the establishment of the elephantgrass.

Impact of Growing Season Precipitation Regime on the Performance of Masson Pine Saplings

The growth and physiological effects of either decreased precipitation (e.g., drought) or increased one (e.g., flooding) on trees have been extensively studied. However, less attention has been paid to the questions of whether and how trees respond to changes in precipitation regime with different rainfall amounts. To investigate the effects of water availability on sapling’s growth, tissue levels of non-structural carbohydrates (NSCs), and nutrients, we carried out a greenhouse experiment with Masson pine (Pinus massoniana Lamb.) saplings grown in precipitation amounts of 300, 500, and 700 mm (3 levels) in combination with two levels of a watering regime (i.e., regular watering vs. pulsed watering, i.e., frequent low rainfall coupled with fewer instances of heavy rain) for a growing season in subtropical China. Pulsed watering caused higher soil pH (&gt;7.5) but lower soil organic carbon and soil nutrients, and consequently led to smaller plant biomass and height of the saplings than regular watering, especially in the water amount treatment of 300 and 500 mm. Additionally, higher levels of NSCs in plant tissue concentrations were observed under pulsed watering than under regular watering, due to greater carbon consumption for supporting higher growth rate and a dilution effect by bigger plant size and biomass in the latter. Our results indicated that the growing season precipitation amount of 300 mm is sufficient for the drought-tolerant tree species P. massoniana. In such a case, the growing season precipitation regime rather than the precipitation amount will have a much stronger impact on the tree performance.

Seedling size and nutrient availability in the fall determine nitrogen resorption and storage compound allocation in Quercus variabilis

Soil fertility and resorption of leaf compounds in the fall can influence resource buildup in plants. However, whether intraspecific differences in seedling size can affect nutrient reserve buildup is unknown. This study examined the effects of seedling size and fall fertilization on the uptake and resorption of nitrogen (N), as well as the allocation of non-structural carbohydrates (NSC) and N in cultivated Quercus variabilis Blume. After the formation of terminal buds (T1), seedlings were stratified into small (shoot height < 30 cm) and large seedlings. During the hardening period, seedlings were treated with three different rates of 15 N-enriched fertilizer (0, 12, or 24 mg N seedling−1) and monitored until leaf fall (T2). Small seedlings had lower N resorption efficiency and resorbed proportionally less N than large seedlings. Fall fertilization notably improved N and NSC reserves, without reducing N resorption efficiency. Large seedlings allocated proportionally less N to leaves than small seedlings although both sizes seedlings absorbed similar amounts of N from fall fertilization. The priority perennial organ for NSC allocation was roots, while N allocation was dependent on the phenological growth stage of the seedling. Roots were prioritized during the rapid growth phase, while stems were prioritized during the hardening period. Under same fertilizer regime during the growth phase, large seedlings tends to have lower N concentration and have higher resorption efficiency compare to small seedlings, fall fertilization can increase N storage in large seedlings and NSC levels in both seedling sizes, without affecting growth.