High Levels Of Soluble Sugars Research Articles

Soluble sugar and organic acid composition and flavor evaluation of Chinese cherry fruits

Chinese cherry is an economically important fruit crop native to China. Flavor quality is greatly influenced by compositions of soluble sugars and organic acids. To better understand the flavor quality of Chinese cherry, we determined sugar and acid components in thirty-eight landrace and cultivar collections, and two wild resources using the HPLC method. Glucose and fructose were the main components, accounting for 85.91% of soluble sugars. Malic acid was the predominant organic acid, with an average proportion of 65.73% of total acids. Correlation and PCA analysis revealed seven key indicators for evaluating fruit flavor. Compared with wild Chinese cherry, the cultivated collections exhibited higher levels of soluble sugars, especially fructose, and lower levels of organic acid, particularly malic acid in fruits. Finally, we have established grading criteria for seven flavor indicators in Chinese cherry. Our study provides valuable references for identifying flavor compounds and improving flavor quality of Chinese cherry.

Impact of low temperature on the chemical profile of sweet corn kernels during post-harvest storage

Fresh sweet corn has a limited shelf-life due to its high moisture and high sugar content. Low temperature storage is an effective technique employed to extend the shelf-life. However, changes in the chemical composition of sweet corn kernels at low temperatures are not fully understood. In this study, kernels stored at low temperature exhibited higher levels of soluble sugars and lower starch content. In total, 1365 metabolites were characterized in sweet corn kernels. 593 and 308 differentially accumulated metabolites (DAMs) were identified in sweet corn kernels stored at normal and low temperature, respectively. 607 DAMs were identified at low temperature compare to normal temperature. DAMs were consistently enriched in flavonoid biosynthesis, linoleic acid metabolism and sphingolipid metabolism. Moreover, dozens of metabolites were identified as potential biomarkers for post-harvest storage effects in sweet corn. These results extend our knowledge of the dynamic changes in sweet corn kernels stored at low temperatures.

Metabolomics integrated with transcriptomics unveil the regulatory pathways of modified atmosphere packaging–maintained leaf quality of Chinese flowering cabbage

Chinese flowering cabbage has a limited shelf-life because of rapid leaf senescence and serious quality deterioration. Modified atmosphere packaging (MAP) is an effective technology used to preserve fresh vegetables. However, its underpinning mechanism is largely unknown. This study found that MAP prevented the decline in chlorophyll loss and Fv/Fm ratio, and kept higher levels of soluble sugars, total phenols and flavonoids, remarkably dampening leaf senescence and maintaining quality of harvested Chinese flowering cabbage. Moreover, in total, 575 differentially accumulated metabolites (DAMs) and 12,470 differentially expressed genes (DEGs) were obtained. Additionally, 151 transcription factors (TFs) were significantly differentially expressed. Importantly, we further developed complex regulatory networks incorporating crucial structural genes and TFs contributing to metabolism of chlorophyll, soluble sugars, amino acids, phenolic acids and flavonoids in postharvest Chinese flowering cabbage. Above all, our findings provide new insights into the regulatory pathways of MAP-maintained leaf quality in postharvest Chinese flowering cabbage.

Physiological and transcription analyses reveal regulatory pathways of 6-benzylaminopurine delaying leaf senescence and maintaining quality in postharvest Chinese flowering cabbage

The regulatory role of cytokinins (CTKs) in leaf senescence has been documented in different species, including Chinese flowering cabbage. However, its physiological and molecular basis relatively remains unknown. In this study, exogenous application of a CTK analogue 6-benzylaminopurine (6-BA) significantly retarded leaf senescence of Chinese flowering cabbage, with less chlorophyll degradation and lower accumulation of reactive oxygen species (ROS) and malondialdehyde compared with the control group. Meanwhile, higher levels of soluble sugars and proteins, flavonoids, cellulose, amino acids, total phenols, procanthocyanins, and vitamin C were retained in 6-BA-treated leaves. 6-BA treatment also prevented the decline in endogenous CTK content and the increase in ethylene, abscisic acid, and jasmonic acid contents. Moreover, the comparative transcriptome analysis revealed that a total of 21,895 differently expressed genes (DEGs) were identified from four comparisons of 6-BA treatment versus the control during senescence. Further analysis showed that most of the identified DEGs were enriched in ROS, respiratory metabolism, and phytohormone pathways, and a total of 50 classes of transcription factors that were possibly involved in modulating these DEGs were obtained. The transcriptional levels of 18 DEGs were verified by Quantitative real-time PCR (qRT-PCR), which confirmed the accuracy of the transcriptomic data. Overall, these findings and data provide a comprehensive view of physiological and molecular events concerning with the CTK-mediated leaf senescence and -maintained quality in economical leafy vegetables.

Exogenous Melatonin Improves Pear Resistance to Botryosphaeria dothidea by Increasing Autophagic Activity and Sugar/Organic Acid Levels.

Pear is an important fruit tree worldwide, but it is often infected by the pathogen Botryosphaeria dothidea, which causes pear ring rot disease. To explore the effect of exogenous melatonin on the disease resistance of pear, we treated inoculated pear fruits with different concentrations of melatonin. The results showed that 100 μΜ of melatonin had the most significant effect with resistance to B. dothidea. In addition, melatonin treatment significantly reduced the diameter of disease lesions and enhanced the endogenous melatonin content in pears inoculated with B. dothidea. Compared with the control treatment, melatonin treatment suppressed increases in reactive oxygen species (ROS) and activated ROS-scavenging enzymes. Treatment with exogenous melatonin maintained ascorbic acid-glutathione at more reductive status. The expression levels of core autophagic genes and autophagosome formation were elevated by melatonin treatment in pear fruits. Silencing of PbrATG5 in Pyrus pyrifolia conferred sensitivity to inoculation that was only slightly attenuated by melatonin treatment. After inoculation with B. dothidea, exogenous melatonin treatment led to higher levels of soluble sugars and organic acids in pear fruits than H2O treatment. Overall, our results demonstrate that melatonin enhances resistance to B. dothidea by increasing autophagic activity and soluble sugar/organic acid accumulation.

High relative humidity enhances chilling tolerance of zucchini fruit by regulating sugar and ethanol metabolisms during cold storage

High relative humidity (RH) cold room (RH: 98 ± 2%) controlled by a ‘dry fog’ system and normal cold room (RH: 74 ± 2%) were used to store zucchini fruit to investigate the regulation of high RH on chilling tolerance and sugar and ethanol metabolisms under cold stress. High RH storage inhibited chilling injury (CI) and maintained higher activities of sucrose synthase-synthesis and sucrose phosphate synthase and contents of glucose, fructose and sucrose in zucchini fruit. Meanwhile, high RH-stored fruit exhibited lower activities of hexokinase, phosphofructokinase, and pyruvate kinase as compared with the control. Besides, the accumulation of acetaldehyde and ethanol under cold stress was decreased by high RH storage together with the inhibition of the increase in activities of alcohol dehydrogenase, pyruvate decarboxylase and expressions of related genes. Taken together, high RH storage enhanced chilling tolerance in zucchini fruit by maintaining high levels of soluble sugars and inhibiting ethanol production.

Effect of biological synthesis of nanoparticles from Penicillium chrysogenum as well as traditional salt and chemical nanoparticles of zinc on canola plant oil productivity and metabolic activity

With the rapid advancement of nanotechnologies, it is more likely that biological systems may be exposed to an excessive amount of nanoparticles (NPs). The effect of NPs on plants, on the other hand, has yet to be investigated. The study's objective was to explore the comparative and effect of traditional salt (ZnSO4), chemical and biological zinc oxide nanoparticles (ZnONPs, ZnObNPs) respectively through foliar treatment on photosynthetic traits, soluble sugars, proteins, phenols, oil content, and mineral content. 40, 90 days old seedlings of canola were foliar with distilled water (control), 50 or 100 mg/l of ZnSO4, ZnONPs, and ZnObNPs, respectively. Plants grown with ZnObNPs (100 mg/l) exhibited better growth and photosynthetic characteristics and higher levels of soluble sugars, proteins, phenols, oil content, and mineral content than non-treated plants at 50, 100, and 160 days after sowing (DAS). In conclusion, ZnObNPs can be used to improve canola plants by up-regulating the non-antioxidant defense system as phenol, osmolyte and increased oil content, mineral content.

Effects of residue stoichiometric, biochemical and C functional features on soil aggregation during decomposition of eleven organic residues

Soil aggregation is deeply impacted by the quality of organic materials. However, the organic material features that control soil aggregation dynamics are still largely unknown. In this study, a total of 11 organic residues including vetch (alfalfa, hairy, and Chinese milk), straw (rice, maize, wheat, miscanthus, soybean, and sorghum) and manures (cattle and pig) were characterized by stoichiometric, biochemical and C functional features. The soil respiration, mean weight diameter (MWD) and glomalin-related soil protein (GRSP) levels were measured during 56 d of incubation. The results showed that stoichiometric features had no impact on soil respiration and aggregate stability except the N content. Residue decomposition was positively affected by soluble sugars but negatively affected by lignin and cellulose in the first 14 d (P < 0.05). Soluble sugars positively influenced the MWD up to 28 d, and cellulose continued this effect at 56 d (P < 0.05). Soil respiration and MWD were positively associated with alkyl and carbonyl C but negatively related to the alkyl and di-O-alkyl C fractions in the first two weeks, while adverse effects on the MWD were found at 56 d of incubation (P < 0.05). Organic residue input increased the GRSP level in the order of manure > straw > vetch. The GRSP content had a negative effect on the MWD up to 28 d (P < 0.05) but was not related at 56 d of incubation. Overall, high levels of soluble sugars of residues resulted in transient aggregate stability, but persistent aggregate stability was mainly contributed by the cellulose, O-alkyl C and di-O-alkyl C features.

Solubilization of Lignocellulosic Biomass Using Pretreatments for Enhanced Methane Production during Anaerobic Digestion of Manure

Pretreatment of dairy manure can disrupt the lignocellulosic structure and produce higher levels of soluble sugars, which can be effectively utilized by anaerobic microbes to produce methane (CH4)....

Leaf Soluble Sugars and Free Amino Acids as Important Components of Abscisic Acid-Mediated Drought Response in Tomato.

Water deficit has a global impact on plant growth and crop yield. Climate changes are going to increase the intensity, duration and frequency of severe droughts, particularly in southern and south-eastern Europe, elevating the water scarcity issues. We aimed to assess the contribution of endogenous abscisic acid (ABA) in the protective mechanisms against water deficit, including stomatal conductance, relative water potential and the accumulation of osmoprotectants, as well as on growth parameters. To achieve that, we used a suitable model system, ABA-deficient tomato mutant, flacca and its parental line. Flacca mutant exhibited constitutively higher levels of soluble sugars (e.g., galactose, arabinose, sorbitol) and free amino acids (AAs) compared with the wild type (WT). Water deficit provoked the strong accumulation of proline in both genotypes, and total soluble sugars only in flacca. Upon re-watering, these osmolytes returned to the initial levels in both genotypes. Our results indicate that flacca compensated higher stomatal conductance with a higher constitutive level of free sugars and AAs. Additionally, we suggest that the accumulation of AAs, particularly proline and its precursors and specific branched-chain AAs in both, glucose and sucrose in flacca, and sorbitol in WT, could contribute to maintaining growth rate during water deficit and recovery in both tomato genotypes.

Comparative transcriptome analysis reveals synergistic and disparate defense pathways in the leaves and roots of trifoliate orange (Poncirus trifoliata) autotetraploids with enhanced salt tolerance

Polyploid plants often exhibit enhanced stress tolerance relative to their diploid counterparts, but the physiological and molecular mechanisms of this enhanced stress tolerance remain largely unknown. In this study, we showed that autotetraploid trifoliate orange (Poncirus trifoliata (L.) Raf.) exhibited enhanced salt tolerance in comparison with diploid progenitors. Global transcriptome profiling of diploid and tetraploid plants with or without salt stress by RNA-seq revealed that the autotetraploids displayed specific enrichment of differentially expressed genes. Interestingly, the leaves and roots of tetraploids exhibited different expression patterns of a variety of upregulated genes. Genes related to plant hormone signal transduction were enriched in tetraploid leaves, whereas those associated with starch and sucrose metabolism and proline biosynthesis were enriched in roots. In addition, genes encoding different antioxidant enzymes were upregulated in the leaves (POD) and roots (APX) of tetraploids under salt stress. Consistently, the tetraploids accumulated higher levels of soluble sugars and proline but less ROS under salt stress compared to the diploids. Moreover, several genes encoding transcription factors were induced specifically or to higher levels in the tetraploids under salt stress. Collectively, this study demonstrates that the activation of various multifaceted defense systems in leaves and roots contributes to the enhanced salt tolerance of autotetraploids.

Relationship Between Carbon Mobilization and Root Growth Measured by Carbon-11 Tracer in Arabidopsis Starch Mutants

Experiments designed to quantify the physiological and metabolic status of Arabidopsis thaliana seedlings across their photoperiod used wild-type (Col-0) and genotypes deficient in starch biosynthesis (adg1-1, pgm-1) and in starch degradation (sex1-1) in combination with radioactive 11CO2 tracer. Measurements of root allocation and root exudation of 11C-photosynthates were conducted at 1 and 8 h into a 10-h photoperiod. Additionally, bioassays conducted on leaflets provided a measure of ‘new’ carbon partitioning (as 11C) into structural and non-structural carbohydrates. As expected, starch biosynthesis increased across the photoperiod for Col-0 controls. This increase was correlated with systematic decreases in soluble sugar synthesis and sink allocation across the photoperiod. We showed that this was a causal effect, which could be eliminated in the adg1-1 and pgm-1 mutants that were deficient in starch biosynthesis. Furthermore, these genotypes exhibited systematically higher levels of soluble sugars and sink allocation relative to Col-0 and sex1-1, which resulted in very different root growth traits including (i) increased root area balanced by shorter primary roots; (ii) increased number of lateral roots; and (iii) decreased root gravitropism. These differences in growth traits were correlated with higher observed levels of root auxin in these genotypes and to lower starch levels in their root tips. In a broader context, we find that carbon storage in the aboveground tissues can strongly influence root growth and root architecture belowground.

Impaired phloem loading in zmsweet13a,b,c sucrose transporter triple knock-out mutants in Zea mays.

Crop yield depends on efficient allocation of sucrose from leaves to seeds. In Arabidopsis, phloem loading is mediated by a combination of SWEET sucrose effluxers and subsequent uptake by SUT1/SUC2 sucrose/H+ symporters. ZmSUT1 is essential for carbon allocation in maize, but the relative contribution to apoplasmic phloem loading and retrieval of sucrose leaking from the translocation path is not known. Here we analysed the contribution of SWEETs to phloem loading in maize. We identified three leaf-expressed SWEET sucrose transporters as key components of apoplasmic phloem loading in Zea mays L. ZmSWEET13 paralogues (a, b, c) are among the most highly expressed genes in the leaf vasculature. Genome-edited triple knock-out mutants were severely stunted. Photosynthesis of mutants was impaired and leaves accumulated high levels of soluble sugars and starch. RNA-seq revealed profound transcriptional deregulation of genes associated with photosynthesis and carbohydrate metabolism. Genome-wide association study (GWAS) analyses may indicate that variability in ZmSWEET13s correlates with agronomical traits, especifically flowering time and leaf angle. This work provides support for cooperation of three ZmSWEET13s with ZmSUT1 in phloem loading in Z.mays.

Evaluation of salinity tolerance in honeysuckle (Lonicera japonica) using growth, ion accumulation, lipid peroxidation, and non-enzymatic and enzymatic antioxidants system criteria

ABSTRACTTo evaluate their salt tolerance, two-year-old potted honeysuckle plants were exposed to 50, 100, and 150 mM NaCl, respectively. The effects of salt stress on growth parameters, ion concentration, lipid peroxidation, and the enzymatic antioxidant system in honeysuckle were studied. Salt stress reduced biomass accumulation and root activity, and also induced oxidative stress, as indicated by elevated levels of O2·-, malondialdehyde content, and electrolytic leakage. Increased salinity resulted in a slight decline in the K+ concentration in different plant tissues, but a significant boost in Na+ levels, which were much higher in roots than in other tissues. The concentrations of Ca2+ and Mg2+ increased significantly in leaves, but remained unchanged in shoots and decreased slightly in roots. Higher levels of soluble sugars and proline were observed in the plants after 30 days of NaCl treatment, suggesting that compatible osmolytes had been synthesised to acclimatise to the salinity. Under the treatments, major antioxidant enzymes involved in the reactive oxygen species scavenging system, including superoxide dismutase, ascorbate peroxidase, catalase and peroxidase were activated. The increased activities of the antioxidant enzymes were significant and occurred in a time-dependent manner.

Differences in Sugar Accumulation and Mobilization between Sequential and Non-Sequential Senescence Wheat Cultivars under Natural and Drought Conditions.

Wheat leaf non-sequential senescence at the late grain-filling stage involves the early senescence of younger flag leaves compared to that observed in older second leaves. On the other hand, sequential senescence involves leaf senescence that follows an age-related pattern, in which flag leaves are the latest to undergo senescence. The characteristics of sugar metabolism in two sequential senescence cultivars and two non-sequential senescence cultivars under both natural and drought conditions were studied to elucidate the underlying mechanism of drought tolerance in two different senescence modes. The results showed that compared to sequential senescence wheat cultivars, under natural and drought conditions, non-sequential senescence wheat cultivars showed a higher leaf net photosynthetic rate, higher soluble sugar levels in leaves, leaf sheaths, and internodes, higher leaf sucrose synthase (SS) and sucrose phosphate synthase (SPS) activity, and higher grain SS activity, thereby suggesting that non-sequential senescence wheat cultivars had stronger source activity. Spike weight, grain weight per spike, and 100-grain weight of non-sequential senescence cultivars at maturity were significantly higher than those of sequential senescence cultivars under both natural and drought conditions. These findings indicate that the higher rate of accumulation and the higher mobilization of soluble sugar in the leaves, leaf sheaths and internodes of non-sequential senescence cultivars improve grain weight and drought tolerance. At the late grain-filling stage, drought conditions adversely affected leaf chlorophyll content, net photosynthetic rate, soluble sugar and sucrose content, SS and SPS activity, gain SS activity, and weight. This study showed that higher rates of soluble sugar accumulation in the source was one of the reasons of triggering leaf non-sequential senescence, and higher rates of soluble sugar mobilization during leaf non-sequential senescence promoted high and stable wheat yield and drought tolerance.

Relationship between Sucrose Metabolism and Anthocyanin Biosynthesis During Ripening in Chinese Bayberry Fruit

Two cultivars of Chinese bayberry fruit cvs 'Dongkui' and 'Biqi' with five different ripening stages were used to investigate the relationship between anthocyanin biosynthesis and sugar metabolism during fruit development. The results showed that anthocynin accumulated with the increased ripening stage in both of the two cultivars of bayberries. As compared to 'Biqi' fruit, a higher level of anthocyanin content was observed in 'Dongkui' fruit due to the increased expression of anthocyanin biosynthetic and regulatory genes especially MrCHI, MrDFR1, MrANS, and MrMYB1. Meanwhile, 'Dongkui' fruit also experienced higher levels of soluble sugars including sucrose, glucose, and fructose and expression of genes such as MrSPS1, MrSPS2, MrSPS3, MrINV1, MrINV2, and MrINV3 involved in sugar metabolism. Correlation analysis showed anthocyanin content had a significant relationship with all the three soluble sugars in bayberry fruit. Therefore, our results suggested that the higher anthocyanin content in 'Dongkui' fruit might be associated with its increased levels of soluble sugars.

The effect of biodegradable direct covers on the root development, yield and quality of cucumber

ABSTRACT The results of three years (2009-2011) of field studies using two types of biodegradable nonwoven covers (aromatic polyester IBWCH 75 g m-2 and polylactic acid PLA 54 g m-2) on the yield, quality and root development of cucumber are presented. Seeds of parthenocarpic cucumber (‘Mirabelle’ F1) were sown directly into the field at the beginning of May/June and covered with nonwoven field covers. A plot that remained uncovered served as the control. The covers were kept in place until the first flowers appeared. Cucumbers were harvested every three days for 5-6 weeks. Fruits were evaluated for dry matter, soluble sugars and nitrate content. After the last harvest, whole plants were harvested and evaluated for weight, surface area, total length and average diameter of the roots. The experiment showed that the covers increased the marketable yield of cucumber in 2009 and 2010 (regardless of the type of polymer), but did not influence the yield in 2011. In 2011 the fruits from the covered plots had higher levels of soluble sugars and dry matter in comparison to the control. The covers did not influence root development.

Induced Response of Sugarcane Variety Co 86032 for Thermotolerance

A study was conducted to investigate the induced and non-induced response of sugarcane variety Co 86032 by heat acclimation both under in vivo and in vitro conditions. For in vivo condition, 30 days old sugarcane settlings (Co 86032) were subjected to optimum induction temperature (40 °C with 10 h time) followed by critical temperature condition of 48 °C with 10 h. For in vitro condition, calli of Co 86032 were subjected to optimum induction temperature condition of 42 °C with 10 h time followed by critical temperature condition of 48 °C with 15 h. Adaptive response of settlings and calli by heat acclimation were estimated in terms of soluble protein, total sugars, total phenolics, proline, glycine-betaine (GB) and ROS scavenging enzymes activities (SOD, POX and APX) and isozyme pattern (SOD and POX). Higher levels of soluble sugars, proteins, proline and GB were observed in pretreated settlings and calli. Significant differences in responses of SOD, POX and APX activities were observed in both induced and non induced settlings and calli. However heat acclimations (induced) led to higher activities of these enzymes and thereby protect the cells from oxidative damage. Exposure to high temperature caused a significant increase in lipid peroxidation (MDA content) and cell membrane injury (%), however pre treated settling and calli recorded lesser cell membrane damage. Formation of additional protein bands of different molecular weights (90, 70 and 27 kDa) showed the expression of these proteins upon heat acclimation particularly at 40 °C in settlings and 42 °C in calli.

Nitrogen deposition limits photosynthetic response to elevated CO2 differentially in a dioecious species

Sexual dimorphisms of dioecious plants are important in controlling and maintaining sex ratios under changing climate environments. Yet, little is known about sex-specific responses to elevated CO(2) with soil nitrogen (N) deposition. To investigate sex-related physiological and biochemical responses to elevated CO(2) with N deposition, Populus cathayana Rehd. was employed as a model species. The cuttings were subjected to two CO(2) regimes (350 and 700 μmol mol(-1)) with two N levels (0 and 5 g N m(-2) year(-1)). Our results showed that elevated CO(2) and N deposition separately increased the total number of leaves, leaf area (LA), leaf mass, net photosynthetic rate (P(n)), light saturated photosynthetic rate (P(max)), chlorophyll a (Chl a), and chlorophyll a to chlorophyll b ratio (Chl a/b) in both males and females of P. cathayana. However, the effects on LA, leaf mass, P(n), P(max), Chl a and Chl a/b were weakened under the combined treatment of elevated CO(2) and N deposition. Males had higher leaf mass, P(n), P(max), apparent quantum yield (Φ), carboxylation efficiency (CE), Chl a, Chl a/b, leaf N, and root carbon to N ratio (C/N) than did females under elevated CO(2) with N deposition. In contrast to males, females had significantly higher levels of soluble sugars in leaves and greater starch accumulation in roots and stems under the same condition. The results of the present work imply that P. cathayana females are more responsive and suffer from greater negative effects on growth and photosynthetic capacity than do males when grown under elevated CO(2) with soil N deposition.

Effects of plant growth regulators on growth and carbohydrate accumulation in shoots and roots of two almond rootstock seedlings

Introduction. Prunus amygdalus and P. webbii can be used as rootstocks for almond cultivars due to their adaptability to severe environmental conditions. However, the time required for seedlings to reach a suitable size for transplanting may take 1 to 3 years. Our study tested the effects of foliar application of growth regulators on the vegetative growth and carbohydrate accumulation in shoots and roots of these species. Materials and methods. Six-week-old seedlings were treated with gibberellic acid (GA3) (100 mg·L–1) alone or with GA3 followed by ethephon [(100 and 200) mg·L–1], or chlormequat chloride (CCC) [(500 and 1000) mg·L–1], or paclobutrazol (PBZ) [(500 and 1000) mg·L–1]. Results and discussion. Most levels of plant growth regulators significantly enhanced seedling growth. However, GA3 alone was most effective on stem height, leaf area, and shoot fresh and dry weights of both almond species. The thickest stems of P. amygdalus and P. webbii were obtained from the application of 100 mg GA3·L–1 followed by application of (1000 and 500) mg PBZ·L–1, respectively. In both species, PBZ significantly increased leaf chlorophyll content compared with the controls as well as with the other treatments. Application of GA3 alone on P. webbii and of GA3 followed by 100 mg ethephon·L–1 on P. amygdalus showed the highest root number, and root fresh and dry weights. High levels of soluble sugars and starch in the shoots and roots of both species were observed when GA3 application was followed by PBZ. Conclusion. These results demonstrated that application of plant growth regulators to the seedlings might be a useful way of enhancing growth of P. amygdalus and P. webbii and reducing the time and cost of seedling production.