Increased Shoot Height Research Articles

Yield and quality changes in lucerne of different fall dormancy ratings under three defoliation regimes

Abstract This study determined how fall dormancy rating (FD2, FD5 or FD10) of lucerne genotypes affected crop yield and quality. One field experiment was measured for three growing seasons as a seedling crop and then three defoliation frequency regimes (DF) of 28 (DF28), 42 (DF42) or 84 (DF84) days were imposed (October 2014 to April 2017). Annual shoot dry matter (DM) yields ranged from 5.2 t DM/ha in DF28 crops to 17.5 t DM/ha in DF84 crops. Higher shoot DM was associated with greater shoot elongation which was modified by photoperiod (Pp). In an increasing Pp environment, the rate of DM accumulation in shoots was ∼ 91 kg/ha for each 1.0 cm increase in shoot height. In a decreasing Pp environment, the rate of DM accumulation in shoots was constant at ∼50 kg/ha/cm. In the DF84 crops, shoot yield declined due to leaf senescence by ∼31 kg/ha/cm when lucerne was ≥65 cm height. The leaf stem ratio (LSR) declined by 0.56 for each 1.0 cm increase in plant height. The crude protein (CP) and metabolisable energy (ME) accumulation in whole shoots or in leaf, soft stem and hard stem followed an allometric relationship. As DM increased, CP and ME increased in a similar pattern for all treatments. Thus the relationship between the yield and quality of lucerne was independent of genotype and phenological stage and was explained allometrically by the leaf and stem ratio, associated with changes in plant height, as affected by photoperiod. These results suggest universal defoliation management strategies can be developed based on ontogeny and independently of genotype, growth stage and growing conditions.

Efficacy of Trichoderma asperellum TC01 against anthracnose and growth promotion of Camellia sinensis seedlings

Tea plant (Camellia sinensis) is a perennial evergreen woody plant that is economic importance worldwide. Its health functions and distinctive taste depend on the production of secondary metabolites, which are affected by biotic and abiotic stresses. Biological control is considered a feasible alternative to chemical control as well as an eco-friendly method for controlling pathogens. In this study, we investigated the role of Trichoderma asperellum TC01 in the regulation of C. sinensis growth and the activation of defence responses against Colletotrichum gloeosporioides C62 by developing a biocontrol–plant–pathogen interaction system. When C. sinensis was co-cultivated with T. asperellum TC01, it was able to reduce 58.37% of disease severity compared with other treatments. Furthermore, compared with control plant growth, T. asperellum TC01-treated plants showed an increase in shoot height (7.5%), stem diameter (34.09%), shoot fresh weight (81.18%), root fresh weight (93.75%), shoot dry weight (85.71%) and root dry weight (115.38%) at 45 days after inoculation under greenhouse conditions. RNA sequencing analysis revealed that 48 h after inoculation, key genes were up-regulated in the flavonoid biosynthesis pathway of TC01-treated plants (T4) and down-regulated in leaves of C. gloeosporioides C62-treated plants compared with that of the control plants, indicating that TC01 triggers flavonoid and phenylpropanoid pathways during the early stages of the interaction with C. sinensis. Furthermore, higher expression levels of genes associated with the jasmonic acid and ethylene signalling pathway in the roots of TC01- and C62-treated plants (T3) than in either TC01- or C62-treated plants, indicated that TC01 triggered the induced systemic response in C. sinensis. Genes involved in the flavonoid, phenylpropanoid, jasmonic acid and ethylene play an important role in the resisitance against anthracnose. These results indicate induction of defense mechanisms by TC01 is potentially a powerful approach for controlling Camellia sinensis disease, which may provide a management opportunity for the sustainable use of TC01 treatments in tea plantations.

EFFECT OF COLD STRATIFICATION ON SEED GERMINATION OF THE MULTIPURPOSE FRUIT SHRUB, ZIZIPHUS LOTUS (L.) LAM. (RHAMNACEAE)

Shrubs and trees of the genus Ziziphus are a good example of naturally occurring multipurpose plant species with great potential in arid regions. This study was conducted to investigate the effect of cold stratification on seed germination and seedling growth of Ziziphus lotus (L.) Lam. Seeds were subjected to 0, 45, 90 and 120 days of cold stratification at 5°C. We also examined fruit, kernel and seed morphology. For each treatment period, four replicates of 50 seeds were incubated in plastic containers between two layers of moist sand at 15% and under greenhouse conditions for 15-day period. At the end of the experiment, the final germination percentage (FGP), shoot length and root length were assessed. The results clearly indicated that increasing duration of cold stratification improved seed germination. The most effective stratification period was 120 days where Z. lotus recorded 83% of FGP and 16.5 cm of total seedling length. Cold stratification treatments significantly increased shoot height, root length, as well as seedling total length. 120 days stratification treatment resulted in the highest shoot and root length (6.80 cm and 9.75 cm, respectively). An overview on the emergence of Z. lotus seedlings during a 15-day period was also illustrated.

Improvement of Early Growth of Endemic Sulawesi Trees Species Kalappia celebica by Arbuscular Mycorrhizal Fungi in Gold Mining Tailings

Kalapi (Kalappia celebica Kosterm.) is an endemic species of Sulawesi and listed in the IUCN red list as an endangered species. In addition, information about silviculuture of K. celebica type in the world is still limited. One important component of silvicultural techniques to support conservation efforts of K. celebica is the application of fertilizers such as mycorrhizal biofertilizers. The aim of the study was to examine the improvement of initial growth of K. celebica by inoculation of arbuscular mycorrhizal fungi (AMF) on gold tailings media. This research was conducted in the greenhouse of the Indonesian Mycorrhizal Association (AMI) branch of Southeast Sulawesi in March - July 2019. The study was designed by using a completely randomized design with 4 AMF inoculums treatments namely control, Acaulospora delicata, Ambiospora appendicula, and Mixed AMF types. Each treatment was repeated 3 times with 5 plant units of each treatment. The results showed that the AMF colonization ranged from 42.2 to 74.6%. The colonization of AMF significantly increased the early growth of K. celebica aged 4 months. Inoculation of A. delicata significantly increased shoot height, number of leaves, shoot and total dry weight. There was no difference of AMF effect in both diameter of the stem and roots dry weight. The dependence of K. celebica on mycorrhizal fungi was high about 51-71% (Mycorrhizal inoculation effect). AMF inoculation improves the initial growth of K. celebica, therefore, it can contribute to the conservation of tropical endangered tree species.

Pre-treatment of two contrasting water-stressed genotypes of cassava (Manihot esculenta Crantz) with ascorbic acid. I. Growth, physiological and antioxidant responses.

Water deficit-stress at early growth stage is a major constraint of cassava production. Ascorbic acid is a non-enzymatic antioxidant that mitigates oxidative damage caused by water stress in plants. Growth, physiological and antioxidant defense system responses of two contrasting water-stressed cassava genotypes to pre-treatment with foliar application of ascorbic acid (AA) were investigated. The objectives of this study were to assess the growth, proline, photosynthesis pigments and antioxidant activities of young water-stressed cassava plants pre-treated with ascorbic acid. The study consisted of IITA-TMS-IBA980581 (drought tolerant) and IITA-TMS-IBA010040 (drought sensitive) cassava genotypes treated with six doses (0.00, 0.25, 0.50, 0.75 and 1.00mM) of AA before beingsubjected to water deficit (45.0% field capacity) and a water sufficient AA-untreated control. In both genotypes, water stress reduced shoot height (40.3%), leaf area (42.5%), and number of root (54.5%), biomass (28.6%), relative water content (RWC, 3.2%) and photosynthetic pigments (300.0%). However, water stress increased proline (91.3%), endogenous AA (112.0%), catalase (CAT, 300.0%) and superoxide dismutase (SOD, 15.3%) in both genotypes. Compared with IITA-TMS-IBA010040, leaf area, biomass, number of root and shoot height of IITA-TMS-IBA980581 were higher by 7.3, 24.6, 25.9 and 13.1%, respectively. By less than a quarter, chlorophylls a and b, activity of superoxide dismutase and relative water content of IITA-TMS-IBA980581 were higher compared with IITA-TMS-IBA010040. However, proline content of IITA-TMS-IBA010040 was higher than IITA-TMS-IBA980581 by 14.3%. Pre-treatment with AA improved growth parameters, photosynthetic pigments, RWC, endogenous AA, activity of CAT and SOD, but decreased proline in both genotypes with an optimum concentration at 0.5mM. Pre-treatment with 0.5mM AA increased shoot height, area of leaves, leaf number, number of root and dry weight by 46.3, 44.7, 14.4, 88.2 and 37.5%, respectively. Pre-treatment with 0.5mM AA doubled chlorophylls, tripled carotenoids content, doubled endogenous AA and slightly enhanced RWC (2.1%) and SOD (2.0%) when compared with AA-untreated water stressed plants. But pre-stress application of AA reduced proline content by one-fold, increased CAT activity by one-fold in IITA-TMS-IBA980581 and by one-third in IITA-TMS-IBA010040. The study concluded that pre-treatment of cassava young plants with AA before water deficit could alleviate oxidative stress.

The effect of the combination of arbuscular mycorrhiza and rhizobacteria and doses of NPK fertilizer on the growth of Sorghum bicolor (L.) Moench

Sorghum bicolor (L.) Moench is one of the agricultural commodities that has important economic value. The use of fertilizer is done to increase productivity in order to follow the demand for sorghum which is quite high. Farmers widely use chemical fertilizers because they are cheap and easy to apply, but it has a negative impact on the environment. Sorghum growth naturally depends on microbes in the root area such as arbuscular mycorrhiza and rhizobacteria which have been known to increase sorghum growth. Arbuscular mycorrhiza and rhizobacteria as biological fertilizers can reduce the use of chemical fertilizers. This research aimed to study the effect of a combination of arbuscular mycorrhiza and rhizobacteria and doses of NPK fertilizer on sorghum growth. This study used two treatment factors, namely combination of microbes (arbuscular mycorrhiza, Azospirillum sp. and Klebsiella sp.) and doses of NPK (without NPK, 25% NPK, 50% NPK, 75% NPK, 100% NPK). Sorghum seeds of each treatment were individually grown on zeolite medium and were maintained in the greenhouse for two months. Plant growth parameters, colonization percentage of arbuscular mycorrhiza, rhizobacterial population, and root phosphate content were measured. Combination of Azospirillum sp. and Klebsiella sp. significantly increased shoot height and number of leaves. Combination of arbuscular mycorrhiza, Azospirillum sp. and Klebsiella sp. produced the highest dry weight. The dose of 25% NPK significantly increased all plant growth parameters. Combination of two rhizobacteria produced the highest root P content.

Alginate gel entrapped ectomycorrhizal inoculum promoted growth of cuttings ofEucalyptusclones under nursery conditions

Plant inoculation with ectomycorrhizal fungi (EMF) maximizes the productive potential of forest stands. Thus, the inoculation efficiency of calcium alginate gel entrapped EMF vegetative mycelium was evaluated in a commercial nursery using cuttings of Eucalyptus clones GG100 and GG680. The cuttings were inoculated with Pisolithus microcarpus G. Cunn. (Cooke & Massee), Hysterangium gardneri E. Fisch., and Scleroderma areolatum Ehrenb. The cuttings were cultivated under low phosphate fertilization and compared with uninoculated control treatments with reduced phosphate (low P control) and full phosphate (high P control) fertilization. Pisolithus microcarpus inoculation increased shoot height, root collar diameter, shoot dry mass, total dry mass, and frequency of maximum score for root ball formation of the two clones compared with the low P control treatment. Also, in relation to the low P control treatment, H. gardneri inoculation increased shoot dry mass in GG100 rooted cuttings. Scleroderma areolatum inoculation did not enhance any characteristic of Eucalyptus rooted cuttings. Inoculation of vegetative mycelium with EMF impregnated in calcium alginate gel intensified rooted cutting growth in a commercial Eucalyptus nursery and decreased the phosphate dose required. Based on the comparison of two Eucalyptus clones, efficiency of the inoculants in promoting benefits depends on the fungus and the Eucalyptus clone. Pisolithus microcarpus is most promising for inoculation in Eucalyptus cuttings.

The study of effectiveness root-up types and concentrations on root growth rate of potato (Solanum tuberosum L.) derived from cutting bud

The aim of this study is to know the effect of root-up size and concentration on root potato growth on the number of different leaf stem leaves. This research was conducted using Randomized Complete Block Design at 3 factors and 3 replicates. The first factor was the Root-up Types [RT], consisting of RA, RB, RC, and Rotten-F (as a comparison); the second factor was Root Up Concentration [RC] consisting of C5%, C10%, C15%, C20%, and C25%); and the third factor was the Number of Leaf on the Cuttings [NL] consisting of NL-1, NL-2, and NL-3. The contrasting orthogonal test shows Root-Up vs Control treatment was highly significant in all observed variables, except in stem diameter was increased. Based on data analysis, the Root-up vs Control treatment had a very real effect on all variables, except in stem diameter increase. In Root-up treatment: RT-RC-NL, there were no significant interaction in all observed variables. In RT-RC, there were an interaction between shoot height increase, number of leaves, and root length. RTC with concentrations of 10-25% showed higher growth, better leaf count and root length. In RT-NL, interaction occurs on number of leaves, RTC with the number of leaves 1, 2, and 3 on the shoot cuttings showed a better number of leave. RC-NL occurred in the interaction of the increase in shoot height and number of leaves. RC of 20% with NL 1, 2, and 3 on shoot cuttings show highest increase and highest leaf number. Based on this study, the use of Root-up C with 10-20% concentration could be used as a reference for shoot cuttings multiplication.

Promotion of seed germination and seedling growth of Zea mays by magnesium hydroxide nanoparticles synthesized by the filtrate from Aspergillus niger

An approach for green synthesis of magnesium hydroxide nanoparticles [Mg(OH)2NPs] has been developed and its efficacy in seed germination, in vitro and in vivo plant growth promotion was studied on Zea mays at different concentrations. Mg(OH)2NPs at 500 ppm showed improved seed germination (100%) and growth. The effect of Mg(OH)2NPs was analyzed by measurement of plants height and chlorophyll a fluorescence using plant efficiency analyzer. The seedlings grown in MS medium supplemented with Mg(OH)2NPs showed significant increase in shoot height (11.96 ± 0.4 cm) and root length (3.92 ± 0.4 cm). Similarly, for in vivo studies, the enhanced shoot height (44.2 ± 1.6 cm) and root length (29.2 ± 1.3 cm) was recorded as compared to plants treated with their bulk counterpart. However, 500 ppm bulk Mg showed comparatively lower shoot height (38 ± 1.5 cm) and root length (21.6 ± 2.3 cm). The chlorophyll a fluorescence measurements revealed that plants treated with Mg(OH)2NPs showed maximum performance index and minimum dissipation as compared to control and plants treated with bulk Mg.In addition, atomic absorption spectrophotometric analysis performed for both in vitro and in vivo grown plants, revealed that leaves and roots of the plants treated with Mg(OH)2NPs demonstrated higher Mg contents. It was found that Mg content in leaves and roots for in vitro plants were 131.45 and 103.52 mg/kg, respectively; whereas for in vivo grown plants it was 132.58 and 114.58 mg/kg, respectively. Therefore, Mg(OH)2NPs can be potentially used for enhancement of seed germination and seedling growth promotion.

Isolation and characterization of endophytes from nodules of Mimosa pudica with biotechnological potential

Legumes establish symbiotic relationships with different microorganisms, which could function as plant growth promotion microorganisms (PGPM). The finding of new PGPM strains is important to increase plant production avoiding or diminishing the use of industrial fertilizers. Thus, in this work we evaluated the plant growth promotion traits of ten strains isolated from Mimosa pudica root nodules. According to the 16S rDNA sequence, the microorganisms were identified as Enterobacter sp. and Serratia sp. To the best of our knowledge this is the first report describing and endophytic interaction between Mimosa pudica and Enterobacter sp. These strains have some plant growth promoting traits such as phosphate solubilization, auxin production and cellulase and chitinase activity. Strains identified as Serratia sp. inhibited the growth of the phytopathogenic fungi Fusarium sp., and Alternaria solani and the oomycete Phytophthora capsici. According to their biochemical characteristics, three strains were selected to test their plant growth promoting activity in a medium with an insoluble phosphate source. These bacteria show low specificity for their hosts as endophytes, since they were able to colonize two very different legumes: Phaseolus vulgaris and M. pudica. Seedlings of P. vulgaris were inoculated and grown for fifteen days. Enterobacter sp. NOD1 and NOD10, promoted growth as reflected by an increase in shoot height as well as an increase in the size and emergence of the first two trifolia. We could localize NOD5 as an endophyte in roots in P. vulgaris by transforming the strain with a Green Fluorescent Protein carrying plasmid. Experiments of co-inoculation with different Rhizobium etli strains allowed us to discard that NOD5 can fix nitrogen in the nodules formed by a R. etli Fix− strain. The isolates described in this work show biotechnological potential for plant growth promoting activity and production of indoleacetic acid and siderophores.

Growth responses of the intertidal seagrass Zostera japonica to manipulated sea level rise conditions

Although most seagrasses inhabit subtidal areas, a few species occur in the intertidal zone. The seagrass, Zostera japonica Asch. & Graebn., is an intertidal seagrass species, and thus this species may be vulnerable to environmental changes associated with sea level rise due to climate change. We examined the effects of continuous submergence conditions, which might be caused by sea level rise, on the growth of the intertidal seagrass, Z. japonica. In the present study, submerged conditions were generated in a Z. japonica meadow in the intertidal zone using transparent cylindrical cores, and the growth responses to the inundation conditions were examined. Daily photon flux density and temperature were not significantly different between the manipulated submerged and the control intertidal conditions during the experimental period. Increases in shoot height, biomass, and leaf productivity were among the acclimatory responses of Z. japonica to the inundation conditions. Shoot density, however, decreased rapidly in the submerged conditions as a result of the self-shading induced by taller and larger shoot sizes. Thus, prolonged inundation, which would be induced by a rise in sea level, had both positive and negative effects on the growth of the intertidal seagrass, Z. japonica, which exhibited plasticity at the individual and population levels. According to the results of our study, the restricted distribution of Z. japonica in the intertidal zone may not be a consequence of tidal inundation stress in the subtidal zone.

In vitro response of three contrasting cassava (Manihot esculenta Crantz) varieties to mannitol-induced drought stress

Abstract In vitro selection of drought-tolerant cassava varieties is essential for rapid breeding for drought tolerance. The objectives of this study were to determine the response of three contrasting cassava varieties to mannitol-induced drought stress to establish its suitability for in vitro screening and examine relationships among growth parameters. Plantlets were raised from nodal segments on Murashige and Skoog (MS) medium containing 0 (control), 5, 10, 15, 20, 25 and 30 g/l mannitol. Variety CH 140 had the highest survival of explants and frequency of root formation, while MV 99/0395 recorded the highest number of chlorotic leaves and the lowest survival of explants. The lowest numbers of leaves were produced at 25 and 30 g/l mannitol by the three varieties. In CH 140, the highest number of leaves was produced in medium free of mannitol, while the highest number of leaves was produced at 5 and 10 g/l mannitol in MV 99/0395 and TMS 01/1206, respectively. In TMS 01/1206, number of roots produced decreased as the concentration of mannitol in culture media increased, whereas in CH140, number of roots increased as the concentration of mannitol increased before decreasing; while in MV 99/0395, number of roots was not affected by an increase in mannitol concentration. As the concentration of mannitol in the culture media increased shoot height of plantlets decreased with a sharp decline at 20 mg/l mannitol. Concentration of mannitol and survival of explants had significant negative correlation with all parameters. However, frequency of root formation only had significant positive correlation with shoot length. The study concluded that differential responses were expressed by the three varieties to mannitol-induced drought stress and mannitol at 20 g/l concentration was a suitable in vitro drought inducing-agent for screening cassava varieties for drought tolerance.

In vitro response of three contrasting cassava (Manihot esculenta Crantz) varieties to mannitol-induced drought stress

Abstract In vitro selection of drought-tolerant cassava varieties is essential for rapid breeding for drought tolerance. The objectives of this study were to determine the response of three contrasting cassava varieties to mannitol-induced drought stress to establish its suitability for in vitro screening and examine relationships among growth parameters. Plantlets were raised from nodal segments on Murashige and Skoog (MS) medium containing 0 (control), 5, 10, 15, 20, 25 and 30 g/l mannitol. Variety CH 140 had the highest survival of explants and frequency of root formation, while MV 99/0395 recorded the highest number of chlorotic leaves and the lowest survival of explants. The lowest numbers of leaves were produced at 25 and 30 g/l mannitol by the three varieties. In CH 140, the highest number of leaves was produced in medium free of mannitol, while the highest number of leaves was produced at 5 and 10 g/l mannitol in MV 99/0395 and TMS 01/1206, respectively. In TMS 01/1206, number of roots produced decreased as the concentration of mannitol in culture media increased, whereas in CH140, number of roots increased as the concentration of mannitol increased before decreasing; while in MV 99/0395, number of roots was not affected by an increase in mannitol concentration. As the concentration of mannitol in the culture media increased shoot height of plantlets decreased with a sharp decline at 20 mg/l mannitol. Concentration of mannitol and survival of explants had significant negative correlation with all parameters. However, frequency of root formation only had significant positive correlation with shoot length. The study concluded that differential responses were expressed by the three varieties to mannitol-induced drought stress and mannitol at 20 g/l concentration was a suitable in vitro drought inducing-agent for screening cassava varieties for drought tolerance.

Rhizobia promote the growth of rice shoots by targeting cell signaling, division and expansion.

The growth-promotion of rice seedling following inoculation with Sinorhizobium meliloti 1021 was a cumulative outcome of elevated expression of genes that function in accelerating cell division and enhancing cell expansion. Various endophytic rhizobacteria promote the growth of cereal crops. To achieve a better understanding of the cellular and molecular bases of beneficial cereal-rhizobia interactions, we performed computer-assisted microscopy and transcriptomic analyses of rice seedling shoots (Oryza sativa) during early stages of endophytic colonization by the plant growth-promoting Sinorhizobium meliloti 1021. Phenotypic analyses revealed that plants inoculated with live rhizobia had increased shoot height and dry weight compared to control plants inoculated with heat-killed cells of the same microbe. At 6days after inoculation (DAI) with live cells, the fourth-leaf sheaths showed significant cytological differences including their enlargement of parenchyma cells and reduction in shape complexity. Transcriptomic analysis of shoots identified 2,414 differentially-expressed genes (DEGs) at 1, 2, 5 and 8 DAI: 195, 1390, 1025 and 533, respectively. Among these, 46 DEGs encoding cell-cycle functions were up-regulated at least 3 days before the rhizobia ascended from the roots to the shoots, suggesting that rhizobia are engaged in long-distance signaling events during early stages of this plant-microbe interaction. DEGs involved in phytohormone production, photosynthetic efficiency, carbohydrate metabolism, cell division and wall expansion were significantly elevated at 5 and 8 DAI, consistent with the observed phenotypic changes in rice cell morphology and shoot growth-promotion. Correlation analysis identified 104 height-related DEGs and 120 dry-weight-related DEGs that represent known quantitative-trait loci for seedling vigor and increased plant height. These findings provide multiple evidences of plant-microbe interplay that give insight into the growth-promotion processes associated with this rhizobia-rice beneficial association.

Growth-Promoting Ability of Rhodopseudomonas palustris G5 and Its Effect on Induced Resistance in Cucumber Against Salt Stress

The objective of this study was to investigate the potential of Rhodopseudomonas palustris G5 in promoting growth and inducing salt resistance in cucumber (Cucumis sativus L.). In this study, the growth-promoting potential of the bacteria was studied by measuring the ability to produce indole-3-acetic acid (IAA) and 5-aminolevulinic acid (ALA), fix nitrogen, and solubilize potassium and phosphate. The greenhouse pot experiments were set up to study how strain G5 affected growth and salt resistance of cucumber seedlings. The results showed that strain G5 exhibited plant growth-promoting attributes such as the production of IAA and ALA, as well as nitrogen-fixing, potassium-solubilizing, and phosphorus-solubilizing ability. In pot trials, strain G5 increased shoot height, root length, fresh weight, dry weight, total chlorophyll content, and soluble sugar content of cucumber seedlings under salt stress, compared to the seedlings that were exposed to salt stress in the absence of the strain G5. Furthermore, antioxidant enzyme activity analysis showed that strain G5 strongly increased the activity of superoxide dismutase, peroxidase, and polyphenol oxidase in cucumber seedlings under salt stress. In addition, strain G5 treatment decreased H2O2 and malondialdehyde contents of salt-stressed seedling. In sum, these results showed that strain G5 enhanced growth and induced systemic resistance in cucumber seedlings under salt stress by the production of IAA, ALA, and soluble sugars, the induction of antioxidant enzymes as well as nutrient adjustment of nitrogen, phosphorus, and potassium.

Copper nanoparticles together with cold atmospheric plasma improves the growth and physiological indices of Dracocephalum moldavica in hydroponic system

This experiment was conducted to investigate the effect of copper nanoparticles and cold atmospheric plasma on growth and physiological indices of Dracocephalum moldavica herbal plant under hydroponic culture conditions. The factors investigated in this experiment were copper nanoparticles at four levels of zero (control), 25, 50, and 75 ppm and cold atmospheric plas-ma at three times of zero (control), 20, and 30 seconds. The results showed that application of cold atmospheric plasma led to an increase in the shoot height, root length, shoot dry weight, root dry weight, leaf area, chlorophyll a, chlorophyll b, total chlorophyll, soluble leaf protein; it also decreased proline content. In addition, there was no significant difference between cold atmospheric plasma at the two durations of 20 and 30 seconds. Moreover, compared with the control and non-nanoparticle copper treatments, the use of copper nanoparticles improved the measured indices; accordingly, when making its greatest effect, the use of copper nanoparticles led to 27.77% increase in shoot height, 73.76% in root length, 67.98% in shoot dry weight, 87.67% in root dry weight, 22.83% in leaf area, 76.19% in soluble leaf protein in treatment with 25 ppm of copper and 39.42%, 50%, and 42.36% increase in chlorophyll a, chlorophyll b, total chlorophyll, respectively in treatment with 50 ppm of copper nanoparticles. Considering the obtained results, it can be concluded that the use of 25 ppm of copper nanoparticles (due to the application of nanoparticle instead of non-nanoparticle copper) within 20 seconds of cold atmospheric plasma improves the growth and physiological indices of D. moldavica herbal plant under hydroponic culture conditions.

Allelopathic Effect of Bidens Pilosa on Seed Germination and Growth of Amaranthus Dubius

Allelopathy is the inhibitory effect of one plant on another by releasing chemicals through leaching, root exudation and residue decomposition. Allelopathic inhibition involves the interaction of different classes of chemicals which affect germination, plant growth and development. Studies have been done showing that Bidens pilosa has allelopathic effects on maize, sorghum and lettuce but information on it’s effect on Amaranthus dubius is lacking. Amaranthus dubius has become one of Kenya’s most important vegetables. It’s famous for its high protein content and medicinal properties. This study was done to investigate allelopathic effects of B. pilosa on germination and growth of A. dubius. Different concentrations of B. pilosa extract were prepared (0%,25%, 50%, 75%, and 100%) using tap water as control . Twenty seeds were germinated in petri dishes lined with filter paper, then soaked with the aqueous extract solutions. The treatments were replicated four times and data was collected for two weeks. Growth tests were carried out in the greenhouse using 24 3Litre pots. Twenty seeds were planted in each pot and leaves of B.pilosa of different amounts (0g, 20g, 40g, 60g, 80g, and 100g) were added into the soil. Treatments were replicated four times and data collected for six weeks and subjected to Analysis of Variance using SAS package. Treatment means were compared using Least Significance Difference (P≤0.05). The aqueous extract of B. pilosa significantly reduced germination rate. Fresh leaf biomass of B. pilosa significantly increased shoot height, leaf number,and leaf area, fresh and dry weights. Leaf biomass of B. pilosa had no significant effect on root length and chlorophyll content. The study revealed that B. pilosa has potential use as green manure in crop production.

Effect of Rhodopseudomonas palustris G5 on seedling growth and some physiological and biochemical characteristics of cucumber under cadmium stress

At present, we investigated whether Rhodopseudomonas palustris G5 strain treatments diminished the damage on cucumber seedlings caused by cadmium (Cd) stress. Growth and physiological parameters of cucumber seedlings were determinated at laboratory after co-treating seedlings with Rhodopseudomonas palustris G5 strain and different concentrations of Cd (50, 100, 150, 200, 300 mg L-1). The results indicated that Cd stress significantly reduced shoot height, root length, total chlorophyll content, root activity, but increased malondialdehyde (MDA) content. In addition, lower concentrations of Cd stress increased soluble sugar and soluble protein contents, and improved the activities of superoxide dismutase (SOD; EC: 1.15.1.1) and peroxidase (POD; EC: 1.11.1.7), but higher concentrations of Cd decreased the soluble sugar and soluble protein contents, and inhibited SOD and POD activities. G5 strain application markedly reduced the toxic effects of Cd on cucumber seedlings. In sum, G5 strain treatment significantly alleviated damage on cucumber seedlings caused by Cd, and increased shoot height, root length, total chlorophyll content, root activity, the contents of soluble sugar and soluble protein, as well as the activities of SOD and POD, but decreased MDA content compared with non- treating plants.

Bacterial endophytes enhance phytostabilization in soils contaminated with uranium and lead

ABSTRACTThe combined use of plants and bacteria is a promising approach for the remediation of polluted soil. In the current study, the potential of bacterial endophytes in partnership with Leptochloa fusca (L.) Kunth was evaluated for the remediation of uranium (U)- and lead (Pb)-contaminated soil. L. fusca was vegetated in contaminated soil and inoculated with three different endophytic bacterial strains, Pantoea stewartii ASI11, Enterobacter sp. HU38, and Microbacterium arborescens HU33, individually as well as in combination. The results showed that the L. fusca can grow in the contaminated soil. Bacterial inoculation improved plant growth and phytoremediation capacity: this manifested in the form of a 22–51% increase in root length, 25–62% increase in shoot height, 10–21% increase in chlorophyll content, and 17–59% more plant biomass in U- and Pb-contaminated soils as compared to plants without bacterial inoculation. Although L. fusca plants showed potential to accumulate U and Pb in their root and shoot on their own, bacterial consortia further enhanced metal uptake capacity by 53–88% for U and 58–97% for Pb. Our results indicate that the combination of L. fusca and endophytic bacterial consortia can effectively be used for the phytostabilization of both U- and Pb-contaminated soils.

Automated ebb-and-flow subirrigation for citrus liners production. I. Plant growth

Ebb-and-flow subirrigation is a closed system that applies water to the bottom of the containers, reducing water and nutrient losses due to recirculation of fertilizer solution (FS). The technology can improve plant growth and eliminate the improper disposal of salts into the environment. Subirrigation is widely used in the ornamental industry, and sensor-based ebb-and-flow benches can be used by the citrus nursery industry. There is a need for establishing water and fertilizer guidelines to produce citrus rootstocks. The objectives of this study were: 1) design and build an ebb-and-flow subirrigation equipment, 2) automate the system operation using soil moisture sensors, 3) evaluate the system performance on plant growth, and 4) determine the water and fertilizer guidelines to produce Rangpur lime (Citrus×limonia) liners in 56-cm3 cone-shaped containers. The treatments were four volumetric water content (VWC) to trigger subirrigation (0.12, 0.24, 0.36 and 0.48m3m−3), three FS concentrations (25%, 50% and 75% of the fertilizer recommendation) and a control (nursery manual overhead irrigation using breaker nozzles), arranged in a completely randomized 4×3+1 factorial plus design, with three replications. The system was automated by 39 capacitance sensors connected to a data logger, multiplexer and relay drivers, which controlled independent submersible pumps. Subirrigation was turned on when VWC dropped below the set thresholds. Sensors effectively monitored the substrate moisture and controlled subirrigation. Treatments with highest VWC had higher substrate moisture and number of irrigations over time (p<0.0001). The volume of water applied doubled from treatments 0.12–0.48m3m−3 (p<0.0001). Subirrigation increased shoot height, stem diameter, dry weight, leaf area, physiological parameters (leaf intracellular concentration of CO2, transpiration, stomatal conductance, and net photosynthesis), and water use efficiency in response to increase in VWC and FS (p<0.0001). Subirrigation shortened the crop cycle in 30 days, anticipating the liners transplant for grafting, allowing another cultivation cycle in the nursery during the year. VWC of 0.48m3m−3 and FS concentration of 50% of the recommended value for overhead irrigation are indicated for Rangpur lime liner production in 56-cm3 containers.