Gibberellic acid affects growth and flowering of Philodendron‘Black Cardinal’

Changes in net photosynthetic rate (P_N), stomatal conductance (g_s), intercellular CO₂ concentrations (C_i), transpiration rate (E) and water use efficiency (WUE) were measured in Plantago major L. plants grown under sufficient soil water supply or under soil water stress conditions. The plants had high P_N in a wide range of soil water potential and temperature regimes. Soil water had little effect on P_N under ambient CO₂ concentrations, which was explained by a high carboxylation rate, but increased the dark respiration rate. Carboxylation activity at low C_i depended on RuBP regeneration, whereas at high C_i it depended on the phosphate regeneration rate. The g_s and E values were low in plants under stress as compared to the controls that resulted in an increase of WUE. The results obtained show that Plantago major plants have different ways of adaptation to soil water deficit conditions.     

Influence of gabaculine on growth,chlorophyll synthesis,and δ-aminolevulinic acid synthase activity in Euglena gracilis

Euglena gracilis is capable of forming the heme and chlorophyll precursor δ-aminolevulinic acid (ALA) by two routes: from glutamate via the five-carbon path in the chloroplasts, and by ALA synthase-mediated condensation of succinyl-CoA and glycine, probably in the mitochondrion. 5-Amino-1,3-cyclohexadienyl carboxylic acid (gabaculine), a powerful inhibitor of ALA formation via the five-carbon path, was administered to E. gracilis Klebs strain Z Pringsheim cells growing in the light or dark, and its effects on growth, chlorophyll accumulation and extractable ALA synthase activity were measured. Gabaculine had no effect in vitro on ALA synthase or ALA dehydratase, even at 100 μM. Administration of 100 μM gabaculine to wild-type cells growing in the light slowed growth, inhibited chlorophyll accumulation, and induced an increase in extractable ALA synthase activity. Chlorophyll accumulation in the light was abolished by prior administration of the compound to growing cells for 6 h in the dark, whereas chlorophyll accumulation in cells without gabaculine began immediately after transfer to light. Extractable ALA synthase activity from gabaculine-pretreated dark-grown cells was initially lower than the activity from untreated cells, but it did not undergo a further decline after transfer of the cells to the light, whereas the activity from untreated cells dropped to less than one eighth the dark level after 2 h in the light, and by 4 h had fallen to a level five times lower than that extractable from gabaculine-treated cells. These results suggest that suppression of ALA synthase activity by light in untreated cells is related to light-induced activation of the five-carbon ALA biosynthetic pathway in the plastids, and may result from a contribution by a product of the five-carbon pathway to non-plastid tetrapyrrole pools in the light.     

Influence of method of application of paclobutrazol on soil residues and growth retardation in a ‘Starkrimson-Delicious’ apple orchard

A 3-year field study was conducted to determine the influence of mode of application of the gibberellin-inhibitor paclobutrazol (PP333), [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4 triazol-1-yl)pentan-3-ol], on PP333 soil residue levels and vegetative growth retardation of 10-year-old Starkrimson Delicious (Malus Domestica Borkh.) spur-type apple trees. Treatments were applied in March, 1986 and consisted of foliar or soil sprays (200 ppm, 7 × applications at petal fall (+) 2, 4, 6, 8, 10 and 12 weeks) or a single soil drench (8.2 g A.I./tree) applied to the collar at petal fall. Foliar sprays were applied with and without a plastic ground cover to evaluate the influence of foliar runoff on the degree of soil absorption and its subsequent effect on vegetative growth. PP333 was extracted over a 3 year period (1986–88) from 400 cm² soil patches located at the drip line of each tree, with the exception of soil drenches which were sampled near the collar. PP333 soil extracts were purified and quantitatively analyzed by HPLC. PP333 soil residue levels following foliar sprays were comparable to the soil spray treatment for each year and decreased at a rate of 50% per year from 1986–1988. Foliar sprays retarded terminal growth in the year of application, whereas the soil spray did not inhibit growth until the following year. PP333 residue levels were highest in the soil drench where growth retardation was evident in 1987 and 1988. The greatest carry-over effect occurred in the soil treatments, especially the soil drench application which resulted in the highest soil residue rates throughout the 3 year period.     

Influence of exogenous abscisic acid on germination and plantlet conversion frequencies of hybrid larch somatic embryos (Larix × leptoeuropaea)

The effect of exogenous abscisic acid, provided to somatic embryos during the maturation step, on endogenous abscisic acid and its main conjugated form (abscisic acid glucose ester), germination and conversion frequencies is presented in this paper. Abscisic acid measurements were obtained after a methanolic extraction, a fractionation through high performance liquid chromatography, quantitation with an immunoassay and identification of the quantitated compound using gas chromatography-mass spectrometry. Results show that endogenous abscisic acid and abscisic acid glucose ester levels are clearly correlated with the exogenous abscisic acid concentration provided to the embryos. Maturation was clearly enhanced by exogenous abscisic acid, but no correlation was found between abscisic acid concentration and germination frequency. Conversely, development of the aerial part of the germinated somatic embryos was dependent upon the abscisic acid concentration in the culture medium and results suggest that this dependence could be related to the endogenous abscisic acid content.     

Effect of exogenous abscisic acid (ABA) on the morphology,phytohormones, and related gene expression of developing lateral roots in ‘Qingzhen 1’ apple plants

Plant Cell, Tissue and Organ Culture (PCTOC) - Lateral roots (LRs) are critical for plant stress tolerance and productivity. Understanding how hormones and genes interact in a fluctuating...     

In vitro production of flowering shoots in ‘German Red’ carnation: effect of uniconazole and gibberellic acid

Summary Callus regenerated near the base of senescing petals of flower bud explants of German Red carnation (Dianthus caryophyllus L.) produced adventitious flowering microshoots on MS-medium containing benzylaminopurine (8.9 M) and naphthaleneacetic acid (2.7 M). When these microshoots were subcultured with some callus, additional adventitious flowering microshoots were produced from the callus. The production of adventitious flowering shoots continued for many subcultures spanning a period of more than two years. Uniconazole (6.9 M) increased the number of adventitious shoots formed by as much as two-fold but decreased shoot length by about 50%. In contrast, GA₃ (2.9 M) decreased adventitious shoot formation and increased shoot length. Regardless of the growth regulator treatment, virtually all of the adventitious shoots produced flower buds. Thus, the growth regulators influenced flowering only indirectly by altering the number of adventitious shoots produced in vitro. These results demonstrate that the flowering habit of the adventitious shoots of German Red carnation is highly persistent and the flowering stimulus continues to be transmitted to the newly formed microshoots through the callus.     

Influence of rootstocks on growth,yield, fruit quality and leaf mineral element contents of pear cv. ‘Santa Maria’ in semi-arid conditions

Background

Rootstocks play an essential role to determining orchard performance of fruit trees. Pyrus communis and Cydonia oblonga are widely used rootstocks for European pear cultivars. The lack of rootstocks adapted to different soil conditions and different grafted cultivars is widely acknowledged in pear culture. Cydonia rootstocks (clonal) and Pyrus rootstocks (seedling or clonal) have their advantages and disadvantages. In each case, site-specific environmental characteristics, specific cultivar response and production objectives must be considered before choosing the best rootstock. In this study, the influence of three Quince (BA 29, Quince A = MA, Quince C = MC) and a local European pear seedling rootstocks on the scion yield, some fruit quality characteristics and leaf macro (N, P, K, Ca and Mg) and micro element (Fe, Zn, Cu, Mn and B) content of ‘Santa Maria’ pear (Pyrus communis L.) were investigated.

Results

Trees on seedling rootstock had the highest annual yield, highest cumulative yield (kg tree⁻¹), largest trunk cross-sectional area (TCSA), lowest yield efficiency and lowest cumulative yield (ton ha⁻¹) in the 10^th year after planting. The rootstocks had no significant effect on average fruit weight and fruit volume. Significantly higher fruit firmness was obtained on BA 29 and Quince A. The effect of rootstocks on the mineral element accumulation (N, K, Ca, Mg, Fe, Zn, Cu, Mn and B) was significant. Leaf analysis showed that rootstocks used had different mineral uptake efficiencies throughout the early season.

Conclusion

The results showed that the rootstocks strongly affected fruit yield, fruit quality and leaf mineral element uptake of ‘Santa Maria’ pear cultivar. Pear seedling and BA 29 rootstock found to be more prominent in terms of several characteristics for ‘Santa Maria’ pear cultivar that is grown in highly calcareous soil in semi-arid climate conditions. We determined the highest N, P (although insignificant), K, Ca, Mg, Fe and Cu mineral element concentrations on the pear seedling and BA 29 rootstocks. According to the results, we recommend the seedling rootstock for normal density plantings (400 trees ha⁻¹) and BA 29 rootstock for high-density plantings (800 trees ha⁻¹) for ‘Santa Maria’ pear cultivar in semi-arid conditions.     

Effects of nutrient addition on growth and rhizosphere pH of Leucadendron ‘Safari Sunset’

A greenhouse experiment was conducted to establish the optimal fertilization management for Leucadendron Safari Sunset (Leucadendron salignum × L. laureolum). Addition of NPK and micronutrient fertilizer or raising phosphorus concentration by itself increased total fresh weight and improved plant growth. Elevating the total nutrients or P concentration increased N and P concentrations. Clusters of proteoid roots were present along the root system of plants irrigated with tap-water, whereas few proteoid roots developed on plants irrigated with complete nutrient solution when only P was omitted, and none developed in any of the other treatments with P present.The pH in leachate of plants irrigated with tap water or with high nutrient levels (100, 20 and 100 mg L^-1 of N, P and K, respectively) was consistently lower compared with leachate without plants. Increasing concentration resulted in a significant change in the pH values (pH in leachate with plant – pH in leachate without plant) from negative to positive. This phenomenon is probably related to rhizosphere effects due to plant and microbial activity.     

Influence of Agrobacterium rhizogenes strains on hairy root induction and ‘bacoside A’ production from Bacopa monnieri (L.) Wettst.

Stable lines of hairy roots were established from leaf explants of Bacopa monnieri using different strains (A4, R1000, SA79, MTCC 532 and MTCC 2364) of Agrobacterium rhizogenes. The efficiency of hairy roots induction of these strains varied significantly and the maximum transformation frequency (75 %) was observed in case of strain SA79 using leaf explants followed by internode (55 %) in the presence of acetosyringone. Different parameters such as cell density of Agrobacterium suspension, co-cultivation period and infection time influenced the root induction frequency. Maximum frequency of root induction was obtained with bacterial density of 0.6 OD₆₀₀, 2 days of co-cultivation period and 10 min of infection time. Integration of T-DNA in the genome of hairy roots was confirmed by PCR amplification of rolB gene. Elimination of Agrobacterium from the established root cultures was ascertained by amplifying the DNA fragment specific to 16S rDNA and virD gene. All lines of hairy roots except strain A4 induced showed higher growth rate and accumulated higher levels of ‘bacoside A’ than the untransformed roots. Maximum biomass accumulation (6.8 g l^?1) and ‘bacoside A’ content (10.02 mg g^?1 DW) were recorded in case of the hairy root line induced by strain MTCC 2364.     

Influence of Prohexadione-Calcium on the Growth and Quality of Summer ‘Jen-Ju Bar’ Guava Fruit

A 2-year trial was conducted to investigate the influence of prohexadione-calcium (ProCa) on the fruit quality of summer ‘Jen-Ju Bar’ guava (Psidium guajava L.). ‘Jen-Ju Bar’ trees were treated with various concentrations of ProCa: 0 (as control), 125, 250, and 500 mg L^?1, which significantly inhibited spring shoot growth. Summer guava fruits of the trees subjected to ProCa exhibited higher levels of total soluble solids and higher values of total soluble solids to titratable acidity ratio compared with control fruits. Summer guava fruits from trees treated with ProCa were firmer than those from untreated trees. ProCa sprays significantly affected pulp weight, core weight, pulp thickness, and pulp-to-core ratio. No other fruit quality characteristics were significantly affected by ProCa treatment.     

Three genetic systems controlling growth, development and productivity of rice (Oryza sativa L.): a reevaluation of the ‘Green Revolution’

The Green Revolution (GR-I) included worldwide adoption of semi-dwarf rice cultivars (SRCs) with mutant alleles at GA20ox2 or SD1 encoding gibberellin 20-oxidase. Two series of experiments were conducted to characterize the pleiotropic effects of SD1 and its relationships with large numbers of QTLs affecting rice growth, development and productivity. The pleiotropic effects of SD1 in the IR64 genetic background for increased height, root length/mass and grain weight, and for reduced spikelet fertility and delayed heading were first demonstrated using large populations derived from near isogenic IR64 lines of SD1. In the second set of experiments, QTLs controlling nine growth and yield traits were characterized using a new molecular quantitative genetics model and the phenotypic data of the well-known IR64/Azucena DH population evaluated across 11 environments, which revealed three genetic systems: the SD1-mediated, SD1-repressed and SD1-independent pathways that control rice growth, development and productivity. The SD1-mediated system comprised 43 functional genetic units (FGUs) controlled by GA. The SD1-repressed system was the alternative one comprising 38 FGUs that were only expressed in the mutant sd1 backgrounds. The SD1-independent one comprised 64 FGUs that were independent of SD1. GR-I resulted from the overall differences between the former two systems in the three aspects: (1) trait/environment-specific contributions; (2) distribution of favorable alleles for increased productivity in the parents; and (3) different responses to (fertilizer) inputs. Our results suggest that at 71.4 % of the detected loci, a QTL resulted from the difference between a functional allele and a loss-of-function mutant, whereas at the remaining 28.6 % of loci, from two functional alleles with differentiated effects. Our results suggest two general strategies to achieve GR-II (1) by further exploiting the genetic potential of the SD1-repressed and SD1-independent pathways and (2) by restoring the SD1-mediated pathways, or ‘back to the nature’ to fully exploit the genetic diversity of those loci in the SD1-mediated pathways which are virtually inaccessible to most rice-breeding programs worldwide that are exclusively based on sd1.     

Influence of indole-3-butyric acid and propagation method on growth and development of in vitro- and ex vitro-derived lowbush blueberry plants

The effects of four indole-3-butyric acid (IBA) concentrations and two propagation methods were studied in a lowbush blueberry (Vaccinium angustifolium Ait.) clone collected from natural stands in Newfoundland and Labrador, Canada. Lowbush blueberry cultures were established in vitro from nodal explants on a modified cranberry (V. macrocarpon Ait.) tissue culture medium containing zeatin (2 μM). Blueberry plants propagated by in vitro shoot proliferation (TC) and by conventional softwood cuttings (SC) were evaluated for growth and morphology. Significant interactions for morphological characteristics were observed among the treatments. The IBA concentration had an effect on morphology of propagated plants, increasing the concentration of IBA increased stem length and leaves per stem across propagation methods. Stems per plant increased with IBA concentration up to 20 μM in SC plants, but not in TC plants. Plant vigor was affected by neither IBA concentration nor propagation method. The TC plants produced longer and more stems with more leaves per stem than the conventional cuttings. In vitro culture on zeatin-containing nutrient medium apparently induces the juvenile branching characteristics that favored enhanced vegetative growth with more stems and leaf production. It is suggested that IBA may serve as a physiologically active form of auxin in contributing to increased stem and leaf production in lowbush blueberry SC plants but not in TC plants.     

Influence of cold pretreatment on shoot regeneration from callus in date palm (Phoenix dactylifera L.) cv. ‘Barhee’

Mass propagation of date palm through indirect somatic embryogenesis or organogenesis has attracted the interest of commercial producers. But, this technique still faces some problems that hindered the production of date palm plantlets in vitro. Tissue browning is one of the serious problems that reduce callus growth and shoot regeneration. So the objective of the present study is to investigate the effect of cold pretreatment on callus growth, shoot regeneration, and polyphenol oxidase (PPO) activity during the callus culture. Results showed that a high survival rate of callus cultures (100%) were obtained when cultures were incubated in low temperature (cold treatment) for 45 and 75?days. On the other hand, total amount on phenolic compounds was also reduced to 0.47 and 0.53?mg GAE/g after same period of incubation (45 and 75?days respectively) at low temperature. In additional, our results showed that the highest frequency of shoot formation (66.67 and 73.34, %) and the highest shoot numbers (7.8 and 8.6 shoots/100?mg) were obtained from callus treated with low temperature for 45 and 75?days, respectively.     

Effect of liquid culture on the growth and development of miniature rose (Rosa chinensis Jacq. ‘Minima’)

The growth of miniature rose (Rosa chinensis Jacq. Minima) shoots cultured on liquid medium was greater relative to those cultured on two-phase (solid + liquid) medium or solid medium alone. Shoot multiplication ratio (number of multiple shoots per explant per subculture) on liquid medium was higher with 17.8–26.6 M 6-benzyladenine at compared to that at 0–8.9 M. Shoots grown on 30 ml or more of liquid medium had a higher multiplication ratio than those grown on 10 or 20 ml. The growth and multiplication ratio increased when the culture period was extended from 3 to 6 weeks, although plantlets began to exhibit some chlorosis by the 6^th week. These conditions were maintained over four subcultures for cultivars Baby Katie, Lavender Jewel, Red Sunblaze and Royal Sunblaze, with no significant change in multiplication ratio over time.Abbreviations BA 6-benzyladenine - NAA 1-naphthaleneacetic acid     

Effects of the planting density on water relations and production of ‘Chemlali’ olive trees (Olea europaea L.)

Water relations are a key factor limiting olive production. In this study, effects of plating density on physiological aspects and productivity of ‘Chemlali’ olive trees were analyzed under rain-fed conditions in four planting densities (156, 100, 69 and 51 trees ha⁻¹), in an experimental olive orchard located in the center of Tunisia. Seasonal changes in leaf relative water content (RWC), leaf water potential, stomatal conductance (g _s), CO₂ assimilation rate and tree production were studied. Accompanying the changes in leaf water status, all the monitored trees reduced leaf stomatal conductance (g _s) and photosynthetic rate (A) throughout the summer drought, mirroring the increase in soil moisture deficit and vapor pressure deficit. However, the decrease in gas exchange was much more pronounced in high planting densities than in low ones. Our results confirm that the increase of tree-to-tree water competition with planting density was significant in the dry climate of Tunisia. Thus, planting density is critical when planting new olive orchards in arid regions.     

Exogenous gibberellic acid increases the fruit weight of ‘Comte de Paris’ pineapple by enlarging flesh cells without negative effects on fruit quality

In mainland China, the most popular pineapple cultivar is ‘Comte de Paris’. Gibberellic acids have been widely applied to enhance fruit growth in various species. To evaluate the effect of gibberellic acid (GA₃) on ‘Comte de Paris’ pineapple production and quality, pineapple fruits were sprayed with GA₃ at concentrations of 5, 20, 50, or 100 mg l⁻¹ at both 0 and 15 days after flowering (DAF). Fruits were sampled every 15 days from 0 to 60 DAF (maturation) for flow cytometric analysis and histological observation. The results showed that the treatments with the three highest concentrations of GA₃ significantly increased fruit weight, and the most effective concentration was 50 mg l⁻¹ GA₃, which increased the flesh weight by 20.3% compared to the control. Although treatment with GA₃ had little effect on the total soluble solids and fruit juice pH, it increased the vitamin C content. Although flow cytometric analysis showed that the 50 mg l⁻¹ GA₃ treatment had only a slight impact on the number of S phase cells, histological observations indicated that the increase of fruit volume and flesh weight under this GA₃ treatment was not due to the increase of cell number but a result of the increase of cell area in the fruit flesh.     

The effects of exogenous auxin and rol genes on root formation in Rosa hybrida L. ‘Moneyway’

The effect of indole-3-butyric acid (IBA) on the formation of non-transformed and rol gene transformed roots on stem slices of in vitro cultured shoots of Rosa hybrida L. Moneyway was examined. Formation of adventitious roots on this rootstock was dependent on the IBA dose; it was not affected by the presence of other root primordia on the same explant. Application of 0.32 to 1 M IBA during 5 days, followed by transfer to medium without hormones resulted in maximum root formation (90%) after three weeks. The formation of such untransformed roots was completely inhibited by transfer to medium with 5 mg 1^–1 kanamycin two days after excision. Ri roots were formed upon inoculation with A. rhizogenes LBA9402 harbouring two plasmids: pRi1855, comprising the rol genes and the binary plasmid p 35Sgusintron with the nptII gene for kanamycin resistance and the CaMV 35Sgusintron gene. The formation of these Ri roots on kanamycin-containing medium was independent of the presence of IBA. Stem slices inoculated with a disarmed A. tumefaciens GV3101, harbouring only the nptII gene, formed callus and subsequently roots in the presence of kanamycin exclusively on medium with high IBA concentrations (10 or 100 M). Root formation at 100 M IBA was considerably improved by transformation with the rolB gene under the influence of the strong CaMV 35S promoter. In addition, low IBA (0.1 and 1 M) stimulated the formation of roots only on stem slices transformed with A. tumefaciens harbouring the rolA+rolB+rolC genes; the rooting response at 10 M IBA was much improved. It was concluded that the 35SrolB gene and especially a combination of rolA, B and C genes promote the rooting response.Abbreviations BAP 6-benzylaminopurine - FeEDDHA ferric ethylenediamine di(o-hydroxyphenylacetate) - IBA indole-3-butyric acid - LSD least significant difference - RIM root induction medium - SE standard error - X-gluc 5-bromo-4-chloro-3-indolyl glucuronide