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 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.     

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.     

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...     

Effect of ‘Mixtalol’ on growth,yield and yield components of Indian mustard (Brassica juncea)

Mixtalol (a mixture of long chain aliphatic alcohols varying in chain length from C₂₄ to C₃₂) applied to Brassica juncea plants as foliar spray caused an increase in secondary and tertiary branching with consequent enhancement in seed yield through increased number of inflorescences and siliquae per plant. The percentage of immature siliquae and shattering of siliquae decreased with this treatment. Mixtalol increased total dry matter of plants, partitioning coefficient and harvest index. The contents of starch, protein and oil were also higher in seeds from Mixtalol treated plants.     

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.     

Studies on Mg,B, and Zn deficiencies in acid ‘Wilder’ soil of California

Summary A greenhouse study of some aspects of infertility of an acid soil of California, namely the ‘Wilder’ soil, was undertaken. Experiments with white-rooted radish showed that the soil when limed to near neutrality with CaCO₃ indicated deficiencies of boron and magnesium. When sweet corn was used as a test crop, zinc deficiency was exposed in limed soil. The plant tissue tests and morphological observations corroborated this. The apparent decrease in zinc content in sweet corn in presence of the added phosphate was taken to be a dilution effect. The work was carried out in Department of Soils and Plant Nutrition, University of California, Davis.     

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 plant-growth-promoting bacteria on germination,growth and nutrients’ uptake of Onobrychis sativa L. under drought stress

The study was conducted to investigate the effect of growth-promoting bacteria (Azotobacter vinelandii?=?A, Pantoea agglomerans?+?P. putida?=?P, combined A?+?P, control) on the germination, growth and nutrient uptake of Onobrychis sativa L. under drought stress (field capacity (FC), 0.7?FC, 0.4?FC). The results showed that the highest and lowest germination rate (GR) was related to the P and control treatments in FC level, respectively. The maximum root and shoot length at the FC level was related to the treatment A. In the A?+?P treatment, the maximum shoot dry weight was measured in 0.7?FC level. The lowest root dry weight was also related to the A?+?P treatment in the FC level. Bio-fertilizers had the maximum impact in increasing the nutrients uptake in 0.7?FC and FC levels. The fertilizers in 0.7?FC and FC levels increased the plant traits and played no significant role in mitigating the effects of drought stress.     

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 water temperature and waterborne cadmium toxicity on growth performance and metallothionein–cadmium distribution in different organs of Nile tilapia,Oreochromis niloticus (L.)

Cadmium (Cd) is believed to be one of the most abundant and ubiquitously distributed toxins in the aquatic system. This metal is released to the aquatic environment from both anthropogenic sources, such as industrial, agricultural and urban effluents as well as natural sources, such as rocks and soils. Otherwise, the temperature increase of water bodies, which has been observed due to global climatic changes, has been shown to increase Cd toxicity for several aquatic animal species including fish. In the present study, Nile tilapia, Oreochromis niloticus (L.), (26.0±0.38 g) were reared at 20, 24, 28, or 32 °C and exposed to 0.0 or 0.5 mg Cd/L for 8 weeks to investigate effects of water temperature, Cd toxicity and their interaction on fish performance as well as metallothionein (MT) and Cd distribution in different fish organs. It was found that fish reared in Cd-free group at 28 °C showed the optimum growth and feed intake, while Cd-exposed fish showed low growth and feed intake irrespective to water temperature. A synergetic relationship between water temperature and Cd toxicity was observed where Cd toxicity increased as water temperature increased and the worse growth was obtained in Cd-exposed fish reared at 32 °C. Additionally, the highest Cd residues in different fish organs were detected in Cd-exposed fish reared at 32 °C. Similarly, MT concentrations in different fish organs increased as water temperature increased especially in Cd-exposed fish groups. A high positive correlation between MT and Cd concentrations in fish organs was detected. The distribution of MT and Cd levels was in the order of liver>kidney>gills>muscles. The present study revealed that the optimum water temperature suitable for Nile tilapia growth is 28 °C. Additionally, Cd exposure had a deteriorate effect on the growth and health of Nile tilapia. This hazardous effect increased as water temperature increased. Further, liver and kidney were the prime sites of Cd accumulation, while Cd load in the muscles was the lowest as compared to the other investigated organs.     

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.