Genes for dwarfing and photoperiod flowering response inPharbitis nil choisy

Dwarfing and sensitivity to the duration of a single inductive dark period for flowering ofPharbitis nil in F₂ progeny of a cross between the tall strain Tendan, and the dwarf, Kidachi appear to be controlled by the alleles at two independent loci. Progeny of a similar cross between the tall strain Violet and the dwarf Kidachi at F₂ and F₃ also showed single locus segregation for tall: dwarf plants. In this cross, differences in photoperiodic response could be identified in F₃ families but they were not simply inherited. There was some evidence of difficulties with classification of the F₂ plants, but also, the flowering of the F₁ between the two less sensitive strains Tendan and Violet indicated complex inheritance of their photoperiodic response. Complementary dominant alleles at three independent loci may be necessary for flowering in even shorter dark periods with the sensitive strain Kidachi. The dwarf strain Kidachi has a reduced gibberellin (GA) content (Barendse and Lang 1972), it flowers in a short dark period without terminal flowering, and it responds positively to GA application both for flowering and growth. However, since control of dwarfing and photoperiodic sensitivity can be separated genetically, there is no strick link between the gibberellin responsiveness of Kidachi for its growth and flowering. Despite the complexity of flowering genetics in Violet×Kidachi, a short-dark-period-sensitive, terminal flowering and tall F₇ line was obtained in a pedigree previously held heterozygous for the dwarf: tall character but not selected for flowering time. Thus, flowering in a short dark period can also be obtained in the presence of the non-dwarfing allele from strain Violet, again demonstrating genetic independence.     

Formation of bound gibberellins inPharbitis nil

Summary Developing seeds ofPharbitis nil accumulate free as well as bound gibberellins until a maximum level is reached at approximately 25 days after anthesis. Seeds from CCC-treated parent plants have a strongly reduced level of free as well as bound gibberellins. When different spray reagents were used it was found that trichloroacetic acid in particular was suitable to locate non-hydrolysed bound GA fractions on thin-layer plates. Chromatography showed two major bound GA fractions, determined with spray reagents as well as by means of hydrolysis.³H-GA₁ applied to youngPharbitis plants was converted to two water-soluble compounds present in the aqueous phase. The rate of conversion was significantly enhanced when³H-GA₁ and¹⁴C-glucose were applied to the same plants. Chromatography indicated that one of the conversion products of³H-GA₁ became at least partly associated with the applied¹⁴C-glucose (or its products). This suggestion was also supported by the fact that mild acid hydrolysis of the aqueous fraction resulted in the reappearance of³H-GA₁ and a conversion product of³H-GA₁, including a¹⁴C-radioactivity peak cochromatographing with¹⁴C-glucose. However, the conversion products obtained with³H-GA₁ applied to plants appeared to be chromatographycally different from any of the bound-GA fraction established by means of hydrolysis or spray reagents in developing seeds.Abbreviation GA(s) gibberellin(s).     

Gibberellins in seedlings and flowering trees of Prunus avium L

Extracts of acids from mature seeds, germinating seeds, first, second and third year seedlings as well as mature, flowering trees of sweet cherry (Prunus avium L. cv. Stella) were analysed by gas chromatography-mass spectrometry. The presence of the known gibberellins (GAs) GA1 (1), GA3 (4), GA5 (7), GA8 (11), GA19 (14), GA20 (12), GA29 (13), GA32 (5), GA85 (2), GA86 (3) and GA87 (6) was confirmed by comparison of their mass spectra and Kovats retention indices with those of standards or literature values. In addition, 16alpha,17-dihydrodihydroxy GA25 (16) was identified and its stereochemistry confirmed by rational synthesis. The 12alpha,13-dihydroxy GAs, GA32 (5), GA86 (2), GA86 (3) and GA87 (6), were detected in mature seeds, germinating seeds and young seedlings, but not in flowering plants. The 13-hydroxy GAs, GA1 (1) and GA3 (4), were present in germinating seeds and, in addition to these, GA5 (7), GA8 (11), GA19 (14), GA20 (12) and GA29 (13) were detected in seedlings and mature flowering plants. In germinating seeds and seedlings (while the plants were growing actively), concentrations of the 12alpha,13-dihydroxy GAs, measured by bioassay, declined and those of the 13-hydroxy GAs increased. The results are discussed with reference to the known and predicted effects of the GAs on the vegetative growth and flowering of P. avium plants.     

Micropropagation of flowering dogwood (Cornus florida) from seedlings

A method for regenerating whole plants from nodal (axillary bud) cultures of seedlings was developed for flowering dogwood (Cornus florida L.). The seed source significantly influenced the rate of proliferation, although cultures initiated from each of the seven mother trees produced some shoots. Woody plant medium (WPM) was superior to either Murashige and Skoog or Schenk and Hildebrandt basal medium. 6-Benzyladenine (BA) at 2.2 or 4.4 m stimulated the generation of significantly more useable shoots (1 cm) compared to all other concentrations (0.5–22.5 m tested. Thidiazuron (TDZ) at 0.6 and 1.1 m supported proliferation, but strongly inhibited shoot elongation. TDZ initiated cultures transferred to medium containing 4.4 m BA produced usable shoots after five additional subcultures. Shoots generated adventitious roots when exposed to either a 12-h pulse of relatively high concentrations (246–1230 m or continuous lower concentrations (0.5–49.0 m of indolebutyric acid (IBA) for longer periods. Microshoots produced the significantly greatest number of roots when subjected to 4.9 m IBA in WPM over a 4-week period. Whole plants were acclimatized to the laboratory conditions and subsequently to the greenhouse. The methodology described here should be useful in a breeding program by supplying multiple copies of unique, recombinant genotypes.     

Effect of interruption of the nyctoperiod with an R/FR-mixture of various ratios of red and far-red light on flowering in Lemna gibba G3

A brief R pulse inserted in the 15-hr nyctoperiod of the 9L15D regime almost always promoted flower formation of a long-dayduckweed, Lemna gibba G3. This R effect was partially reversedby subsequent FR, which suggests that phytochrome is involvedin the floral processes occurring in the nyctoperiod. The null% R value (% of R in the R/FR-mixture that exerts no effecton flowering) was high during the initial 7.5 hr of the nyctoperiod,then rapidly decreased. The starting time of the rapid decreasein the null % R value was hardly affected by a change in temperaturein the nyctoperiod. A similarly high initial level of the null% R value followed by a rapid decrease was observed when thenyctoperiod was extended to 39 hr. At hour 15 of the 39-hr nyctoperiod,flower promotion by the R puke was not reversed by subsequentFR, although the spectral dependence of the light pulse effectdid not exclude the possible involvement of phytochrome. Atabout hour 21 of the 39-hr nyctoperiod, the null % R value beganto increase rapidly, and almost reached the initial high levelat hour 24 when R-FR reversibility was also restored. These results suggest that the Pfr-level remained high duringthe initial hours of the nyctoperiod, followed by a rapid decreaseirrespective of the temperature of the nyctoperiod. This rapiddecrease in the Pfr-level may play a role in the time measurementof the photoperiodic floral induction of L. gibba G3. (Received February 13, 1979; )     

Pre-selection for juvenile period, flowering and picking time in apple seedlings

The length of the juvenile period was found to be associated with the degree of juvenility (degree to which seedlings show juvenile symptoms) and with the time leaf buds break in spring. The time of bud break was also related to time of flowering; bud break and juvenility were not interrelated. The observations suggest that preselection on the basis of a low degree of juvenility and early bud break together would substantially increase the proportion of early-bearing and, to a smaller extent, that of early-flowering seedlings in the selected material. The shift towards earlier flowering was not accompanied by an advance of the date at which flowering ended, at least when the selection limit is based on the progeny mean. The degree of leaf fall (colour) during autumn appeared to be closely related to the time the fruits become picking ripe; no significant relation existed between this parameter and juvenility or bud break. The degree or time of leaf fall (colour) is a possible pre-selection criterion of the time of picking.

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Samenvatting De duur van de jeugdperiode bleek verband te houden zowel met de mate van juveniliteit als met de tijd dat de bladknoppen in het voorjaar uitlopen. Er bestond ook samenhang tussen uitlopen en bloeitijd, maar geen samenhang tussen het uitlopen en de mate van juveniliteit. Het is waarschijnlijk, dat voor-selectie op zowel geringe juveniliteit als vroeg uitlopen het percentage vroeg produktieve zaailingen in het geselecteerde materiaal aanzienlijk zou verhogen; in mindere mate ook het percentage vroeg-bloeiende zaailingen. De verschuiving naar vroeger bloeiend ging niet gepaard met een vervroeging van het tijdstip waarop de bloei eindigde. De mate van bladval (verkleuring) gedurende de herfst bleek sterk gecorreleerd te zijn met de pluktijd van de vruchten. De mate of de tijd van bladval kan dienen om de zaailingen in een vroeg stadium op pluktijd te selecteren.

     

Effect of aluminium on alfalfa seedlings

Summary The effects of various concentrations of aluminium on developing alfalfa seedlings were studied. The unifoliate leaf size and the dry weight of the young seedling, when grown on an Al concentration of 20 ppm, may be used as a valuable screening technique.Contribution No. 200 from the Research Station, Central Experimental Farm, Ottawa, Ontario.Part of this work was conducted while the author was stationed at the Research Station, La Pocatiere, Quebec.     

Transformation of Medicago truncatula via infiltration of seedlings or flowering plants with Agrobacterium

Two rapid and simple in planta transformation methods have been developed for the model legume Medicago truncatula. The first approach is based on a method developed for transformation of Arabidopsis thaliana and involves infiltration of flowering plants with a suspension of Agrobacterium. The second method involves infiltration of young seedlings with Agrobacterium. In both cases a proportion of the progeny of the infiltrated plants is transformed. The transformation frequency ranges from 4.7 to 76% for the flower infiltration method, and from 2.9 to 27.6% for the seedling infiltration method. Both procedures resulted in a mixture of independent transformants and sibling transformants. The transformants were genetically stable, and analysis of the T2 generation indicates that the transgenes are inherited in a Mendelian fashion. These transformation systems will increase the utility of M. truncatula as a model system and enable large-scale insertional mutagenesis. T-DNA tagging and the many adaptations of this approach provide a wide range of opportunities for the analysis of the unique aspects of legumes.     

Effect of planting date on flowering time in wheat

The time from seed germination to anthesis varied for spring wheat in experiments in climate chambers with plants grown hydroponically at different nitrogen regimes. Time to anthesis was related to the time of seed germination during the calendar year. Seed germinating earlier in the calendar year required a shorter time to anthesis compared to seed germinating later in the year, a pattern found for all the spring wheat cultivars investigated. Time to anthesis was also found to be independent of factors such as year in which the seed was produced, nitrogen regime used, or year or site of cultivation. We suggest the existence of an annual rhythm for flowering in spring wheat. This variation in time to flowering can be due either to external factors or more likely to an endogenous rhythm in the plant. When investigating plant processes, it is of importance to be aware of such a rhythm, since it may influence the results depending on when during the year the experiments are performed.     

育苗容器对紫叶紫薇容器苗生长、开花及生理的影响

【目的】探讨不同育苗容器对紫叶紫薇容器苗生长、开花及生理的影响,筛选出紫叶紫薇容器苗培育的适宜育苗容器,为紫薇容器高效育苗提供理论依据。【方法】以紫叶紫薇优良新品种‘丹红紫叶’为研究对象,设计了不同育苗容器类型和规格共9个处理,测定不同处理对容器苗生长、开花及生理的影响。【结果】（1）不同育苗容器对紫叶紫薇容器苗的生长、开花及生理影响显著,容器苗的生长、根系、生物量、花期、花径、花序、可溶性蛋白含量、可溶性糖含量、叶绿素相对含量、净光合作用速率、气孔导度、蒸腾速率等指标随着育苗容器规格的增大而增加,均达到显著性差异。（2）C3D3处理（直径25 cm、高25 cm黑色控根容器）的地径生长量、总根长、总根表面积、总根体积、根尖数、地上部干重、地下部干重、总干重、花期、都是最大,比最小的C1D1处理（直径16 cm、高16 cm黑色塑料营养杯）分别显著高817.12%、108.12%、94.60%、75.66%、144.14%、135.67%、228.45%、164.65、20d;C1D3处理（直径25 cm、高25cm黑色塑料营养杯）的苗高生长量、冠幅生长量、叶面积、花序长和宽最高,比最低的C1D1处理分别显著高116.05%、81.39%、114.95%、70.44%和65.79%。（3）C3D3处理的叶绿素相对含量、水分利用效率最大,C1D3处理的可溶性蛋白和可溶性糖含量、净光合速率、气孔导度最高;各处理的胞间CO2浓度、水分利用效率之间无显著性差异。（4）黑色控根容器在地径生长量、根系生长指标、生物量、花期和花径、叶绿素相对含量及净光合速率方面表现最佳。（5）各指标隶属函数法综合分析得分排序为：C3D3>C1D3>C2D3>C3D2>C2D2>C1D2>C2D1>C3D1>C1D1。【结论】紫叶紫薇2年生苗的最适宜育苗容器是直径25 cm、高25 cm黑色控根容器。     

Effect of exogenous gibberellins on flowering in Pinus sylvestris grafts

Ethanolic sprays of gibberellins were applied to developing shoots of about 12-year-old Scots pine (Pinus sylvestris L.) grafts during the shoot elongation period in two consecutive years. Both male and female flowering was increased by these treatments in both years. The effect was particularly distinct in male flowering. However, different clones showed varying responses to the treatment. This variation was associated with both the genotype and the environmentally determined year-to-year fluctuation in flowering. Differences among clones were analysed further by introducing a model earlier developed for comparisons of the growth rhythm in various woody and herbaceous species.     

Effect of flowering on vegetative growth and further reproduction in

Flowering intensity and plant size were monitored in 155 Festuca novae-zelandiae individuals over four years to determine if trade-offs exist between inflorescence production and vegetative growth, and between inflorescence production in different years. Less than half of the population flowered in any one year, 36% of individuals did not flower at all, and only 17% flowered in all four years of the study. Mean number of inflorescences per individual per year varied from 1.54 to 5.53 (maximum = 85). No trade-offs were detected between flowering frequency and intensity; individuals that flowered more frequently also produced more inflorescences in each flowering episode. No trade-off was detected between current and future reproduction, rather flowering intensity was positively correlated between years. Growth, as measured by diameter increment, was positively related to flowering frequency and flowering intensity, both across all individuals studied and within 1m x 1m plots. The presence of a positive relationship between growth and reproduction within plots argues against meso-scale variability in environment factors being the cause of the results from analyses involving all individuals. Clearly reproduction in F. novae-zelandiae does not incur a marked cost in growth or future reproduction. The assumptions underlying theoretical expectations of such trade- offs may not be valid for long-lived clonal plants such as F. novae-zelandiae.     

Effect of pesticides on ectomycorrhizae ofPinus sylvestris seedlings

Summary Knowledge of the effect of pesticides on the formation of forest tree mycorrhizae is important as pesticides are nowadays used in forestry. The effect of the fungicide Dithane M-45 and the herbicide Gramoxone on the growth ofPinus sylvestris L. seedlings and on the development of their mycorrhizae was studied. Investigations involved seedlings inoculated with pure cultures of mycorrhizal fungi in flasks with perlite under aseptic conditions, in Mitscherlich pots filled with perlite under semi-aseptic conditions, and on peat substrate in outdoor beds. No change in seedling growth and the mycorrhiza formation occurred when water suspension of the fungicide Dithane M-45 was used at the recommended dose. The highest rates of this fungicide had no phytotoxic effect although the growth of treated seedlings was reduced due to complete or partial inhibition of mycorrhizal formation. In contrast, even low doses of Gramoxone reduced the growth of the inoculated and non-inoculated seedlings which were more sensitive than their mycorrhizal fungi. The soil sterilization of outdoor beds with an application of a water suspension of Dithane M-45 at recommended doses reduced mycorrhizal development and seedling growth. Seedlings inoculated simultaneously with pure cultures ofSuillus granulatus showed a slightly better growth than untreated controls.     

Effect of vanadium on the growth of soybean seedlings

Pot experiments were conducted in a glasshouse to investigate the effects of vanadium (V) on the growth of soybean seedlings in two soils. As the concentration of V added to the fluvo-aquic soil (Fluvaqents) exceeded 30 mg V kg^-1 soil, the dry matter yields of shoots and roots were significantly decreased (>1%LSD), and the leaves of soybean seedlings turned yellow and withered and the roots were short and beginning to rot. In the red earth (Oxisols), no marked stunting was observed (<5% LSD), even when the concentration of V added to the soil was as high as 75 mg V kg^-1. As the concentrations of vanadium in soybean seedling were closely related to the concentration of soluble vanadium in soil solutions at pH 5–9 in the soil equilibrium solution, the fluvo-aquic soil had lower adsorption capacity for V than the red earth, there was much higher concentration of soluble V in the soil solution, so the symptom of V toxicity appearing in the plants grown on fluvo-aquic soil was easily observed. In addition, the ratio of the total Mo to the total V in shoots decreased slightly with increase of concentration of V added to soils. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of salinity on antioxidant responses of chickpea seedlings

The changes in the activity of antioxidant enzymes, like superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase, and growth parameters such as length, fresh and dry weight, proline and H₂O₂ contents, chlorophyll fluorescence (Fv/Fm), quantum yield of PSII and the rate of lipid peroxidation in terms of malondialdehyde in leaf and root tissues of a chickpea cultivar (Cicer arietinum L. cv. Gökçe) under salt treatment were investigated. Plants were subjected to 0.1, 0.2 and 0.5 M NaCl treatments for 2 and 4 days. Compared to controls, salinity resulted in the reduction of length and of the fresh and dry weights of shoot and root tissues. Salinity caused significant (P < 0.05) changes in proline and MDA levels in leaf tissue. In general, a dose-dependent decrease was observed in H₂O₂ content, Fv/Fm and quantum yield of photosynthesis under salt stress. Leaf tissue extracts exhibited three activity bands, of which the higher band was identified as MnSOD and the others as FeSOD and Cu/ZnSOD. A significant enhancement was detected in the activities of Cu/ZnSOD and MnSOD isozymes in both tissues. APX and GR activities exhibited significant increases (P < 0.05) in leaf tissue under all stress treatments, whereas no significant change was observed in root tissue. The activity of CAT was significantly increased under 0.5 M NaCl stress in root tissue, while its activity was decreased in leaf tissue under 0.5 M NaCl stress for 4 days. These results suggest that CAT and SOD activities play an essential protective role against salt stress in chickpea seedlings.     

Effect of benzyladenine on development of derooted watermelon seedlings

We have examined the effects of benzyladenine (BA) on derooted watermelon ( Citrullus vulgaris Schrad., cv. Fairfax) seedlings with special attention to the cotyledons. The growth regulator was supplied either as a droplet of solution between the cotyledons (application from above) or through the hypocotyl stump (application from below). Application of BA from above stimulates several developmental parameters of cotyledons [growth, lipid breakdown, chlorophyll and carotenoid accumulation, hydroxypyruvate reductase (EC 1.1.1.81.) activity]. The stimulation is much smaller with application from below. Also the distribution of labelled BA changes according to the method of application. The bulk of the label remains in the cotyledons when BA is supplied from above and in the hypocotyl when it is supplied from below. The absolute amount of radioactivity found in the cotyledons after 24 h of treatment is approximately the same in both cases. This seems to indicate that the different effects of the two treatments depend on concentration ratios of BA (or metabolic derivates) between hypocotyl and cotyledons rather than on absolute growth regulator levels.     

Effect of paclobutrazol on membrane lipids in apple seedlings

The effect of paclobutrazol [( 2RS, 3RS )-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2, 4-triazol-1-yl) pentan-3-ol] on the fatty acid composition of polar lipids and on the sterol content in apple ( Malus domestica Borkh. cv. York Imperial) seedlings was determined. Polar lipids isolated from leaves, stems and roots included mono- and digalactosyldiglycerides and the phospholipids phosphatidylinositol, phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The predominant fatty acids in membrane polar lipids were palmitic (C16:0), linolnic (C18:2) and linolenic (C18:3). The predominant sterol, both free and esterified, was β-sitosterol. There were no significant alterations in the fatty-acid composition of glyco- and phospholipids from paclobutrazol-treated apple seedlings. In contrast, a significant decrease in the content of β-sitosterol and campesterol occurred in treated tissues. The decline in sterol content continued with increasing duration of paclobutrazol treatment, and was most pronounced in the root tissue.     

Effect of chlorsulfuron on ethylene evolution from sunflower seedlings

The effect of the herbicide chlorsulfuron (2-chloro-N-[(4-methoxy - 6 - methyl -1, 3,5 - triazin - 2 - yl)aminocarbonyl]benzenesulfonamide) on ethylene production in light-grown sunflower (Helianthus annuus L.) seedlings was examined. Application of chlorsulfuron to the apex stimulated ethylene production in all tissues examined: cotyledons, hypocotyls, and roots. The greatest stimulation occurred in the upper portion of the hypocotyl adjacent to, and including, the cotyledonary node. Ethylene evolution from hypocotyls excised from treated seedlings was stimulated over control levels 1 day after herbicide application and reached a maximum (approx. 75 x control or 17 nl/g f wt/h) 2 to 3 days after treatment. Labeling and inhibitor studies indicated that the ethylene produced was derived primarily from methionine. Chlorsulfuron treatment stimulated the rate of accumulation of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), as well as the ability of the tissue to convert exogenous ACC to ethylene. Chlorsulfuron had little effect on ethylene production when administered to the hypocotylsin vitro. Removal of the cotyledons from treated seedlings reduced the rate of ethylene evolution from the hypocotyls. These results suggest that stimulation of ethylene production in sunflower hypocotyls by chlorsulfuron is not a wound response but rather is dependent on factors derived from the cotyledons.