Effect of varying number of short days, gibberellic acid and ascorbic acid on the flowering of soybean

Both the cultivars of soybean, namely E.C. 2579 and Punjab I,studied were found to be qualitative short day plants. Evenone SD was sufficient to cause flower bud initiation in E.C.2579, although flower opening required 3 SDs. Pb. I did notshow flower bud initiation with less than 10 SDs. In Pb. I thenumber of flowers with 20 SDs was higher than continuous SD,indicating the favourable effect of long days prior to induction. Exogenous application of GA₃ and AA singly and in combinationsubstituted for the additional photoperiodic requirements ofincompletely induced plants of Pb. I, but were ineffective undercontinuous LDs. Treatment with these regulators of plants havingreceived 8 SDs resulted in initiation of flower buds, whichfailed to open into flowers. In plants subjected to 10 SDs flower buds were initiated withall these treatments except control. Floral buds did not openinto flowers with any treatment or combination not containingGA₃. (Received March 28, 1970; )     

Hastening effect of intercalated long days on short-day induction in Impatiens balsamina,a qualitative short day plant

Summary The inductive effect of short-day (SD) cycles on floral-bud initiation in Impatiens balsamina was enhanced and the minimum requirement for SD cycles for flowering reduced by intercalated long days (LDs). Thus, floral buds developed into flowers with only 4 SD cycles in plants receiving them individually or in pairs alternating with LDs, but failed to develop in those receiving 4 SD sycles consecutively. The number of flowering plants increased while the periods to floral-bud initiation and flowering, calculated from the day of completion of 4 and 8 SD cycles, respectively, decreased with an increase in the number of intercalated LDs.     

Effect of varying lengths of inductive and supplementary non-inductive photoperiods on vegetative growth and flowering of Impatiens balsamina

The photoperiodic requirement for flowering in Impatiens balsaminachanges with the length of the photoperiod. Floral buds wereinitiated with two 8 hr but with four 15 hr photoperiods andflowers opened with four 8 hr but twenty-eight 15 hr photoperiods.A part of the photoperiodic requirement for floral inductionin this plant can be substituted by LDs containing 4 or morehours of darkness (10). It indicates the identical nature ofthe floral stimulus produced during the dark period, whetherit forms a part of the inductive or non-inductive cycles. Theeffect of these supplementary non-inductive photoperiodic cyclesin causing floral bud initiation also depends on the lengthof the first inductive obligatory cycle. More floral buds andflowers were produced on plants exposed to 15 hr than 8 hr photoperiods,probably due to the higher number of leaves that were producedunder the former condition of weaker induction. The shorterthe dark period in the photoperiodic cycle, the weaker the induction,the slower the rate of extension growth but the more differentiationof leaves. ¹ Present address: Department of Biology, Guru Nanak Dev University,Amritsar-143005, India. (Received November 9, 1977; )     

Effect of Gibberellic Acid and Monophenols on Flowering of lmpatiens balsamina in Relation to the Number of Inductive and Non-inductive Photoperiodic Cycles

A single treatment of plants with GA₃ (gibberellic acid) is not adequate to cause induction under LD (long day: 24-h photo-period) condition, but its effect is added to the sub-threshold induction caused by one SD (short day: 8-h photoperiod) cycle. Floral bud initiation is hastened, and the number of floral buds and flowers per flowering plant increases in plants receiving a single treatment with the combination GA₃+ SA (salicylic acid) accompanying a single SD cycle. However, the increase on 10 replicate basis is more marked in plants receiving three treatments with the combination GA₃+β-N (β-naphthol) and five treatments with the combination GA₃+ SA accompanying six and 10 SD cycles, respectively. The number of floral buds and flowers decreases with an increase hi the number of SD cycles, but it is higher in plants treated with GA₃, SA or GA₃+β-N than in the water-treated controls. — Under long days, treatment of plants with the combinations GA₃+ SA or GA₃+β-N accelerates the initiation as well as increases the number of floral buds. While a minimum of five treatments with GA₃ or of 25 with SA or β-N alone is needed for floral bud initiation under a 24-h photoperiod, three treatments are adequate to induce floral buds with the combination GA₃+ SA or GA₃+β-N under continuous illumination. Ten or more treatments with these combinations under a 24-h photoperiod produce more flowers than the same treatments under an 8-h photoperiod.     

Photoperiodic Regulation of Flowering in Cowpeas (Vigna unguiculata (L.) Walp.)

To test the proposition that photoperiodic controls synchronizethe flowering of cowpeas, Vigna unguiculata (L.) Walp. [V. sinensis(L.) Savi], the day-length requirements for floral initiationand for flowering were investigated in several short-day accessions.No evidence was found of different critical photoperiods atdifferent stages of development, but exposure to only 2–4short days was required for floral initiation compared withabout 20 for development to open flowers. Pod setting was increasedafter exposure to even one short day more than the number requiredfor flower opening. Floral buds at higher nodes appeared to require fewer shortdays for development to flowering than buds at the lower nodes,and displayed faster rates of development. Inflorescence budsdid not resume development if they were exposed to 15 or morelong days following inflorescence initiation. Thus, any tendencytowards synchronous flowering in cowpeas is not due to the criticalday-length for flower development being shorter than that forflower initiation, but could be the result of cumulative photoperiodicinduction of plants and the more rapid development of later-formedflowers. Vigna unguiculata (L.) Walp., cowpeas, flower initiation, flower development, fruit set, photoperiodism     

Effect of Intercalated Long Days and Light Interruption of Dark Period on Flowering, Extension Growth and Senescence of impatiens balsamina

Plants of Impatiens balsamina L. grown under long days were divided into 5 lots to receive 1, 2, 4, 8 and 16 consecutive short day (SD) cycles respectively. Each lot was divided into 5 groups to receive 1, 2, 4, 8 and 16 long day (LD) cycles subsequent to SD regime and the cycles were repeated till the end. Observations on the number, position and time of emergence of floral buds, flowers and extension growth were recorded. The floral buds are initiated and these develop into flowers even when Individual SDs are intercalated with 16 LD cycles, showing that the sub-threshold stimulus is not wiped off but becomes effectively summated through a long non-inductive period. The floral bud initiation in lots receiving less than 4 and flowering in those receiving less than 8 consecutive SD cycles are delayed with decreasing number of consecutive SDs and increasing number of intercalating LDs. This progressive delay is probably due to the delay that is caused by these treatments in the completion of requisite number of SD cycles. The first node to show floral bud initiation is shifted up with increasing intercalated LDs only in plants receiving less than 4 SD cycles and not in those receiving more. Some of the lower floral buds in plants receiving less than 8 consecutive SD cycles either abort or revert to vegetative growth. The first node to flower is, therefore, shifted up. The number of such buds increases either with a decrease in the number of consecutive SDs or an increase in the number of intercalated LDs. The number of floral buds produced in plants receiving 2 or more and flowers in those receiving 4 or more consecutive SD cycles does not differ much with the number of intercalated LDs, but decreases in those receiving less number of SDs. Some nodes bear more than one floral bud and flower. Such nodes are observed in plants receiving individual SD cycles only when intercalated with individual LDs but in all groups in plants receiving 16 consecutive SD cycles. The rate of extension growth increases with an increase in the number of consecutive SDs. The rate in plants receiving individual SDs closely resembles that of plants grown under continuous LDs and that of consecutive 16 SDs with that of control SD plants. The attainment of maximum and the consequent steep fall preceding senescence is successively delayed with an increase in the number of intercalated LDs in plants receiving 16 consecutive SD cycles. Light interruption of the dark period inhibits both the initiation of floral buds and their development Into flowers. showing that in this plant. short days are necessary both for the initiation of floral buds and their development into flowers.     

Effect of Number of Photoperiodic Cycles on Flowering and Fruiting in Early and Late Varieties of Okra (Abelmoschus esculentus (L.) Moench.)

Early and late varieties of the short day plant, Abelmoschusesculentus (L.) Moench. (= Hibiscus esculentus L.), were subjectedto various numbers of short days (SD; 10 h natural daylight)before transfer to 16 h long days. Short day treatments werestarted at the time of cotyledon release following seed germination,and their effects on the induction and development of flowersand fruits were recorded. While early okra required 6 SD cyclesfor the induction of flowering in all plants, late okra required14. However, both varieties needed more than 20 SD cycles forflower opening; flower buds produced by plants given fewer SDcycles abscinded with little or no development. In both varieties,the number of flower buds produced on each plant increased asthe number of short day cycles was increased from 5 to 20; flowerbuds were initiated at more axillary bud sites on the main stem.Three fruits were formed on each plant of both varieties subjectedto more than 30 SD cycles but, while the last formed fruit abscindedwithout development, the other two developed and became filledwith seeds. However, the greatest yield in fruit dry weightwas from plants kept under SD throughout and also in late okraplants given 55 SD. In general, the total number of seeds perplant increased as a larger number of SD cycles were imposed.     

Significance of timing and number of short-day cycles for initiation and subsequent development of floral buds in Lemna perpusilla 6746

Time courses of the flowering process in Lemna perpusilla 6746,a short-day plant, were studied using selected fronds in relationto the order of emergence. Various numbers of short-day cycleswere interposed during continuous light. The floral buds evokedby short-day cycles developed to a floral stage determined bythe number of short-day cycles 3 days after the transfer toconsecutive long-day cycles, but aborted on the next day, regardlessof the floral stages. At least 2 long-day cycles were requiredfor the abortion of the floral buds at any stage of development.These results suggest the importance of the number of short-daycycles not only for initiation but also for development of floralbuds. (Received February 4, 1977; )     

Effect of decapitation, phosfon D and cycocel on the flowering of Impatiens balsamina exposed to varying numbers of short days

Impatiens balsamina L., a qualitative short day plant, requiresmore short days for the development of floral buds into flowersthan for their initiation. Phosfon D and cycocel reduce thenumber of short days required for flowering, increase the numberof floral buds and flowers and delay their reversion to vegetativegrowth when transferred to noninductive conditions. The effectof decapitation of the main shoot subsequent to the emergenceof floral buds resembles that of retardants indicating thatthe effect of the latter in flower promotion in this plant maybe by virtue of their effect on cessation of apical dominanceas a consequence of which reserve food materials may be channeledto axillary floral buds enabling them to develop into flowers. (Received January 9, 1969; )     

In Vitro Culture of Hermaphrodite Floral Buds of Cucumis melo L.: Microsporogenesis and Ovary Formation

A method has been described by which floral buds of hermaphroditemelons isolated at various stages from archesporium to preleptotenein the pollen mother cells (PMC) can be grown through to pollen-grainformation in culture. Floral buds cultured for this period ina medium with thymidine-methyl-³H (³H-T) showed incorporationof label into the nuclei of tapetal cells and PMCs. The labelincorporated into the PMC was probably due to pre-meiotic DNAsyn-thesis. In other tissues of the floral buds, ³H-T incorporationproceeded through meiosis. Metabolic and environmental factorsinvolved in normal differentiation of the microsporogenous tissueof floral buds cultured in vitro are discussed.     

Determinate Floral Buds of Plantain (Musa AAB) as a Site of Adventitious Shoot Formation

Floral buds of the ‘False Horn’ plantain clonesMusa (AAB) ‘Harton Verde’, ‘Harton Negra’,and ‘Currare’ terminate in a large single floralstructure. The apices of these floral buds are here designatedas determinate since they have lost the ability to produce additionalfloral initials or buds. Terminal peduncle segments can be culturedin a modified Murashige and Skoog (1962) medium supplementedwith N⁶-benzyl-aminopurine (5 mg I^–1). Under these conditions,this apparent inability to yield buds can be overcome as vegetativeshoot clusters form in the axils of the bracts. Rooted plantletsare obtainable by treating shoots with naphthaleneacetic acid(1 mg I^–1) and activated charcoal (0.025%). The adventitiousorigin of the shoots has been established. Musa cultivars, plantains, floral bud, adventitious buds, tissue culture     

Regeneration from Leaf Squares of Peperomia sandersii A .DC: a Relationship between Rooting and Budding

Evidence is presented to show that in leaf squares of Peperomiasandersii bud initiation does not occur independently of rooting.Buds were formed close to the point of origin of roots and,in treatments where rooting was delayed, budding was affectedsimilarly. Promotion of root formation by pretreatment of squareswith 3-indolylbutyric acid was accompanied by increases in thenumber of buds initiated. Kinetin and N⁶-benzyladenine whichinhibited the initiation of roots also inhibited the initiationof buds. This was in contrast to the effect of these two compoundson leaf squares of Begonia rex where rooting was similarly inhibitedbut bud initiation was markedly promoted. When leaf squaresof Peperomia were grown in contact with relatively high concentrationsof kinetin buds were occasionally formed in the absence of roots.Removal of roots from leaf squares of Peperomia by excisionprevented the formation of buds.     

Floral Development in Sonja White Clover (Trifolium repens) a Papilionoid Legume

Floral development in Sonja white clover was examined usingscanning electron microscopy. Florets and bracts were foundto arise from common primordia initiated as protuberances fromthe apical meristematic area of the inflorescence. The patternof floret initiation on the inflorescence was acropetal, theoldest florets resting basally. Floral organ initiation withineach floret was acropetal, petals being initiated before stamens.Floret development was zygomorphic, each whorl of floral organsdeveloping unidirectionally from the abaxial side. There wasfound to be overlapping in the timing of initiation and developmentof these organs. Antesepalous stamens were found initially tooutgrow their antepetalous counterparts. Early petal developmentwas synpetalous. Eglandular hairs were found basally on thecalyx cup and on the pedicel. Procumbent hairs were found tobe more numerous and randomly distributed on the abaxial surfacesof the mature calyx cup. Trifolium repens L., Sonja cultivar, white clover, scanning electron microscopy, floral development, inflorescence     

Photoperiodic studies on growth and development of Impatiens balsamina L.

Summary In the short-day plant Impatiens balsamina it was found that, while floral buds are initiated with 3 short-day (SD) cycles, at least 8 such cycles are required for flowering. The numbers of floral buds and open flowers bear a linear relationship with the number of SD cycles. The induced floral buds revert to vegetative growth unless the plants receive the minimum number of SD cycles needed for flowering, this reversion occurring in a basipetal direction. The rate of extension growth of the stem increases with increasing numbers of SD cycles. The high rate is maintained longer in plants receiving 32 or more SD cycles, but the subsequent fall is also steeper in these plants than in plants receiving less inductive cycles. Senescence also occurs in these plants and appears to be related to the magnitude of reproductive development and the high rate of extension growth.     

Floral induction by gibberellic acid in Impatiens balsamina,a qualitative short-day plant

Summary In the qualitative short-day plant Impatiens balsamina, gibberellic acid (GA₃) not only promoted the formation of floral buds in response to suboptimal photoinductive conditions and reduced the number of SD cycles that are required for their development into flowers, but also caused initiation of floral buds under non-inductive photoperiods. In plants treated with repeated applications of GA₃, the floral buds developed into flowers irrespective of whether the apex was left intact or was removed. In those that received a single application of GA₃ the floral buds developed into flowers only in decapitated plants.     

Initial Anatomical Changes Associated with Tuber Formation on Single-node Potato (Solanum tuberosum L.) Cuttings: A Re-evaluation

Cell division and cell expansion during early stages of tuberdevelopment were studied using developing axillary buds on single-leafcuttings from potato (Solanum tuberosum L.). Cuttings takenfrom plants induced to form tubers, by short day (SD) treatment,were compared with cuttings from non-induced (long day, LD)plants. In the apical zone of the buds, cell division occurredfrom the first day after cutting, in both LD and SD cuttings.The planes of these divisions were transverse, associated withelongation of the buds. At day 5, a new orientation of celldivision was observed in the subapical zone of SD cuttings only.These divisions were longitudinal, associated with radial growth.Cell expansion occurred in both SD and LD cuttings, and wasnot uniquely related to the onset of tuber formation. Copyright1999 Annals of Botany Company Solanum tuberosum L., potato, tuber formation, cell division, cell expansion.     

Significance of Spermidine in the Initiation of Adventitious Buds in Stem Segments of Torenia

When stem segments of Torenia fournieri Lind. were culturedin vitro, the initiation of adventitious buds, which is usuallyinduced by cytokinin, was induced by application of polyamines,such as putrescine and spermidine. Addition of arginine hada slight inductive effect. When cyclohexylamine, an inhibitorof spermidine synthase, was added simultaneously with putrescine,induction of the initiation of buds by putrescine was stronglyinhibited. However, application of the inhibitor together withspermidine had no effect on the spermidine-induced initiationof buds. The induction of initiation of buds by a cytokinin,by a calcium ionophore, by cyclic AMP, and by a phorbol ester,which was accompanied in each case by elevation of the levelsof endogenous spermidine, was also inhibited by cyclohexylamine.These results suggest the involvement of spermidine in the initiationof adventitious buds in stem segments of Torenia. ²Present address: Radiation Effects Research Foundation, Hijiyamakouen5-2, Minami-ku, Hiroshima, 732 Japan.     

Photoperiod and Temperature Effects on Late Developmental Stages of Stylosanthes guianensis

Seedlings of Stylosanthes guianensis var. guianensis cv. Cookand S. guianensis var. pauciflora cv. Bandeirante were defoliatedand placed in a naturally lit glasshouse at 23/18 °C, 28/23°C or 33/28 °C (day/night). After exposure to 14 h daysand after floral induction with 30 cycles of 11 h, plants wereallocated to 11, 12, 13 or 14 h during flowering and seed formation. Floral initiation occurred after 10–15 short-day cycles.Flower appearance was hastened by warm temperatures and spikenumber per plant at 20 d after flower appearance was negativelyrelated to temperature and greater in Cook than in Bandeirante.Exposure to 13- and 14-h days reduced the continued differentiationof inflorescences in Bandeirante, and in Cook in warm temperatures.Floret number per spike was greatest at 23/18 °C and a higherproportion of florets aborted in Bandeirante at 33/ 28 °C.Variations in seed setting of the bi-articulate loment of Bandeiranteare described. Highest potential seed yield occurred if afterfloral induction 11 or 12 h days were maintained with 23/18°C or 28/23 °C temperatures. Photoperiod, temperature, development, Stylosanthes guianensis, flowering     

An Effect of Copper Deficiency on the Initiation and Development of Flower Buds of Chrysanthemum morifolium Grown in Solution Culture

The effects of various levels of copper on the initiation anddevelopment of flower buds in two cuhivars of Chrysanthemummorifolium grown in solution culture have been examined. Plantswere harvested at regular intervals during a short-day photoperiod,and buds scored according to an arbitrary 22-stage scale offlower development. A critical level of copper has been determinedbelow which flower bud initiation is much retarded.