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*Corresponding author’s e-mail: sailendri_patra@yahoo.co.in.

Agric. Sci. Digest., 35 (3) 2015: 173-177Print ISSN:0253-150X / Online ISSN:0976-0547

Efficacy of GA3 on growth and flowering regulation of in vitro raised hybridgerbera under shade netS.K. Patra*, S. Beura and T. Shasani

Department of Floriculture and Landscaping,College Of Agriculture, OUAT, Bhubaneswar- 751 003, India.Recieved: 30-05-2015 Accepted: 22-07-2015 DOI: 10.5958/0976-0547.2015.00039.7

ABSTRACTStudy was carried out to find out the effect of plant bioregulators on growth and flower of in vitro raised hybrid gerberaplants under shade net. The findings of the investigation revealed that GA3 100 ppm accelerated both vegetativegrowth and flowering characters such as stalk length, number of flowers per plant, flower diameter throughout theinvestigation period from January to June 2011.

Key words: Gerbera, GA3, Shade net, PPM.INTRODUCTION Gerbera, a jubilant cut flower is used in fresh and dryflower arrangement, floral decoration, exhibition and in highclass bouquet. It is widely used as a decorative garden planti.e. they are planted in beds, pots, borders and in rockery forgarden display. It is one of the most popular cut flowergaining importance day by day. To meet the demand of highvalue cut flower crop of gerbera, it is necessary to enhancethe production both in quantitative and qualitative aspects.Growth regulators are used to overcome the factors limitingthe growth and yield to harness maximum benefit. It is alsoobserved that foliar application of growth regulatorsstimulate flowering to get maximum yield. Works have beendone by Lal and Mishra,1986; Singh et al., 1991 and Panwaret al., 2006 in different ornamental crops on this aspect.However the work done on gerbera is meager. Therefore,considering the commercial importance of this high valuecrop and problem associated with this crop, to get maximumflower production the present experiment was carried out.MATERIALS AND METHODS

The present experiment was carr ied out atDepartment of Floriculture and Landscaping, College ofAgriculture, OUAT, Bhubaneswar in the year 2011 to studythe flowering regulation of in vitro raised hybrid gerbera cv.Cassiana under shade net structure by plant bioregulators. Theexperiment consisted of one hundred thirty five gerbera plantsplanted in clay pots laid out in complete randomized designhaving three replications and nine treatment combinations withfive number of plants per replication. Observations wererecorded for each plant selected from each treatment in everymonth to record the growth parameters such as plant spread,number of leaves per plant and yield components like numberof flower per plant, stalk length, flower diameter.

Treatment combinations are;T1 = Control (water) T2 = 25 ppm GA3 T3 = 50 ppm GA3T4 = 75 ppm GA3 T5 = 100 ppm GA3 T6 = 125 ppm GA3

T7 = 150 ppm GA3 T8 = 175 ppm GA3 T9 = 200 ppm GA3

RESULTS AND DISCUSSION Study on efficacy of GA3 on growth and floweringregulation of in vitro raised hybrid gerbera under shade netstructure for a period of six months (January 2011 to June2011) revealed that, character like plant spread, number ofleaves per plant, stalk length, number of flowers per plantand flower diameter increased from the month of January toMarch being highest in March by the application of GA3100ppm and reduced from March 2011 to June 2011 in adecreasing manner.

Vegetative growth: In the present investigationdifferent concentrations of gibberllic acid such as25,50,75,100,125,150,200 and 250 ppm were used as a foliarspray at 4th leaf stage of in vitro raised hybrid gerbera cv.Cassiana under shade net. Among all the concentrations ofgibberellic acid, 150 ppm increased the plant spreadthroughout the period of six months followed by GA3 100and 125 ppm (Table 1).

In case of gerbera plant spread was measured as amajor vegetative growth due to its rosette type of growthhabit instead of plant height. Another growth character suchas number of leaves per plant was found to be maximumwith GA3 100 ppm throughout the observation periods.Increase in the concentration of GA3 from 25 to 150 ppmincreased the plant spread in an increasing order. Increasein the concentration of GA3 from 25 to 100 ppm increasethe number of leaves per plant(Table 2).

174 AGRICULTURAL SCIENCE DIGEST

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T 1 = C

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200

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GA

3

Volume 35 Issue 3 (2015) 175

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The results corroborated with the findings ofBhatacharya (1993b) who reported increased vegetativegrowth of Raktagandha roses by application of GA3 as foliarspray at 50-500 ppm concentration and also with Beura(1989)in dahlia where GA3 200 ppm increased the shoot :root ratio.GA3 also increased the growth of impatiens and balsam56 days under 8 and 28 hours photoperiod (Nanda et al.,1973)

Mittal et al,(1967) observed that GA3 treated dahliaplant were taller in height than untreated one. Shanmugan etal.(1973) found that GA3 treated chrysanthemum varietieshad increased plant height and intermodal length. Nanjanand Muthuswamy (1975) reported that GA3 treatment in roseincreased shoot and internode length. Bhatacharya(1984)reported that GA3 at 10 and 100 ppm was effective inincreasing vegetative growth in gladiolus. Singh et al.(1991)observed that GA3 treatment on African marigold at 22 daysafter planting constantly increased the plant growth.Increased vegetative growth might have been due toincreased photosynthesis and respiration which enhancedcarbon dioxide fixation in the treated plant (Broughton etal.,1970). The increase in vegetative growth might beattributed to the physiological action of GA3 where GA3

increased the size of meristematic region and proportion ofcell of undergoing cell division.

Flowering: In the present study GA3 at 100 ppm hadspectacular effect on flowering characters such as stalk length ,number of flowers per plant and flower diameter throughoutthe observation period i.e from January 2011 to June 2011in vitro raised gerbera cv. Cassiana under shade net. Longerstalk, more number of flowers per plant and larger flowerswere obtained by foliar application of GA3 at 100 ppm.Increase in concentration from 25 to 100 ppm increased thestalk length, number of flowers per plant and flower diameterin an increasing rate and further increase in concentrationup to 200 ppm decreased the floral character in decreasingrate. The effect was more spectacular during the month ofMarch where stalk length ,number of flowers per plant andflower diameter were maximum with 100 ppm GA3. Folliarspray of GA3 100 ppm (Table 1) had significant effects onfloral characters from January 2011 to March 2011 beingoptimum during the month of March. The effect graduallyreduced from March 2011 to June 2011(Table 2). Howeverthroughout the observation period. GA3 100 ppm was foundto be ideal for enhancing the flower stalk. GA3 treatmentwas in agreement with the findings of Sen and Naik (1977)reported that application of GA3 increased auxin productionin the leaves and bulbs which stimulate flower stalkelongation in papaver. The reproductive phase of annual plant

with the outcome of complex form of chemical changesinside the plant .PBRs are group of substances whichmanipulated development of flower bud primordial ,budinitiation, development of flower bud and opening of flowers.In this experiment foliar application of GA3 produced longerstalk, more number of flowers, larger flower and effect wasmore spectacular at 150 ppm. Application of GA3 attributedproduction of more number of leaves at early stage of growthwhich than had sufficient time to accumulate carbohydrates.GA3 100 ppm produced maximum number of flowers perplant. This might be due to enhanced induction of flowerbud break i.e. differentiation of floral primordial in the apicalgrowing region by GA3 which lead to increased productionof flower per plant (Singh and Srivastava, 2008). Use ofgibberellic acid as foliar spray increased the stalk length andproduced more number of larger flower. This might be dueto increase in cell elongation and rapid mobilisation andaccumulation of metabolites which probably influenced floralmorphogenesis thus render maximum flower per plant(Singh,2004).

GA3 induced promotion of flowering which due toincreased synthesis as well as translocation of floweringhormone. Increase in stalk length with GA3 application canbe attributed to active cell elongation in the flower to increasethe sink strength of actively growing part. GA3 has reportedto induce on entire development programme by activationof master regulatory gene in the later stage of corolladevelopment which contributed to improve flower size,maximum number of flowers per plant with GA3 application.Bhattacharya (1993) reported that GA3 200 ppm markedlyincrease the flower production in lilium. GA3 10 to 100 ppmincreased flower size, stalk length and enhanced thenumber, size and weight in Hippeastrum hybridum(Bhattacharya(1984). The biggest flower with longer stalklength were obtained with GA3 100 ppm. The enhancementof flower size be due to increase in length of petals andpedicels. Zieslin et al.(1974) reported that the enlargementof flower size caused by drawing of photosynthates to theflower as a consequence of intensification of sink. It isconfirmatory with the study of Rajagopalan and AbdulKhader (1994) in chrysanthemum.

CONCLUSION On the basis of the findings of the present study, it isconcluded that application of GA3 at 100ppm couldsuccessfully manipulate the growth and flowering behaviorof the gerbera. However, further research is the need of theday for this particular majestic flower so that it becomes thenumero uno in the floricultural trade in the upcoming years.

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Biochem bophys Acta, 222: 491-500.Lal, H and Mishra, S.P.,(1986). Effect of GA3 and MH on growth and flowering of marigold and aster. Progressive

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