Poliaminas y Aji

8/14/2019 Poliaminas y Aji

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APPLICATIONOFPOLYAMINES IMPR OVES GERMINATIOND EARLY SEEDLING GROW TH OE HOT PEPPER zizKhan'*, KhurramZiaP,Muhammad Amjad , and Qumer IqbaF

Polyamines are low molecular weight organic compounds involved in diverse range of biological processes in ail livingorganisms. Seed priming is a technique that improves seed performance by rapid and uniform germination with normaland vigorous seedlings. A laboratory study was performed to explore the benefits of seed priming with polyamines on seedgermination and seedling growth of hot pepper {Capsicum anmtum L.) Hot pepper seeds were primed in aerated solutionof putrescine, sperm ine. or spennidine (25 , 50. 75 . and 100 mM) for 48 h at 25 2 C . Significant results (P < 0.05) w ereobserved for different a ttributes of seed germination and early seedling growth. Polyam ines priming resulted in earlierand synchronized germination via improving final germination percentage, time to 50% germ ination, mean germinationt ime, germination energy, germination speed and germination index compared with control. Improvement in shoot androot length, seedling fresh and dry weight, seedling growth rate and seedling vigor index was clearly indicative of positiveeffects of seed priming with polyamines. Out of all polyamines, putrescine proved to be better at low concentrations (i.e. 25and 50 mM) for most of the traits related to seed emergence and seedling growth.Key words Seed priming.Capsicum anmium polyamines.

uality seed is the basis for agriculture productionand for a better crop stand especially in case of

(Pervez2009). Similarly, high yield of the vegetable crops

Crops lacking a good stand show reduced efficacy

Hot pepper {Capsicum annuum L.), comm only knownas chili, is an important vegetable as well as spice cropof Pakistan. The yield of hot pepper is much lower inthird world countries. One of the main causes for thispoor yield is lack of a good stand establishment andreduced early growth as stressed by adverse environmentGermination and emergence of pepper seeds is often slowand non-uniform under normal as well as stress condition(Wein, 1999; Demir and Okcu, 2004). Similarly, Andreoland Khan (1999) foutid slow and erratic emergencand establishment of pepper seeds, especially undecool conditions. Pepper and tomato have non-starchyendosperm and this offered a mechanical barrier to thgrowing embryo resulting in poor germination (Andreoland Khan, 1999). High germination and uniform standestablishment for chili pepper production is essential tmaintaining profitable yields.

Improvement in stand establishment can be obtainedby advancements in seed quality and seed enhancementsgenetic improvement, as well as improved seedingtechniques. Seed priming is a technique of seedenhancement that improves seed performance by rapidand uniform germination, normal and vigorous seedlingswhich resulted in faster and higher rate of germinationand emergence in different crops (Farooq et al. 20072008) , which also helps seedlings to grow in biotic oabiotic stress conditions (Ashraf and Foolad, 2005; Khan


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Seeds performance of many vegetables can beimproved by inclusion of plant growth regulators duringpriming and other pre-sowing treatments (Ashraf andEoolad, 2005; Khan et al 2009b). Polyamines (PAs)are small polycationic molecules found ubiquitouslyin all organisms. Their function has been reported in avariety of biological processes including transcription,RN A mod ification, protein syn thesis and the mod ulationof enzyme activities (Takahashi and Kakehi, 2010).PAs are essential for growth, development, and celldifferentiation in plants (Kusano etal 2008). Moreover ,PAs are also accumulated in plants and perform theirfunction in plants under normal as well as stressconditions. Exogenous PAs may influence germinationof isolated embryos depending on the type of polyamine,its concentration, and the state of the embryo dormancy( E a r o o q e i f l / . , 2 0 1 1 ) .

Some studies have shown the positive effects ofPAs on seed germination, seedling vigor, growth anddevelopment of different crops when seeds were primedwith PAs e.g. wheat (Iqbal andAshraf 2005; Earooq etal 2011), sunflower (Earooq et al 2007), rice (Earooqetal 2008) and tom ato (Afzal etal 2009). Nonetheless ,no study has been reported to evaluate the effects ofpolyamine seed priming on hot pepper. Therefore, thecurrent study was proposed to assess benefits (if any)linked to seed priming with PAs on hot pepper throughexploring responses at seed germination and early growthstages .

M T E R I L S N D M E T H O D SThe proposed study was conducted to determine the effectof seed priming treatments with PAs on emergence andseedling vigor of hot pepper cv. Hot Queen. Seeds of hotpepper 'Hot Queen' were obtained from Yousuf SeedCorporation Registered, Eaisalabad, Pakistan. The initialseed moisture was 8.1 (dry weight basis).Priming treatmentSeeds were surface sterilized by dipping in sodiumhyp och lorite (5 ) solutio n for 5 min and dried on filterpaper. These surface sterilized seeds were primed inaerated solution of PAs (putrescine, spermidine, andspermine) each at concentrations of 25, 50, 75, and 100mM, for 48 h at 25 2 C under dark conditions. Afterpriming treatment, seeds were washed with distilledwater and dried at room temperature on filter paper inshade for 24 h. Seeds were then packed in polythenebags and stored in a refrigerator 5 2 C for further use.Germ ination test

in an incubator (Earooqet al 2008). The experimenperformed following completely randomized design four replicates. Seeds with visible radicle were considas germinated. Data were recorded daily for germincount following seedling evaluation protocol given ihandbook of the Association of Official Seed Ana(AOSA, 1990).

Einal germination percentage (EGP) was calculatthe end of experiment. Mean germination times (Mwere calculated according to the equation of EllisRoberts (1981): 2 Dnwhere n is the number of seeds germinated on dthe number of days counted from the beginningermination.

The time taken to 50 germination T50)was calcaccording to the following modified formula by Faroal (2005):

nj - nwhereN is the final number of emerged seeds andnthe cumulative number of seeds germinated by adjseed count at timestandtjrespectively, whenn N

Germination index (GI) was calculated accordinthe following formula given by Association of OfSeed Analysts (AOSA, 1983):_,, Nof germinated seeds Nof germinated .seeG I= _ +-H _ ^ ... . Days offirstcount Days offinalcount

Germination speed (GS) was derived from the forpresented by Kotowski (1926). Germination en(GE) was recorded on the 7* day after planting. It ipercentage of germinating seeds 7 d after planting relto the total number of seeds tested.Emergence testPrimed and un-primed seeds (50 seeds per repliwere sown in 20 x 20 cm plastic trays filled with wafine sand and irrigated with half-strength Ho aglasolution, kept at 25 2 C under 16:8 h photoperioan incubator (Khan et al 2009a). The experimentperformed following completely randomized design four replicates.

Seedlings from each replicate were harvested randafter 14 d of emergence and shoot and root lengthmeasured from collar region with the help of measutape and averaged to obtain mean shoot and root leSeedling fresh weight was recorded immediately harvesting of seedlings from each replicate whileweight was obtained by drying at 105 C for 24 h in


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Plilrescinc .SpeniiiiiePolyamine seed treatments

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Figure 4. Effect of seed priming with polyamine on a) seedling fre.shweight and b) seedling dry weight in hot pepper (cv. Hot Queen).

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D25mM D50iiAt o7SmM nlOOiuM ( a )

Pu leseme

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Spcnnioe Spcnrudine353 5 ^O.t5

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(b )

Control Piitresciiie SpciiniiiePolyamine seed treatments

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Figu re 5. Effect of seed prim ing w ith polyam ine on a) seedling vigor index(SVI), and b) seedling growth rate (SGR) in hot pepper (cv. Hot Qu een).lower concentrations of all PAs played their role inimproving seed germination while mixed behavior wasobserved for seedling growth.

DISCUSSIONIt could be concluded from the study that seed primingwith PAs significantly enh anced the germination and eariyseedling growth of hot pepper com pared to untreated seedswhile this response was diverse for different PAs and theirconcentrations. Polyamines have tremendous potentialto improve the early stand establishment of hot peppercrop.Earlier, it was observed that primed onion seeds hadhigher level of PAs as compared to control and there waspositive correlation between seedling vigor and PAs level(Basra et al 1994). This leads towards the hypothesisthat seed priming increased the PAs level inside tissueswhich further improved the seed vigor and seedlinggrowth. Enhanced germination and vigor of hot pepperseeds could be the result of enhanced metabolic activities(efficient mobilization and utilization of seed reserves

Seedling growth has also been improved by the priming with all PAs which in turn indicates invigoseedling vigor. These results could be clearly obsethrough higher root and shoot length, seedling fand dry weights, SVI and SGR. Improvement in grattributes might be the result of increased cell divwithin the apical meristem, causing augmented seedgrowth (Huang and Villanueva, 1992; Earooq et2008) . Polyamines are key players in modulatingdivision and its rate (C vik rov ae i a/., 1999). This ind ithe importance of PAs in plant development which cbe the reason behind performance of PAsin this sDuring this study, all of the PAs stimulated the germination and seedling growth compared to controPut was found more effective. Put at lower concentrawas found better as compared to other PAs, wconfirms the results of Earooq et al (2008) but coto the findings of Farooq et al (2007) and Earooq e(2011).

C O N C L U S I O N SIt is concluded from the above results that althall polyamines (putrescine, spermine, or spermidpromoted the earlier germination as well as synchronit and imparted higher seedling vigor, putresperformance was the best.

Aplicacin exgena de poliaminas para mejorar germinacin y el crecimiento temprano de p lntulasaj Las poliaminas son compuestos orgnicos de bajo pmolecular implicados en numerosos procesos biolgien todos los organismos vivos. El acondicionamientosemillas es una tcnica que mejora el comportamiede las semillas respecto a una germinacin ms rpidauniforme, con plntulas normales y vigorosas. Se realun estudio de laboratorio para explorar los beneficdel acondicionamiento de semillas con poliaminsobre la germinacin y el crecimiento de plntulas aj {Capsicum annuum L.) Las semillas de aj fucolocadas en solucin acuosa aireada de putresciespermina o espermidina (25, 50, 75 y 100 mM), dura48 h a 25 2 C. Se observaron resultados significativ(P < 0,05) para los diferentes atributos de germinacin semillas y crecimiento de plntulas. El acond icionamiecon poliaminas adelant la germinacin y sincronizporcentaje final de germinacin, tiempo hasta 50 germinacin, tiempo medio de germinacin, energde germinacin, velocidad de germinacin, e ndde germinacin en comparacin con el control. mejoramiento de longitud de tallo y raz, peso frescoseco de plntulas, tasa de crecimiento de plntulas y


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Poliaminas y Aji