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Enhancement of Seedling Establishment in Rice by Selected Growth Regulators as Seed Treatment Sri Wahyuni 1 , Uma Rani Sinniah 2 , Rajan Amarthalingam 2 , and Mohd. Khanif Yusop 2 1 Indonesian Institute for Rice Research, Sukamandi 2 Faculty of Agriculture, Universiti Putra Malaysia, Selangor D.E., Malaysia ABSTRAK. Perbaikan Penampilan Bibit Padi dengan Seed Treatment Menggunakan Zat Pengatur Tumbuh. Meskipun tanam benih langsung (tabela) mempunyai beberapa keuntungan dibanding- kan dengan tanam pindah, penampilan bibit yang merana menjadi salah satu problem pada sistem tabela. Penelitian ini dilakukan untuk mengetahui pengaruh zat pengatur tumbuh terhadap penampilan bibit. Benih padi varietas Memberamo diberi perlakuan dengan meng- gunakan empat macam zat pengatur tumbuh yaitu, GA 3 , IAA, NAA, dan IBA pada lima konsentrasi yang berbeda. Hasil penelitian me- nunjukkan bahwa GA 3 mempercepat kemunculan bibit dan me- ningkatkan pertumbuhan batang bibit, tetapi batang padi panjang dan kurus. Semua perlakuan dengan menggunakan auxin meningkatkan bobot kering akar dengan atau tanpa peningkatan pada panjang akar. Perlakuan dengan auxin juga menghasilkan batang bibit yang sama atau lebih tinggi dibanding dengan tanaman kontrol. Perlakuan benih dengan 20 IBA mg/l memberikan peningkatan terbaik pada per- tumbuhan akar dan sedikit merangsang pertumbuhan batang varietas Memberamo, sehingga perlakuan tersebut disarankan sebagai per- lakuan yang sesuai untuk meningkatkan ketegaran bibit padi. Kata kunci: Padi, benih, zat pengatur tumbuh, penampilan bibit. ABSTRACT. Although wet seeded rice has been reported to have advantages compared to transplanting, poor establishment is one of problems that usually occurs in this system. The experiment was carried out to study the effect of growth regulators as seed treatment to seedling establishment of rice. Rice seeds of Memberamo cultivar were treated with four growth regulators i.e. GA 3, IAA, NAA and IBA in five different concentrations as seed treatment. Results showed that GA3 induces favourable early shoot emergence and improved shoot length of seedlings, but the shoots were spindly growth. All treatment with auxins improved root dry weight of seedlings with or without improvement in the root lengths. The auxin treatments result in similar or longer shoots compared to the controls. Seed treatment with 20 mg IBA/l has the best improvement in root growth and slightly promotes shoot growth of Memberamo rice seedlings, thus the treatment is proposed as a suitable treatment to improve seedling stand establishment of Memberamo cultivar. Key words: Rice, seed, growth regulator, seedling establishment. W et seeded rice has some advantages compared to transplanting such as less labor require- ment, shorter crop duration and more efficient in water usage (Erguisa et al . 1990, De Datta 1986, Bhuiyan et al. 1995). Apart from these advantages, the farmers generally are faced to poor stand establish- ment besides lodging problem. Poor stand establishment is largely due to seeds subjected to anaerobic condition when land preparation is not done well. This condition causes seeds to have low germination which can lead to low plant density. Low plant density not only will directly reduce yield but also indirectly can increase lodging due to the empty place in rice cultivation which results in lowered the mutual support of rice in community (Watanabe 1997). Seeds which emerge early with uniformity in shoot growth and good root system are important in establishment of an optimum seedling stand in wet seeded rice. It is known that growth regulators control many processes within a plant. There are also various reports about the effect of exogenously applied of plant growth regulators on plant growth and development (Pan and Zao 1994, Kang et al . 1993, Dunand 1992, Bevilaqua et al . 1993, Asborno et al . 1999). It is believed that the use of suitable hormone can induce early emergence and rooting, and together help in providing a good an- chorage of the plant and better seedling establishment. Gibberellic acid -3 (GA 3 ) has been known as a growth regulator used to improve germination of several seeds and shoot growth (Dunand 1992, Bevilaqua et al . 1993). While auxins such as IAA, IBA and NAA generally are used to promote root initiation, adventitious root formation and early development of root (Bellamine et al . 1998, Pan and Tian 1999). The objective of the study is to modify growth and development of rice during seedling stage. The anticipated output is the improvement of seedling stand as reflected by sturdy and healthy seedlings. MATERIALS AND METHODS The experiment was conducted in an enclosed cage at Ladang II of Universiti Putra Malaysia from January to Februari 2001. Prior to sowing Memberamo rice seeds were treated by soaking them in the growth regulator solutions or in distilled water as control for 24 hours, drained and allowed to germinate for 48 hours. The treatment consisted of four growth regulators i.e. GA 3 (gibberellic acid-3), IAA (indole-3 acetic acid), NAA (naphthalene acetic acid) and IBA (indole-3 butyric acid) in 5 different concentrations. The levels of GA3 were 10, 25, 50, 75 and 100 mg/L; IAA were 25, 50, 100, 150 and 200 mg/L; whereas equal concentrations of 10, WAHYUNI ET AL.: ENHANCEMENT OF SEEDLING ESTABLISHMENT IN RICE 51

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Enhancement of Seedling Establishment in Rice by Selected Growth Regulators as Seed Treatment

Sri Wahyuni1, Uma Rani Sinniah2, Rajan Amarthalingam2, and Mohd. Khanif Yusop2

1Indonesian Institute for Rice Research, Sukamandi2Faculty of Agriculture, Universiti Putra Malaysia, Selangor D.E., Malaysia

ABSTRAK. Perbaikan Penampilan Bibit Padi dengan SeedTreatment Menggunakan Zat Pengatur Tumbuh. Meskipun tanambenih langsung (tabela) mempunyai beberapa keuntungan dibanding-kan dengan tanam pindah, penampilan bibit yang merana menjadisalah satu problem pada sistem tabela. Penelitian ini dilakukan untukmengetahui pengaruh zat pengatur tumbuh terhadap penampilan bibit.Benih padi varietas Memberamo diberi perlakuan dengan meng-gunakan empat macam zat pengatur tumbuh yaitu, GA3, IAA, NAA,dan IBA pada lima konsentrasi yang berbeda. Hasil penelitian me-nunjukkan bahwa GA3 mempercepat kemunculan bibit dan me-ningkatkan pertumbuhan batang bibit, tetapi batang padi panjang dankurus. Semua perlakuan dengan menggunakan auxin meningkatkanbobot kering akar dengan atau tanpa peningkatan pada panjang akar.Perlakuan dengan auxin juga menghasilkan batang bibit yang samaatau lebih tinggi dibanding dengan tanaman kontrol. Perlakuan benihdengan 20 IBA mg/l memberikan peningkatan terbaik pada per-tumbuhan akar dan sedikit merangsang pertumbuhan batang varietasMemberamo, sehingga perlakuan tersebut disarankan sebagai per-lakuan yang sesuai untuk meningkatkan ketegaran bibit padi.

Kata kunci: Padi, benih, zat pengatur tumbuh, penampilan bibit.

ABSTRACT. Although wet seeded rice has been reported to haveadvantages compared to transplanting, poor establishment is one ofproblems that usually occurs in this system. The experiment wascarried out to study the effect of growth regulators as seed treatmentto seedling establishment of rice. Rice seeds of Memberamo cultivarwere treated with four growth regulators i.e. GA3, IAA, NAA and IBA infive different concentrations as seed treatment. Results showed thatGA3 induces favourable early shoot emergence and improved shootlength of seedlings, but the shoots were spindly growth. All treatmentwith auxins improved root dry weight of seedlings with or withoutimprovement in the root lengths. The auxin treatments result in similaror longer shoots compared to the controls. Seed treatment with 20 mgIBA/l has the best improvement in root growth and slightly promotesshoot growth of Memberamo rice seedlings, thus the treatment isproposed as a suitable treatment to improve seedling standestablishment of Memberamo cultivar.

Key words: Rice, seed, growth regulator, seedling establishment.

Wet seeded rice has some advantages comparedto transplanting such as less labor require-ment, shorter crop duration and more efficient

in water usage (Erguisa et al. 1990, De Datta 1986,Bhuiyan et al. 1995). Apart from these advantages, thefarmers generally are faced to poor stand establish-ment besides lodging problem.

Poor stand establishment is largely due to seedssubjected to anaerobic condit ion when landpreparation is not done well. This condition causesseeds to have low germination which can lead to low

plant density. Low plant density not only will directlyreduce yield but also indirectly can increase lodgingdue to the empty place in rice cultivation which resultsin lowered the mutual support of rice in community(Watanabe 1997). Seeds which emerge early withuniformity in shoot growth and good root system areimportant in establishment of an optimum seedlingstand in wet seeded rice.

It is known that growth regulators control manyprocesses within a plant. There are also various reportsabout the effect of exogenously applied of plant growthregulators on plant growth and development (Pan andZao 1994, Kang et al. 1993, Dunand 1992, Bevilaqua etal. 1993, Asborno et al. 1999). It is believed that the useof suitable hormone can induce early emergence androoting, and together help in providing a good an-chorage of the plant and better seedling establishment.

Gibberellic acid -3 (GA3) has been known as agrowth regulator used to improve germination ofseveral seeds and shoot growth (Dunand 1992,Bevilaqua et al. 1993). While auxins such as IAA, IBAand NAA generally are used to promote root initiation,adventitious root formation and early development ofroot (Bellamine et al. 1998, Pan and Tian 1999).

The objective of the study is to modify growth anddevelopment of rice during seedling stage. Theanticipated output is the improvement of seedlingstand as reflected by sturdy and healthy seedlings.

MATERIALS AND METHODS

The experiment was conducted in an enclosedcage at Ladang II of Universiti Putra Malaysia fromJanuary to Februari 2001. Prior to sowing Memberamorice seeds were treated by soaking them in the growthregulator solutions or in distilled water as control for 24hours, drained and allowed to germinate for 48 hours.The treatment consisted of four growth regulators i.e.GA3 (gibberellic acid-3), IAA (indole-3 acetic acid), NAA(naphthalene acetic acid) and IBA (indole-3 butyricacid) in 5 different concentrations. The levels of GA3were 10, 25, 50, 75 and 100 mg/L; IAA were 25, 50, 100,150 and 200 mg/L; whereas equal concentrations of 10,

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20, 30, 40 and 50 mg/L were used for NAA and IBA. Theconcentrations used in this study were selected basedon literature study. The pre-germinated seeds werethen sown in container (diameter 28 cm and 36 cm inheight) filled with 12 kg soil of Jawa series (silty clay)from lowland rice area, Tanjong Karang, Selangor.Thirteen seeds were sown in each container(equivalent to 60 kg seeds per ha) and eachexperimental unit consisted of two containers. Theexperiment was arranged in a completely randomizeddesign (CRD) with four replications.

Shoot length was measured at 3, 7, 10 and 17 daysafter sowing (DAS) from 5 plants per replicate. Rootlength and root dry weight were measured at 10 and 17DAS. At each sampling time, five plants per replicatewere pulled out together with the soil from thecontainers, washed to detach soil and measurementsrecorded. Shoot length was measured from the base ofcoleoptile and the tip of the highest leaf and root lengthfrom the base of coleoptile to the tip of the longest root(Yoshida 1981). Root dry weight was recorded using thestandard procedure of the AOSA (1981) whereby thesamples were dried in an oven at 80oC for 24 hours,kept in a dessicator for about two hours followed byweight determined. The data were subjected to ana-lysis of variance (ANOVA) using SAS Software Release6.12 by SAS Institute Inc., USA. Duncan’s Multiple RangeTest (DMRT) was used to compare the treatment meanat p=0.05.

RESULTS AND DISCUSSION

The effect of growth regulators on shoot growth of rice seedlings

At very initial stage (3 DAS) GA3 treatment in variousconcentrations induced shoot emergence where alltreated seedlings had longer shoots compared to thecontrols and auxins treated plants (Table 1). IncreasingGA3 concentration raised the improvement of shootgrowth and the longest shoot obtained at application of100 mg/L GA3. Similar results were shown in theprevious study (Dunand 1992, Bevilaqua et al. 1993,Asborno et al. 1999). Exogenous application of GA3enhanced the ability of endogenous GA3 (Prakash andPrathapesenan 1990) that stimulated activity ofα-amylase in germinating seed (Linn and Kao 1995,Kaur et al. 1998) resulted in improved seedlingemergence. The effect of GA3 was still present inseedling until ten DAS and it maintained longer shootlengths compared to control and other treated plants.These results were consistent with previous reports

(Grzesik and Chojnoski 1992, Kang et al. 1993).Gibberellic acids promoted growth by increasingplasticity of the cell wall, followed by the hydrolysis ofstarch to sugar which reduced the water potential inthe cell resulting in the entry of water into the cellcausing elongation (Arteca 1995).

In comparison, shoot lengths of auxins (IAA, IBA,and NAA) treated plants were comparable to thecontrols at three to ten DAS. Subsequently, observationat 17 DAS showed that there was no significantdifference in shoot lengths amongst treated anduntreated plants. One reason for this condition may bedue to the inability of auxins in enhancing α-amylaseactivity. Furthermore, previous study in the cotyledonsof chickpea showed that auxin was not as effective asGA3 in improving the activity of α- amylase (Kaur et al.1998).

Although GA3 treated seedlings were taller thancontrol and auxins treated seedlings, the shoots wasspindly (thin and tall) (Plate 1). Visual observation in

Table 1. The effect of growth regulators as seed treatment on shootlength of rice.

Shoot length (cm)Seed treatment

3 DAS 7 DAS 10 DAS 17 DAS

Control 6.00 ef 14.27 e 18.17 d 39.30GA3

10 mg/L 8.77 d 20.15 c 26.80 c 39.5725 mg/L 10.10 c 26.37 b 29.13 bc 39.4350 mg/L 11.63 ab 27.44 b 30.07 b 39.7075 mg/L 11.60 b 27.33 b 30.40 b 40.23100 mg/L 12.83 a 31.27 a 33.00 a 41.83

IAA25 mg/L 6.23 ef 17.10 d 18.33 de 41.5750 mg/L 6.23 ef 16.90 d 18.20 de 41.77100 mg/L 6.37 ef 16.87 d 18.20 de 40.40150 mg/L 6.27 ef 17.00 d 18.40 de 40.80200 mg/L 6.03 ef 16.80 d 18.73 d 39.80

NAA10 mg/L 5.23 f 15.00 de 18.40 de 36.8320 mg/L 5.93 ef 17.10 d 20.00 d 42.5030 mg/L 5.90 ef 16.33 de 18.47 de 40.3740 mg/L 5.90 ef 16.00 de 17.70 de 40.9750 mg/L 5.40 ef 16.00 de 17.67 de 39.40

IBA10 mg/L 6.47 e 17.30 d 19.17 d 41.2020 mg/L 6.10 ef 16.83 d 19.10 d 42.9730 mg/L 5.33 ef 16.30 de 18.67 d 41.1040 mg/L 5.27 ef 16.07 de 18.33 de 41.8750 mg/L 5.37 ef 15.97 de 18.27 de 40.40

cv (%) 10.50 7.78 7.10 11.25 (ns)

Means within columns followed by the same letter are not significantly different at 0.05 levelof probability based on DMRT, ns = not significant.

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the field showed that GA3 treated seedling appeared tobe susceptible to lodging even at the seedling stage.The situation was presumably due to the elongation inmeristematic zone which was faster than the enlarge-ment as addition of GA3 improve shoot elongation(Arteca 1995). In contrast, although auxins treatedseedlings were similar in height but the seedlingperformance was better than the controls with thickerstem and broader leaves (Plate 1).

The effect of growth regulators on root growth of rice seedlings

The treatments had no effect on root length androot dry weight at ten DAS. However, subsequently (17DAS), the treatments significantly influenced both rootparameters. Root length of GA3 treatment in allconcentrations was comparable to the controls andreflected into the root dry weights. Although exogenousapplication of IAA and NAA resulted in comparable rootlengths to the controls, except for 20 and 30 mg/L NAA,the root dry weights of IAA and NAA treated seedlingswere higher than the controls. While seed treatmentwith IBA in all levels resulted in a significantenhancement in root length and root dry weightcompared to the controls. These results clearly showed

that auxins treatments promoted root growth with orwithout improvement in the root length. This is inagreement with other studies that auxins promote rootinitiation, adventitious root formation and earlydevelopment of roots (Pan and Zao 1994, Bellamine etal. 1998). In addition, the results also showed that theresponse of seedlings to dif ferent kinds andconcentrations of auxin was varied in term of rootlength. The highest root dry weight was obtained byapplication of 20 mg/L IBA, even though the longestroot was obtained in treatment with 30 mg/L IBA (Table2).

Exogenous application of growth regulatorsobviously influenced shoots and roots development(Plate 1). It is clearly showed an improvement in rootgrowth of auxins treated seedlings with IBA at 20 mg/Lshowing the best improvement. Different patterns ofroot development amongst treatments also wererecorded in the present study (Plate 2). The plate

Table 2. The effect of growth regulators on root length and dry weightof rice.

Root dry weight Root length (cm) (mg/seedling)

Seed treatment 10 DAS 17 DAS 10 DAS 17 DAS

Control 6.53 9.97 de 3.43 24.30 fGA3

10 mg/L 6.77 10.13 de 3.40 25.60 f 25 mg/L 6.70 10.30 de 3.93 29.40 ef50 mg/L 6.70 10.43 bcde 3.80 29.20 ef75 mg/L 6.63 10.60 bcde 3.80 29.80 def100 mg/L 6.83 12.87 abcd 4.07 32.80 bcdef

IAA25 mg/L 7.37 12.50 abcd 3.67 40.43 bcde50 mg/L 6.97 11.77 abcde 3.57 41.73 bc100 mg/L 6.70 11.70 abcde 3.60 39.70 bcde150 mg/L 6.87 12.50 abcd 4.10 40.83 bcde200 mg/L 6.40 12.00 abcd 3.90 39.80 bcde

NAA10 mg/L 7.63 9.54 e 4.00 37.17 cde20 mg/L 7.70 13.60 abc 4.17 44.40 ab30 mg/L 7.67 13.50 abc 3.97 40.67 bcde40 mg/L 7.67 13.03 abcd 4.07 41.43 bcd50 mg/L 7.33 12.10 abcd 3.90 38.10 bcde

IBA10 mg/L 6.83 13.57 abc 3.80 40.80 bcde20 mg/L 8.00 13.77 ab 4.03 53.57 a30 mg/L 8.27 14.00 a 3.90 42.40 abc40 mg/L 8.00 13.90 a 4.13 41.40 bcd50 mg/L 6.57 13.50 abc 3.87 38.20 bcde

cv (%) 14.17 (ns) 15.94 14.28 (ns)

Means within columns followed by the same letter are not significantly different at 0.05 levelof probability based on DMRT,ns = not significant.

Plate 1. The effects of growth regulators on shoot and root growth ofrice seedling at 15 days after sowing.

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showed that auxin improved adventitious rootformation, whereas GA3 improved growth of root hairs.

CONCLUSIONS

Exogenously applied GA3 successfully inducedearly shoot emergence and improved shoot growth inthe initial stage, but the shoots were spindly growth.The GA3 had no effect on root growth.

Seed treatments with auxins improved root dryweight at seedling stage with or without improvementin the root lengths, whereas the effect on shoot growthwas variable.

Seed treatment with IBA at 20 mg/L IBA had thehighest root dry weight and was able to provide bettershoot growth. Thus, it is proposed that 20 mg/L IBA is asuitable concentration used as seed treatment in orderto improve shoot and root growth of Memberamo riceseedlings.

REFERENCES

AOSA. 1981. Rules for testing seeds. Proc. Assoc. of Seed Anal. 60:1-126.

Arteca, R.N. 1995. Plant growth substances: Principles andapplications. Chapman & Hall, New York. 332p.

Asborno, M.D., A.A Vidal, R. Bezus, and J. Beltrano. 1999. Rice:Temperature and gibberellic acid effect on initial growth stages.Agro Ciencia 15 (1) : 47-53 (Spanish, abstract in English).

Bellamine, J., C. Penel, H. Greppin, and T. Gaspar. 1998. Confirmationof the role of auxin and calcium in the late phases of adven-titious root formation. Plant Growth Regul 26: 191-194.

Bevilaqua, G.A.P., S.T. Peske, B.G. Santos-Filho, and L.M.L. Baudet.1993. Performance of irrigated rice seed treated with growthregulator. I. Effect on emergence in the field. Revista Brasileirade Sementes 15 (1): 67-74 (Portuguese, abstract in English).

Bhuiyan, S.I., Sattar, M.A., and Khan, M.A.K. 1995. Improving wateruse efficiency in rice irrigation through wet seeding. Irrig. Sci.16:1-8.

De Datta, S.K. 1986. Technology development and the spread of directseeded flooded rice in Southeast Asia. Exp.Agric. 22: 417- 426.

Dunand, R.T. 1992. Enhancement of seedling vigor in rice (Oryzasativa L.) by seed treatment with gibberellic acid. Pages 835-845In Karssen, C.M., L.C. Van-Loon, and D. Vreugdenhill, eds.,Progress in Plant Growth Regulation. Proceeding of the 14 th

International Conference on Plant Growth Substances,Amsterdam, 21-26 July, 1991. Kluwer Academic Publishers,Netherlands.

Erguisa, A., B. Duff, and C. Khan. 1990. Choice of rice cropestablishment technique: transplanting vs wet seeding. IRRIRes. Paper Series No.39: 1-10.

Grzesik, M. and M. Chojnowski. 1992. Effect of growth regulators onplant-growth and seed yield of Zinnia elegans ’Red Man’. SeedSci. and Technol. 20: 327-330.

Kang, C.K., J.O. Lee, Y.S. Park, and Y.D. Rho. 1993. Effect of plantgrowth regulators on rooting and root-mat formation in infantrice seedling for machine transplanting. RDAJ. of Agric. Scie.Rice 35 (2): 7-11 (Korean, Abstract in English).

Kaur, S., A.K. Gupta, and N. Kaur. 1998. Gibberellic acid and kinetinpartially reverse the effect of water stress on germination andseedling growth in chickpea. Plant Growth Regul. 25: 29-33.

Plate 2. The effect of growth regulators on adventitious roots of seedlings at three days after sowing.

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Linn, C. and C.H. Kao. 1995. Na Cl stress in rice seedling: starchmobilization and the influence of GA3 on seedling growth.Botanical Bull. Acad. Sinica 36: 169-173.

Pan, R. and R.J. Zhao. 1994. Synergic effect of plant growth retardantand IBA on the formation of adventitious roots in hypocotylscuttings of mung bean. Plant Growth Regul. 14: 15-19.

Pan, R., R.J. Zhao, and Tian, X. 1999. Comparative effect of IBA, BSAA,and 5,6- Cl-IAA-Me on the rooting of hypocotyls in mung bean.Plant Growth Regul. 27: 91-98.

Prakash, L. and G. Prathapasenan. 1990. Interactive effect of NaClsalinity and gibberellic acid on shoot growth, content of absisicacid and gibberellin-like substances and yield of rice (Oryzasativa L. variety GR-3). Plant Sci. 100: 173-181.

Watanabe,T. 1997. Lodging resistance. p.567-577 In T. Matsuo, Y.Futsuhara, F. Kikuchi, H. Yamaguchi, (Eds.), Science of the riceplant. Vol. III. Genetics. Food and Agriculture Policy ResearchCenter, Tokyo, Japan.

Yoshida, S. 1981. Fundamentals of rice crop science. InternationalRice Research Institute, Los Banos, Philippines. 269 p.

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Plate 1. The effects of growth regulators on shoot and root growth of rice seedling at 15 days after sowing.

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