The impact of ethylene gas application on young-tapping rubber trees

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Journl of Agriculturl Technology 2012 Vol. 8(4): 1497-1507 Journl of Agriculturl Avilble Technology online http://www.ijt-tse.com 2012, Vol. 8(4): 1497-1507 ISSN 1686-9141 The impct of ethylene gs ppliction on young-tpping rubber trees Thongchi Sinoi nd Syn Sdoodee * Deprtment of Plnt Science, Fculty of Nturl Resources, Prince of Songkl University, Ht Yi, Songkhl 90112, Thilnd. Thongchi Sinoi nd Syn Sdoodee (2012) The impct of ethylene gs ppliction on young tpping rubber trees. Journl of Agriculturl Technology 8(4): 1497-1507.. The ethylene gseous stimultion hs been introduced by rubber smllholders in southern Thilnd to increse ltex production, lnd productivity nd tpping lbour efficiency. Some smllholders lso pply ethylene gseous stimultion even in young-tpping rubber trees. This my cuse dverse impct on the rubber tree. Therefore, n experiment ws estblished t the Thep Reserch Sttion in Songkhl province to investigte the effect of ethylene gs stimultion on the young-tpping rubber tree. Nine-yer-old RRIM 600 clones were used for study. The experiment ws designed s one tree plot design with 6 tretments; T1: S/3 2d/3 6d/7, T2: S/6 3d 6d/7, T3: S/6 3d 6d/7. ET2.5% P 1(2) 12/y (m), T4: S/6 3d 6d/7. ETG99% RRIMFLOW -60-36/y (9d), T5: S/6 3d 6d/7. ETG60% LET -40-48/y (6d) nd T6: S/6 3d 6d/7. ETG99% Double Tex -60-36/y (9d). There were twenty replictes in ech tretment. The result showed tht the cup lump production of the T4 tretment provided the highest yield (3186.05 g tree -1 nd 91.03 g tree -1 tpping -1 ) nd it ws significntly different from the remining tretments. Dry rubber content (DRC) of the T4, T5 nd T6 tretments tended to decrese. However, there ws no significnt difference mong the tretments. Brk consumption of T2, T3, T4, T5 nd T6 ws significntly less thn tht of the conventionl tpping system (T1). There ws no significnt difference on rdil trunk growth mong the ll tretments. Sucrose, inorgnic phosphorus nd thiol content of the ethylene stimultion tretments resulted to lower thn the conventionl tpping system. This indicted tht ltex production of young-tpping rubber tree ws incresed by ethylene stimultion, however, it ffected ltex physiology. This my led to negtive impct in long term. Hence, it needs to be investigted further for long term impct of using ethylene gseous stimultion. Key words: Heve brsiliensis, ltex yield, ethylene stimultion, ltex biochemistry Introduction Tpping system efficiency is n importnt fctor for the ltex production of rubber tree (Heve brsiliensis). As well s tpping system hs been developed vrious to rubber smllholders doption. There were mny reports * Corresponding uthor: Syn Sdoodee; e-mil: syn.s@psu.c.th 1497

of pproprite tpping systems to enhnce ltex production comprising low frequency tpping system (Obouyeb et l., 2009; Soumhin et l., 2009; Prsnn et l., 2010; Kudligm et l., 2010; Soumhin et l., 2010) nd Double Cut Alternte (DCA) tpping system (Chntum et l., 2011; Sdoodee et l., 2012). With the continuous increse of rubber price nd decrese of ech smllholder s rubber plnttion size, high frequency tpping system hve been implemented to enhnce hrvesting i.e. dily tpping (d1), two dys out of three (2d/3) nd three dys out of four (3d/4) (Chntum et l., 2011). However, this ffects ltex regenertion time with n increse of tpping pnel dryness (TPD) (Obouyeb et l., 2011) nd growth in life cycles of rubber tree. Reserchers hve been trying to improve tpping systems by using stimulnts. The chemicl stimulnts of 2-chloroethylphosphonic cid (Ethephon or Ethrel) hs been used to enhnce ltex yield by incresing the durtion of ltex flow fter tpping, reduced tpping frequency nd incresed lnd or lbor productivity (Sivkumrn nd Chong, 1994; Sivkumrn, 2002; Jetro nd Simon, 2007; Lcote et l., 2010; Njukeng et l., 2011; Trore et l., 2011). d Auzc (1989) reported tht ethylene rection t the inner brk, incresed pressure nd elsticity of lticiferous cell, decresed the cogulte of ltex. Njukeng et l. (2011) suggested tht the frequency nd concentrtion of stimultion should be dpted s n spect of the clone, tree ge nd tpping system. Recently, the RRIMFLOW, LET nd Double Tex equipments or more hve been commercil dopted by rubber smllholders in Thilnd. Sivkumrn (2002) reported tht the RRIMFLOW system could enhnce ltex yield nd increse the income of tppers round two to three fold due to the incresed tpper productivity. This RRIMFLOW system hs not widely known due to limit dt presented on this spect in vrious publictions on the RRIMFLOW system (Sivkumrn et l., 2007). Normlly, ethylene gs stimultion is recommended for the ppliction over 15-yer-old rubber tree, but some smllholders pply in young-tpping rubber trees becuse of misunderstnding. Therefore, the objective of this study ws to investigte the impct of ethylene gs ppliction on young-tpping rubber trees s guideline for the smllholders. Mterils nd methods The experiment ws crried out during September 2010 to Mrch 2012 t the Thep Reserch Sttion, Thep district (100 o 94 E 6 o 79 N) in Songkhl province, Thilnd. The rubber tree vr. RRIM 600 plnted in 2001 with spcing of 7 3 m (476 trees h -1 ) ws used in the experiment. The tpping ws strted in 2008 t 1.50 m from the ground (pnel BO-1) nd tpping in this experiment ws implemented in 2010 t 0.90 m from the ground. At this stge, 1498

Journl of Agriculturl Technology 2012, Vol. 8(4): 1497-1507 the trunk girth verge ws round 50.1 cm mesured 1.70 m from the ground. The soil texture in the experimentl plot ws sndy lom with ph 5.5 (Coted, isohyperthermic, Typic Qurtzipsmments). The experimentl design ws one tree plot design (OTPD) comprising 20 replictes per tretment. There were six tretments (T1-T6) which modified from Vijykumr et l. (2009) nd Sopchoke (2010) s follows: T1 = S/3 2d/3 6d/7 (Third spirl downwrd cut t two dys tpped by one dy rest, six dys tpping follows one dy rest), T2 = S/6 3d 6d/7 (Six spirl downwrd cut t every three dys tpped, six dys tpping follows one dy rest), T3 = S/6 3d 6d/7. ET2.5% P 1(2) 12/y (m) (Six spirl downwrd cut t every three dys tpped, six dys tpping follows one dy rest; stimulted with Ethephon of 2.5% ctive ingredient with 1 g of stimulnt pplied on pnel on 2 cm bnd, 12 pplictions per yer), T4 = S/6 3d 6d/7. ETG99% RRIMFLOW -60-36/y (9d), (Six spirl downwrd cut t every three dys tpped, six dy tpping follows one dy rest; stimulted with Ethylene gs of 99% RRIMFLOW system ctive quntity with 60 ml, 36 pplictions per yer t 9-dy intervl), T5 = S/6 3d 6d/7. ETG60% LET -40-48/y (6d) (Six spirl downwrd cut t every three dys tpped, six dy tpping follows one dy rest; stimulted with Ethylene gs of 60% LET system ctive quntity with 40 ml, 48 pplictions per yer t 6-dy intervl) nd T6 = S/6 3d 6d/7. ETG99% Double Tex -60-36/y (9d) (Six spirl downwrd cut t every three dys tpped, six dy tpping follows one dy rest; stimulted with Ethylene gs of 99% Double Tex system ctive quntity with 60 ml, 36 pplictions per yer t 9-dy intervl). The instlltion positions of RRIMFLOW, LET nd Double Tex equipments were followed the commercil recommendtion (Figure 1). The schedule of pnel mngement is shown in Figure 2. The ltex yield ws collected from cup lumps which used to determine dry rubber production in grm per tree (g tree -1 ), in grm per tree per tpping (g tree -1 tpping -1 ). The other prmeters of dry rubber content, girth increment (mesured t 1.70 m height from the ground) nd brk consumption were recorded. Ltex dignosis ws crried out during September to November 2011 to determine sucrose, inorgnic phosphorus nd thiol content (Gohet nd Chntum, 1999). 1499

T1 T2 T3 T4 T5 T6 Fig. 1. The tpping systems: T1 = S/3 2d/3 6d/7, T2 = S/6 3d 6d/7, T3 = S/6 3d 6d/7. ET2.5% P 1(2) 12/y (m), T4 = S/6 3d 6d/7. ETG99% RRIMFLOW -60-36/y (9d), T5 = S/6 3d 6d/7. ETG60% LET -40-48/y (6d), T6 = S/6 3d 6d/7. ETG99% Double Tex -60-36/y (9d) Height from the ground (cm) Height from the ground (cm) Fig. 2. Mngement of tpping pnels (BO-1, BO-2, BO-3, BO-4, BO-5, BO-6) of tpping systems (1/3S 2d/3 6d/7 nd 1/6S d3 6d/7) during experiment 1500

Journl of Agriculturl Technology 2012, Vol. 8(4): 1497-1507 Results nd discussions Rubber production per yer The cumultive cup lump (g tree -1 ) ws showed significntly different mong the six tretments s shown in Figure 3A. The T4 provided the highest cumultive cup lump (3186.05 g tree -1 ). In ddition, the ethylene gseous stimultion tretments in T4, T5 nd T6 expressed significntly higher cumultive cup lump thn the ethephon stimultion tretment (T3). Although the ethylene gseous stimultion tretments incresed cumultive cup lump, there ws no significntly different from the conventionl tpping system (T1). Similrly, Jetro nd Simon (2007) reported tht 2-chloroethylphosphonic cid cused n increse of rubber yield nd vried with seson. The increse in of yield per yer ws due to hormonl stimultion which prolonged period of ltex flow per ctivtion of lticiferous metbolism (Trore et l., 2011). It ws evident tht the verge cup lumps (g tree -1 tpping -1 ) mong the six tretments were significntly different (Figure 3B). The T4 tretment provided the highest verge cup lump (91.03 g tree -1 tpping -1 ). Sivkumrn (2002) lso reported tht the RRIMFLOW short cut tpping system incresed in yield productivity, tpping efficiency. Besides, the ethylene gseous stimultion tretments (T4, T5 nd T6) expressed higher verge cup lump thn the remining tretments. Jetro nd Simon (2007) supported tht the yield (g tree -1 tpping -1 ) of stimulted tree ws significntly higher thn the non-stimulted trees. Dry rubber content (%DRC) All tretments of rubber tree were no significntly different, nd the percentge dry rubber content vried from 41.33 to 44.62 percentges s shown in Figure 3C. However, the ethylene gseous stimultion tretments in T4, T5 nd T6 tended to lower percentge of dry rubber content thn the other tretments. Hock nd Sivkumrn (2003) nd Leconte et l. (2006) reported tht the dry rubber content of ltex from ethylene ppliction of rubber trees ws lower thn conventionl tpping. Brk consumption The brk consumption mong the six tretments ws shown significntly different s seen in Tble1. Especilly, the conventionl tpping system (T1) expressed significntly higher brk consumption thn the other tretments becuse of higher frequencies. However, reduction in brk consumption is 1501

benefit to increse the life spn nd delys the replnting. Less brk consumption lso provides increse time for brk renewl (Kudligm et l., 2010). Growth There ws no significntly different of girth incresed mong the six tretments. Silpi et l. (2006) reported tht ethylene hd no effect on the growth rtes of tpped trees nd ethephon concentrtions hd no dverse effects on tree helth (Prsnn et l., 2010). However, the tree growth of the ethylene gseous stimultion tretments of T4, T5 nd T6 tended to be lower thn T1, T2 nd T3 tretments. Trore et l. (2011) found tht the non-stimulted trees hd girth increment which ws superior to stimulted trees. Besides, girth increment the stimulted trees decresed becuse the trees were submitted to importnt stimultion, crry long the ftigue of trees due to overexploittion nd overstimultion (Jcob et l., 1995 refer to Trore et l., 2011). Ltex physiology The verge sucrose content, inorgnic phosphorus content nd thiol content of rubber trees in the six tretments during September to November 2011 were shown in Tble1. The sucrose content mong the six tretments ws shown significntly different from the dt gthered in September nd October, except in November 2011. Although the ethylene gseous stimultion tretments of T4, T5 nd T6 were higher sucrose content thn T1, T2 nd T3 tretments in September but they tended to decrese in October to November. However, sucrose content of the ethephon stimultion tretment (T3) expressed which similrly compred to the conventionl tpping system (T1). There ws significntly different of inorgnic phosphorus content in September mong the six tretments except October nd November. In ddition, the ethylene gseous stimultions of T4, T5 nd T6 cused higher inorgnic phosphorus content in September, but lower in October nd November thn the conventionl tpping system (T1). However, inorgnic phosphorus content of the ethephon nd ethylene gseous stimultion tretments of T3, T4, T5 nd T6 tended to decrese in October nd incresed in November. Lcote et l. (2010) reported tht the effect of ethylene stimultion on PB 217 clone ws high sucrose content nd low inorgnic phosphorus content. There ws significnt difference of thiol content mong the six tretments in October, except in September nd November. Thiol content seemed to increse continuously in the ll tretments. However, the ethephon nd ethylene 1502

Journl of Agriculturl Technology 2012, Vol. 8(4): 1497-1507 gseous stimultion tretments of T3, T4, T5 nd T6 tended to lower thiol content thn the conventionl tretment (T1). Jetro nd Simon (2007) reported tht the higher thiol of the stimulted trees could be due to good level of metbolic ctivition tht ws not ccompnied by stress. High stress leds to degrdtion rections which reduce thiol level. Cumultive cup lump (g/t) 4000 3500 3000 2500 2000 1500 1000 500 0 0 c b (A) Averge cup lump (g/t/t) 120 80 40 0 c c b (B) 1503

Dry rubber content (%) 45 44 43 42 41 40 39 380 ns T1 T2 T3 T4 T5 T6 Tretments T1 = S/3 2d/3 6d/7 T2 = S/6 3d 6d/7 T3 = S/6 3d 6d/7. ET2.5% P 1(2) 12/y (m) T4 = S/6 3d 6d/7. ETG99% RRIMFLOW -60-36/y (9d) T5 = S/6 3d 6d/7. ETG60% LET -40-48/y (6d) T6 = S/6 3d 6d/7. ETG99% Double Tex -60-36/y (9d) (C) Fig. 3. Comprison of cumulted cup lump (g tree -1 ) (A), verge cup lumps (g tree -1 tpping -1 ) (B) nd verge dry rubber content (DRC) (C) of rubber trees in the six tretments during September 2010 to Mrch 2012 Tble 1. Brk consumption of rubber trees in the six tretments during September 2010 to Mrch 2012 Tretments Brk consumption (cm) T1 = S/3 2d/3 6d/7 20.21 T2 = S/6 3d 6d/7 18.46b T3 = S/6 3d 6d/7. ET2.5% P 1(2) 12/y (m) 18.24b T4 = S/6 3d 6d/7. ETG99% RRIMFLOW -60-36/y (9d) 18.59b T5 = S/6 3d 6d/7. ETG60% LET -40-48/y (6d) 19.06b T6 = S/6 3d 6d/7. ETG99% Double Tex -60-36/y (9d) 18.54b F-test * C.V. 8.66 Mens with different letters in the sme column indicte significnt difference t P 0.05, DMRT. 1504

Journl of Agriculturl Technology 2012, Vol. 8(4): 1497-1507 Averge increse of girth (cm.) 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 ns T1 T2 T3 T4 T5 T6 Tretments T1 = S/3 2d/3 6d/7 T2 = S/6 3d 6d/7 T3 = S/6 3d 6d/7. ET2.5% P 1(2) 12/y (m) T4 = S/6 3d 6d/7. ETG99% RRIMFLOW -60-36/y (9d) T5 = S/6 3d 6d/7. ETG60% LET -40-48/y (6d) T6 = S/6 3d 6d/7. ETG99% Double Tex -60-36/y (9d) Fig. 4. Averge girth increment of rubber trees in the six tretments during September 2010 to Mrch 2012 Tble 2. Averge of sucrose content, inorgnic phosphorus content nd thiol content of rubber trees in the six tretments during September to November 2011 Tretments Sucrose (mm L -1 ) Inorgnic phosphorus (mm L -1 ) Thiol (mm L -1 ) Sep Oct Nov Sep Oct Nov Sep Oct Nov T1 = S/3 2d/3 6d/7 7.35b 6.10b 5.69 8.32bc 9.79 18.15 0.24 0.48 0.77 T2 = S/6 3d 6d/7 9.38b 7.83 6.17 5.11c 7.30 11.43 0.27 0.34bc 0.76 T3 = S/6 3d 6d/7. ET2.5% P 1(2) 12/y 9.07b 6.72b 4.90 8.14bc 4.75 13.87 0.20 0.51 0.59 (m) T4 = S/6 3d 6d/7. ETG99% RRIMFLOW 18.58 5.02b 4.81 17.14 6.37 17.05 0.10 0.44b 0.70-60- 36/y (9d) T5 = S/6 3d 6d/7. ETG60% LET -40-15.06 5.08b 4.79 9.48bc 6.00 16.49 0.21 0.45b 0.62 48/y (6d) T6 = S/6 3d 6d/7. ETG99% Double Tex - 60-36/y (9d) 16.42 4.30b 3.68 13.12b 5.60 14.50 0.14 0.26c 0.61 F-test * * ns * ns ns ns * ns C.V. 27.16 24.89 36.74 25.93 38.55 23.63 32.44 16.71 23.31 Mens with different letters in the sme column indicte significnt difference t P 0.05, DMRT ns = no significnt difference 1505

Conclusion Ethylene stimulnt tpping system enhnced ltex production in grm per tpping of young-tpping of rubber trees. However, there ws no significntly different of cumultive ltex production compred with the conventionl tpping system. In ddition, dry rubber content (% DRC) nd girth increment of ethylene stimultion tpping system tended to decrese from regulr. Brk consumption ws significntly reduced under the stimulnt ppliction tretments. However, ltex physiology tended to be ffected under the stimulte tretments; this my led to negtive impct in the long term. Acknowledgement This work ws supported by the Higher Eduction Reserch Promotion nd Ntionl Reserch University Project of Thilnd, Office of the Higher Eduction Commission. References Chntum, P., Lcote, R., Leconte, A. nd Gohet, E. (2011). An innovtive tpping system, the double cut lterntive, to improve the yield of Heve brsiliensis in Thi rubber plnttions. Field Crops Reserch 121: 416-422. d Auzc, J. (1989). Historiricl ccount of the hormonl stimultion of ltex yield. In Physiology of Rubber Tree Ltex (eds. J. d Auzc, J.L. Jcop nd H. Chrestin) Florid: CRC Press Inc. Gohet, E. nd Chntum, P. (1999). Microdignostic ltex trining RRIT-DOA, Chchoengso Rubber Reserch Center, 22-26 November 1999. Hock, L.C. nd Sivkumrn, S. (2003). Enhncing rubber production to meet incresing demnd for nturl rubber. Pper presented t IRRDB Symposium Chllenges for Nturl Rubber in Globliztion 15-17 September 2003, Ching Mi, Thilnd. Jetro, N.N. nd Simon, G.M. (2007). Effect of 2-chloroethylphosphonic cid formultions s yield stimulnts on Heve brsiliensis. Africn Journl of Biotechnology 6: 523-528. Kudligm, K.V.V.S., Rodrigo, V.H.I., Fernndo, K.M.E.P. nd Yp, P.A.J. (2010). Response of low frequency hrvesting systems of rubber under drier climtic conditions in Sri LnK. Proceedings of the 15 th Interntionl Forestry nd Environment Symposium, University of Sri Jyewrdenepur, Sri Lnk 26-27 November 2010 pp 62-69. Lcote, R., Gbl, O., Obouyeb, S., Eschbch, J.M., Rivno, F., Din, K. nd Gohet, E. (2010). Longterm effect of ethylene stimultion on the yield of rubber trees is linked to ltex cell biochemistry. Field Crops Reserch 115: 94-98. Leconte, A., Vysse, L., Sntisopsri, V., Kruprsert, C., Gohet, E. nd Bonfils, F. (2006). On frm testing of ethephon stimultion nd different tpping frequencies, effect on rubber production nd qulity of rubber. Frn co-thi project 2005-2008. Njukeng, J.N., Muenyi, P.M., Ngne, B.K. nd Ehbe, E.E. (2011). Ethephon stimultion nd yield response of some Heve clones in the humid forests of south west Cmeroon. Interntionl Journl of Agronomy 2011:1-5. Obouyeb, S., Coulibly, L.F., Gohet, E., Yo, T.N. nd Ake, S. (2009). Effect of tpping systems nd height of tpping opening on clone PB 235 gronomic prmeters nd it s susceptibility to tpping pnel dryness in south-est of Cote d Ivoire. Journl of Applied Biosciences 24: 1535-1542. 1506

Journl of Agriculturl Technology 2012, Vol. 8(4): 1497-1507 Obouyeb, S., Soumhin, E.F., Okom, K.M., Boko, A.M.C.K., Dick, K.E. nd Lcote, R. (2011). Reltionship between tpping intensity nd tpping pnel dryness susceptibility of some clones of Heve briliensis in southwestern Cote d Ivoire. Agriculture nd Biology Journl of North Americ 2: 1151-1159. Prsnn, W.R.A.C., Rodrigo, V.H.I., Abeysinghe, D.C. nd Kudligm, K.V.V.S. (2010). Stimulnt levels to be used with two low intensity hrvesting (LIH) systems of rubber under wet nd intermedite zones of Sri Lnk. Proceedings of the 15 th Interntionl Forestry nd Environment Symposium, University of Sri Jyewrdenepur, Sri Lnk 26-27 November 2010 pp 265-272. Sdoodee, S., Leconte, A., Rongswt, S., Rukkhun, J., Huynui, T. nd Chintim, H. (2012). First tests of Double Cut Alternte rubber tpping system in southern Thilnd. Ksetsrt Journl (Nturl Science) 46: 33-38. Silpi, U., Thler, P., Ksemsp, P., Lcointe, A., Chntum, A., Adm, B., Gohet, E., Thniswnyngkur, S. nd Améglio, T. (2006). Effect of tpping ctivity on the dynmics of rdil growth of Heve brsiliensis trees. Tree physiology 26: 1579-1587. Sivkumrn, S. nd Chong, K. (1994). Yield stimultion in rubber: current sttus nd improvements for enhnced productivity. In: Proceedings of the interntionl Plnters Conference, Mlysi, pp 396-408. Sivkumrn, S. (2002). Exploittion systems to mximize yield productivity nd enhnce profitbility in rubber. In: Globl Competitiveness of Indin Rubber Plnttion Industry: Rubber Plnters Conference, Indi 2002, (Ed. C. Kuruvill Jcob), Kottym, pp 163-174. Sivkumrn, S., Ismil, T., Thm, F.K. nd Thm, F.C. (2007). RRIMFLOW system of exploittion: ssessment of performnce on renewed brk. CRRI & IRRDB Interntionl Rubber Conference 2007. 12-13 November 2007, Siem Rep, Cmbodi. Sopchoke, P. (2010). Interntionl symbol of hrvesting technology. Pr Rubber Bulletin 31: 34-45. Soumhin, E.F., Obouteb, S. nd Anno, P.A. (2009). Low tpping frequency with hormonl stimultion on Heve brsiliensis clone PB 217 reduces tpping mnpower requirement. Journl of Animl & Plnt Sciences 2: 109-117. Soumhin, E.F., Obouteb, S., Dick, K.E., Dogbo, D.O. nd Anno, A.P. (2010). Low intensity tpping systems pplied to clone PR 107 of Heve brsiliensis (Muell. Arg.): results of 21 yers of exploittion in south-estern Cote d Ivoire. Africn Journl of Plnt Science 4: 145-153. Trore, M.S., Dirrssoub, M., Okom, K.M., Dick, K.E., Soumhin, E.F., Coulibly, L.F. nd Obouyeb, S. (2011). Long-term effect of different nnul frequencies of ethylene stimultion on rubber productivity of clone GT1 of Heve brsiliensis (Muell. Arg.) in south est of Cote d Ivoire. Agriculture nd Biology Journl of North Americ 2: 1251-1260. Vijykumr, K.R., Gohet, E., Thoms, K.U., Xiodi, W., Sumrmdji, Rodrigo, L., Do Kim Thnh, Sopchoke, P., Krunichmy, K.S.T.K. nd Mohd Akbr, S. (2009). Specil communiction: Revised interntionl nottion for ltex hrvest technology. Journl of Rubber Reserch 12:103-115. (Published in July 2012) 1507