SummaryWater stress affect many physiological andbiochemical processes of oil palm. A series ofexperiments were conducted to characterize thewater stress-induced changes in physiologicalrespons of oil palm to water stress, in glass housecondition. The experiment consisted of (1)permanent leaf wilting point measured based onsoil water content, leaf water content, specificleaf area and leaf water potential . Plants wereconducted by termination of watering to theplants, and control plants were maintained wellwatered during 0,3,6,9,12,15,18 and 21 days ofMK356 and MK365 clones. Experiment (2)effect of water stress on changes of leaf waterpotential, protein bands pattern, proline,glycine-betaine, osmotical sugar, and abcisicacid (ABA) of MK356 and MK365 clones.Water stress was induced by termination ofwatering to the plants and maintained wellwatered during 0, 7,14, and 18 days.Experiment (3) changes of protein bands patternby total protein and electrophoresis SDS-PAGEand SDS-PAGE 2D protein. of H2(D10DxD8D)x(L9TxL2T); H12 (D8D Self) x(L9T x L2T). H3 and H9 (BJ028D x BJ2117P)hybrids. H2 and H12, H3 and H9 potentiallytolerant and untolerant to water stress,respectively. The results showed that permanentwilting point reached in 18 days of water stress.Water stress caused the decreased soil watercontent, leaf water potential, leaf water content,relative leaf water content , and relative leafarea of two clones. Water potential, leaf watecontent dan relative leaf water content ofMK365 decrease faster compare with MK356.Soil water content sharply decrease after 6 hoursand in 18 days of water stress leaf waterpotential value < - 2.55 Mpa. Proline, glycine-betaine and glucose content were affect by waterstress. Interaction among water stress and cloneswere significantly appear in stachiose content.Leaf water potential values decrease, whereasproline, ABA and glycine-betaine contentsincrease during water stress especially inMK356. Generally showed that ABA content inMK356 higher than MK 365. The differencesresponses of MK356 with MK 365 obtained fromprolin,xylose and ABA content. Induction of newprotein pI 4.7-36 kDa, pI5.3-34 kDa, pI 4.6-32kDa and pI 5.3-36 kDa obtained from hybridspotentially tolerant to water strees, none inuntolerant hybrids.RingkasanCekaman kekeringan mempengaruhiproses fisiologis dan biokimia tanaman kelapasawit. Serangkaian percobaan bertujuan untukmengkarakterisasi perubahan fisiologis tanamankelapa sawit terhadap cekaman kekeringan,dalam kondisi rumah kaca telah dilakukan.Percobaan terdiri atas (1) penetapan titik layupermanen, berdasarkan perubahan potensial airdaun, kadar air daun, kadar air daun relatif, danluas daun relatif dengan perlakuan tanpa dandengan penyiraman selama 0, 3, 6, 9, 12, 15, 18dan 21 hari. Percobaan (2) penetapan perubahankadar prolin, glisin-betain, gula-gula osmotikaldan asam absisik (ABA), terhadap cekamankekeringan. Perlakuan adalah tanpa dan denganpenyiraman selama 0, 7, 14, dan 18 hari.Percobaan (3) analisis perubahan pola pita proteindaun hibrida H2 (D10DxD8D)x(L9TxL2T); H12(D8D Self) x (L9T x L2T). H3 dan H9 (BJ028Dx BJ2117P) terhadap cekaman kekeringan dengantotal protein, dan pola pita protein dengan SDSPAGE dan SDS-PAGE 2D. H2 dan H12 serta H3dan H9 masing-masing berpotensi toleran danpeka terhadap cekaman kekeringan. Hasil yangdiperoleh menunjukkan bahwa titik layupermanen dicapai pada hari ke 18 setelah dibericekaman kekeringan. Cekaman kekeringanmenurunkan kadar air tanah media tumbuh,potensial air daun, kadar air daun, kadar air daunrelatif, dan luas daun relatif untuk kedua klon.Potensial air daun, kadar air daun dan kadar airdaun relatif klon MK365 menurun lebih cepatdibandingkan dengan klon MK356. Kadar airtanah menurun tajam setelah 6 hari dibericekaman air dan potensial air daun mencapai<-2.55 MPa pada 18 hari setelah diberi cekaman.Cekaman kekeringan nyata berpengaruh terhadapkadar prolin, glisin betain dan glukosa. Interaksiantar lama cekaman kekeringan dan perbedaanklon diperoleh pada perubahan gula stahiosa.Tampak bahwa semakin menurun nilai potensialair daun menyebabkan kadar prolin semakinmeningkat. Hal yang sebaliknya terjadi terhadapkadar glisin-betain yang mengalami penurunanterutama untuk klon MK356. Kadar ABAMK356 dan MK365 meningkat sejalan dengansemakin lama diberi cekaman. Secara umumtampak bahwa kadar ABA pada MK356 lebihtinggi dibandingkan dengan MK 365. Perbedaanrespons klon MK356 dengan MK 365 terjadipada kadar prolin, gula silosa dan ABA.Hibridaberpotensi toleran memberikan respon terhadapcekaman kekeringan dengan menginduksi proteinbaru pI 4,7-36 kDa, pI5,3-34 kDa, pI 4,6-32 kDadan pI 5,3- 36 kDa, sedangkan pada hibridayang berpotensi peka protein tersebut tidakditemukan