PENGARUH CEKAMAN KURANG AIR TERHADAP BEBERAPA KARAKTER FISIOLOGIS TANAMAN NILAM (Pogostemon cablin Benth)

ABSTRAK Nilam (Pogostemon cablin Benth) merupakan salah satu tanaman penghasil minyak atsiri yang dikenal dengan minyak nilam (patchouli oil). Salah satu kendala dalam pengembangan tanaman nilam adalah peka terhadap kekurangan air. Perubahan iklim cenderung menyebabkan lebih sering terjadi kekeringan di sejumlah wilayah termasuk Indonesia sehingga dalam pengembangan tanaman nilam diperlukan varietas toleran terhadap cekaman kurang air. Terdapat tiga varietas unggul nilam (Tapaktuan, Sidikalang, dan Lhokseumawe) dengan produksi minyak (290-375 kg/ha) dengan kadar patchouli alkohol 32–33%. Penelitian bertujuan untuk mengevaluasi respon fisiologis 4 varietas/aksesi tanaman nilam terhadap cekaman kurang air. Penelitian dilaksanakan di rumah kaca di Bogor pada tahun 2012. Penelitian menggunakan RAK faktorial dengan tiga ulangan. Faktor  pertama  4  varietas/aksesi  nilam  (V)  yaitu  Sidikalang, Lhokseumawe, Tapaktuan, dan Bio-4. Faktor kedua empat interval penyiraman (W) yaitu 1, 3, 6, dan 9 hari sekali. Evaluasi pengaruh cekaman kurang air dilakukan terhadap beberapa karakter fisiologi tanaman nilam. Pengamatan dilakukan antara lain terhadap peubah kadar lengas tanah, konduktivitas stomata (Gs), laju transpirasi (Tr), kandungan air nisbi (KAN), potensial air daun (PAD) dan kandungan prolin daun. Hasil penelitian menunjukkan bahwa terjadi penurunan kadar lengas tanah, konduktivitas stomata, laju transpirasi, dan KAN pada semua varietas, sedangkan PAD dan kadar prolin meningkat seiring dengan semakin lamanya interval penyiraman. Kadar prolin tertinggi pada interval 9 hari sekali pada varietas Sidikalang. Tidak terdapat perbedaan respon varietas/aksesi nilam yang diuji. Kata kunci: Pogostemon cablin Benth, cekaman kurang air, karakter fisiologis. ABSTRACT Patchouli (Pogostemon cablin Benth) is one of plant that produces patchouli oil call patchouli oil. However, patchouli is susceptible to drought. The effect of global warming which changes rainfall pattern caused droughts in several regions including Indonesia. Therefore, it is important to find patchouli variety which is relatively tolerant to drought. Tapaktuan, Sidikalang, dan Lhokseumawe are three varieties of patchouli which produce high essential oil (290-375 kg/ha) with high patchouli alcohol content (32–33%). The objective of this research was to evaluate the physiological responses of four varieties/clone of patchouli to drought. The experiment was conducted at greenhouse at Cimanggu, Bogor from February to July 2012. The research was designed in randomized factorial block design (RBD) with three replications. The first factor was four varieties/clone of patchouli (V) Sidikalang, Lhokseumawe, Tapaktuan, and Bio-4. The second factor was four watering intervals (W) every 1, 3, 6 and 9 days of watering. Parameters evaluated were physiological characteristics, soil moisture content, stomatal conductance, transpiration rate (Tr), leaf water potential, relative water content, and proline content of leaf. The results showed that soil moisture content, stomatal conductivity, transpiration rate and relative water content decreased, while leaf water potential and proline levels increased along with the increase of watering intervals. The highest proline level was at interval of nine days watering treatment on Sidikalang varieties. However, all varieties/clone have not different responses to water deficit. Key words: Pogostemon  cablin  Benth,water  deficit,  physiological characteristics