Abstract. Nio SA, Mereh RJ, Ludong DPM. 2021. Short communication: Physiological response to drought in North Sulawesi (Indonesia) local rice (Oryza sativa) cultivars at the tissue level in hydroponic culture. Biodiversitas 22: 58-64. Water availability influenced the metabolism processes in the plants and this condition could change water balance in the cells as well as restricting the growth and production of crops. This study aimed to evaluate the effect of in vitro polyethylene glycol (PEG) 8000-induced water deficit on the relative water content and chlorophylls (total, a, and b) concentration as physiological response in leaf segments of North Sulawesi (Indonesia) local rice cultivars (cvs. Superwin, Ombong, Burungan, and Temo). The rice leaves were cut into 1 cm x 1 cm segments and were treated under both control (0 MPa) and water deficit (-0.25 and -0.5 MPa) using PEG 8000 as osmoticum. The experiment was factorial completely randomized block design with 4 sampling times (0, 4, 8, and 12 hours) and three replicates. Interaction of water deficit duration and PEG 8000 treatment resulted in a significant difference in leaf relative water content. The leaf relative water content at PEG -0.5 MPa after 8 and 12 hours of treatments was lower than at control (PEG 0 MPa) when the treatment commenced (0 hour). The concentration of chlorophylls (total, a, and b) were significant differences among cultivars and water deficit durations. This study showed that leaf relative water content was a potential physiological indicator of PEG 8000-induced water deficit in North Sulawesi local rice at the tissue level in hydroponic culture.

KANDUNGAN AIR PADA SEGMEN DAUN TANAMAN PADI (Oryza sativa L.) LOKAL SULAWESI UTARA SAAT KEKERINGAN YANG DIINDUKSI DENGAN POLIETILEN GLIKOL 8000 ABSTRAKPenelitian ini telah dilakukan untuk mengkaji kandungan air sebagai respon fisiologi pada segmen daun tanaman padi lokal Sulut (varietas Temo, Ombong, Burungan, dan Superwin) terhadap kekeringan yang diinduksi dengan PEG 8000 secara in vitro. Segmen daun padi dipotong-potong 1 cm x 1 cm dan diberi tiga macam perlakuan PEG 8000 (dengan potensial air/PA medium 0; -0,25; dan -0,5 MPa), dan empat waktu pengambilan sampel (0, 4, 8 dan 12 jam) dalam tiga kali ulangan. Hasil penelitian menunjukkan bahwa bahwa faktor varietas, faktor waktu perlakuan,  faktor konsentrasi PEG 8000, dan interaksi antara ketiga faktor tersebut tidak menyebabkan perbedaan kandungan air segmen daun yang nyata.Kata kunci: Cekaman kekeringan, PEG 8000, Potensial air, Segmen daun LEAF WATER CONTENT IN LEAF SEGMENTS OF NORTH SULAWESI LOCAL RICE (Oryza sativa L.)  UNDER POLYETHYLENE-GLYCOL- 8000-INDUCED DROUGHTED DROUGHTABSTRACTA study was conducted to evaluate leaf water content as one of physiological responses in leaf segments of North Sulawesi local rice (cv. Temo, Ombong, Burungan, and Superwin) under PEG 8000- induced-drought. The rice leaves were cut into 1 cm x 1 cm segments and treated withPEG 8000 solutions  (medium water potential or PA of 0; -0.25; and -0.5 MPa),four sampling times (0, 4, 8 and 12 hours) and 3 replicates. The results indicated that factors of varieties, treatment period, concentration of PEG 8000, and interaction among these factors did not result in any differences in water content of rice leaf segments.Keywords: Drought stress, PEG 8000, Water potential, Leaf segment