BIODIVERSITAS ISSN: 1412-033X Volume 21, Number 1, January 2020 E-ISSN: 2085-4722 Pages: 170-178 DOI: 10.13057/biodiv/d210122 Selection of drought-tolerant local rice cultivars from East Nusa Tenggara, Indonesia during vegetative stage YUSTINA CAROLINA FEBRIANTI SALSINHA 1 , DIDIK INDRADEWA 2 , YEKTI ASIH PURWESTRI 1,3 , DIAH RACHMAWATI 1,♥ 1 Department of Tropical Biology, Faculty of Biology, Universitas Gadjah Mada. Jl. Teknika Selatan, Sekip Utara, Sleman 55281, Yogyakarta, Indonesia Tel./fax.: +62 274-564305, ♥ email: drachmawati@ugm.ac.id, yustina.c.f@mail.ugm.ac.id 2 Department of Agronomy, Faculty of Agriculture, Universitas Gadjah Mada. Jl. Flora, Bulaksumur, Sleman 55281, Yogyakarta, Indonesia 3 Research Center for Biotechnology, Universitas Gadjah Mada. Jl. Teknika Utara, Barek, Sleman 55281, Yogyakarta, Indonesia Manuscript received: 2 September 2019. Revision accepted: 19 December 2019. Abstract. Salsinha Y C F, Indradewa D, Purwestri Y A, Rachmawati D. 2020. Selection of drought-tolerant local rice cultivars from East Nusa Tenggara during vegetative stage. Biodiversitas 21: 170-178. East Nusa Tenggara (NTT), with the predominance of dry climate, has the potential of the plant with high tolerance to drought. This research was conducted to select drought-tolerant rice cultivars. There were eight NTT-rice cultivars tested: Pak morin (P1), Mapan (P2), Pak Mutin (P3), Gogo Fatuhao (P4), Seratus-malam Boawae (P5), Padi-Putih Kuatnana (P6), Padi-Putih Maumere (P7) and Gogo Sikka (P8) with 2 control cultivars tested: Ciherang (drought- susceptible) and IR-64 (drought tolerant). The treatment included were 100% FC (control), 50% FC (moderate) and 25% FC (severe drought) during vegetative stage. The morphological analysis of plant (plant height, number of leaves and tillers and root architecture) showed cultivars P1, P5 and P6 possess the best characteristics for tolerating drought. The physiological analysis (plant photosynthetic rate, stomatal conductance, intercellular CO2-concentration, and transpiration rate) showed cultivar P5 and P6 possess the best characteristics for tolerating drought. The high levels of chlorophyll and carotenoid contents during drought conditions were observed in P5, P6, and P7 cultivars. Based on the relative water content, membrane stability index and proline levels, highest-resistance cultivar was P5 and P7 while the cultivar with high sensitivity to drought stress was P3. Based on the morphophysiological characteristics, it can be concluded that P5, P6, and P7 cultivar have the potential as drought-tolerant rice. Keywords: Drought tolerance, East Nusa Tenggara, field capacity, local rice, morphophysiology INTRODUCTION Climate change has detrimental effects on plants, especially in terms of water supply for their productivity and development (Yang et al. 2016). According to Taiz and Zeiger (2002), water stress conditions are physiological phenomena that cause deviations in the physiological functions and photosynthesis of plants as well as development and growth that has irreversible effects. To increase crop productivity in water stress conditions, it requires efforts to improve plant adaptation to abiotic stress in sub-optimal land (Singh et al. 2017; Mishra et al. 2019). Based on Meteorological, Climatological, and Geophysical Agencies (BMKG), most of the East Nusa Tenggara (NTT) region is consisted of several islands including Timor, Sumba, Flores, Alor, Rote and several other islands with diverse geographical conditions and dominated by the dry climate. From 2001 to 2010 NTT had a relatively low mean rainfall of 0-12 mm in the dry month (May-October) and 50-300 mm in the wet month (November-April) (Hosang et al. 2016). To increase food production in the NTT region, agricultural business is carried out through the development of drought-tolerant upland rice. East Nusa Tenggara region has many cultivars of local upland rice germplasm of about 21 upland rice lines that are cultivated through traditional techniques. Based on the evaluation of the Indonesian Center for Agricultural Biotechnology and Genetic Resources (BB-Biogen) Bogor, it is known that the NTT region has 91 accessions of food plants from 19 districts with 61 accessions of local rice plants spread in 11 districts in NTT (Hosang et al. 2016). Morphophysiologically, plants in drought conditions have decreased germination index, plant height, and biomass. Meanwhile, physiological and biochemical effects lead to reduced levels of chlorophyll, stomatal conductance, water potential, relative cell water content, and increased ABA levels that lead to reduced activity in photosystems I and II (Pandey and Shukla, 2015). In this condition, there is an increase in electronic leakage (EL) of the cell which shows the damage to cell membranes due to oxidative stress. This is related to water limitations or decreased relative water content in vegetative plants which are exposed to drought (Yang et al. 2016). Drought-tolerant rice plants are characterized by their ability to carry out adaptation and tolerance strategies in the form of adjustment of water osmotic potential and relative water content (RWC) of leaves, and also morphological and anatomical adaptations in the form of changes in plant organ structure and biochemical adaptation through activation of oxidative defense mechanisms (Swapna and Shylaraj 2017). Chlorophyll and carotenoid levels are also important characters related to the photosynthetic activity (Pandey and Shukla 2015).