Physiological and oxidative defense responses of local rice cultivars “Nusa Tenggara Timur-Indonesia” during vegetative drought stress

Abstract

Drought is the main abiotic factor that reduces productivity of crops such as rice in the suboptimum area. This study aimed to identify drought-tolerance of local rice cultivars “Nusa Tenggara Timur-Indonesia” through their oxidative defense mechanism. In this study, 17 local rice cultivars and two control cultivars (Ciherang and Situ Bagendit) were used. Drought was imposed by using three levels of FTSW: FTSW 1 (control), 0.5 (moderate drought), and 0.2 (severe drought) during the vegetative stage. Growth parameters such as plant height, number of tillers, number of leaves, and total dry weight were higher in Boawae 100 Malam, Hare Tora, and Padi Putih Kuatnana than other cultivars. The analysis of relative water content, chlorophyll, carotenoid, and proline content also indicated that the Boawae 100 Malam, Gogo Sikka, and Hare Tora cultivar showed a higher result compared to control and other cultivars. These characters tend to correlate with the higher activity of antioxidant enzymes in Boawae 100 Malam and Gogo Sikka, when exposed to severe drought conditions. Based on principal component analysis of the physiological changes and enzymatic antioxidant activity, the Gogo Sikka, Boawae 100 Malam, and Hare Tora cultivars were classified as rice cultivars with higher drought tolerance.