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. Thess 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

Short Communication: Evaluation of F6 generation of upland rice promising lines for drought stress tolerance

“…Different genetic responses in each line cause differences in the level of damage caused by leaf rolling, thought to be related to the water content in the foliage (Opalofia et al 2018). Drought stress causes changes in chlorophyll pigment, leaf rolling causes a decrease in the rate of photosynthesis (Salsinha et al 2021), the ability of the transpiration rate to keep the potential of leaf water remains high in times of water shortage (Afrianingsih et al 2018). Resistant genotypes can avoid water stress and increase the ability of roots to absorb water from the soil (Gaballah et al 2021).…”

“…The response of rice plants to drought stress was preceded by the physiological response in the form of a reduction of transpiration rate to reduce water loss by closing stomata, reducing stomata number, and decreasing leaf surface area by leaf rolling (Salsinha et al 2021). However, the most critical component that determines the survival of the rice reproductive organs is related to the supply of assimilation.…”

“…ABA phytohormone plays a role in opening the stomata's closure to reduce water loss during transpiration. Drought stress causes loss of cell turgor pressure and stomatal closure so that the carbon assimilation rate decreases, resulting in a decrease in plant biomass (Salsinha et al 2021). One gene that controls drought-resistant traits in rice plants is the WRKY gene (Sahebi et al 2018).…”