Water-efficient rice performances under drought stress conditions

Abstract

<abstract> <p>The use of varieties that are able to adapt well to extreme environments is one strategy to overcome the challenges of decreasing production in sub-optimal land. Indonesian tropical rice varieties (Jatiluhur, IPB 9G, IPB 3S, Hipa 19, Mentik Wangi, Ciherang, Inpari 17, and Mekongga) have been tested and established as water-used-efficient varieties in an optimal environment. However, to date, these varieties have not been examined in the suboptimal area, in particular, drought stress conditions. Therefore, this study aimed to evaluate the adaptation response of production, morphological, and physiological character of several water-efficient rice varieties under drought stress in the field. The study was designed in a split-plot with two factors and 4 replications, where the first factor (main plot) was drought stress stages i.e. vegetative (Dv), reproductive (Dr), generative (Dg), and control (Dc). The second factor was rice varieties, consisting of eight varieties, i.e., Jatiluhur, IPB 3S, IPB 9G, Hipa 19, Mentik Wangi, Ciherang, Inpari 17, and Mekongga. The experiment was conducted from May to December 2018 in Muneng Kidul Village, Probolinggo Regency, East Java Province. The experimental variables were morphology, production, leaf scrolling score during drought stress, drought sensitivity index, water use efficiency, physiology and root anatomy. The result showed that upland rice varieties were more tolerant to drought stress and had a higher water use efficiency than lowland rice varieties. This shows that Jatiluhur and IPB 9G which are indicated to be adaptive to drought stress, and have the ability to regulate water use more efficiently when drought stress occurs. Therefore, water use efficiency could be used as selection characters under drought conditions in rice particularly tropical upland rice. Moreover, morphological characters, i.e., grain yiled per plot, weight of pithy grain, weight of shoot biomass and weight of roots could be the selection characters to predict drought tolerant tropical rice. According to physiological characters, photosynthesis rate, transpiration rate, proline content, malondialdehyde content, leaf water potential and leaf greenness could be used as a selection tool to predict water use efficient genotypes in rice. However, further studies are needed to understand the complex mechanisms of water use efficiency by combining various approaches.</p> </abstract>

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

“…The plant height, root length, root volume, leaf number and productive tillers number were not significantly different among genotype treatments in the generative phase. Drought stress in the generative phase did not affect differences in plant height because plant height growth occurred in the vegetative phase (Darmadi et al 2021). Root organs are no different because each rice plant will maintain water content by increasing water absorption in the soil.…”

“…Water is important in metabolic processes affecting rice crop growth and development. The response of rice plants exposed to drought stress at morphological stages includes leaf rolling and reduced leaf area (Darmadi et al 2021), reduction in the number of stomata, thus reducing transpiration rate (Kartika et al 2020), disruption of growth, panicle initiation, flowering and decreased yields (Gaballah et al 2021), and a significant decrease in the rate of photosynthesis at all growth stages (Zhu et al 2020).…”

Suppression of cuticular wax biosynthesis mediated by rice LOV KELCH REPEAT PROTEIN 2 supports a negative role in drought stress tolerance

“…However, different rice varieties have different requirements for water during cultivation and different abilities to adapt to water‐limited conditions. For instance, upland rice varieties with high water‐use efficiency are better adapted to drought stress than lowland varieties (Darmadi et al, 2021). Some factors that contribute to these differences in drought tolerance have been identified; for example, genetic variation at the locus 9‐cis‐epoxycarotenoid dioxygenase ( Nced , Os12g043520), encoding a key rate‐limiting enzyme in the ABA biosynthetic pathway.…”

“…Second, the chaperone activity of OsGI enhances OsLKP2 protein stability and helps alleviating wax biosynthesis under drought conditions. Rice, which is primarily grown in paddy fields, is one of the most drought-sensitive crop plants, requiring large amounts of water for survival (Darmadi et al, 2021). However, different rice varieties have different requirements for water during cultivation and different abilities to adapt to water-limited conditions.…”

Application of selection index for rice mutant screening under a drought stress condition imposed at reproductive growth phase

“…The response of rice plants to drought stress is dependent on the level and phase of rice growth (Moonmoon and Islam 2017). Rice plants are most sensitive to drought at the reproductive phase, as reported by many researchers (Zulfqar et al 2016;Zhang et al 2018;Darmadi et al 2021), which is 20 days before to 10 days after flowering (Kumar 2011). Drought stress in the flowering phase caused a reduction in pollen count per stigma, pollen viability, and pollen germination rate (Gang-Shun et al 2018).…”