Aerobic rice genotypes displayed greater adaptation to water-limited cultivation and tolerance to polyethyleneglycol-6000 induced stress

Abstract

Water scarcity and drought have seriously threatened traditional rice cultivation practices in several parts of the world including India. In the present investigation, experiments were conducted to see if the water-efficient aerobic rice genotypes developed at UAS, Bangalore (MAS25, MAS26 and MAS109) and IRRI, Philippines (MASARB25 and MASARB868), are endowed with drought tolerance or not. A set of these aerobic and five lowland high-yielding (HKR47 and PAU201, Taraori Basmati, Pusa1121 and Pusa1460) indica rice genotypes were evaluated for: (i) yield and yield components under submerged and aerobic conditions in field, (ii) root morphology and biomass under aerobic conditions in pots in the nethouse, (iii) PEG-6000 (0, −1, −2 and −3 bar) induced drought stress at vegetative stage using a hydroponic culture system and (iv) polymorphism for three SSR markers associated with drought resistance traits. Under submerged conditions, the yield of aerobic rice genotypes declined by 13.4-20.1 % whereas under aerobic conditions the yield of lowland indica/Basmati rice varieties declined by 23-27 %. Under water-limited conditions in pots, aerobic rice genotypes had 54-73.8 % greater root length and 18-60 % higher fresh root biomass compared to lowland indica rice varieties. Notably, root length of MASARB25 was 35 % shorter than MAS25 whereas fresh and dry root biomass of MASARB25 was 10 % and 64 % greater than MAS25. The lowland indica were more sensitive to PEG-stress with a score of 5.9-7.6 for Basmati and 6.1-6.7 for non-aromatic indica rice varieties, than the aerobic rice genotypes (score 2.7-3.3). A set of three microsatellite DNA markers (RM212, RM302 and RM3825) located on chromosome 1 which has been shown to be associated with drought resistance was investigated in the present study. Two of these markers (RM212 and RM302) amplified a specific allele in all the aerobic rice genotypes which were absent in lowland indica rice genotypes.

Agronomic performances of aromatic and non-aromatic M1 rice under drought stress

“…The two-weekold rice seedlings were grown hydroponically (Wang et al 2013), and the source of nutrient was from Hoagland solution (Hoagland and Arnon 1950). The solution was replaced once a week and the water level was adjusted on the alternate days (Sandhu et al 2012). Besides, pH of solution was also monitored every two days.…”

Bridging the Rice Yield Gaps under Drought: QTLs, Genes, and their Use in Breeding Programs

“…Secondary traits are important indicators of different physiological, molecular, and developmental changes involved in drought resistance, tolerance, and adaptation mechanisms. The effectiveness of selection for secondary traits such as root thickness, penetration ability and depth, greater hydraulic conductance, xylem thickness and osmotic adjustment, leaf area [85,86], leaf water potential [87], fresh and dry root weight, root volume, relative water content [26], root length [25], photosynthesis [88], early flowering, and harvest index [89] in rice to improve yield under drought is yet to be successfully demonstrated. This also goes for the anthesis-silking interval in maize [90], greenness in sorghum [91], and water-use efficiency in wheat [92].…”

Assessment of Seedling Growth of Deepwater Rice Genotypes under Osmotic Stress Condition

“…The lowest node length was found for Birpala and the highest for Lalkhama (Table 4). Sandhu et al [18] also reported that lowland indica were more sensitive to PEG stress by reducing seedling and root length. Table 4: Mean performance of different genotypes/varieties for different plant characters.…”