Root Distribution and Its Impacts on the Drought Tolerance Capacity of Hybrid Rice in the Sichuan Basin Area of China

Drought is one of the major factors limiting rice yield worldwide. A total of 46 hybrid rice varieties were chosen to investigate their root distribution and their response to drought. A field experiment was carried out in a dry shed building to evaluate the drought tolerance capacity of hybrid rice varieties on the basis of CTIRDE (complex tolerance index of rice under drought environment) values. Next, the experiment was conducted in a specially designed pot system and seed bags to analyze the root distribution and activity of antioxidant enzymes in different rice varieties. Moreover, the DEEPER ROOTING 1 (DRO1) gene was sequenced to elucidate its role in the root distribution of typical rice varieties. On the basis of CTIRDE values, the 46 hybrid rice varieties were classified as tolerant (CTIRDE ≥ 0.75), semi-tolerant (0.75 > CTIRDE > 0.65), or sensitive (CTIRDE ≤ 0.65) to drought stress. The tolerant varieties (Chuanguyou208 and Deyou4727) displayed a significantly larger length, had higher number and weight of roots in the 30–50 cm soil layer, and exhibited a significantly higher activity of Superoxide dismutase (SOD) and Peroxidase (POD) enzymes in roots during the drought stress period. The DRO1 gene sequencing results revealed that the tolerant and sensitive varieties exhibited a single-nucleotide polymorphism (SNP) in the 3-exon region, and the tolerant varieties (Chuanguyou208 and Deyou4727) exhibited a larger root growth angle with the horizontal axis, hence developing a deeper root system as compared with the other two group varieties. A significant correlation was found not only between the DRO1 gene and root distribution but also between DRO1 and the activity of SOD and POD enzymes. Conclusively, as a key feature, a deep root system enabled tolerant rice varieties (Chuanguyou208 and Deyou4727) to avoid drought stress by absorbing more water stored in deep soil layers. The root distribution, activity of POD and SOD enzymes in roots, and DRO1 gene can be used to screen tolerant rice varieties that can survive better under drought stress during the seedling stage of rice growth.

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Evaluation of the tolerance of Thai indigenous upland rice germplasm to early drought stress using multiple selection criteria

Plant Genetic Resources ◽

10.1017/s1479262115000428 ◽

2015 ◽

Vol 15 (2) ◽

pp. 109-118 ◽

Cited By ~ 1

Author(s):

Kittichai Narenoot ◽

Tidarat Monkham ◽

Sompong Chankaew ◽

Patcharin Songsri ◽

Wattana Pattanagul ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Selection Criteria ◽

Upland Rice ◽

Block Design ◽

Rice Variety ◽

Tolerance Index ◽

Rice Varieties ◽

Rice Germplasm ◽

Drought Tolerance Index

Drought remains the most important factor that affects rice productivity, especially in rainfed areas, worldwide. Upland rice is one of the crop choices of farmers in the rainfed environment. Although upland rice varieties require less water than lowland rice varieties, yields often remain limited by drought, particularly in the period of early growth. The aims of this study were to identify the traits related to early drought tolerance in upland rice varieties, and to identify the potential sources of germplasm for early drought tolerance. A total of sixty upland rice varieties were planted in a factorial experiment with a randomized complete block design with 3 replications in the rainy seasons of 2011 and 2012, under greenhouse conditions. Based on the drought tolerance index (DTI), the test germplasm sources were classified into three groups: (i) susceptible; (ii) moderately tolerant; (iii) tolerant to drought stress. Grain yield (GY) showed significant negative correlations with the leaf rolling score (r= − 0.623, P< 0.01), the leaf death score (LDS) (r= − 0.673, P< 0.01) and the recovery score (r= − 0.746, P< 0.01), while leaf dry matter (r= 0.698, P< 0.01) and leaf water potential (r= 0.618, P< 0.01) had significant positive correlations with GY. These findings indicate the suitability of the DTI as the selection criteria for early drought tolerance in a breeding programme. In addition, the upland rice germplasm accessions KKU-ULR011, KKU-ULR012, KKU-ULR125, KKU-ULR199 and KKU-ULR292 were identified as having high levels of stability for drought tolerance in both the 2011 and 2012 experiments, suggesting their potential for further use for rice variety improvement for drought tolerance.

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Towards the consideration of soil-root resistances in root water uptake models with macroscopic representations of hydraulic root architecture

10.5194/egusphere-egu21-8151 ◽

2021 ◽

Author(s):

Jan Vanderborght ◽

Valentin Couvreur ◽

Felicien Meunier ◽

Andrea Schnepf ◽

Harry Vereecken ◽

...

Keyword(s):

Root System ◽

Soil Water ◽

Water Uptake ◽

Root Distribution ◽

Root Architecture ◽

Soil Layer ◽

Root Water Uptake ◽

Hydraulic Architecture ◽

Root Segments ◽

Soil Volume

Plant water uptake from soil is an important component of terrestrial water cycle with strong links to the carbon cycle and the land surface energy budget. To simulate the relation between soil water content, root distribution, and root water uptake, models should represent the hydraulics of the soil-root system and describe the flow from the soil towards root segments and within the 3D root system architecture according to hydraulic principles. We have recently demonstrated how macroscopic relations that describe the lumped water uptake by all root segments in a certain soil volume, e.g. in a thin horizontal soil layer in which soil water potentials are uniform, can be derived from the hydraulic properties of the 3D root architecture. The flow equations within the root system can be scaled up exactly and the total root water uptake from a soil volume depends on only two macroscopic characteristics of the root system: the root system conductance, Krs, and the uptake distribution from the soil when soil water potentials in the soil are uniform, SUF. When a simple root hydraulic architecture was assumed, these two characteristics were sufficient to describe root water uptake from profiles with a non-uniform water distribution. This simplification gave accurate results when root characteristics were calculated directly from the root hydraulic architecture. In a next step, we investigate how the resistance to flow in the soil surrounding the root can be considered in a macroscopic root water uptake model. We specifically investigate whether the macroscopic representation of the flow in the root architecture, which predicts an effective xylem water potential at a certain soil depth, can be coupled with a model that describes the transfer from the soil to the root using a simplified representation of the root distribution in a certain soil layer, i.e. assuming a uniform root distribution.

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Discrimination of drought tolerance in a worldwide collection of safflower (Carthamus tinctorius L.) genotypes based on selection indices

Acta agriculturae Slovenica ◽

10.14720/aas.2021.117.1.1656 ◽

2021 ◽

Vol 117 (1) ◽

pp. 1

Author(s):

Pooran GOLKAR ◽

Esmaeil HAMZEH ◽

Seyed Ali Mohammad MIRMOHAMMADY MAIBODY

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Geometric Mean ◽

Resistance Index ◽

Stability Index ◽

Carthamus Tinctorius ◽

Tolerance Index ◽

Breeding Programs ◽

Drought Tolerance Indices ◽

Tolerance Indices

Improvement of elite safflower genotypes for drought-tolerance is hampered by a deficiency of effective selection criteria. The present study evaluated 100 genotypes of safflower in terms of their drought tolerance over a period of three years (2016–2018) under both non-stress and drought-stress conditions. The eight drought-tolerance indices of tolerance index (TOL), mean productivity (MP), geometric mean productivity (GMP), stress susceptibility index (SSI), stress tolerance index (STI), yield stability index (YSI), drought resistance index (DI), and harmonic mean (HARM) were calculated based on seed yield under drought (Ys) and non-drought (Yp) conditions. A high genetic variation was found in drought tolerance among the genotypes studied. The MP, GMP, and STI indices were able to discriminate between tolerant and drought-sensitive genotypes. Plots of the first and second principal components identified drought-tolerant genotypes averaged over the three study years. Cluster analysis divided the genotypes into three distinct groups using the drought tolerance indices. Ultimately, eight genotypes (namely, G3, G11, G13, G24, G33, G47, G58, and G61) from different origins were detected as more tolerant to drought stress suitable for use in safflower breeding programs in drought-affected areas. The most tolerant and susceptible genotypes could be exploited to produce mapping populations for drought tolerance breeding programs in safflower.

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Characteristics of the root system in two Brazilian upland rice varieties which exhibit contrasting behavior towards drought tolerance

Semina Ciências Agrárias ◽

10.5433/1679-0359.2020v41n2p421 ◽

2020 ◽

Vol 41 (2) ◽

pp. 421-434

Author(s):

Leandro Martins Ferreira ◽

◽

Cristiana Maia de Oliveira ◽

Leilson Novaes Arruda ◽

Renan Pinto Braga ◽

...

Keyword(s):

Drought Tolerance ◽

Root System ◽

Upland Rice ◽

Rice Varieties

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Assessing Genetic Diversity of Rice Varieties under Drought Stress Conditions

Notulae Scientia Biologicae ◽

10.15835/nsb315618 ◽

2011 ◽

Vol 3 (1) ◽

pp. 114-123 ◽

Cited By ~ 11

Author(s):

Mina ABARSHAHR ◽

Babak RABIEI ◽

Habibollah SAMIZADEH LAHIGI

Keyword(s):

Drought Stress ◽

Grain Yield ◽

Stress Tolerance ◽

Geometric Mean ◽

Minimum Variance ◽

Stress Conditions ◽

Productivity Index ◽

Stress Index ◽

Tolerance Index ◽

Rice Varieties

In order to compare different rice genotypes grown under drought stress conditions a field experiment was conducted. In this study thirty different genotypes of native, breeded and upland cultivars were evaluated. Analysis of variance showed significant differences among genotypes in respect of all vegetative and morphological traits. Genotypes were devided into three groups by cluster analysis based on all studied traits with minimum variance method (Wards Method). The total average indicates significant differences among groups in respect of all morphological and physiological characteristics. In addition, eight drought stress tolerance indices including: sensitivity to stress index (SSI), drought response index (DRI), relative drought index (RDI), tolerance index (TOL), mean productivity index (MP), stress tolerance index (STI), geometric mean productivity index (GMP) and harmonic mean index (HM) were calculated according to their grain yield under drought stress and normal conditions. In general, results of this experimnet revealed that, among rice cultivars Domsephid, Deylamany, Hasansaraei, Sadri, Anbarboo and Domsiah had the highest sensitivity referring to drought stress and produced the lowest grain yield. Also, genotypes of IR24 (breeded of IRRI), Nemat, Sephidroud, Kadoos and Bejar (breeded of Iran) and Vandana, upland cultivar (originally from India) had the highest tolerance to drought stress and produced the highest grain yield. In conclusion, it was suggested that, these cultivars are suitable for drought stress conditions and are appropriate for hybridization with the aim of increasing drought tolerance.

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Dissection of Maize Drought Tolerance at the Flowering Stage Using Ge-Nome-Wide Association Study

10.21203/rs.3.rs-1187674/v1 ◽

2021 ◽

Author(s):

Siffat Ullah Khan ◽

Yanxiao Zheng ◽

Zaid Chachar ◽

Xuhuan Zhang ◽

Guyi Zhou ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Candidate Genes ◽

Pyridoxal Phosphate ◽

Association Studies ◽

26S Proteasome ◽

Regulatory Subunit ◽

Tolerance Index ◽

Genome Wide Association Studies ◽

Flowering Stage

Abstract Drought is one of the most critical environmental factors constraining corn production especially when it occurs during flowering, resulting in serious yield losses. In this study, anthesis to silk interval (ASI), plant height (PH), and ear biomass at the silking date (EBM) of 279 inbred lines were evaluated under water-stress (WS) and well-water (WW) field conditions for three consecutive years. Averagely, ASI was extended by 25.96%, ear biomass was decreased by 17.54%, and the PH was reduced by 12.47% under drought stress conditions. Genome wide association studies (GWAS) were carried out using phenotypic values under WS, WW and drought-tolerance index (WS-WW or WS/WW) applying mixed linear model controlling both population structure and relative kinship. Totally, 71, 159, and 21 SNPs were significantly (P < 10-5) associated with ASI, ear biomass, and PH, respectively. Candidate genes encoding ARABIDILLO 1 protein, glycoprotein, Tic22-like and Zinc finger family protein for ASI, and 26S proteasome non-ATPase regulatory subunit-9 for EBM, were identified under both WW and WS conditions. Pyridoxal phosphate transferase was associated with EBM under drought stress treatment in consecutive two years. Furthermore, most candidate genes were evidenced to be drought responsive in the association panel. Meanwhile, the favourable/drought tolerance haplotypes were identified based on haplotype analysis. These findings provide insights into the genetic basis of drought tolerance at the flowering stage especially for the female inflorescence development and will facilitate high drought tolerant maize breeding.

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Root System Distribution Influences Substrate Moisture Measurements in Containerized Ornamental Tree Species

HortTechnology ◽

10.21273/horttech.23.6.754 ◽

2013 ◽

Vol 23 (6) ◽

pp. 754-759 ◽

Cited By ~ 1

Author(s):

Taryn L. Bauerle ◽

William L. Bauerle ◽

Marc Goebel ◽

David M. Barnard

Keyword(s):

Root System ◽

Tree Species ◽

Root Distribution ◽

Fine Root ◽

Soil Layer ◽

Specific Root Length ◽

Root Systems ◽

Moisture Sensor ◽

Substrate Moisture ◽

Moisture Variability

Substrate moisture sensors offer an affordable monitoring system for containerized tree production. However, root system distribution can vary greatly among species within ornamental container production systems, resulting in variation within substrate readings among sensors within a container. The aim of this study was to examine the relationship of substrate moisture sensor readings in six ornamental trees to their root distribution patterns within a container. Following root anatomical analysis, tree root systems were dissected by root order as a means to separate fine (uptake) roots and coarse (transport) roots. Substrate moisture variability was measured through the deployment of 12 substrate moisture sensors per container. Of the tree species studied, we found the following two patterns of root distribution: a shallow, “conical-shaped,” root system, with the broadest portion of the root system in the shallow soil layer, and a more evenly distributed “cylindrical-shaped” root system. Root system distribution type influenced substrate moisture reading variability. Conical root systems had lower substrate moisture variability and high fine root variability, whereas the opposite was true for cylindrical root systems—most likely due to the larger, coarse woody mass of roots. We were unable to find any correlations between fine root morphological features including root diameter, length, or surface area and substrate moisture variability. However, higher specific root length was associated with higher substrate moisture variability. Classifying a tree’s root system by its growth and distribution within a container can account for variation in substrate moisture readings and help inform future decisions on sensor placement within containerized systems.

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Combining Ability for Drought Tolerance in Upland Rice Varieties at Reproductive Stage

Journal of Agricultural Science ◽

10.5539/jas.v9n3p138 ◽

2017 ◽

Vol 9 (3) ◽

pp. 138 ◽

Cited By ~ 2

Author(s):

G. M. Malemba ◽

F. M. Nzuve ◽

J. M. Kimani ◽

M. F. Olubayo ◽

J. W. Muthomi

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Combining Ability ◽

Upland Rice ◽

Block Design ◽

Field Evaluation ◽

Rice Production ◽

Rice Varieties ◽

F2 Population ◽

Drought Conditions

Rice is an important food crop for human population ranking second among the mostly consumed cereal grains worldwide. Upland rice production is greatly constrained by drought stress resulting from rainfall variation patterns. Cultivation of drought tolerant varieties is considered the best option for drought management in rice production. The already released upland rice varieties are drought susceptible and have poor grain attributes hence, the aim of this study was to determine the combining ability for drought tolerance in upland rice. Four upland NERICA and two upland rice varieties were selected as parents for generating F1s crosses following 6 × 6 complete diallel. The generated 30 F1 crosses were advanced to F2 population for field evaluation. The F2 progenies together with six parents were planted in two sites; KALRO-Mwea Center Farm and Kirogo research Farm following a randomized complete block design in three replications. Drought stress was initiated 45 days after sowing after which data was collected on drought and agronomic parameters. The study revealed large genetic variations among the genotypes used. Both GCA and SCA were significant indicating the importance of both additive and non additive gene action in the expression of studied traits. In this study NERICA 2 and NERICA 15 were identified as good combiners for drought tolerance and grain yield under drought conditions. The single crosses namely; NERICA 15 × NERICA 2, NERICA 1 × NERICA 15, NERICA 11 × NERICA 15 and NERICA 2 × NERICA 15 were identified as superior for improving yield under drought conditions.

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Brassica Rapa SR45a Regulates Drought Tolerance via the Alternative Splicing of Target Genes

Genes ◽

10.3390/genes11020182 ◽

2020 ◽

Vol 11 (2) ◽

pp. 182 ◽

Cited By ~ 2

Author(s):

Muthusamy ◽

Yoon ◽

Kim ◽

Jeong ◽

Lee

Keyword(s):

Alternative Splicing ◽

Drought Stress ◽

Stress Response ◽

Drought Tolerance ◽

Brassica Rapa ◽

Target Genes ◽

Tolerance Index ◽

Dependent Manner ◽

Loss Of Function ◽

Splicing Patterns

The emerging evidence has shown that plant serine/arginine-rich (SR) proteins play a crucial role in abiotic stress responses by regulating the alternative splicing (AS) of key genes. Recently, we have shown that drought stress enhances the expression of SR45a (also known as SR-like 3) in Brassica rapa. Herein, we unraveled the hitherto unknown functions of BrSR45a in drought stress response by comparing the phenotypes, chlorophyll a fluorescence and splicing patterns of the drought-responsive genes of Arabidopsis BrSR45a overexpressors (OEs), homozygous mutants (SALK_052345), and controls (Col-0). Overexpression and loss of function did not result in aberrant phenotypes; however, the overexpression of BrSR45a was positively correlated with drought tolerance and the stress recovery rate in an expression-dependent manner. Moreover, OEs showed a higher drought tolerance index during seed germination (38.16%) than the control lines. Additionally, the overexpression of BrSR45a induced the expression of the drought stress-inducible genes RD29A, NCED3, and DREB2A under normal conditions. To further illustrate the molecular linkages between BrSR45a and drought tolerance, we investigated the AS patterns of key drought-tolerance and BrSR45a interacting genes in OEs, mutants, and controls under both normal and drought conditions. The splicing patterns of DCP5, RD29A, GOLS1, AKR, U2AF, and SDR were different between overexpressors and mutants under normal conditions. Furthermore, drought stress altered the splicing patterns of NCED2, SQE, UPF1, U4/U6-U5 tri-snRNP-associated protein, and UPF1 between OEs and mutants, indicating that both overexpression and loss of function differently influenced the splicing patterns of target genes. This study revealed that BrSR45a regulates the drought stress response via the alternative splicing of target genes in a concentration-dependent manner.

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Drought tolerance related to root morphology and stomatal structure of the 12 seasonal rice varieties (Oryza sativa L.) under artificial drought conditions

Ministry of Science and Technology, Vietnam ◽

10.31276/vjst.63(2).27-32 ◽

2021 ◽

Vol 63 (1) ◽

pp. 27-32

Author(s):

Ngoc Son Tran ◽

◽

Cong Thanh Vo ◽

Lan Huong Vo ◽

Thi Yen Nhi Dang ◽

...

Keyword(s):

Oryza Sativa L ◽

Block Design ◽

Water Flux ◽

Soil Layer ◽

Root Diameter ◽

Deep Soil ◽

Deep Roots ◽

Rice Varieties ◽

Drought Tolerant ◽

Drought Conditions

Drought-tolerant rice varieties are one of the best choices to avoid the effects of drought. A Randomized Complete Block Design (RCBD) with three replications was used for the experiment. 12 seasonal rice were tested under artificial drought conditions. The criteria were assessed through the morphology, root anatomical structure, and stomatal leaves that were suitable for the drought environment. The results showed that 3 seasonal rice were well adapted to this condition.Sophinh had the smallest density and area of stomata (529.3 stomata/mm2 and 88.6 μm2 respectively), they helped reduce water loss. Xuong ga do had the highest ratio of deep roots 58.7% which could increase the ability to take water from the deep soil layer. Bang nau had a thick root diameter of 876.3 μm and a stele root area of 54.4x103 μm2 containing a high number and more areas of late metaxylems (5.6 and 12x103 μm2 respectively). These factors helped increase water flux from root to shoot. Correlation among the density of stomata, number of roots, and the number of late metaxylem were negative while correlation among diameter of roots, number of late metaxylem, and total areas of late metaxylem were positive. These results were useful for developing drought-tolerant rice varieties.

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