Tolerant Rice Varieties Research Articles

Growth Response and Yield of Saline Tolerant Rice Varieties to Bio-fertilizer Application at Central Java North Coastal Saline Paddy Field

Extension of rice production to coastal area of some islands in Indonesia is subjectd to problems that include: high salinity, poor soil fertility and limited number of available saline tolerant varieties. A field experiment was carried out to study the growth response and yield of several saline tolerant rice varieties to bio-fertilizer application at northern coastal area paddy field of Pemalang, Central Java, Indonesia. Four rice varieties that consisted of saline tolerant varieties Inpari Unsoed 79 Agritan, Inpari 34 Salin, and Banyuasin, and one saline intolerant variety Ciherang, were grown and treated with foliar application of commercial bio-fertilizers Bio-P60, Herbafarm and Biofarm which are known to contain active microorganisms. These rice varieties and bio-fertilizers were arranged in Randomized Complete Blocked Design with three replicates. Rice crop management were carried out following recommendation of locale rice management practice. The results demonstrated that BioP60 and Biofarm have greater effect on leaf chlorophyll content as compared to Herbafarm. The lowest percentage of empty grains per panicle was found on Biofarm application (19.6%). No significant diference was observed on the effect of bio-fertilizers on other growth variables and yield. Growth performance and yield variation were observed among the four rice varieties when grown on saline paddy field (EC of 0.65 dS/m, 6.7 pH, 5.37 cmol/kg exchangeable-Na). Ciherang and Inpari Unsoed 79 Agritan demonstrated greater grain weight per effective plot and greater grain weight per hectare. No interaction effect between bio-fertilizer application and varieties was observed on all growth variables and yield of the rice.

Morphology changes of rice root nucleus under iron stress

Understanding the response of the Root Apical Meristem (RAM) region under environmental stress is a long-standing issue in plant biology. Our previous study successfully gave new evidence in the epigenetic level that there is a heterochromatinization, especially in the proximal meristem region in rice under environmental stresses (high iron and salinity). These changes are suspected to be responsible for the reduction of the growth rate of RAM. On this study, we used sensitive (Ciherang), moderate (Nipponbare) and tolerant (Mentong and Siam Arjuna) rice varieties to see the meristematic cell response under high iron content environment. For the methodology, we use the nucleus size as the indicator for cell phase. Normal meristematic cells are dominant in the interphase stage (spread to G0, S, and G1 phase). However, our observation and quantitative analysis showed that iron stress reduced the S, G0, and cell cycle phase and pushed the cell to form G0-like phase. There is no significant difference between tolerant and sensitive rice varieties response, this proves that this response is a general mechanism in abiotic stresses.

Selecting Traits for Drought Tolerance Screening in Rice

Drought is one of major constrains for rice production in Indonesia. Development of drought tolerant rice variety is believed as an efficien and effective strategy to face the challange. Nevertheless, drought is a complex trait thus many approach had been implemented in the selection of drought tolerant rice genotypes. This study aimed to search traits correlated with drought tolerance in rice plant. Two screening methods, i.e. seedling box and mini pot methods was conducted into 60 rice genotypes. The experiments were conducted during dry season 2016. The results showed that based on % recovery, TIL24 had the highest (82.5 %) while number of green leaves had strong positive correlation with root length, root number in zone 1 (horizontal), 2 (medium), and 3 (vertical), total root number, leaf rolling, and plant recovery. Nevertheless, proportion of root in zone 3 negatively correlated with shoot length, green leaf number, root number in zone 1 and 2, total root number, and plant recovery. It seem that proportion of vertical root compensate with other traits in developing drought tolerance, while number of green leaf under stress and root number in zone 2 correlated more with traits supporting drought tolerant in rice.

Identification of gene action on rice tolerance to low temperature stress

The development of low temperature tolerant rice varieties is needed to increase national rice productivity. Crosses and selection are the stages of the activity of developing low temperature tolerant plants. The effectiveness of selection depends very much on the action of the genes that control the selection character. Epistatic gene action will inhibit the progress of selection on self-pollinating crops such as rice. The purpose of this study was to estimate the gene action of the character of rice growth at low temperature stresses, and predict whether the growth character was controlled by the action of additive genes or by the action of epistasis genes. The research was conducted from July 2017-March 2018 at Brastagi Experimental Farm, Karo District, altitude 1340 meters above sea level with average temperature of 19 °C. The genetic material used was 191 F2 plants from the crossing of Situbagendit x Red Sigambiri and each 10 parents. The results showed that the character of plant height, panicle exsertion, age of flowering, and production had a middle value that varied with heritability values from low to high. The action of duplicate epistasis additive genes occurs in the character of generative phase plant height and flowering age while the character of plant height in germination phase, panicle exsertion and production is governed by the action of complementary epistasis genes. The characters observed have a pattern of distribution that is continuous and controlled by many genes.

Promising upland rice lines as new shading tolerant varieties with good grain quality

The utilization of coconut plantation land to increase rice planting area is a potential effort to maintain food sustainability in Indonesia. The development of shading tolerant rice varieties has been undertaken through plant breeding programs. Preliminary yield trial of upland rice genotypes under coconut plantation with 50% light intensity have been carried out in the village of Cilincing, Tegalbulued District, Sukabumi in the WS 2017. The genotype consists of 36 rice lines 4 check varieties, i.e Inpago 8, Limboto, Situpatenggang, and Jatiluhur. The result showed that the height of the lines ranged from 70.8 cm - 111.1 cm and the number of productive tillers were between 3 - 11.9 tillers. The line B15341-1B-TB-29 showed the earliest flowering time of 83 days after sowing (DAS). The panicle length of rice genotypes ranged from 29.4 cm - 21.8 cm and the average weight of 1000 grains of the line was 25.7 g. The ranges of filled grain per panicle of the lines were 47-157 grains. B14908C-MR-1-25-1-3 had the highest amount of the number of filled grain per panicle. Amylose levels of those genotypes were in the range of 17-22% and the rice texture was sticky to medium. The shape and size of the rice were long to medium. There were six promising rice, namely B14981B-TGB-4, B15344B-TB-30, B15175C-TGB-39, B15209B-MR-17-1, B14908C-MR-1-25-1-3, and B14192E-MR-33 that have the potential to be released as new shade-tolerant varieties.

Iron toxicity-induced physiological and metabolite profile variations among tolerant and sensitive rice varieties

ABSTRACTIron toxicity stress causes physiological and metabolic changes in rice and other plants. To date, there is little information about the metabolite profile of rice under Fe toxicity conditions. In fact, metabolite has a contribution to the physiological condition of plants. Plant metabolomics is a study of low-molecular weight metabolites in plants under certain conditions. The objective of the research was to investigate physiological and metabolic changes in rice under Fe toxicity stress. Two-week-old seedlings of four rice varieties with various Fe toxicity tolerance levels were stressed hydroponically with 400 ppm FeSO4.7H2O for 10 d. Numerous physiological characters were observed and untargeted metabolomic analysis was carried out using gas chromatography-mass spectrophotometry (GC-MS). The results showed Fe toxicity induced physiological and metabolite variation in rice. By comparing the metabolites synthesized in Fe toxicity-stressed plants with control plants, it showed that elaidic acid, linoleic acid, and linolenic acid could be as metabolite marker candidates for rice response to Fe toxicity stress. When plants exposed to Fe toxicity stress, elaidic acid increased, whereas linoleic- and linolenic acid decreased. The alteration of fatty acid composition in the root and shoot suggests the alteration of metabolites is one of the tolerance strategies of rice to Fe toxicity stress. This finding offers an insight about the tolerance strategies of rice under Fe toxicity stress related to the maintenance process of the cell membranes during this stress. The genes underlying biosynthesis of the fatty acid could be a target of future research on responsible genes for Fe toxicity tolerance in rice.

Redox homeostasis in the growth zone of the rice leaf plays a key role in cold tolerance.

We analysed the cellular and molecular changes in the leaf growth zone of tolerant and sensitive rice varieties in response to suboptimal temperatures. Cold reduced the final leaf length by 35% and 51% in tolerant and sensitive varieties, respectively. Tolerant lines exhibited a smaller reduction of the leaf elongation rate and greater compensation by an increased duration of leaf growth. Kinematic analysis showed that cold reduced cell production in the meristem and the expansion rate in the elongation zone, but the latter was compensated for by a doubling of the duration of cell expansion. We performed iTRAQ proteome analysis on proliferating and expanding parts of the leaf growth zone. We identified 559 and 542 proteins, of which 163 and 210 were differentially expressed between zones, and 96 and 68 between treatments, in the tolerant and sensitive lines, respectively. The categories protein biosynthesis and redox homeostasis were significantly overrepresented in the up-regulated proteins. We therefore measured redox metabolites and enzyme activities in the leaf growth zone, demonstrating that tolerance of rice lines to suboptimal temperatures correlates with the ability to up-regulate enzymatic antioxidants in the meristem and non-enzymatic antioxidants in the elongation zone.

Impact of saline intrusion and adaptation options on rice- and fish-farming households in the Mekong Delta of Vietnam

Saline intrusion is threatening rice- and fish-farming households in the Mekong Delta of Vietnam. This study was conducted, based on interviews with 390 rice- and fish-farming households in An Giang, Can Tho, and Soc Trang—upstream, midstream, and downstream provinces, respectively—in the Mekong Delta, Vietnam. The results revealed that saltwater intensively intruded inland during the dry season and seriously affected rice- and fish-farming households. Not only the productivity of rice and fish was affected, but also household income, and the quality of natural resources and environment deteriorated. The fish-farming households faced the most serious effects and had fewer adaptation options compared to households undertaking farming with rice and integrated rice- and fish-farming. Households in all groups have developed adaptation options following the increasing degree of salinity, including: (1) changing their agricultural activity calendar, (2) using tolerant rice varieties and fish species, (3) changing cropping patterns and farming practices, (4) applying integrated production models, and (5) diversifying non-farming activities.

Evaluating producer preferences and information processing strategies for drought risk management tools in Bangladesh

We use stated preference data to study farmers’ preferences for two alternative strategies to manage drought risks in Bangladesh. A choice experiment on drought tolerant rice varieties and weather index insurance was administered to 2306 farmers. Two overarching preference classes or meso-groups were identified using an equality constrained latent class model, each containing various patterns of attribute non-attendance. Our analysis finds that farmers rely on information processing strategies to simplify risk management tool decisions to mitigate drought risk. Differences in the use of farm inputs, and access to savings mechanisms, both formal and informal, are shown to affect decision making.

Assessing trait contribution and mapping novel QTL for salinity tolerance using the Bangladeshi rice landrace Capsule

BackgroundSalinity is one of the most widespread abiotic stresses affecting rice productivity worldwide. The purpose of this study was to establish the relative importance of different traits associated with salinity tolerance in rice and to identify new quantitative trait loci (QTL) conferring tolerance to salinity at seedling stage. A total of 231 F2:3 plants derived from a cross between a sensitive variety BRRI dhan29 (BR29 hereafter) and Capsule, a salt tolerant Bangladeshi indica landrace, were evaluated under salt stress in a phytotron.ResultsOut of the 231 F2 plants, 47 highly tolerant and 47 most sensitive lines were selected, representing the two extreme tails of the phenotypic distribution. These 94 plants were genotyped for 105 simple sequence repeat (SSR) and insertion/deletion (InDel) markers. A genetic linkage map spanning approximately 1442.9 cM of the 12 linkage groups with an average marker distance of 13.7 cM was constructed. QTL were identified on the long arm of chromosome 1 for Na+ concentration, K+ concentration, Na+-K+ ratio and survival; chromosome 3 for Na+ concentration, survival and overall phenotypic evaluation using the Standard Evaluation system (SES); and chromosome 5 for SES. A total of 6 pairwise epistatic interactions were also detected between QTL-linked and QTL-unlinked regions. Graphical genotyping indicated an association between the phenotypes of the extreme families and their QTL genotypes. Path coefficient analysis revealed that Na+ concentration, survival, Na+-K+ ratio and the overall phenotypic performance (SES score) are the major traits associated with salinity tolerance of Capsule.ConclusionsCapsule provides an alternative source of salinity tolerance aside from Pokkali and Nona Bokra, the two Indian salt tolerant landraces traditionally used for breeding salt tolerant rice varieties. Pyramiding the new QTL identified in this study with previously discovered loci, such as Saltol, will facilitate breeding varieties that are highly tolerant of salt stress.

Screening Gogo Rice Local Aceh Cultivars Drought Tolerant Under Polyetilene Glycol 6000

Efforts for increasing rice production nationally, it is necessary to increase the productivity of a land. Utilization of marginal lands like drought land potential to increase rice production nationally. One effort to utilize marginal land like dry land is the use of high-yielding drought tolerant varieties. Until now high-yielding drought tolerant varieties still relatively rare. For this reason, it is necessary to create high-yielding drought tolerant varieties from plant breeding program. One of the standard programs in plant breeding to create high-yielding drought tolerant varieties is provision of genetic material as parental. Local varieties gogo rice Drought-tolerant potential to be used as parental in the plant breeding program to create of high-yielding drought tolerant rice varieties. For this reason, it is necessary to test drought tolerance of local rice cultivars. The study used 10 cultivars exploration results in East Aceh Regency namely Gameso, Sibengkok, Ramos Gunung, Sidol, Sigedul, Rias Kuning, Rias putih, Sibontok, Serumu, and Sileso. Drought tolerance testing using PEG solution (Polyethylene Glycol) 6000 156. 75 g / liter of H2O which is equivalent to the osmotic potential of -3 BAR and aquades as control (0 BAR) an germination stage and early vegetative stage. The results of the study show that 10 cultivars tested in the germination stage, 6 cultivars were selected as drought tolerant cultivars. Furthermore, 6 cultivars tested in the early vegetative stage showed the ability to recover at day 35 and then at day 42 showed no symptoms of drought. 6 drought tolerant cultivars are Gameso, Ramos Gunung, Sigedul, Rias Kuning, Sibontok, and Sileso.

Evaluasi Kemudahan Transfer Marka SSR Padi Untuk Menganalisis Keragaman Genetik Famili Poaceae Toleran Kekeringan

ABSTRACT Anticipating climate change and its impacts on crop production, it requires the development of adaptive rice varieties that respond to drought stress and minimize the damage while keeps growing and maintaining yield. The aim of this study was to evaluate the transferability of rice simple sequence repeat (SSR) markers to Poaceae family and analyze the genetic diversity among 16 accessions of Poaceae family (12 genera and 14 species) using 41 rice SSR markers. The result revealed that the transferability of rice SSR markers was varied. High amplification produced in rice group (>70%) and low amplification in grass group (<30%) with an average of 35.2%. A total of 128 cross-species alleles were identified with an average of 3 alleles/locus. The value of gene diversity ranged from 0.15 to 0.83 with an average of 0.53 and the value of Polymorphic Information Content (PIC) ranged from 0.14 to 0.80 with an average of 0.46. The results of phylogenetic analysis determined two clusters at similarity coefficient of 0.72. The first cluster consisted of 14 accessions from Poaceae family (12 genera and 14 species) while the second cluster consisted of two cultivated rice varieties (Inpari 30 and Situ Bagendit). The genetic relatedness data revealed from this study could be used as basic information for parental selection. The 14 accessions of Poaceae family have a potential for drought tolerant donor and separated clearly from cultivated rice varieties (Inpari 30 and Situ Bagendit) for recipient parents in spike-stalk injection method (SIM) to develop drought tolerant rice varieties. Keywords: Cross amplification, Drought tolerant, Inpari 30, Situ Bagendit

Drought Tolerant Rice Variety Sahbhagi dhan Option in North Chotanagpur Region of Jharkhand for Sustainability and towards Food Security: A Hope for Rain Fed Areas

Drought Tolerant Rice Variety Sahbhagi dhan Option in North Chotanagpur Region of Jharkhand for Sustainability and towards Food Security: A Hope for Rain Fed Areas

Parameters and Secondary Characters for Selection of Tolerance Rice Varieties under Stagnant Flooding Condition

Determination of secondary characters during stagnant flooding (SF) is considered important for breeders as the selection criteria in developing SF rice tolerant varieties. Aims of this study were to find agronomical variation and to determine secondary traits that were related to SF tolerance among the rice varieties. Experiment was conducted at Indonesian Center for Rice Research in 2015. Ten rice genotypes were grown in RCBD with three replications under normal and gradual flooding conditions. Agronomic data were gathered and analysed using combined ANOVA, correlation, multiple linear regressions and genetic variability. Results showed that 92.3% variance of stress tolerance index (STI) were presented from a linear model involving weight of 100-grains, panicle length, stem diameter, intensity of leaf green color and stem length. Stem length, intensity of leaf green color, and panicle length had broad genetic variability and high heritability these characters were important criteria when selecting the traits under flowing stress. Number of productive tillers was correlated with grain yield under SF and highly heritable, thus considered as one of determining characters for stagnant flooding tolerance. Based on STIStd, Ciherang and INPARI 30 showed more adaptive performance, while IR 42 had the least when grown under 50-60 cm stagnant water depth.

Functional screening of genes from a halophyte wild rice relative Porteresia coarctata in Arabidopsis model identifies candidate genes involved in salt tolerance

High soil salinity is one of the most important environmental stressors, and is an increasing concern under the alarmingly global climate uncertainties. Salinity affects the growth and productivity of food crops, including rice, and ultimately threatens global food security and sustainability. Conventional breeding efforts to develop salt tolerant rice varieties utilizing its primary gene pool have resulted in limited success due to the mutligenic inheritance of salt tolerance traits. On the other hand, Porteresia coarctata, the only halophyte wild rice, offers tremendous opportunities to improve salt tolerance in rice. However, reports on the characterization of its rich genetic resources are scanty. The present study was undertaken to functionally identify salt responsive genes of P. coarctata in Arabidopsis model using a cDNA overexpression (COX) strategy. COX-mediated hunting of transgenic Arabidopsis expressing a cDNA library of P. coarctata under control of a maize ubiquitin promoter identified 12 candidates that were involved in salt tolerance for seed germination, and seedling and reproductive growth. Of these, four genes coding for a metallothionein, a ribosomal protein, a photosystem II 10 kDa protein, and a ferredoxin:thioredoxin reductase conferred enhanced salt tolerance phenotypes, such as better root and shoot growth, and tissue tolerance by maintaining higher relative water content, membrane stability and protecting cells from reactive oxygen species. These genes could be ideal candidates for improving salt tolerance in rice; however, further studies are needed to ascertain their direct functional relevance in salt tolerance mechanisms.

Verifikasi Lokus Aluminum Tolerance (Alt) pada Tiga Populasi BC3F1 Padi

Most of marginal lands in Indonesia are in the form of acid dry land with low available P and high Al concentrations. Development of tolerant rice varieties to P deficiency and Al toxicity is one way to increase rice production. This study aimed to select BC3F1-Pup1+Alt genotypes from three crosses based on foreground and background markers. This research was conducted at the Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development, Bogor, from August to December 2015. The materials used were 300 genotypes of BC3F1 Dodokan-Pup1+Alt, BC3F1 Situ Bagendit-Pup1+Alt, BC3F1 Batur-Pup1+Alt, and the parents. The research included selection in modified Yoshida’s nutrient solutions (0.5 ppm P dan 60 ppm Al) followed by foreground selection and background selection. Selection using Yoshida’s nutrient solution resulted in 150 genotypes with longer root than the recipient parent in each of the BC3F1 populations. Selection with foreground markers using markers RM1361 and RM12031 produced 85 genotypes of BC3F1 Dodokan-Pup1+Alt (56.6%), 105 genotypes of BC3F1 Situ Bagendit-Pup1+Alt (70%), and 77 genotypes of BC3F1 Batur-Pup1+Alt (51.33%). Selection using background markers revealed that genotype number 116 (BC3F1 Dodokan-Pup1+Alt), number 2 (BC3F1 Situ Bagendit-Pup1+Alt), and number 129 (BC3F1 Batur-Pup1+Alt) were the best genotypes with percentage of parent recovery of 95%, 90%, and 90.5%, respectively. These three genotypes were verified to have Alt loci and had the largest genetic proportion of restoring parents. Keywords: Alt, background markers, foreground markers, Pup1, upland rice

Comparative transcriptome profiling of low light tolerant and sensitive rice varieties induced by low light stress at active tillering stage

Low light intensity is a great limitation for grain yield and quality in rice. However, yield is not significantly reduced in low light tolerant rice varieties. The work therefore planned for comparative transcriptome profiling under low light stress to decipher the genes involved and molecular mechanism of low light tolerance in rice. At active tillering stage, 50% low light exposure for 1 day, 3 days and 5 days were given to Swarnaprabha (low light tolerant) and IR8 (low light sensitive) rice varieties. Illumina (HiSeq) platform was used for transcriptome sequencing. A total of 6,652 and 12,042 genes were differentially expressed due to low light intensity in Swarnaprabha and IR8, respectively as compared to control. CAB, LRP, SBPase, MT15, TF PCL1 and Photosystem I & II complex related gene expressions were mostly increased in Swarnaprabha upon longer duration of low light exposure which was not found in IR8 as compared to control. Their expressions were validated by qRT-PCR. Overall study suggested that the maintenance of grain yield in the tolerant variety under low light might be results of accelerated expression of the genes which enable the plant to keep the photosynthetic processes moving at the same pace even under low light.

Phytotoxicity of imazapyr+imazapic on tolerant rice varieties Guri INTA CL and IRGA 424 RI

ABSTRACT Rice varieties from the Clearfield® system may present different tolerance levels to imidazolinone herbicides in function of application rate. The objective of this research was to evaluate the phytotoxicity of different rates of the formulated mixture of the herbicides imazapyr+imazapic applied on two tolerant irrigated rice varieties. The experiment was carried out in 2015/16 and 2016/17 growing seasons. A randomized complete block design was used in a factorial 2x6 with five replications. The factor A was composed by the tolerant rice varieties Guri INTA CL and IRGA 424 RI, and the factor B by rates of the formulated mixture of the herbicides imazapyr+imazapic (525+175 g a.i. kg-1) of 0, 140, 210, 280, 350, and 420 g c.p. ha-1. In the first growing season, it was observed maximum phytotoxicity of 8.5% while in the second the highest percentage was 13%. The number of stems m-2, plant height, shoot dry matter, SPAD index, and grain yield were not influenced (p≥0.05) by herbicide rates. The application of the formulated mixture of the herbicides imazapyr+imazapic causes low initial phytotoxicity to the tolerant rice varieties Guri INTA CL and IRGA 424 RI up to three times the recommended rate, not influencing their grain yield.

Screening of Rice Apoplast Associated Endophytic Bacterial Isolates for Moisture Stress Tolerance and Plant Growth Promoting Traits

Investigations were made to identify, screen and characterize rice apoplastic fluid endophytic bacterial strains for osmotic stress tolerance and plant growth promoting activity. These bacterial strains were identified phylogentically as Bacillus subtilis TSAC5, Bacillus subtilis TSAA2, Bacillus sp. R2AA10, Bacillus cereus R2AA7, Bacillus marisflavi TSAC7, Cupriavidus alkaliphilus TSAC1, Delftia sp. TSAC2, Janibacter melonis R2AA1, Microbacterium oleivorans R2AA6, Kocuria rosea R2AA5, Pseudomonas aeruginosa NAAI3 and Sphingobium yanoikuyae R2AI1. Of these 12 strains, eight were obtained from drought tolerant rice varieties such as Anna R4 and IR DRT 64 and four from normal rice variety CO51. These endophytes exhibited varied level of osmotic stress tolerance created using different concentrations of PEG 6000 (-1.5, -3.0, -4.0, -4.5, -5.0 and -5.5 MPa) under in vitro conditions in liquid and solid medium. Among the 12 strains, Cupriavidus alkaliphilus TSAC1, Delftia sp. TSAC2, Bacillus marisflavi TSAC7, Janibacter melonis R2AA1, Kocuria rosea R2AA5, Pseudomonas aeruginosa NAAI3 and Sphingobium yanoikuyae R2AI1 showed moisture stress tolerance up to -5.5 MPa. Further increase in moisture stress of -6.0 MPa inhibited growth of 12 tested strains. These strains also exhibited Indole acetic acid (IAA), gibberellic acid (GA3) and extracellular polysaccharide (EPS) production and also showed ACC deaminase (ACCD) activity. Maximum extracellular proline production was found in Bacillus marisflavi TSAC7 under both normal and water stressed conditions. Higher IAA productivity was registered in Janibacter melonis R2AA1 followed by Cupriavidus alkaliphilus TSAC1 and Sphingobium yanoikuyae R2AI1 in the absence of PEG 6000. In the presence of PEG 6000 Delftia sp. TSAC2 recorded maximum IAA productivity. Bacillus subtilis TSAA2 showed greater ACC deaminase activity. EPS production was in the order of Pseudomonas aeruginosa NAAI3 followed by Sphingobium yanoikuyae R2AI1. Sphingobium yanoikuyae R2AI1 produced maximum quantity of GA3 both under normal and water stressed condition. None of the tested strains indicated insoluble phosphate, silicate and zinc solubilisation.

Marker Assisted Breeding to Develop Multiple Stress Tolerant Varieties for Flood and Drought Prone Areas

BackgroundClimate extremes such as drought and flood have become major constraints to the sustainable rice crop productivity in rainfed environments. Availability of suitable climate-resilient varieties could help farmers to reduce the grain yield losses resulting from the climatic extremities. The present study was undertaken with an aim to develop high-yielding drought and submergence tolerant rice varieties using marker assisted introgression of qDTY1.1, qDTY2.1, qDTY3.1 and Sub1. Performance of near isogenic lines (NILs) developed in the background of Swarna was evaluated across 60 multi-locations trials (MLTs). The selected promising lines from MLTs were nominated and evaluated in national trials across 18 locations in India and 6 locations in Nepal.ResultsGrain yield advantage of the NILs with qDTY1.1 + qDTY2.1 + qDTY3.1 + Sub1 and qDTY2.1 + qDTY3.1 + Sub1 ranged from 76 to 2479 kg ha− 1 and 396 to 2376 kg ha− 1 under non-stress (NS) respectively and 292 to 1118 kg ha− 1 and 284 to 2086 kg ha− 1 under reproductive drought stress (RS), respectively. The NIL, IR96322–34-223-B-1-1-1-1 having qDTY1.1 + qDTY2.1 + qDTY3.1 + Sub1 has been released as variety CR dhan 801 in India. IR 96321–1447-651-B-1-1-2 having qDTY1.1 + qDTY3.1 + Sub 1 and IR 94391–131–358-19-B-1-1-1 having qDTY3.1 + Sub1 have been released as varieties Bahuguni dhan-1′ and ‘Bahuguni dhan-2’ respectively in Nepal. Background recovery of 94%, 93% and 98% was observed for IR 96322–34-223-B-1-1-1-1, IR 96321–1447-651-B-1-1-2 and IR 94391–131–358-19-B-1-1-1 respectively on 6 K SNP Infinium chip.ConclusionThe drought and submergence tolerant rice varieties with pyramided multiple QTLs can ensure 0.2 to 1.7 t ha− 1 under reproductive stage drought stress and 0.1 to 1.0 t ha− 1 under submergence conditions with no yield penalty under non-stress to farmers irrespective of occurrence of drought and/or flood in the same or different seasons.