Promising Rice Lines Research Articles

Genetic performance, heritability, and correlation of traits in new plant type of rice lines for highland ecosystem

Rice cultivation is crucial in providing global food needs, particularly in highland areas with distinct environmental conditions. Adapting promising rice lines suitable for highland ecosystems is essential to ensure sustainable rice production in such regions. This study assesses the agronomic performance, heritability, and correlation of traits in new promising rice lines adapted to highland ecosystems. The latest promising rice lines are designed with the unique environmental conditions of highland regions in mind. This research was conducted in Buntu Barana’ Village, Tikala Sub-district, with an elevation of 858.4 m above sea level. The study was carried out in rain-fed semi-irrigated paddy fields. The research was conducted from May 2023 to January 2024. The research methodology involves testing various agronomic traits for yield production components of the new type of promising rice lines at different highland locations. The research procedures included the selection of viable seed strains, seeding, fertilization, balanced irrigation, control of plant pest organisms, harvesting, and post-harvesting. Evaluated agronomic traits encompass plant height, days to maturity, number of productive tillers, length of panicles, number of filled grains per panicle, and grain yield. Additionally, heritability analysis is performed to assess the extent to which observed trait variations are attributed to genetic factors. Research findings reveal significant variations in agronomic traits among the new type of promising rice lines. The highest grain yield is achieved in genotype UKIT102-2-056, which is 8.3 tons per hectare of paddy rice. These lines exhibit objective adaptation to the highland ecosystem, with some lines demonstrating superior performance in specific parameters, especially early maturity, namely 97 days after planting. Heritability analysis indicates that certain traits have high heritability levels, suggesting a significant role of genetic factors in controlling these traits. Furthermore, this study unveils correlation patterns among the observed agronomic traits. Significant positive and negative correlations among several traits indicate complex interrelationships among these agronomic characteristics. These findings offer further insights into the relationships between these traits and can be utilized to develop more adaptive rice lines in highland environments.

Investigating the dynamics of upland rice (Oryza sativa L.) in rainfed agroecosystems: an in-depth analysis of yield gap and strategic exploration for enhanced production

IntroductionAddressing the global demand for rice production necessitates innovative approaches to enhance upland rice yield in rainfed agroecosystems, considering the challenges posed by increasing population, limited land fertility, low productivity, and water availability.MethodsIn this study, our study investigated the impact of biochar and organic fertilizer on ten promising rice lines (G1 – G10) and two control (G11 – G12) cultivars under rainfed conditions. The experimental design used a split-plot design with four soil amendments as main plots, namely control, organic fertilizer, biochar, and biochar + organic fertilizer and 12 rice genotypes as subplot.ResultsThe absolute attainable yield gaps, differentiating organic and control (GAP1), biochar + organic and control (GAP2), and biochar and control (GAP3), ranged from 1.5 to 3.7 or increased of 91–580%, 0.8 to 3.5 (72–560%), and 0.6 to 2.58 tons/ha (58–472%), respectively. Notably, G2 + organic exhibited the highest positive absolute yield gap, ranging from 1.1 to 5.38 tons/ha, based on the yield gap matrix. Furthermore, genotype main effect plus genotype-environment interaction (GGE) biplot analysis identified G2 as the most promising rice line, displaying superior yield performance for cultivation in biochar and organic amended soils.DiscussionThese findings provide valuable insights for farmers, governments, and stakeholders, offering a roadmap to optimize rainfed areas for rice production, serving as practical guidance to enhance overall rice productivity in rainfed agroecosystems.

Development of High Yielding Rice Varieties Tolerant to Phosphorus Deficiency

Improvement of nutrient-use efficiency (NUE) in rice is important for increasing productivity. Rice varieties with tolerance to phosphorus (P) deficiency increase the productivity in P-deficient fields. Therefore, the objective of this study was to develop high yielding, P-deficiency tolerant rice varieties to enhance the NUE. High yielding and popular rice varieties (Bg300 and Bg94-1) and known P-deficiency tolerant rice varieties (H4 and At353) were used as female and male parents, respectively, in a crossing program. Single seed descent approach was used for rapid generation advancement. Bg300/At353 and Bg94-1/H4 crosses were advanced from F2 to F6 in planthouse condition under minimum fertigation for restricted growth. In F7 generation, 310 recombinant inbred lines (RIL) in both crosses were space-planted and 40 RILs were selected from each cross. Selected RILs were screened in a hydroponic system at 10 μM P level to select the best lines for P-deficiency tolerance. Multiple plant traits were used for selection and the most promising 20 rice lines were selected as the best performers under P-deficient hydroponic conditions. Marker assisted selection was carried out to confirm the presence of PSTOL1 gene. Selected rice lines were evaluated for agronomic traits and yield parameters. Ten promising rice lines were identified as high yielding lines with accepted agronomic traits.

Selection of drought-tolerant rice genotypes under cajuput (Melaleuca cajuputi subsp. cajuputi) agroforestry system

Abstract. Taryono, Supriyanta, Wulandari RA, Nurmansyah, Ambarwati E, Arsana IGKD, Aristya VE, Purba AE, Aisya AW, Alam T. 2023. Selection of drought-tolerant rice genotypes under cajuput (Melaleuca cajuputi subsp. cajuputi) agroforestry system. Biodiversitas 24: 4791-4802. Rice production can be increased by expanding rice cultivation area on agroforestry land. However, planting rice in agroforestry system, which is generally rainfed, might cause drought stress and eventually can reduce rice yields. The study aimed to select rice genotypes under drought stress conditions in a rainfed agroforestry system with cajuput or kayu putih (Melaleuca cajuputi subsp. cajuputi Powell). Ten promising rice lines and four control cultivars were grown during the dry season from March-July 2022 at the Menggoran Forest Management Resort, Playen Forest Section, Yogyakarta Forest Management, Indonesia. The observation was conducted on drought stress tolerance (sensitivity and recovery), molecular identification, and yield of rice cultivars. The results showed that G5 was the genotype with drought tolerance and had the best recovery compared to the other promising rice lines and control cultivars. The molecular identification of the 14 rice genotypes using 20 SSR markers detected 108 alleles with a PIC value of 0.707. The G5, G4, and G9 had higher yields than the control cultivars. The BLUE showed that the yield of G5, G4, and G9 were 6.59, 5.93 and 5.50 tons ha-1, respectively, while for BLUP by 6.45, 5.87 and 5.43 tons ha-1, respectively. Furthermore, there were four clusters consisting of cluster 1 (G9), cluster 2 (G7), cluster 3 (G5 and Inpago 12), and cluster 4 (Inpari 42, G6, Inpari 30 Ciherang Sub 1, Situ Bagendit, G3, G4, G10, G2, G1, and G8). The findings of this study recommend G4, G5, and G9 as promising rice lines which tolerant to drought stress under M. cajuputi agroforestry system and can be utilized in future plant breeding programs.

Molecular and phenotypic markers for pyramiding multiple traits in rice

Abstract Gene pyramiding has been developed for effective resistant genes, such as bacterial blight resistance genes. However, in this report, pyramiding for multiple traits is presented. We evaluated 28 pyramided rice lines derived from 7 hybridizations of valuable parents for high yield potential, early maturity, aroma, high grain quality, and resistance to brown planthopper using both simple-sequence repeat markers and phenotypic markers. Pyramided rice genotypes were evaluated with RM282 molecular marker linked to GW3 gene associated with grain weight, RM259 (number of panicles), RM3600 (length of panicles), RM3701 (short panicles), RM19414 (Hd3), RM7601 (Hd2), RM190, and SSIIa (waxy), IFAP and ESP (aroma), RM586 (Bph3 and Bph4), and RM8213 (Qpbh4 and Bph17(t)). Eight genotypes (i.e., #9, #15, #16, #22, #25, #26, #27, and #28) were confirmed to have desired genes associated with multiple important traits based on molecular markers and morpho-agronomic traits. A strong correlation was found between RM19414 and heading date, between specific markers for aroma and sensory test. Meanwhile, a weak correlation was found between RM259 with panicle number, RM586, and RM8213 with trichome density. As presented in this study, gene pyramiding promises a new hope to combine multiple traits in rice breeding. Promising rice lines will be incorporated in the multiple traits breeding program.

Augmented analysis for yield performance and agronomic characteristics of upland rice lines grown under coconut plantation

Establishment of shade-tolerant rice varieties aims to utilize the dry land under tree stands. A field experiment on rice yield under coconut plantation was conducted at farmer field in Calincing Tegalbuleud Sukabumi, West Java, Indonesia. The experiment involved 307 upland promising lines, 42 of which were selected in comparison to four check varieties, namely Jatiluhur, Batutugi, Limboto and Situpatenggang. The experiment was conducted according to augmented design with four replications. The analysis of variance indicated significant difference in yield per ha between blocks and no significant differences in days to flowering, plant height and number of productive tiller between blocks. Meanwhile, significant differences were observed in plant height and number of productive tillers between all check varieties. Under shade of coconut plantation, some lines could perform better and had higher performance than check varieties. Four lines ofB11957SR* 232182SI2MR2PN21, B12743MR18232PN1111, B13498D9, and B12743MR18235PN1031 had significantly higher yield compared to the check variety with the highest yield, which is Limboto. The utperforming lines can be proposed as promising rice lines for shading tolerance. However, most of the lines were proved to be underperforming for yield and its components in prevailing conditions.

Screening and detecting GS3mutant-rice lines generated by CRISPR/Cas9 technology

Screening 41 GS3 putative-edited T0 rice lines of Bac Thom 7 cultivar by PCR, obtained 38 lines carrying the gene encoding Cas9 protein. Sequencing analysis identified two lines D1 and D25, having two nucleotides T, C deleted at positions 127 and 128 as compared to the original sequence. The target mutant lines expressed a significant variation in grain size, from 0.68 to 0.97 cm in length and 0.21 to 0.27 cm in width, of which 15 lines exhibited their larger grain size (from 0.86 to 0.97 cm), and 4 lines were smaller than the control. The 1,000-grain weight ranged from 13.6 to 22.6 g. In which, ten lines showed a higher 1,000-grain weight of 19.22-22.6 g than the control of 17.9 g. This indicated that GS3gene mutation has increased grain size in Bac Thom 7 cultivar. However, there is still a need to further analyse the function of mutant lines as well as evaluate other agro-biological characteristics of these promising rice lines.

SSR MARKERS REVEALED GENETIC DIVERGENCE OF RICE BROWN PLANTHOPPER POPULATIONS MAINTAINED ON TWO SETS OF DIFFERENTIAL HOST VARIETIES

<p>Resistance screening of promising rice lines in Indonesia requires the use of brown planthopper (BPH) biotypes 1, 2, and 3. Three BPH populations have been raised as biotypes 1, 2, and 3 on differential rice host of improved varieties Pelita I-1 (no <em>Bph </em>gene), IR26 (<em>Bph1</em>), and IR42 (<em>bph2</em>), respectively. Three alternative populations have also been developed on the respective traditional varieties TN1 (no <em>Bph </em>gene), Mudgo (<em>Bph1</em>), and ASD7 (<em>bph2</em>). Although these populations displayed two virulent patterns other than biotype 1 to 3 phenotypes, they were expected to be discriminated into two virulence groups by SSR analysis. The study aimed to investigate the level of genetic variation among the six BPH populations using SSR markers and to relate it with the observed virulence patterns. Genotyping of 30 females with 29 polymorphic SSR markers revealed higher genetic parameter values in populations reared on improved varieties than those on traditional varieties. This difference was marked as two population clusters in PCoA plots corresponding to the host variety type, in contrast to the previous assumption that clustering would be based on virulence patterns. The presence of individuals with unwanted virulence allele, either resulting from contamination during the long period of rearing or lack of host adaptation period, is suspected. The result of this study indicates that the six populations are not suitable for resistance screening. Virulence selection must be performed until they attain biotype 1 to 3 phenotypes which can be genetically separated by DNA markers.</p>

Genetic Diversity Analysis and Molecular Characterization of Elite Rice Promising Lines for Yield, Blast Disease Resistance and Rice Stem Borer تحليل التنوع الوراثى والتوصيف الجزيئي لمحصول سلالات الارز المبشرة، ومقاومتها لمرض اللفحة وثاقبة ساق الارز

Developing and cultivating new promising rice lines with high yield potential and blast disease resistance is an important goal of rice breeding. The study was to evaluate some developed new elite rice lines for high yield, blast resistance, effective resistance genes to Pyricularia grisea and rice stem borer insect as well as assessment of the genetic diversity in these lines using microsatellite markers. Significant differences were found among the studied new promising lines and their parents for yield and its component traits. Promising lines; GZ11190-3-13-1-1 and GZ11190-3-13-4-1 gave the highest grain yield compared with their parents; Giza 178 and GZ6296-12-1-2-1-1 and superiority for all studied traits. Also under this study, twenty six isolates were identified as five main groups i.e., IC, ID, IF, IG and IH, but ID and IH groups were considered the most common race, Pib resistance gene was the most effective gene to blast fungus. Promising lines GZ11190-3-13-1-1 and GZ11190-3-13-4-1 proved resistance for all tested isolates under greenhouse condition and moderately resistant for stem borer insect. For genetic diversity analysis, twenty SSR markers were polymorphic amplifying a total of 102 alleles. Characterization of these markers showed high discriminating power with an average polymorphism information content (PIC) of 0.754.Major allele frequency ranged from 0.475 (RM590) to 0.923 (RM5 and RM5313), with an average of 0.705. The cluster analysis based on microsatellite SSR markers grouped 13 rice genotypes into clear separate groups and was able to reveal close genetic relationships between rice genotypes used in rice breeding program.

Virulence and SSR Diversity of Brown Planthopper (Nilaparvata lugens) Adapted on Differential Rice Host Varieties

Brown planthopper biotype 1, 2, 3 and a representative field population are required for resistance screening of promising rice lines in Indonesia, but the current biotype stocks has shown deviation in virulence patterns. The objectives of this study were to develop a set of brown planthopper populations with differential virulence and to investigate their genetic variability using SSR marker. Females originated from two field populations were selected on variety Mudgo (carries Bph1 gene) or ASD7 (bph2 gene) using honeydew excretion as the virulence parameter. Selection cycles resulted in population T, M, A, and R, which was raised and adapted on variety TN1 (carries no Bph gene), Mudgo, ASD7, and Rathu Heenathi (Bph3, Bph17), respectively. Population R was the most virulent as expected and can be used to represent a field population, but the remaining populations still showed high virulence level. AMOVA and PCoA results based on analysis with 38 SSR primer pairs revealed partial genetic separation among populations, with population R was the most genetically distant from the remaining populations. The desired virulence character of the remaining populations is expected could be achieved after further selection and prolonged adaptation on their respective hosts.

Participatory Varietal Selection for Promising Rice Lines

The purpose of rice breeding is to create varieties that are well adapted, highly productive, and acceptable to farmers. However, rice productivity is limited as a result of combined biotic stresses (pests/diseases). This study combines assessment by farmers with the evaluation by breeders with respect to promising rice lines within a range of environments. The aim is to investigate farmers’ preferences and to characterize the yield of promising rice lines, as well as their resistance to pests/diseases by consulting 120 farmers and breeders. This study used an oversite design replicated three times with thirteen promising lines and two varieties, which were all evaluated at farmers’ fields between December 2019 and May 2020. The Importance Performance Analysis was used to compare line performance and farmers’ expectations. Lines Gamapadi-2 and Gamapadi-4 had the highest acceptability scores based on the farmers’ preferences. The yield performances were evaluated using the Finlay–Wilkinson test and the genotypes were evaluated using environmental models (GGE biplot) to determine the most stable lines to be recommended for large-scale planting. The Finlay–Wilkinson and GGE biplot conclusion analyses also showed that the Gamapadi-2 and Gamapadi-4 lines exhibited high potential yield and stability, as well as indications of specific advantages. The results for both lines in all locations indicated no symptoms of brown planthoppers or bacterial leaf blight due to its absence during the field research. These lines in all age ranges at two sites showed no symptoms of leaf blast.

Stakeholder preferences on major characteristics of promising rice lines

The main purpose of plant breeding programs is to improve varieties acceptable to rural communities. Participatory crop improvement for rice lines was initiated using techniques which were designed with the purposes to strengthen the collaboration between breeders and stakeholder especially farmers to produce varieties. Before the promising rice lines released and adopted by farmers, it is necessary to study the preferences on characteristics, especially its quality, because farmers have their own criteria or considerations before adopting a new variety. A bottom-up preferences in this study is to understand the major phenotypic performance, sensory quality, and provide recommendations for improving promising rice lines (Oryza sativa L.). The respondents are farmers, extension workers, members of academic institutions, and local government officers, came from four Regencies (Banyumas, Magelang, Batang, Klaten) that representing the main rice production areas in Central Java province. The attribute data on rice characteristics showed that grain size, plant age, and lemma shape of apiculus was essentially regarded as a major factor for better performing varieties. The respondents’ preference provides recommendations for breeders to release promising rice lines GM 8 and GM 2 into commercial varieties.

The Variability of Qualitative Traits in Promising Rice Lines

Rice is one of the world’s oldest important crops. Qualitative traits can be useful for the identification of promising rice lines. In this study, seventeen advance rice lines were evaluated for qualitative traits. This assessment was carried out to analyse the variability in genotypes, based on 49 important qualitative traits of rice. Data on morphological parameters was collected from each line at suitable phase of growth to check variation. Findings were recorded according to descriptors for rice. Dendrogram was constructed which divided all the genotypes into seventeen major clusters, each subdivided into smaller sub-clusters. The pattern of cluster based on qualitative traits revealed the wide genetic variation. A high level of genetic variability based on qualitative traits was observed in this study. The genetic improvement of the rice needs the availability of genetic variability in promising lines. Significant phenotypic information and these variability has potential to develop quality rice for future breeding programs.

Performance of the agronomic traits of six advanced promising lines of red rice (oryza sativa l.) grown on the paddy field

Rice in Indonesia is still the main staple food, and every year the demand has increased. Indonesian governments have policies to reach self-sufficiency. The strategic programs to increase rice production were through breeding programs. The research was conducted on paddy fields in the village of Ranomeeto District of South Konawe. The study was carried out from October 2018 to April 2019. This study aimed to determine the differences in the agronomic traits in the aspect of vegetative and generative character from some new types of advanced red rice promising lines grown on the paddy field. The experiment was laid out based on Randomized Complete Block Design (RCBD), which consisted of six red rice lines (GS12-1, GS12-2, GS44-1, GS44-2, GS16-1, GS16-2) and one check variety (trisakti). Each treatment was repeated four times, so there were 28 experimental units. Parameters observed were plant height, leaf number, leaf area, number of tillers, panicle length, total grain number, 1000-grain weight, filled grain percentage, unfilled grain percentage and dry weight per m2 The results showed that there were differences in the agronomic traits of the promising rice lines GS12-1, GS12-2, GS44-1, GS44-2, GS16-1, GS16-2, and trisakti variety on paddy field. The new type of advanced red rice promising lines can well be adapted on paddy fields obtained in GS16-1 lines, followed GS16-2 lines and GS44-2 lines.

Source-sink Relationship and Their Influence on Yield Performance of YAU Promising Rice Lines

Fifty YAU promising rice genotypes were used to evaluate source-sink relationship and yield performance in 2017 dry season. The experiment was conducted in the experimental field of Yezin Agricultural University, Nay Pyi Taw, Myanmar. The spacing was 20 cm between row and 20 cm between plants in a randomized complete block design with three replications. The data on physiological traits, yield and yield component traits were collected and analyzed by using STAR and R program. Growth duration1 is positively and significantly correlated with the number of grains panicle-1, filled grains percentage, grain yield, panicle weight, dry weight at heading and harvesting, straw weight and LAI at harvesting, and increase of dry weight from heading to harvesting. Significant positive correlation was found between growth duration2 and decrease of LAI from heading to harvesting indicating that these traits are strongly influenced by source before heading. Significant correlations between yield and physiological and yield component traits were observed except LAI at harvesting and 1000-grain weight. Therefore, yield variation among YAU promising rice lines is more related with source size than with sink size. Decrease of LAI from heading to harvesting and dry weight at maturity exhibited positive direct effect on 1000-grain weight, filled grains percentage and grain number m-2 meaning the relative contribution of source components to the sink. The contribution of the decrease of LAI from heading to harvesting to the grain yield was much higher than that of number of grains, panicle weight and 1000-grain weight. This research finding will be useful for the plant breeder to consider the improvement of yield supporting traits in the breeding program.

Swampy rice lines for iron toxicity tolerance and yield components performance under inland swamp at Sorong, West Papua, Indonesia

Abstract. Maruapey A, Wicaksana N, Karuniawan A, Utami DW, Windarsih G. 2020. Swampy rice lines performance for iron toxicity tolerance and yield components under inland swamp at Sorong, West Papua, Indonesia. Biodiversitas 21: 5394-5402. The extensification of sub-optimal lowland farming strategy is expected to support the increase of rice production. Based on the efforts, the development of tolerant rice varieties to Fe-toxicity to be used in the swampy land area is one of the approaches for increasing rice production. Currently, promising rice lines that are tolerant to Fe-toxicity has been developed using molecular breeding approach for inland swampy area. The objective of this research was to evaluate the performance of 15 promising rice lines that have various genetic backgrounds in inland swamp in Sorong, West Papua. The field experiment was conducted during the second rice planting season (August 2018 to February 2019) to evaluate the performance of the promising rice lines to the morpho-agronomic performance under the lowland swamp conditions. The trial was laid out in a Randomized Complete Block Design (RCBD) consisting of 4 m x 5 m square plots, with 25 cm x 25 cm planting distance and 3 replications. The results revealed that most of the lines had good performances on the Fe-toxicity tolerance, based on bronzing, root length, and biomass characters. The G1 line had the best performance on yield component characters, especially the panicle length. This line also had the highest grain yield (6.15 ton.ha-1) followed by the next promising line of G7 (5.92 ton.ha-1). The genetic performance of these lines showed that they contained IRT (Iron Regulation Transporter) alleles that contributed to partitioning the Fe tolerance mechanism.

Tidal swamp tolerant rice lines: climate change adaptive varieties

Weather phenomenon and erratic rainfall are some of the symptoms of global climate change. These challenges attempt to increase rice production in tidal swamps or submerge land in the long term. An effort to form tolerant rice varieties to stress in tidal swampland has been carried out through crossing between superior varieties and local rice. This study aims to analyze the results of several promising rice lines and search for the potential rice lines to be released as new tidal swampland varieties. The experiment was carried out in tidal swamp rice area centers, in Karang Agung, South Sumatra, Balandean, South Kalimantan and in Indramayu, West Java Indonesia. Fourteen rice lines and four check varieties namely IR42, IR64, Inpara 8 and Inpara 9 were used. Field experiments used a Randomized Complete Block Design (RCBD) with four replications. Results showed that the environment, genotype, and interaction between environmental genotypes had a significant influence on all characters. The appearances of the lines were superior in Karang Agung and less well on Balandean. The yield was positively correlated with plant height, the number of productive tillers and filled grains per panicle. There were five lines with a high yield equivalent to the best check varieties, namely Inpara 9, IR 102860-8: 66-BB, IR 102860-8: 42-BB, IR 101465-8: 23, IR 101465-5: 25, and B13522E-KA-5-B.

Water Productivity of Rice Genotypes with Irrigation and Drainage

AbstractThe aims of this study were: (i) to evaluate the agronomic characteristics of thin‐grain rice genotypes with high yield potential under irrigation conditions; (ii) to quantify water productivity (WP) in thin‐grain rice genotypes, based on crop evapotranspiration (ETC) and irrigation and surface drainage control. Eight genotypes were planted: four varieties, two promising lines and hybrid Clearfield XL745 and IRGA. Direct dry seeding was carried out mechanically at a density of 80 kg ha‐1 for the varieties and 32 kg ha‐1 for the hybrid; drainage was performed every 9.3 m inside of the border. The results indicate that there are significant differences (P > 0.05) among genotypes for grain yield and its components, except for lodging. The varieties and promising rice lines evaluated expressed good productive capacity, but they were surpassed by 19% by the average productivity recorded by the variety IRGA and the hybrid Clearfield. The variation in water demand based on ETC is evident in the optimal irrigation depth applications of 264 mm for the hybrid and 318 mm for the intermediate‐cycle genotypes. The border irrigation method with drainage troughs significantly increases water productivity based on the applied irrigation (WPI), averaging 2.0 kg m‐3. © 2018 John Wiley & Sons, Ltd.

Evaluation of Genotype × Environment Interaction in Rice Based on AMMI Model in Iran

Identification of high-yielding stable promising rice lines and determination of suitable areas for rice lines would be done by additive main effects and multiplicative interaction (AMMI) model. Seven promising rice genotypes plus two check varieties Shiroudi and 843 were analyzed using a randomized complete block design with three replications in three consecutive years (2012, 2013 and 2014). Homogenous error variance was indicated in the nine environments for grain yield. The combined analysis of variance indicated significant effects of environment, genotype and genotype × environment (GE) interactions on grain yield. The significant effect of GE interaction reflected on the differential response of genotypes in various environments and demonstrated that GE interaction had remarkable effect on genotypic performance in different environments. The application of AMMI model for partitioning the GE interaction effects showed that only the first two terms of AMMI were significant based on Gollob's F-test. The lowest AMMI-1 was observed for G7, G2 and G6. G7 and G6 had higher grain yield. According to the first eigenvalue, which benefits only the first interaction principal component scores, G1, G6, G2 and G9 were the most stable genotypes. The values of the sum of first two interaction principal component scores could be useful in identifying genotype stability, and G6, G5 and G2 were the most dynamic stable genotypes. AMMI stability value introduced G6 as the most stable one. According to AMMI biplot view, G6 was high yielding and highly stable genotype. In conclusion, this study revealed that GE interactions were an important source of rice yield variation, and its AMMI biplots were forceful for visualizing the response of genotypes to environments.

Development of High-Yielding Rice Varieties Suitable for Swampy Lands in Indonesia

Productivity of swampy land rice varieties in Indonesia remains low due to abiotic and biotic stresses. Iron toxicity, submergence and long-term flooding are common problems that affect plant growth, sometimes leading to total crop loss. Meanwhile, rice blast, rice tungro virus (RTV), and bacterial leaf blight (BLB) can also lead to severe yield loss. These stresses could be overcome by an integrative approach of cultural practices and planting multi-stress tolerant rice. Here we describe the development of new high-yielding varieties that are adapted to the swampy land environments in Indonesia with multi-stress tolerance to diverse abiotic and biotic stresses. Multi-environmental trials were performed in nine locations to screen for several abiotic and biotic stresses in the field and greenhouse in 2012 and 2013. This study identified promising rice lines that had high grain yield as well as tolerance to iron toxicity and submergence, resistance to BLB and RTV, and good grain quality. The best line was B11377F-MR-34-2, derived from a double cross among Cinglonik, IRBB7, Mamberamo and IR64. It was confirmed that this advanced breeding line carries the submergence tolerance gene, SUB1, through expression analysis of the SUB1A gene. Another promising line was B11586F-MR-11-2-2, having iron toxicity tolerance, resistance to RTV, and high milling recovery. Moreover, these lines have passed the Indonesian national variety release committee and have been named as Inpara8 and Inpara9, and are targeted for dissemination and adoption in the swampy areas.