Lowland Rice Genotypes Research Articles

Variability and Correlation Study on Lowland Green Super Rice in Western Ethiopia

Abstract The success of plant breeding activities entirely depends on the existence of genetic variability with respect to desired traits and selection skills of plant breeders. A field experiment was conducted to evaluate the extent of variability, heritability genetic advance, and character association among yield and yield-related traits in lowland GSR. The experiment was conducted using 20 low-land green supper rice genotypes in the Northwestern part of Ethiopia at Pawe agricultural research center for three consecutive years from 2016-2018 main cropping seasons. A randomized complete block design with three replications was used. The results of the analysis of variance for yield and yield-related characters revealed that highly significant mean square due to genotypes observed for all traits studied, Higher phenotypic co-efficient of variation, compared to genotypic co-efficient of variation was recorded for all the traits studied indicating the variation is not only genetic but also influence of growing environment. The highest PCV was recorded for the trait plant height (32.6) followed by panicle length (23.3). Broad sense heritability analysis showed that days to heading (56.3), plant height (49.8), Days to maturity (42.4%), and panicle length (42.3%) were high. High heritability with the high genetic advance in percent of mean was recorded by plant height (49.8 & 33.54) followed by Panicle length (42.3 & 36.55) which confirms their additive gene action and direct selection of these traits depending on phenotypic expression would be effective for yield improvement. The positive and highly significant phenotypic correlation was observed between days to heading and days to maturity (r = 9385***) plant height was positively correlated with thousand-grain weight (0.50436*) and Panicle length (0.48312*). Grain yield showed negative correlation between Days to maturity (-0.044662*), but weak positive correlation was observed for days to heading (r = 0.33472), plant height (r = 0.18729) and panicle length (r = 0.08771). Therefore, the traits recorded high heritability and higher genetic advance; and the traits showed positive correlation and could be considered as suitable traits for selection and improvement to achieve high-yielding green super rice varieties in rain-fed environments.

Stability Analysis and Yield Evaluation on Some Lowland Rice Genotypesin Nigeria

Improved genotypes can contribute immensely to productivity of high yielding varieties when they are released mainly in the ideal and adapted environments. To enhance adoption and sustainable production of new improved lowland rice genotypes in Nigeria, yield evaluation,analysis of stability models on seven (7) lowland rice genotypes (ARS 161-3-5-5-3-B-BD, ARS 563-14-B-ED, ARS 150-TGR-10-NCRIB-12, ART 64-26-1-1-B-B-ED, D 56-NCRI J-1-1, ART 90--46-1-1-B-B-ED and ART 739-2-6-B-BD) and two national checks (FARO 44 and FARO 57) in 2020 and 2021 for nine (9) environments were under taken. The design was randomized complete block having three replicates. AMMI and GGE Biplot analyses were adopted to identify stable and adaptable genotypes across the environments. The stability as recommended by FINLAY-WILKINSON indicated that genotypes ART 739-2-6-B-BD, ART 90--46-1-1-B-B-ED and ARS 150-TGR-10-NCRIB-12 expressed 21%, 19% and 24% respectively less than 1 in slope for the combined two years analysis. AMMI analysis partitioned the environment into 8 principal components, the variances at all the principal components recorded high but not significant difference at 5% probability except Principal Component 1. This thereforeimplies that principal component 1 has substantive variances that can be exploited. Principal Component PC1, PC2 and PC3 accounted for 99.70% of AMMI experimental variance and ARS 161-3-5-5-3-B-BD as measured by principal components suggested to be not only high yielding, more stable, but also more ideal in all the tested environments

Diurnal Variation of Trace Gas Fluxes during the Vegetative Lag Phase in Furrow-Irrigated Rice Production

Journal of Rice Research and Developments | Best Scientific Journals. Review on Multi-Variate Evaluation of the Genetic Diversity in Different Lowland Rice Genotypes Tested at Pawe, Northwestern Ethiopia

Assessment of Genetic Diversity among Intra- and Interspecific Lowland Rice using Morpho-agronomic Traits and SSR Markers

Rice is staple food in many countries of Africa and a major part of the diet in many others. However, Africa’s demand for rice exceeds production with the deficit of 40% being imported. One way to improve Africa’s rice production is through breeding high yielding varieties suitable for the different environment conditions. This study was conducted to assess the genetic variability and stability performance of 48 lowland rice genotypes including 37 interspecific (Oryza glaberrima × Oryza sativa ssp. indica) and 11 intraspecific (O. sativa ssp. indica × O. sativa ssp. indica) in 12 environments in Nigeria, Benin Republic and Togo using Additive Main Effect and Multiplicative Interaction (AMMI) and Genotype+ Genotype x Environment (GGE) biplot models. The combined analysis of variance revealed significant differences (P<0.01) among the genotypes, environments, and genotypes x environment interaction. Both the AMMI and GGE models identified NERICA-L8 and NERICA-LI2 as the best genotypes for cultivation across environments. Ouedeme environments in Benin Republic were the most stable and ideal for rice cultivation, while Ibadan sites were the most unstable. TOG 5681 had the least yield and was the most unstable across seasons. Genetic diversity was analyzed using 22 important morpho-agronomic traits and 50 simple sequence repeat (SSR) markers and the results were subjected to principal components analysis (PCA). The results revealed that the first eight PC axes (PC1–8) accounted for 75.13% of the total variation, while PC1–4 accounted for 50.39% of the total variation among rice genotypes. However, 10 of the 50 SSR markers were polymorphic and generated 49 alleles (average = 4.9 alleles per locus), suggesting moderate to substantial genetic diversity among the rice genotypes. The polymorphic information content (PIC) ranged from 0.24 to 0.65, with an average PIC value of 0.45. Two structured populations were observed which clustered into five heterotic groups and an outgroup, respectively. This suggests that heterosis could be exploited in the next hybridization program by crossing one of the genotypes in any SSR marker-defined cluster, with the rice accession TOG 5681 in cluster I. The results of this study suggest that morpho-agronomic traits should be used to compliment SSR data in rice diversity studies, especially if a few polymorphic SSR markers are to be used.

Assessment of Genetic Diversity among Intra- and Interspecific Lowland Rice using Morpho-agronomic Traits and SSR Markers

Rice is staple food in many countries of Africa and a major part of the diet in many others. However, Africa’s demand for rice exceeds production with the deficit of 40% being imported. One way to improve Africa’s rice production is through breeding high yielding varieties suitable for the different environment conditions. This study was conducted to assess the genetic variability and stability performance of 48 lowland rice genotypes including 37 interspecific (Oryza glaberrima × Oryza sativa ssp. indica) and 11 intraspecific (O. sativa ssp. indica × O. sativa ssp. indica) in 12 environments in Nigeria, Benin Republic and Togo using Additive Main Effect and Multiplicative Interaction (AMMI) and Genotype+ Genotype x Environment (GGE) biplot models. The combined analysis of variance revealed significant differences (P<0.01) among the genotypes, environments, and genotypes x environment interaction. Both the AMMI and GGE models identified NERICA-L8 and NERICA-LI2 as the best genotypes for cultivation across environments. Ouedeme environments in Benin Republic were the most stable and ideal for rice cultivation, while Ibadan sites were the most unstable. TOG 5681 had the least yield and was the most unstable across seasons. Genetic diversity was analyzed using 22 important morpho-agronomic traits and 50 simple sequence repeat (SSR) markers and the results were subjected to principal components analysis (PCA). The results revealed that the first eight PC axes (PC1–8) accounted for 75.13% of the total variation, while PC1–4 accounted for 50.39% of the total variation among rice genotypes. However, 10 of the 50 SSR markers were polymorphic and generated 49 alleles (average = 4.9 alleles per locus), suggesting moderate to substantial genetic diversity among the rice genotypes. The polymorphic information content (PIC) ranged from 0.24 to 0.65, with an average PIC value of 0.45. Two structured populations were observed which clustered into five heterotic groups and an outgroup, respectively. This suggests that heterosis could be exploited in the next hybridization program by crossing one of the genotypes in any SSR marker-defined cluster, with the rice accession TOG 5681 in cluster I. The results of this study suggest that morpho-agronomic traits should be used to compliment SSR data in rice diversity studies, especially if a few polymorphic SSR markers are to be used.

Phenotypic characterization of two lowland Rice Genotypes Cultivated with Organic Fertilizer

Rice farming in Liberia has long grappled with subpar yields, ranging from 0.5 to 1.5 tonnes per hectare (t/ha), attributed to outdated agronomic practices and the utilization of inferior inbred rice varieties. To alleviate the potential catastrophes and challenges of a changing climate and to improve rice production, we conducted a field experiment to determine the impact of organic fertilizer on the yield and growth attributes of two lowland rice genotypes (Nerica-L19 and the traditional landrace Bold Grain). The experimental layout was Randomized Complete Block Design (RCBD) in split plot arrangement with the main plots being organic fertilizer at a rate of 2.5 t/ha. Results revealed that there were significant differences between the landrace bold grain and the improved genotypes for all traits measured except for panicle length, seed length and stem diameter. Pearson coefficients of correlation analysis showed that days to 50 % flowering correlated significantly with plant height, number of tillers and number of panicles per plant. Nerica-19 exhibited the highest grain yield along with growth traits, suggesting its potential for smallholder farmers and warranting further evaluation across various environments.

Effect of different levels of NPK fertilizer on the growth and yield of lowland rice genotypes in Anwai, Delta state

Effect of different levels of NPK fertilizer on the growth and yield of lowland rice genotypes in Anwai, Delta state

Genotype by Environment Interaction of IPB New Plant Type Rice Lines in Three Irrigated Lowland Locations

One essential objective of rice breeding is to obtain high-yielding varieties. This study aims to (1) determine the effect of genotype (G), environment (E), and genotype by environment (G×E) interaction on agronomic traits and yield of 12 lowland rice genotypes, (2) estimate variance components and repeatability (3) identify promising rice genotypes with good agronomic performance and high yield potential. The trials were conducted in three irrigated lowland locations from June to November 2020, using a randomized complete block design with three replications. The results showed that the G×E interaction effect was significant on days to flowering, days to harvest, plant height, number of tillers, and panicle length. The genotype's main effect was significant on yield. Four IPB lines (IPB189-F-13-1-1, IPB189-F-23-2-2, IPB193-F-17-2-3, and IPB193-F-30-2-1) had a higher average yield than Ciherang and Inpari 32 varieties. The IPB189-F-23-2-2 had a panicle length stability across the three test locations and a higher average yield than the checks.

Genetic Divergence of Lowland Rice (Oryza sativa L.) Genotypes in Uganda

Forty-eight lowland rice genotypes with two checks were evaluated for agronomic performance, genetic variability, heritability, and genetic advance for yield and yield contributing traits. Genotypes SR33859-HB3324-133 (45.7 qha-1), SR33859-HB3324-93 (40.2 qha-1) were the high yielding genotypes above the better check. The analysis of variance showed significant differences for all measured traits and indicating the presence of high genetic variability among genotypes. A highly significant (P≤0.001) correlations were observed between flag leaf length and plant height (rp= 0.76 and rg=0.84), panicle length and plant height (rp= 0.77, rg= 0.90), and panicle length and flag leaf length (rp= 0.75 and rg= 0.89). The estimates of GCV were lower than the respective PCV for all traits, indicating the influence of environmental factors on the expression of the traits. Characters like grain yield (94 % and 90.9), flag leaf length (97 % and 71.6), number of effective tillers per hill (91 % and 67.2) and plant height (99.0 % and 50.7) showed high heritability coupled with moderate genetic advance as percent of the mean, which suggesting that these traits are controlled by the additive type of gene action and selection could be possible for the improvement of these characters. Moderate heritability estimates with low genetic advance as percent of the mean were recorded for flag leaf width and number of days to maturity indicated the presence of non-additive gene effects, and selection for these traits would be poor. As a result, the variability that exists in the germplasm provides an opportunity to use these genotypes in the genetic improvement program.

Profiling the physiological response of upland and lowland rice (Oryza sativa L.) genotypes to water deficit

Profiling the physiological response of upland and lowland rice (Oryza sativa L.) genotypes to water deficit

Responses of Lowland Rice Genotypes under Terminal Water Stress and Identification of Drought Tolerance to Stabilize Rice Productivity in Southern Thailand.

Lowland rice is an important cereal crop that plays a key role in the food security and the economy of Thailand. Terminal water stress (TWS) in rainfed lowland areas poses threats to rice productivity due to stress occurrence at terminal crop stages and extreme sensitivity of rice to TWS. A two-year study was conducted to characterize the performance of yield and yield attributes of twelve Thai lowland rice genotypes under TWS, to identify stress-tolerant genotypes using stress response indices and to identify promising stress indices which are correlated with grain yield (GY) under well-watered (WW) and TWS conditions for their use as rapid identifiers in a rice crop breeding program for enhancing drought stress tolerance. Measurements were recorded under WW and TWS conditions. Highly significant variations were observed amongst assessed genotypes for their yield productivity responses. According to stress response indices, genotypes were categorized into stress-tolerant and stress susceptible genotypes. Genotypes Hom Pathum, Sang Yod, Dum Ja and Pathum Thani-1 were found highly stress tolerant and relatively high yielding; genotypes Look Pla and Lep Nok were stress tolerant, whereas genotypes Chor Lung, Hom Nang Kaew and Hom Chan were moderately tolerant genotypes. Hence, stress-tolerant genotypes could be potentially used for cultivation under rainfed and water-limited conditions, where TWS is predicted particularly in southern Thailand to stabilize rice productivity. Stress tolerance indices, including stress tolerance index (STI), geometric mean productivity (GMP), mean productivity index (MPRO) and harmonic mean index (MHAR), indicated strong and positive associations with GY under WW and TWS; thus, these indices could be used to indicate stress tolerance in rice crop breeding program aimed at a rapid screening of lowland rice genotypes for stress tolerance.

Stability analysis of lowland rice genotypes in rain-fed environments of Northwest Ethiopia

Stability analysis of lowland rice genotypes in rain-fed environments of Northwest Ethiopia

Bioprospecting aerobic rice (Oryza sativa) and mycorrhizal interaction for nutrient uptake and plant growth

With the growing concern of water scarcity in agriculture, aerobic rice (Oryza sativa L.) is a promising mode of cultivation for reducing water use, although the reduced optimal plant growth and yield are major constraints. Arbuscular mycorrhiza (AM) are known to readily colonize rice roots under aerobic conditions, however, the response of upland and lowland rice genotypes has not been investigated. This study was carried out during 2018-19 at ICAR-IARI, New Delhi, using a mycorrhizal consortium and percent colonization was observed to be higher by 58% in upland rice genotypes. AM- upland plants also showed 20% higher plant biomass. AM colonization significantly enhanced rice growth under aerobic conditions, with the upland rice genotypes. Pyari and Satyabhama showed higher response upon AM inoculation. AM colonization increased the total chlorophyll by 54% and the upland rice genotypes showed 51% enhanced nitrogenase activity in their root zones, with highest recorded for Satyabhama. The AM plants showed enhanced activities of nitrate reductase (NR) and glutamine synthetase (GS), and interestingly, the rice genotypes with higher NR and GS (Pyari, Satyabhama) also exhibited more (20%) biomass production and plant N content (36%). Significant varietal differences were recorded in terms of accumulation of antioxidant compounds such as ascorbate, glutathione and proline in AM inoculated plants, which helped to alleviate negative effects of water stress in rice plants under aerobic cultivation.

Variation in Morpho-Agronomic Traits of Lowland Rice (Oryza Sativa) Genotypes of Assam in Response to Phosphorus Fertilization

Variation in Morpho-Agronomic Traits of Lowland Rice (Oryza Sativa) Genotypes of Assam in Response to Phosphorus Fertilization

Stability and Performance Assessment in 18 Short-Duration Rice Genotypes under Rain Fed Lowland Production Conditions of Ethiopia

In order to identify high yielding and stable short-duration lowland rice genotypes, field experiment was conducted with 18 rice genotypes for three consecutive years (2013-2015) at five locations in a randomized complete block design of three replications. Combined analysis of variance showed highly significant differences for the genotype and environments. The genotype by environment interaction (GEI) was also highly significant indicating differential response of genotypes to environments. The partitioning of total sum of squares exhibited that the GEI effect was a predominant source of variation (34.44%), followed by the environment and genotype effects of 24.3% and 19.04%, respectively. The GEI effect was nearly two times higher than that of the genotype effect, suggesting the presence of different environment groups. In the AMMI analysis, the first six interaction principal component axes (IPCA1 to IPCA6) were highly significant and together explained 92.18% of interaction sum of squares. AMMI stability value (ASV) discriminated genotypes G17, G16 and G8 as the stable genotypes. But, based on the yield stability index (YSI), the most stable genotypes with high grain yield were genotypes G16 and G11. AMMI1 and GGE biplots also recommended G16 and G11as stable and high yielding genotypes, whereas G2 as unstable but high yielding. Thus, genotypes G16 and G11could be released for wider adaptation while genotype G2 for specific adaptation. Keywords : Lowland rice, AMMI, GGE, AMMI stability value, yield stability index. DOI: 10.7176/JEES/11-7-02 Publication date: July 31 st 2021

Genetic divergence of lowland rice (Oryza sativa L.) genotypes in Uganda

Zelalem Zewdu.2021.Genetic divergence of lowland rice (Oryza sativa L.) genotypes in Uganda.Journal of Innovative Agriculture.volume 8, issue 2, Pages 34-38. Forty-eight lowland rice genotypes with two checks were evaluated for their agronomic performance, genetic variability, heritability, and genetic advance for yield and yield contributing traits. Among the tested genotypes SR33859-HB3324-133 (45.7 qha-1), SR33859-HB3324-93 (40.2 qha-1) were the high yielding genotypes above the better check. The analysis of variance showed significant differences for all measured traits and indicating the presence of high genetic variability among genotypes. A highly significant (P≤0.001) correlations were observed between flag leaf length and plant height (rp= 0.76, rg=0.84), panicle length and plant height (rp= 0.77, rg= 0.90), and panicle length and flag leaf length (rp= 0.75, rg=0.89). The estimates of GCV were lower than the respective PCV for all traits, indicating the influence of environmental factors on the expression of the traits. Characters like grain yield (94 %, 90.9), flag leaf length (97 %, 71.6), number of tillers per hill (91 %, 67.2) and plant height (99.0 %, 50.7) showed high heritability coupled with moderate genetic advance as percent of the mean, which suggesting that these traits are controlled by the additive type of gene action and selection could be possible for the improvement of these characters. On the other hand, moderate heritability estimates with low genetic advance as percent of the mean were recorded for flag leaf width and number of days to maturity indicated the presence of non-additive gene effects, and selection for these traits would be poor. As a result, the variability that exists in the germplasm provides an opportunity to use these genotypes in the genetic improvement program.

Principal Component Analysis for Yield and Yield Attributed Traits in Lowland Rice (Oryza sativa L.) Genotypes

Principal component analysis was utilized to determine the variation and to estimate the relative contribution of various characters for total variability. The experiment was laid out using randomized block design with three replications during 2017/2018 main cropping season at Fogera, Ethiopia. The first four principal components axes accounted for 85.3% cumulative variance of the total variability for seventeen agronomic characters. PC1, PC2, PC3 and PC4 explained 44.15%, 19.31%, 14.913% and 6.97% of variation from the total variation, respectively. Thus, maximum variation was found in first PC; therefore, selection for characters under PC1 would be desirable. The variability in PC1 was accounted by flag leaf length, panicle length, days to heading and days to 50% flowering, while PC 2 was accounted by harvest index. For future breeding program that employ hybridization, parental material selection should be carried out considering principal components influence to breeders’ interest. Keywords: Genetic variability, Genotype, Principal component analysis, Rice DOI: 10.7176/JEES/11-16-03 Publication date: June 30 th 2021

Genetic Variability and Traits Association Study in Rainfed Lowland Rice (<i>Oryza sativa </i>L.) Genotypes in Southwestern Ethiopia

Background and Objective: Complete knowledge on the extent of genetic variability and interrelationships of yield and components traits is pre-request for designing an effective and efficient selection based rice improvement programs for generating high yielding rainfed lowland rice genotypes. The objective of this study was in order to determine the extent of genetic variability and association of characters with grain yield and among themselves. Materials and Methods: Twenty-five rainfed lowland rice genotypes were evaluated during the 2016 main cropping season at two rainfed lowland agro-ecologies of Southwestern Ethiopia. The experiment was laid out in a simple lattice design and data on 14 yield and yield component traits were collected and subjected to various statistical analyses. Results: Combined analysis of variance across locations revealed significant location, genotype and genotype x location interaction effects for several traits evaluated at p ≤ 0.01. The phenotypic coefficient of variation (PCV) ranged from 2.14% for days to 85% maturity to 18.09% for grain yield, while the genotypic coefficient of variation (GCV) ranged from 0.71% for days 85% to maturity to 10.48% for grain yield. Heritability estimate in broad sense was high for plant height (74.15) and low for days to 85% maturity (11.06) and harvest index (23.47). Plant height displayed high heritability along with moderate genetic advance as percent of mean value and days to 85% maturity and harvest index exhibited low GCV, heritability and genetic advance as percentage of mean estimates. Correlation coefficient analysis of grain yield showed positive and significant association with number of primary branches per panicle at both phenotypic and genotypic levels. Separation of correlation coefficients into direct and indirect effects of component traits on grain yield revealed that number of primary branches per panicle exerted the maximum positive direct effect on grain yield at both genotypic and phenotypic levels. Conclusion: The present study indicated sufficient amount of genetic variability for the majority of the characters studied in rainfed lowland rice genotype for future exploitation in selection based improvement programs.

Responses of Lowland, Upland and Aerobic Rice Genotypes to Water Limitation During Different Phases

Rice yield reduction due to water limitation depends on its severity and duration and on the phenological stage of its occurrence. We exposed three contrasting rice genotypes, IR64, UPLRi7 and Apo (adapted to lowland, upland and aerobic conditions, respectively), to three water regimes (puddle, 100% and 60% field capacity) in pots during the vegetative (GSI), flowering (GSII) and grain filling (GSIII) stages. Stress at all the three stages significantly reduced yield especially in lowland genotype IR64. Effect of water limitation was more severe at GSII than at the other two stages. Stress at GSI stage reduced both source activity (leaf area and photosynthetic rate) and sink capacity (tiller number or panicle number per pot). When stress was imposed at GSII, spikelet fertility was most affected in all the three genotypes. In both GSII and GSIII, although leaf area was constant in all the three water regimes, estimated relative whole-plant photosynthesis was strongly associated with yield reduction. Reduced photosynthesis due to stress at any given stage was found to have direct impact on yield. Compared to the other genotypes, Apo had deeper roots and maintained a better water relation, thus, higher carbon gain and spikelet viability, and ultimately, higher biomass and productivity under water-limited conditions. Therefore, screening for these stage-dependent adaptive mechanisms is crucial in breeding for sustained rice production under water limitation.

Genetic divergence analyses of lowland rice genotypes in North Western Ethiopia

Information on the nature and magnitude of genetic variability is one of the prerequisites for a successful breeding program in selecting genotypes with desirable characters. To estimate the level of genetic divergence of lowland rice genotypes, a field experiment was conducted using thirty-six genotypes during 2017 main cropping season. The experiment was laid out 6x6 simple lattice design. Analyses of variances showed significant differences among traits tested, except harvest index. Principal components PC1, PC2 and PC3 accounted for 64.16% of the total variation. The highest inter-cluster distance was exhibited between cluster I and IV (D2 = 769.77), cluster I and VI (D2=485.33), cluster I and III (D2=232.35), cluster III and IV (D2=312), cluster III and VI (D2=197), cluster IV and VI (D2=746.51), cluster VI and V (D2=259.51) and cluster VI and VII (D2=140.15). The crosses between genotypes selected from cluster I with clusters IV, VI and III; cluster IV with clusters III, VI and V are expected to produce better genetic recombination and segregation in their progenies. The cluster means for cluster VI and I were characterized by early heading and early maturity. While cluster I, II, III, and IV were characterized by high mean performance for grain yield for most of its components. Key words: Cluster analysis, divergence, genetic distance, principal component, rice.