Upland Rice Cultivars Research Articles

Tolerance of local gogo rice sprouts under salinity stress conditions

The expansion of rice planting areas in the future needs to be carried out outside Java, as fertile land in Java is shrinking due to land conversion. Most of the land outside Java consists of marginal land, such as areas with high salinity. High salinity levels in the soil cause a decrease in plant germination, growth, and production. The research aimed to examine the tolerance of each cultivar at each level of NaCl concentration, to obtain cultivars that were tolerant to salinity stress, and to determine the NaCl concentration that suppresses the germination of local upland rice. The research was structured using a completely randomized design with a two-factor factorial pattern. The first was the six upland rice cultivars, namely, dongan, jahara, Pulu Konta, pomegranate, kalendeng, and pulu tau leru, while the second factor was the NaCl concentration consisting of 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1%. Thus, there were 36 experimental units, which were repeated three times so that there were 108 experimental units. The results of the research showed that there was no interaction with all germination variables; cultivar and concentration had a significant effect on maximum growth potential, germination capacity, germination time, plumule length, radicle length and dry weight of sprouts, while cultivar affected the wet weight of sprouts. Kalendeng has a high salinity tolerance. The use of NaCl concentrations of up to 0.6% has been able to reduce the germination capacity of local upland rice. The conclusion of the research showe that there was no interaction between all germination variables.

Evaluating the effects of the CERES-Rice model to simulate upland rice (Oryza sativa L.) yield under different plant density and nitrogen management strategies in Fogera Plain, Northwest Ethiopia

This study assessed the optimal nitrogen (N) fertilizer rate and planting density for the well-adapted upland rice cultivar NERICA_4 on the Fogera Plain. The primary objective was to evaluate the effects of varied planting densities and N-fertilizer rates on upland rice yield and other agronomic parameters. A two-year field study (2020 and 2021) was conducted at the Fogera Rice Research Field Station, testing nine plant densities (75, 87, and 98; 72, 82, and 91; 70, 79, and 89 plants per m2 and two N rates (115 and 138 kg N ha−1). The Crop Simulation Model Crop Environment Resource Synthesis (CSM-CERES-Rice) within the Decision Support System for Agrotechnology Transfer (DSSAT) framework was calibrated and validated using site-specific weather, soil, crop, and agronomic management data from the experiment. Results on the subsequent RMSE, RMSEn, and d index values during the calibration phase were 0.074 t ha−1, 1.82 %, and 0.86 of grain yield; 0.307 t ha−1, 3.36 %, and 0.87 of by-product yield; 0.489 t ha−1, 3.74 %, and 0.79 of top dry biomass yield; and 0.28, 8.24 %, and 0.63 of leaf area index values, respectively. Whereas results on the corresponding RMSE, RMSEn, and d index values during the evaluation phase were: 0.58 t ha−1, 1.33 %, and 0.90 of grain yield; 0.69 t ha−1, 0.58 %, and 0.99 of by-product yield; 0.678 t ha−1, 4.36 %, and 0.67 of top dry biomass yield; and 0.75, 13.92 %, and 0.74 of leaf area index, respectively. The findings of the long-term simulation showed that a 23 % increase in grain yield was achieved with 138 kg N ha−1 and 87 plants per m2 of planting density, as compared to 115 kg N ha−1 and 75 plants per m2 of plant density. The recommended optimum plant density and N fertilizer rate were 138 kg N ha−1 with PD2 of plant density for upland rice production in the Fogera Plain.

Clearfield upland rice intercropped with Urochloa ruziziensis for grain, increased revenue and environmental preservation

AbstractIntercropping perennial forage grasses into cereal crops is an alternative to recover degraded pastures. However, the intercrop of forage grasses, such as Urochloa ruziziensis (R. Germ. and C. M. Evard) Crins (Congo grass), can lead to losses in cereal yield. Therefore, it is necessary to develop management strategies that allow forage grass establishment without major losses in cereal yield in intercropping. The objective was to study the agronomic and economic impacts of intercropping U. ruziziensis into a Clearfield upland rice (Oryza sativa L.) cultivar in the state of Goiás, Brazil, in two growing seasons. Treatments included forage grass seeds sowing method (broadcast or incorporation to the soil) and sowing times (at rice sowing, 20 days after emergence [DAE], and 45 DAE of rice). Also, imazapyr + imazapic herbicide was applied to restrict the competitive effect on rice yield. Monocropping control plots were also evaluated. Grain yield was measured on rice. Forage grass dry matter yield was measured at 30, 60, and 90 days after harvesting (DAH) of rice. Crude protein content was analyzed at 90 DAH. Profitability was calculated for each cropping system relative to rice monocropping. Intercropping of rice and U. ruziziensis sowed at 45 DAE provided the highest grain yield relative to other assessed intercropping treatments as well as rice monocropping. Concurrent sowing of rice and incorporated U. ruziziensis seeding provided the greatest economic return. This reformed cropping system improved land and pasture output, which can reduce the pressure to convert more land to agricultural use.

Improving upland rice (Oryza sativa l.) performance through enhanced soil fertility and water conservation methods

The experiment was conducted at Experimental sites of Tanzania Agricultural Research Institute (TARI) – Ukiriguru, Mwanza, Tanzania. The objective was to improve performance of upland rice through enhanced soil fertility and water conservation methods. A split–split plot experiment in a randomized complete block design with three replications and three factors that were (a) upland rice cultivars (WAB 450, NERICA1 and NERICA4) (b) fertilizer types, (Urea 80Kg N/ha, farm yard manure 5 t/ha and control) (c) three water conservation methods (flat cultivation, open ridge and tie ridge were applied). Rice was sown in seven rows at 30 cm inter–and intra–row spacing. Data on soil, weather, crop growth, yield components and grain yield were collected. Rainfall was 651.2 mm during the cropping season which was poorly distributed. Average temperature was 24oC with mean relative humidity of 75%. Soil analysis results showed that total nitrogen was 0.08 %, phosphorus 2.09mgP/Kg and organic carbon 0.58%. The soil calcium was 3.38 cmolc/Kg and potassium was 0.36cmolc/Kg, while zinc was 0.39 mg/Kg. Cultivars had significant effect on yields which were 2856, 2507 and 2140 Kg/ha for WAB 450, NERICA4 and NERICA1 respectively. Fertilizer types also significantly affected grain yield in the order of urea (3368 Kg/ha) > FYM (2723 Kg/ha) and > control (1421 Kg/ha). Moisture conservation methods significantly affected yield in this order: tie ridges (2710 Kg/ha) > open ridge (2398 Kg/ha) > flat cultivation (2394 Kg/ha). Overall, the study results indicated low fertility status in the soil, although it was found to be suitable for upland rice production with further improvement. It is concluded that rice cultivar, WAB 450 had the highest yield potential, while application of Urea at 80 Kg N/ha gave high grain yield, while tie ridges were the best in soil moisture conservation.

Reasonable dry cultivation methods can balance yield and grain quality of rice

Reducing the water consumption of rice production in China without affecting grain yield and quality is an important challenge. The purpose of this study was to explore whether different dry cultivation methods could improve rice quality while balancing yield to maintain sustainable rice production. A japonica upland rice cultivar and a japonica paddy rice cultivar were cultivated in the field with three cultivation methods: plastic film mulching dry cultivation (PFMC), bare dry cultivation (BC), and continuous flooding cultivation (CF) as control. There was no significant difference in upland rice yield between PFMC and BC, and there was also no significant difference in paddy rice yield between PFMC and CF. Compared with CF, the two varieties yield decreased significantly with BC. Dry cultivation, especially PFMC, could decrease active filling period, chalky rice rate, chalkiness, amylose content, gel consistency, breakdown viscosity, ratio of glutelin to prolamin, leaf senescence, and increase water use efficiency, protein components content, setback viscosity, grain Q-enzyme activity and average filling rate. Compared with paddy rice, upland rice had lower yield, shorter active filling period, lower chalkiness grain rate and gel consistency, and higher amylose content, breakdown viscosity, protein components content and average filling rate. Grain Q-enzyme activity and grain filling parameters were closely related to rice quality. Reasonable dry cultivation methods could balance yield and quality, especially improve the nutritional and appearance quality of rice.

GROWTH RESPONSE OF TWO LOCAL UPLAND RICE CULTIVARS (ORYZA SATIVA L.) ON SALINITY

Increasing the number of inhabitants in Indonesia led to the limited agricultural land so that the paddy fields become narrow and limited, the limited paddy fields caused agricultural production in Indonesia to decline while demand increased. Tidal land cultivation is still rarely performed due to the high salt content (NaCl). The purpose of this study is to obtain upland rice cultivars that are tolerant of salinity stress. The study was conducted in November to December 2019 at the Seed and Science Technology Laboratory of the Faculty of Agriculture, University of Tadulako. The study was arranged using a completely randomized design (CRD) of two factors where the first factor consisted of two levels, namely Logi, and Tako, while the second factor consisted of five levels, namely 0.5%, 0.6%, 0.7%, 0.8%, and 0.9% were repeated three times. The results showed that tako cultivars have a good tolerance to salinity stress compared to logi cultivars, tako cultivars have the fastest germination time and germination capacity above 80%. At a concentration of 0.5% can not inhibit the growth of upland rice, but at a concentration of 0.9% can inhibit the growth of upland rice.

Testing of sprouting, genetic diversity and heritability of some local gogo rice cultivers

Seeds are the beginning of plant life; for this reason, using quality seeds and having superior genetic traits are needed to support the growth and development of plants to be better and provide maximum production. This study aims to obtain local upland rice cultivars with quality seeds and quality with the best germination and traits with superior genetics. This study was carried out at tadulako university’s faculty of agriculture’s seed science and technology laboratory. The research was conducted from November 2018 to December 2019 utilizing a Completely Randomized Design (CRD), using seven cultivars—pulu tau leru, pulu konta, delima, buncaili, jahara, uva buya, and pae bohe—as treatments. Each treatment was repeated four times. The parameters observed were maximum growth potential, germination capacity, germination time, and dry weight of sprouts. The results showed that the uva buya cultivar had the best germination because it produced the maximum growth potential (100.00%) and the best germination (99.50%), and the faster germination time (2.03 days). The dry weight of sprouts is a trait that has good genetic character because it has a high heritability value (91.28%).

WATER STRESS IN MODERN UPLAND RICE CULTIVARS: A MULTIVARIATE STUDY BETWEEN PHYSIOLOGICAL TRAITS AND YIELD

Water stress negatively affects upland rice production. The objective of this study was to identify physiological traits that could depict yield responses under water stress conditions. Three modern upland rice cultivars (C) (BRS A501 CL, BRS Esmeralda and BRS Serra Dourada) were subjected to three water availability levels (W): Control (100% of the field capacity throughout the growing cycle) and 70 and 40% of the water applied to the control during flowering. Yield, spikelet sterility, and 1000-grain weight were influenced by the water availability level (p < 0.05), whereas for the cultivar, only 1000-grain weight was significant. The W × C interaction was not significant for the analyzed yield components. Multivariate analysis revealed that well-irrigated plants were positively associated with grain yield and gas exchange traits, whereas the 40% water availability level was highly related to spikelet sterility and the crop water stress index. The best-fitted model for grain yield was obtained using photosynthesis, stomatal conductance, and transpiration (R2 = 0.76). Thus, physiological parameters can be used to explain the variations in upland rice yield under water stress.

Seed purity assessment of two local upland rice cultivars of Southeast Sulawesi based on agronomic characteristics

This research intended to purify upland rice seeds that have presumably been unintentionally mixed with various types of rice seeds, causing decreased quality or nature of the superior upland rice cultivars. Seed purification effort is needed to restore the purity of the seeds of promising local upland rice cultivars. The second long term goal of this research was to produce basic pure seeds, that are required for further breeding programs, and/or for the purpose of releasing new varieties. This study was the second generation of purification effort, aimed to further select the same or uniform agronomic characteristics of the local upland rice cultivars in each seed lot. Similar with the first generation, the experiment used a Randomized Block Design (RBD) consisting of 15 seed lots as treatment and each seed lot consisted of 4 “grids” (replications). This research was conducted at the Field Laboratory, Experimental Garden II, Faculty of Agriculture, Halu Oleo University. The results showed several characters (i.e., plant height, leaf number, and tiller number etc.) of the two rice cultivars were seem more uniform as compared to the first generation of purification. This indicates that the seeds are gradually purer.

Genetic Diversity and Relationship of Shanlan Upland Rice Were Revealed Based on 214 Upland Rice SSR Markers.

Shanlan upland rice (Oryza sativa L.) is a unique upland rice variety cultivated by the Li nationality for a long time, which has good drought resistance and high utilization value in drought resistance breeding. To explore the origin of Shanlan upland rice and its genetic relationship with upland rice from other geographical sources, 214 upland rice cultivars from Southeast Asia and five provinces (regions) in southern China were used to study genetic diversity by using SSR markers. Twelve SSR primers were screened and 164 alleles (Na) were detected, with the minimum number of alleles being 8 and the maximum number of alleles being 23, with an average of 13.667. The analysis of genetic diversity and analysis of molecular variance (AMOVA) showed that the differences among the materials mainly came from the individuals of upland rice. The results of gene flow and genetic differentiation revealed the relationship between the upland rice populations, and Hainan Shanlan upland rice presumably originated from upland rice in Guangdong province, and some of them were genetically differentiated from Hunan upland rice. It can be indirectly proved that the Li nationality in Hainan is a descendant of the ancient Baiyue ethnic group, which provides circumstantial evidence for the migration history of the Li nationality in Hainan, and also provides basic data for the advanced protection of Shanlan upland rice, and the innovative utilization of germplasm resources.

Early Test of the Tolerance of Upland Rice to Drought in the Germination Phase

Climate change in the form of drought will reduce agricultural production, so it is necessary to develop superior drought-tolerant varieties. The study aimed to determine the drought-tolerant local upland rice cultivars at the germination stage. From September to December 2021, the study was carried out at the Seed Science and Technology Laboratory, Faculty of Agriculture, Tadulako University, Palu, Center Sulawesi, Indonesia. A completely random design (CRD) with a two-factor factorial pattern was employed in the study. Twelve cultivars comprised the first factor, while two superior drought-resistant variants served as comparators. The second factor is osmotic stress, namely P0 = control, P1 = -1 bar, P2 = -2 bar, and P3 = -3 bar, so there are 56 treatment combinations repeated four times, so there are 224 experimental units. The observed variables were maximum growth potential, germination rate, radicle length, plumule length, radicle dry weight, plumule dry weight, sprout dry weight, water volume, and germination rate. The results showed that drought stress through PEG – 1 bar did not affect germination. Using PEG down to -3 bar resulted in a significant reduction in germination. Pulut ko, logi and sina ponding are cultivars that have tolerance to drought stress.

Artificial selection of the Green Revolution gene Semidwarf 1 is implicated in upland rice breeding

Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1 (SD1), which modulates gibberellic acid (GA) biosynthesis, plays a principal role in determining rice plant height. Mutations in SD1 reduce rice plant height and promote lodging resistance and fertilizer tolerance to increase grain production. The plant height mediated by SD1 also favors grain yield under certain conditions. However, it is not yet known whether the function of SD1 in upland rice promotes adaptation and grain production. In this study, the plant height and grain yield of irrigated and upland rice were comparatively analyzed under paddy and dryland conditions. In response to dryland environments, rice requires a reduction in plant height to cope with water deficits. Upland rice accessions had greater plant heights than their irrigated counterparts under both paddy and dryland conditions, and appropriately reducing plant height could improve adaptability to dryland environments and maintain high grain yield formation. Moreover, upland rice cultivars with thicker stem diameters had stronger lodging resistance, which addresses the lodging problem. Knockout of SD1 in the upland rice cultivar IRAT104 reduced the plant height and grain yield, demonstrating that the adjustment of plant height mediated by SD1 could increase grain production in dryland fields. In addition, an SD1 genetic diversity analysis verified that haplotype variation causes phenotypic variation in plant height. During the breeding history of rice, SD1 allelic mutations were selected from landraces to improve the grain yield of irrigated rice cultivars, and this selection was accompanied by a reduction in plant height. Thus, five known mutant alleles were analyzed to verify that functional SD1 is required for upland rice production. All these results suggest that SD1 might have undergone artificial positive selection in upland rice, which provides further insights concerning greater plant height in upland rice breeding.

Pertumbuhan dan Hasil Kandungan Fe dan Zn pada Beras dari Kultivar Padi Ladang di Kabupaten Timor Tengah Utara

Field rice (paddy field) is one of the important crops/commodities and is an integral part of the dry land farming system in North Central Timor district. The content of rice is to meet the needs of carbohydrates in the body. The materials used are harvested grain from the local North Central Timor rice cultivar which has been carried out for the 2022 planting season. A total of 6 field rice in North Central Timor district were to be tested for Fe and Zn content. Grain samples were taken from crops grown in the same season and location, namely in the dry season of 2022. This study aims to identify local Timorese rice varieties that have high and stable Fe and Zn contents. The study was conducted in the Field Laboratory of the Faculty of Agriculture, University of Timor with a non-factorial Randomized Block Design consisting of 6 cultivar treatments V1 V2 V3 V4 V5 and V6 and the XRF Laboratory, BB Padi Sukamandi. Test the content of Fe and Zn using an XRF machine with an x-ray based performance system. A total of 6 types of field rice were tested for the content of Fe and Zn in brown and polished rice and repeated in duplicate. The content of Fe and Zn is expressed in units of ppm. Data processing was carried out using Excel and SAS 9 software. The results showed that there were differences in the growth and production components between the local Timor and East Timor upland rice cultivars. Cultivars with cultivar V2 (muit fua naek) productivity as seen from the t/ha yield of 3.20 tons per ha were significantly higher than the other cultivars. The results of the analysis of Fe and Zn content showed that cultivar V6 (Aen Mael) had the highest Fe content of 15.1 among the other cultivars, and the lowest was cultivar V4 (Aen Ek ELo) which had an Fe content of 13.0. The highest Zn content was in cultivar V5 (Aen Muit Fua Ana) with a Zn content of 27.9 while the lowest was in cultivar V2 (Muit Fua Naek) with a Zn content of 20.4.

DETERMINING THE RIGHT DOSAGE OF INORGANIC FERTILIZERS TO INCREASE GROWTH AND RESULTS THREE LOCAL UPLAND RICE CULTIVARS

Fertilization is one of the important factor to increase production. The aim of this study was to determine the appropriate dosage of inorganic fertilizers to increase the growth and yield of three cultivars of upland rice. This research was conducted at the Center for Research and Development of Gogo Rice, Faculty of Agriculture, Tadulako University, Kalama, Tamarenja Village at an altitude of 180 to 250 above sea level with a latitude of 00o 26'51.5” South Latitude and 119o49'50.6” East Latitude, Sindue District, Donggala Regency, Central Sulawesi Province. The time of the research started from March to August 2020. This research was compiled and carried out using the factorial 2 factors Randomized Block Design (RBD) method. The first factor used three local upland rice cultivars, namely: Pae Bohe, Buncaili, and Uva Buya, while the second factor used six doses of inorganic fertilizers, namely: No fertilization, NPK fertilization 100 kg/ha, 200 kg/ha, 300 kg/ha, 400 kg/ha, and 500 kg/ha. There were 18 combinations, where each treatment was repeated three times so that there were 54 research units. Parameters observed included plant height, number of productive tillers, age of panicle appear, harvest age, number of panicle grains, percentage of empty grain, 1000 grain weight and production. The results showed that the Pae bohe cultivar with fertilization dose of 500 kg/ha produced the highest number of productive tillers (6.69 per clump), the lower percentage of grain pests (5.34%), and the highest production (3.82 tons/ha).

Improvement of morphology, biochemical characters, and molecular changes of local upland rice cv. Sidikalang M3 generation through induction of gamma-ray irradiation

Abstract. Naibaho D, Purba E, Hanafiah DS, Hasibuan S. 2023. Improvement of morphology, biochemical characters, and molecular changes of local upland rice cv. Sidikalang M3 generation through induction of gamma-ray irradiation. Biodiversitas 24: 200-207. Upland rice cultivar Sidikalang is one of the local upland red rice cultivars of North Sumatra, which has the potential to be developed. However, this rice has limited planting area due to factors such as its higher plant height and long duration compared to other rice cultivars. Plant characteristics can be improved through induced mutation using gamma-ray irradiation. This study aimed to determine gamma rays' effect on changes in morphological, biochemical, and molecular characters and to obtain a superior Sidikalang cultivar mutant plant M3 generation. Observations of morphological changes were carried out quantitatively and qualitatively, biochemical analysis (amino acid content) was done using a High Performant Liquid Chromatography analyzer, and molecular analysis was performed using Random Amplified Polymorphism DNA markers. The results showed that 600 Gy gamma-ray irradiation improved quantitative morphological characters (shorter plant height, higher number of tillers and panicles, faster panicle release age) and qualitative morphological characters (flag leaf angle in dwarf mutants became upright) compared to no irradiation. 400 Gy gamma-ray irradiation also increased almost all amino acid content compared to no irradiation. The presence of polymorphic bands in the M3 generation Sidikalang cultivar mutant plant evidenced changes in morphological and biochemical characters.

Tolerância à seca induzida pela superexpressão do gene nuclear rbcL em arroz

Abstract The objective of this work was to determine whether the overexpression of the nuclear Rubisco large subunit (rbcL) improves the drought tolerance of the genetically modified (GM) BRSMG Curinga upland rice (Oryza sativa) cultivar. GM and non-genetically modified (NGM) plants of the same cultivar were compared under the two following water treatments: well watered (WW) and water deficit (WD). The performance of the agronomic traits of GM plants, including grain yield, was superior to that of NGM plants in both treatments. By quantitative polymerase chain reaction, GM plants show a significantly higher expression of the rbcL gene in both WW and WD, as well as a larger amount of abscisic acid. With the RNAseq analysis, almost three times more upregulated genes are identified in GM plants in stage 2 after water restriction, indicating a greater protection against water deficit. The higher expression of genes related to the protection of the cellular metabolism and a series of physiological alterations may be involved in the increase in the drought tolerance of GM rice plants overexpressing the rbcL gene.

Tolerance of Five Upland Rice Cultivars at Various Levels of Drought Stress

The aim of this study was to determine the drought tolerance limit of five upland rice (Paddy Gogo) cultivars in the germination phase. This research was carried out at the Seed Science and Technology Laboratory, Faculty of Agriculture, University of Tadulako, Palu, Indonesia, from September to October 2020. This study was arranged using a completely randomized design (CRD) with a factorial design of 2 factors. The first factor was the cultivar consisting of five cultivars, i.e., Pau Tau Leru, Jahara, Uva Buya, Buncaili, and Kalendeng. The second factor was the Polyethylene Glycol (PEG) concentration which consisted of five levels, i.e., Without PEG, 10%, 20%, 30% and 40% PEG. There were 25 treatment combinations. Each treatment was repeated three times (75 experimental units). The results showed that Uva Buya and Jahara cultivars had a high tolerance for PEG which was characterized by the maximum growth potential, germination power above 85%, and germination time in less than 4 days with the treatment of 40% PEG concentration. Meanwhile, Pau Tau Leru, Buncaili, and Kalendeng cultivars were able to grow and germinate well up to 10% PEG concentration. Both Uva Buya and Jahara cultivars also had a longer and heavier plumule and radicle, and larger roots.

Identifying genes associated with abiotic stress tolerance suitable for CRISPR/Cas9 editing in upland rice cultivars adapted to acid soils.

Five genes of large phenotypic effect known to confer abiotic stress tolerance in rice were selected to characterize allelic variation in commercial Colombian tropical japonica upland rice cultivars adapted to drought-prone acid soil environments (cv. Llanura11 and Porvenir12). Allelic variants of the genes ART1, DRO1, SUB1A, PSTOL1, and SPDT were characterized by PCR and/or Sanger sequencing in the two upland cultivars and compared with the Nipponbare and other reference genomes. Two genes were identified as possible targets for gene editing: SUB1A (Submergence 1A), to improve tolerance to flooding, and SPDT (SULTR3;4) (SULTR-like Phosphorus Distribution Transporter), to improve phosphorus utilization efficiency and grain quality. Based on technical and regulatory considerations, SPDT was targeted for editing. The two upland cultivars were shown to carry the SPDT wild-type (nondesirable) allele based on sequencing, RNA expression, and phenotypic evaluations under hydroponic and greenhouse conditions. A gene deletion was designed using the CRISPR/Cas9 system, and specialized reagents were developed for SPDT editing, including vectors targeting the gene and a protoplast transfection transient assay. The desired edits were confirmed in protoplasts and serve as the basis for ongoing plant transformation experiments aiming to improve the P-use efficiency of upland rice grown in acidic soils.

Integrated genetic analysis of leaf blast resistance in upland rice: QTL mapping, bulked segregant analysis and transcriptome sequencing.

Elite upland rice cultivars have the advantages of less water requirement along with high yield but are usually susceptible to various diseases. Rice blast caused by Magnaporthe oryzae is the most devastating disease in rice. Identification of new sources of resistance and the introgression of major resistance genes into elite cultivars are required for sustainable rice production. In this study, an upland rice genotype UR0803 was considered an emerging source of blast resistance. An F2 mapping population was developed from a cross between UR0803 and a local susceptible cultivar Lijiang Xintuan Heigu. The individuals from the F2 population were evaluated for leaf blast resistance in three trials 7 days after inoculation. Bulked segregant analysis (BSA) by high-throughput sequencing and SNP-index algorithm was performed to map the candidate region related to disease resistance trait. A major quantitative trait locus (QTL) for leaf blast resistance was identified on chromosome 11 in an interval of 1.61-Mb genomic region. The candidate region was further shortened to a 108.9-kb genomic region by genotyping the 955 individuals with 14 SNP markers. Transcriptome analysis was further performed between the resistant and susceptible parents, yielding a total of 5044 differentially expressed genes (DEGs). There were four DEGs in the candidate QTL region, of which, two (Os11g0700900 and Os11g0704000) were upregulated and the remaining (Os11g0702400 and Os11g0703600) were downregulated in the susceptible parent after inoculation. These novel candidate genes were functionally annotated to catalytic response against disease stimulus in cellular membranes. The results were further validated by a quantitative real-time PCR analysis. The fine-mapping of a novel QTL for blast resistance by integrative BSA mapping and transcriptome sequencing enhanced the genetic understanding of the mechanism of blast resistance in upland rice. The most suitable genotypes with resistance alleles would be useful genetic resources in rice blast resistance breeding.

Stem lodging parameters of main culm and primary tiller of upland rice cultivars as affected by nitrogen fertilizer rates

The Ceylon Journal of Science is a peer-reviewed journal published quarterly by the University of Peradeniya, Sri Lanka in March, June, September and December. It is aimed at publishing high quality research articles on topics related to different disciplines in Science. The journal accepts original research articles, book reviews, reviews and mini-reviews, short communications, opinions, research notes, and commentaries and notes. The Journal has its own website https://site.pdn.ac.lk/cjs/. The journal strictly adheres to publication ethics as emphasized by the Committee on Publication Ethics (COPE). It is indexed in Sri Lanka Journals Online (SLJOL), Directory of Open Access Journals (DOAJ), Google Scholar and Zoological Records. According to the Google Scholar;H5-Index: 12H5-Median: 15According to the Exaly (1970 – 2021);Impact Factor: 0.6 (top 19%)Extended IF: 0.6 (top 19%)H-Index: 8 (top 28%)Citations/paper: 1.42