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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. [ABSTRACT FROM AUTHOR]

The identification of effective specialized DNA markers providing the clear control of target locus inheritance by the trait of submergence tolerance has been conducted. Among the studied set of microsatellite markers, two the most informative SSR-markers - RM 7481, PrC3 showed high efficiency in detecting intraspecific polymorphism of rice varieties and lines used in the work. With the use of these markers the clear genotype marking the obtained hybrid rice plants by this trait has been conducted and it is has been verified by phenotype evaluation as a result of laboratory trials. The plant samples carrying the target gene in heterozygous and homozygous state has been selected. About 400 backcrossed self-pollinated rice lines with introgressed and pyramided resistance genes Pi-1, Pi-2, Pi-33, Pi-ta, Pi-b to Pyricularia oryzae Cav. were obtained within the frameworks of program to develop genetic rice sources resistant to blast. The conducted testing for resistance to blast and the assessment by economically valuable traits have allowed to select the prospective rice samples. The plant samples of F2 and BC1F1 generations with combination of resistance to blast genes (Pi) and submergence tolerance gene (Sub1A) in homozygous and heterozygous state that is confirmed be the results of analysis of their DNA have been obtained. The obtained hybrid plants are being tested in breeding nurseries for a complex of economically valuable traits. The best plants will be selected and send to State Variety Testing system. Their involving in rice industry will reduce the use of plant protection chemicals against diseases and weeds, thereby increasing the ecology status of the rice industry. [ABSTRACT FROM AUTHOR]

This study examines the relationship between yields of modern rice varieties and warming temperatures. Data from a long‐running farm‐level survey in the Philippines, with rich information on planted rice varieties, allow us to estimate fixed effect econometric models of rice yields. We find that increases in temperature, especially minimum temperatures, have statistically significant negative impacts on rice yields. Point estimates of the marginal effect of higher temperatures on rice yields indicate that early modern varieties bred primarily for higher yields, pest resistance, and/or grain quality traits (i.e., not necessarily abiotic stress tolerance) tend to be more resilient to heat events than traditional rice varieties. Moreover, the marginal effect point estimates also suggest that more recent rice varieties bred for better tolerance to abiotic stresses are likely more resilient to warming than both traditional varieties and early modern varieties. Notwithstanding the heat resilience pattern suggested by these point estimates, we are unable to find statistically significant differences in the marginal yield response to warming across these three rice varietal groups. These results provide suggestive evidence that rice breeding efforts have improved resilience to warming temperatures and point to several interesting future research directions. [ABSTRACT FROM AUTHOR]

Paddy is one of the most important crops in shifting agriculture in North-East India where rice is the staple food. The rich collection of traditional paddy seeds enables farmers to cultivate paddy across a range of soil and climatic conditions as fields shift from one place to another. In the present study, as many as 40 different varieties of paddy were found to be in use in two villages belonging to the Inpui tribe. This paper details the process by which farmers have come to develop such a highly diverse collection of seeds. It focusses on a traditional process, locally known as =barom nu' by which new breeds of paddy are identified, bred and propagated. As paddy is a self-pollinating plant there is little scope for hybrid varieties to emerge from cross pollination. New variants arise due to genetic mutation in the plant triggered by the environment. Farmers are able to identify new variants due to their in-depth knowledge of paddy. The new variant is harvested and sown separately for a few years to ensure purity of seed after which it is introduced to the village. The study is based on an intensive fieldwork carried out in two Inpui villages of Tamenglong district, Manipur in 2014-15. [ABSTRACT FROM AUTHOR]

Genetic diversity of rice cultivars offers adequate opportunity for added advantage for rice improvement. Current study with 132 traditional rice cultivars had been collected from West Bengal, Manipur and Assam. Those cultivars are being preserved at repository of Uttar Banga Krishi Viswavidyalaya since 2009. Few of them had used in breeding programme to develop new desirable variety with unique characteristics. Those traditional cultivars were phenotypically characterized using PPV&FRA descriptor. In this piece of work, 44 traits were considered to record the morphological differences among the traditional cultivars. All the traditional cultivars showed one or few distinctive features that made different from each other. Finally the traditional cultivars were classified based few anticipated distinctive characters. Amylose content in endosperm was very low in ten, low in twelve, medium in 61 and high in 49 traditional cultivars. Amylose content of milled rice is a significant parameter in respect of consumer preference. Under Indian context, consumers prefer rice with medium amylose content (20-25%) in the endosperm. Strong aroma was emitted by 25, mild aroma by 23 and no aroma in 84 cultivars. [ABSTRACT FROM AUTHOR]

Leaf senescence is one of the most precisely modulated developmental process and affects various agronomic traits of rice. Anti-senescence rice varieties are important for breeding application. However, little is known about the mechanisms underlying the metabolic regulatory process of leaf senescence in rice. In this study, we performed transcriptomic and metabolomic analyses of the flag leaves in Yuenong Simiao (YN) and YB, two indica rice cultivars that differ in terms of their leaf senescence. We found 8524 genes/204 metabolites were differentially expressed/accumulated in YN at 30 days after flowering (DAF) compared to 0 DAF, and 8799 genes/205 metabolites were differentially expressed in YB at 30 DAF compared to 0 DAF. Integrative analyses showed that a set of genes and metabolites involved in flavonoid pathway were significantly enriched. We identified that relative accumulation of PHENYLALANINE AMMONIA-LYASE (PAL), CINNAMATE 4-HYDROXYLASE (C4H), 4-COUMAROYL-COA LIGASE (4CL), CHALCONE SYNTHASE (CHS) and CHALCONE ISOMERASE (CHI) in YN30/0 was higher than that in YB30/0. Three flavonoid derivatives, including phloretin, luteolin and eriodictyol, showed lower abundances in YB than in YN at 30 DAF. We further revealed a MYB transcription factor, which is encoded by OsR498G0101613100 gene, could suppress the expression of CHI and CHS. Our results suggested a comprehensive analysis of leaf senescence in a view of transcriptome and metabolome and would contribute to exploring the molecular mechanism of leaf senescence in rice. [ABSTRACT FROM AUTHOR]

Increasing trends in the occurrence of diabetes underline the need to develop low glycemic index (GI) rice with preferred grain quality. In the current study, a diverse set of 3 K sub-panel of rice consisting of 150 accessions was evaluated for resistant starch and predicted glycemic index, including nine other quality traits under transplanted situation. Significant variations were noticed among the accessions for the traits evaluated. Trait associations had shown that amylose content possess significant positive and negative association with resistant starch and predicted glycemic index. Genome-wide association studies with 500 K SNPs based on MLM model resulted in a total of 41 marker-trait associations (MTAs), which were further confirmed and validated with mrMLM multi-locus model. We have also determined the allelic effect of identified MTAs for 11 targeted traits and found favorable SNPs for 8 traits. A total of 11 genes were selected for haplo-pheno analysis to identify the superior haplotypes for the target traits where haplotypes ranges from 2 (Os10g0469000-GC) to 15 (Os06g18720-AC). Superior haplotypes for RS and PGI, the candidate gene Os06g11100 (H4-3.28% for high RS) and Os08g12590 (H13-62.52 as intermediate PGI). The identified superior donors possessing superior haplotype combinations may be utilized in Haplotype-based breeding to developing next-generation tailor-made high quality healthier rice varieties suiting consumer preference and market demand. [ABSTRACT FROM AUTHOR]

Wild relatives of rice in the genus Oryza (composed of 24 species with 11 different genome types) have been significantly contributing to the varietal improvement of rice (Oryza sativa). More than 4000 accessions of wild rice species are available and they are regarded as a "genetic reservoir" for further rice improvement. DNA markers are essential tools in genetic analysis and breeding. To date, genome-wide marker sets for wild rice species have not been well established and this is one of the major difficulties for the efficient use of wild germplasm. Here, we developed 541 genome-wide InDel markers for the discrimination of alleles between the cultivated species O. sativa and the other seven AA-genome species by positional multiple sequence alignments among five AA-genome species with four rice varieties. The newly developed markers were tested by PCR-agarose gel analysis of 24 accessions from eight AA genome species (three accessions per species) along with two representative cultivars (O. sativa subsp. indica cv. IR24 and subsp. japonica cv. Nipponbare). Marker polymorphism was validated for 475 markers. The number of polymorphic markers between IR24 and each species (three accessions) ranged from 338 (versus O. rufipogon) to 416 (versus O. longistaminata) and the values in comparison with Nipponbare ranged from 179 (versus O. glaberrima) to 323 (versus O. glumaepatula). These marker sets will be useful for genetic studies and use of the AA-genome wild rice species. [ABSTRACT FROM AUTHOR]

Badshah Bhog is a non basmati aromatic traditional rice cultivar. which is not widely cultivated due to some unfavourable traits which were relatively high plant height, late maturity and low average yield. By the utilization of gamma ray irradiation in plant breeding attempted to overcome such problems in crops. The objective of this research is to observe and select M2 mutants of Badshah Bhog from gamma ray irradiation and obtain early maturing short stature plants. The research was conducted by Line sowing method. Established experimental plots for every irradiation doses and comparing the treatment result with the control to identify the effect of irradiation on the growth of Badshah Bhog. The result showed that there have been several plants with potential mutant traits supported the positive and negative character of every individual. The irradiated dose of 300 Grays has the shortest maturity duration of 131 days with the highest productive tiller of 6.67 but very low as compared to control. The irradiated dose of 400 Grays has the shortest Plant height of 97.8 cm. The plant yield of mutant lines in the present study was not affected significantly in any direction which could due to occurrence of polygenic mutations with 'plus' and 'minus' effect equally distributed. Together with short stature plants also plants bearing double spikelet at tip and mid region of panicle observed. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination of rice is a serious food safety issue that has recently been gaining significant public attention. Therefore, reduction of Cd accumulation in rice grains is an important objective of rice breeding. The use of favourable alleles of Cd accumulating genes using marker-assisted selection (MAS) is theoretically feasible. In this study, we validated a segment covering OsHMA3-OsNramp5-OsNramp1 on chromosome 7 of japonica for establishing low-cadmium accumulating indica rice variety. The OsHMA3-OsNramp5-OsNramp1jap haplotype significantly decreased grain Cd concentration in middle-season indica genetic background. The improved 9311 carrying the OsHMA3-OsNramp5-OsNramp1jap haplotype with recurrent parent genome recovery of up to 91.6% resulted in approximately 31.8% decrease in Cd accumulation in the grain and with no penalty on yield. There is a genetic linkage-drag between OsHMA3-OsNramp5-OsNramp1 jap and the gene conditioning heading to days (HTD) in the early-season indica genetic background. Because the OsHMA3-OsNramp5-OsNramp1-Ghd7jap haplotype significantly increases grain Cd concentration and prolongs growth duration, the linkage-drag between OsHMA3-OsNramp5-OsNramp1 and Ghd7 should be broken down by large segregating populations or gene editing. A novel allele of OsHMA3 was identified from a wide-compatibility japonica cultivar, the expression differences of OsNramp1 and OsNramp5 in roots might contribute the Cd accumulating variation between japonica and indica variety. [ABSTRACT FROM AUTHOR]

Under the present study, assessment of genetic variability of 60 numbers of rice landraces was carried out under morphological and molecular level for selection of promising drought tolerant genotypes under upland ecosystem of North East India. Predominance of additive gene action on characters like leaf rolling index, root: culm ratio, grain yield and other yield contributing traits like plant height came out as effective parameters for selection of drought stress tolerant landraces. Molecular analysis revealed moderate genetic diversity with average Polymorphic Information Content values of 0.44 across the rice landraces. No specific clustering patterns of landraces against some morphological traits numbers of productive tillers per plant, numbers of filled grains per plant etc were found. This signifies the polygenic nature of the quantitative characters and influence of environment on them. Precise correlation between the morphological performance of the landraces and their clustering pattern under molecular analysis was found to be effective in identifying suitable landraces like Chikanswarikabar as a promising parent for future breeding programme and also to formulate efficient strategies for sustainable management of rice landraces under rain fed ecosystem. [ABSTRACT FROM AUTHOR]

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The major constraints in hybrid rice breeding are availability of limited number of parental lines with specific desirable traits and lower frequency of restorers among elite breeding lines. The popular, high-yielding mega-rice variety Swarna, has been identified to be a partial restorer (as it has only one of major fertility restorer genes, Rf4) and hence cannot be utilized directly in the hybrid rice breeding. To convert the partial restorer to complete restorer, a cross was made between Swarna and a stable restorer KMR3R possessing Rf3 and Rf4 genes and developed BC1F5 and BC2F4 populations by marker-assisted back cross breeding (MABB). The SSR marker DRRM-RF3-10 linked to Rf3 gene located on chromosome 1, clearly distinguished restorers from partial restorers. All the improved lines of Swarna possessing Rf3 and Rf4 genes showed complete fertility restoration in test crosses with higher grain yield heterosis. Few rice hybrids developed by using converted restorers were evaluated in multi location testing under the All India Co-ordinated Rice Improvement Project (AICRIP). The results indicated that new rice hybrids expressed higher heterosis with matching grain quality attributes like Swarna. This study provides significantly novel and relevant restorers to enhance and economize future hybrid rice breeding programs. [ABSTRACT FROM AUTHOR]

Identification of Quantitative Trait Loci (QTL) has been a challenge for complex traits due to the use of populations with narrow genetic base. Most of QTL mapping studies were carried out from crosses made within the subspecies, either indica × indica or japonica × japonica. In this study we report advantages of using Multi-parent Advanced Generation Inter-Crosses global population, derived from a combination of eight indica and eight japonica elite parents, in QTL discovery for yield and grain quality traits. Genome-wide association study and interval mapping identified 38 and 34 QTLs whereas Bayesian networking detected 60 QTLs with 22 marker-marker associations, 32 trait-trait associations and 65 marker-trait associations. Notably, nine known QTLs/genes qPH1/OsGA20ox2, qDF3/OsMADS50, PL, QDg1, qGW-5b, grb7-2, qGL3/GS3, Amy6/Wx gene and OsNAS3 were consistently identified by all approaches for nine traits whereas qDF3/OsMADS50 was co-located for both yield and days-to-flowering traits on chromosome 3. Moreover, we identified a number of candidate QTLs in either one or two analyses but further validations will be needed. The results indicate that this new population has enabled identifications of significant QTLs and interactions for 16 traits through multiple approaches. Pyramided recombinant inbred lines provide a valuable source for integration into future breeding programs. [ABSTRACT FROM AUTHOR]

Genetic erosion refers to the loss of genetic variation in a crop. In China, only a few original landraces of rice (Oryza sativa) were used in breeding and these became the primary genetic background of modern varieties. Expanding the genetic diversity among Chinese rice varieties and cultivating high-yielding and high-quality varieties with resistance to different biotic and abiotic stresses is critical. Here, we used the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein9(Cas9) genome editing system to edit Semi-Dwarf1 (SD1) in the elite landraces Kasalath and TeTePu (TTP), which contain many desired agronomic traits such as tolerance to low phosphorous and broad-spectrum resistance to several diseases and insects. Mutations of SD1 confer shorter plant height for better resistance to lodging. Field trials demonstrated that the yield of the new Kasalath and TTP mutant lines was better than that of the wild type under modern cultivation and that the lines maintained the same desirable agronomic characteristics as their wild-type progenitors. Our results showed that breeding using available landraces in combination with genomic data of different landraces and gene-editing techniques is an effective way to relieve genetic erosion in modern rice varieties. [ABSTRACT FROM AUTHOR]

Glutinous cytoplasmic male sterile (CMS) line is necessary to select hybrid glutinous rice combination with high yield and quality. To develop glutinous CMS with low amylose content, in this study, we firstly knocked out the granule-bound starch synthase OsWaxy in 209B using CRISPR/Cas9 mediated genome editing technology and successfully obtained a glutinous maintainer line WX209B. Comparing with maintainer line 209B, WX209B showed decreased amylose contents and similar agronomic characters. And then, through one generation of hybridization and two generations of backcrossing with WX209B as the male parent and 209A as the female parent, the glutinous CMS line WX209A was successfully achieved. Our study provides a strategy to efficiently breed for the glutinous cytoplasmic male sterile line by combining CRISPR/Cas9-mediated gene editing technology with conventional backcross breeding method in a short period, which prepares the ground for further breeding of hybrid glutinous rice variety. [ABSTRACT FROM AUTHOR]

A study which identified a rice gene, HIS1 (hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor sensitive 1), that confers resistance to benzobicyclon and other beta-triketone herbicides indicating its usefulness for breeding herbicide-resistant crops, is presented. Topics covered include how HIS1 detoxifies betatriketone herbicides, allele inherited by BBC-sensitive rice variants and outcome of the forced expression of HIS1 in Arabidopsis.

Commercial application of nuclear genetic male sterility has been improved recently by a novel technique, Seed Production Technology (SPT), which incorporates transgenic maintainer lines capable of propagating non‐transgenic nuclear male‐sterile lines for use as female parents in hybrid production. Here, we identified a rice nuclear male‐sterile mutant, Oswbc11, with abnormal pollen development and lipid transport. We finely mapped the Oswbc11 gene into a 12.5‐kb region on chromosome 10 and found one candidate gene, which had a base substitution (C to T) resulting in a premature stop codon and was functionally confirmed by CRISPR/Cas9 technology. Gene OsWBC11 encodes a sub‐family member of adenosine triphosphate‐binding cassette transporter, which participates in the active transport of a wide range of molecules across membranes. Moreover, the agronomic traits of Oswbc11 mutants showed no significant differences compared to the wild‐type control except for the seed setting rate. These results indicated that Oswbc11 gene could be used in rice hybrid breeding as a recessive nuclear male‐sterile gene combined with CRISPR/Cas9 and the SPT technology and applied in different rice varieties. [ABSTRACT FROM AUTHOR]

Summary: Selenium (Se) is an essential trace element for humans and other animals, yet approximately one billion people worldwide suffer from Se deficiency. Rice is a staple food for over half of the world's population that is a major dietary source of Se. In paddy soils, rice roots mainly take up selenite. Se speciation analysis indicated that most of the selenite absorbed by rice is predominantly transformed into selenomethinone (SeMet) and retained in roots. However, the mechanism by which SeMet is transported in plants remains largely unknown. In this study, SeMet uptake was found to be an energy‐dependent symport process involving H+ transport, with neutral amino acids strongly inhibiting SeMet uptake. We further revealed that NRT1.1B, a member of rice peptide transporter (PTR) family which plays an important role in nitrate uptake and transport in rice, displays SeMet transport activity in yeast and Xenopus oocyte. The uptake rate of SeMet in the roots and its accumulation rate in the shoots of nrt1.1b mutant were significantly repressed. Conversely, the overexpression of NRT1.1B in rice significantly promoted SeMet translocation from roots to shoots, resulting in increased Se concentrations in shoots and rice grains. With vascular‐specific expression of NRT1.1B, the grain Se concentration was 1.83‐fold higher than that of wild type. These results strongly demonstrate that NRT1.1B holds great potential for the improvement of Se concentrations in grains by facilitating SeMet translocation, and the findings provide novel insight into breeding of Se‐enriched rice varieties. [ABSTRACT FROM AUTHOR]

Despite evidence from previous case studies showing that agronomic traits partially determine the resulting yield of different rice (Oryza sativa L.) varieties, it remains unclear whether this is true at the ecotype level. Here, an extensive dataset of the traits of 7686 rice varieties, released in China from 1978 to 2017, was used to study the relationship between yield and other agronomic traits. We assessed the association between yield and other agronomic traits for four different rice ecotypes, i.e., indica inbred, indica hybrid, japonica inbred, and japonica hybrid. We found that associations between agronomic traits and yield were ecotype-dependent. For both the indica inbred and indica hybrid ecotypes, we found that greater values of certain traits, including the filled grain number per panicle, 1000-grain-weight, plant height, panicle length, grains per panicle, seed setting rate, long growth period, low panicle number per unit area, and low seed length/width ratio, have accounted for high grain yield. In the japonica inbred and japonica hybrid ecotypes, we found that only high panicle number per unit area and long growth period led to high grain yield. Indirectly, growth period consistently had a positive effect on yield in all ecotypes, and plant height had a positive effect on yield for the indicas and japonica inbred only. Plant height had a negative effect for the japonica hybrid. Altogether, our findings potentially have valuable implications for improving the breeds of rice ecotypes. [ABSTRACT FROM AUTHOR]

The Magnaporthe oryzae avirulence gene AvrPib is required for the resistance mediated by its cognate resistance gene Pib, which has been intensively used in indica rice breeding programs in many Asian countries. However, the sequence diversity of AvrPib among geographically distinct M. oryzae populations was recently shown to be increasing. Here, we selected a field population consisting of 248 rice blast isolates collected from a disease hotspot in Philippine for the analysis of AvrPib haplotypes and their pathogenicity against Pib. We found that all of the isolates were virulent to Pib and each of them contained an insertion of Pot3 transposon in AvrPib. Moreover, Pot3 insertion was detected in different genomic positions, resulting in three different AvrPib haplotypes, designated avrPib-Hl to H3. We further conducted a genome-wide Pot2 fingerprinting analysis by repetitive element palindromic polymerase chain reaction (PCR) and identified seven different lineages out of 47 representative isolates. The isolates belonging to the same lineage often had the same AvrPib haplotype. In contrast, the isolates having the same AvrPib haplotypes did not always belong to the same lineages. Both mating types MAT1-1 and MAT1-2 were identified in the population in Bohol and the latter appeared dominant. On the host side, we found that 32 of 52 released rice varieties in the Philippines contained Pib diagnosed by PCR gene-specific primers and DNA sequencing of gene amplicons, suggesting that it was widely incorporated in different rice varieties. Our study highlights the genetic dynamics of rice blast population at both the AvrPib locus and the genome-wide levels, providing insight into the mechanisms of the mutations in AvrPib leading to the breakdown of Pi/j-mediated resistance in rice. [ABSTRACT FROM AUTHOR]

'Asemi1' is a rice variety derived from a cross between ‘IR71667’, which has a Jinmibyeo background with a long basic vegetative phase, and ‘IR77863’, which has a Shinunbongbyeo background with a high yield and early maturity, by the rice breeding team at NICS, RDA, in 2014. The heading date of ‘Asemi1’ is July 29, 14 days earlier than that of the check variety ‘Hwaseong’. It has a culm length of 84 cm and 110 spikelets per panicle. ‘Asemi1’ is resistant to blast disease, but susceptible to other viruses and planthoppers. The milled rice of this variety exhibits translucent, clear non-glutinous endosperm and a short grain shape. The protein content (7.3%) was higher than that of ‘Hwaseong’, and the amylose content (19.6%) was similar to that of ‘Hwaseong’. The milled rice recovery rate of ‘Asemi1’ was similar to that of ‘Hwaseong’. However, the head rice rate of ‘Asemi1’ was lower than that of ‘Hwaseong’. The milled rice yield of ‘Asemi1’ was 5.92 MT/ha, which was higher than that of ‘Hwaseong’ in ordinary cultivation. ‘Asemi1’ was suitable for adaptation to a wide region of tropical Asia (Registration No. 6809). [ABSTRACT FROM AUTHOR]

Highlights • The projected increase in nighttime air temperatures could reduce rice yields through impairing biochemical and physiological processes. • We quantified the effects of projected day/night temperatures (TTs) on carbon assimilation and photosystem mechanisms in two rice cultivars. • Carbon assimilation and photosystem mechanisms along with other physiological parameters varied under changing day/night temperatures. • Cultivar Rex exhibited significantly higher dark respiration, and pigment contents but lower J max than IR6 across TTs. • The information could be useful for developing breeding tools to enhance thermotolerance in US rice cultivars for future climatic conditions. Abstract Ambient temperature has a profound effect on agricultural production. Generally, sub- and supra-optimal temperatures have a negative effect on growth/yield, provided the deviation for optimal is large enough. On average, mean global temperatures are projected to increase by 0.3 to 0.6 °C per decade over the next century. Nighttime temperatures (T N) are projected to increase faster (20%–40% by 2100) than day maximum temperatures (T D). Therefore, an experiment was conducted to determine the effects of projected sub- and supra-optimal day/night temperatures on two diverse rice (Oryza sativa) cultivars, IR6 and Rex, during reproductive growth. At flowering, nine different day/night temperature treatments (TTs) were imposed and maintained until harvesting using sunlit growth chambers (SPAR units). Alterations to plant metabolism were evaluated using CO 2 response functions, also, to survey gas exchange readings under ambient conditions. Net photosynthesis (A N) declined under both T D and T N effects. The decline in maximum carboxylation rate allowed by Rubisco (V cmax) and maximal rate of electron transport allowed by the thylakoid reactions (J max), with increasing T N mainly contributed to the decline in A N. Dark respiration rates (R D) declined with increasing temperatures could be a cultivars acclimation mechanism to prevent excessive carbon losses. Cultivars varied mainly for primary photochemistry, with cultivar Rex exhibited significantly higher R D , and pigment contents but lower J max than IR6 across TTs. The information on genetic, biochemical and physiological processes in these two diverse cultivars under varied temperature regimes could be useful for developing breeding tools to enhance thermotolerance in US rice cultivars for future climatic conditions. [ABSTRACT FROM AUTHOR]

‘Hyowon 3’, a medium-maturing glutinous rice variety was developed by the rice breeding team of Pusan National University in 2013. This cultivar was developed from a cross between ‘Hongna’ which is a landrace from the Korean peninsula showing good glutinous properties, and ‘Junam’, which has stable productivity. During the F3 –F8 generations, breeding lines were selected using a pedigree breeding method. As a result, the promising line (JS24-6-95-11-5-2-1-1-1-B) with good glutinous properties was advanced and designated as ‘SP 107’. This variety headed on Aug. 16, which is 3 days later than ‘Dongjinchal’ in the middle plane. The average culm length and panicle length of this variety were 80.7 cm and 20.1 cm, respectively. This variety yielded approximately 14.1 tillers per hill and 104 spikelets per panicle. The ratio of ripened grain was about 93.0%, and the 1,000-grain weight was 19.30 g in brown rice. The yield performance was 492 kg/10a in a local adaptability test. [ABSTRACT FROM AUTHOR]

‘Jinkwang’, a japonica rice variety, was developed by a cross between ‘Hopum’ (IT23527) and the F1 hybrid of ‘Unkwang’ (IT217814) and ‘Koshihikari’ (IT157335) by the rice breeding team at NICS in 2016. ‘Unkwang’ shows an early maturity and high yield and ‘Koshihikari’ is a high-quality variety. The growth duration of ‘Jinkwang’ in the paddy field was 114 days in the middle plain region in Korea, which was six days later than that of ‘Jopyeong’. The culm length of ‘Jinkwang’ was 62 cm, which was 13 cm shorter than that of ‘Jopyeong’. The panicle of ‘Jinkwang’ was composed of 100 spikelets. The viviparous germination rate of ‘Jinkwang’ was 28.3%. ‘Jinkwang’ showed resistance to blast and bacterial blight (K1, K2, and K3 races); however, it was susceptible to stripe virus, dwarf and black-streaked dwarf viruses, and plant hoppers. The milled rice grains of ‘Jinkwang’ showed an excellent palatability index (0.42) and lower protein content (6.2%) than that of ‘Jopyeong’. The grain milling characteristics were better than those of ‘Jopyeong’, especially in terms of brown/rough rice ratio and milled/rough rice ratio (75.9%). ‘Jinkwang’ showed a milled rice productivity of 5.91 MT/ha at eight sites under ordinary cultivation conditions. (Registration No. 7318). [ABSTRACT FROM AUTHOR]

‘Jungmo1033’, a japonica rice variety, was developed by the rice breeding team at the National Institute of Crop Science (NICS) in 1992. It is derived from a cross between a native variety ‘Jagwangdo’, which has translucent milled rice and medium maturity; and ‘Hwayeong’, which is an elite line with bacterial blight resistance and mid-late maturity. The heading date of ‘Jungmo1033’ was August 10 in the middle plain area of Korea, which was two days later than that of ‘Hwaseong’. ‘Jungmo1033’ has a culm length of 79 cm, which was 5 cm shorter than that of ‘Hwaseong’, and 105 spikelets per panicle. ‘Jungmo1033’ showed resistance to bacterial blight (K1, K2, and K3 races) and stripe virus, but susceptibility to the K3a race of bacterial blight, dwarf and black-streaked dwarf viruses, and planthoppers. The milled rice of this variety exhibited translucency and a medium short grain shape. It had an excellent appearance and lower amylose content (19.1%) than that of ‘Hwaseong’. The characteristics related to grain milling were better than those of ‘Hwaseong’, especially head rice milling recovery ratio and head rice ratio (94.8%). ‘Jungmo1033’ showed a milled rice productivity of 5.38 MT/ha at 11 sites under ordinary cultivation conditions. (Registration No. 5723) [ABSTRACT FROM AUTHOR]

Phytic acid (PA) is considered as antinutrient in food and feed. Several low phytic acid (lpa) rice (Oryza sativa L.) mutants have been generated through induced mutation. Lpa mutant lines often exhibit inferior agronomic performance, and cross-breeding is applied to minimize these effects. The impact of such crossing steps on the PA contents in the resulting progenies is unknown. Therefore, three lpa rice mutants differing in mutation type were crossed with commercial rice cultivars, and PA contents in the progenies were determined for various generations grown at different locations. The PA contents of the lpa progenies were differently expressed for the investigated mutation-types and were dependent on environment and/or PA contents of the crossing parents. Nevertheless, for all three mutants, the homozygous lpa progenies always displayed significantly lower PA contents than the original wild-types subjected to the mutation. This demonstrated that cross-breeding of lpa rice mutants with commercial cultivars does not compromise the intended PA reduction and is a useful tool to obtain mutants stably expressing the intended lpa trait. [ABSTRACT FROM AUTHOR]

SUMMARY Rice is an important food crop in China, and the development of hybrid rice is a crucial way to increase grain yield. The creation of dual-purpose nuclear-sterile lines for two-line hybrid breeding has become vital for commercial rice breeding. We constructed the pC1300-2x35S::Cas9-sgRNA PTGMS2-1 expression vector for editing the male fertility gene PTGMS2-1 in two widely compatible rice varieties, 93-11 and Huazhan, by using the CRISPR/Cas9 system. We obtained the marker-free photoperiod-/thermo- sensitive genic male-sterile (P/TGMS) lines in T 1 generation. According to the experiments in phytotron with four temperature and photoperiod treatments, we found the temperature is the main factor for restoring the pollen fertility of ptgms2-1 mutants in 93-11 and Huazhan, and the photoperiod also has some effects on pollen fertility in two different rice backgrounds. The application of cultivating new male-sterile lines by genome editing system will significantly accelerate the rice breeding process. [ABSTRACT FROM AUTHOR]

Purpose: Herbicide-resistant rice varieties in combination with post-emergent broad-spectrum herbicides improve the eff ectiveness of weed management in rice fi elds. Herbicide-resistance can be acquired naturally or induced by classical or modern breeding techniques. In the present study, screening of Sri Lankan rice varieties to glufosinate was examined and attempts were made to develop glufosinate-resistant rice varieties with the help of the breeding technique, mutagenesis. Research Method: Natural glufosinate-resistance was studied in seven (7) traditional and eighteen (18) inbred rice varieties under 0.27, 0.30 and 0.33 kg ha -1 glufosinate concentrations. Induced glufosinateresistance in seed-derived calli of four glufosinate-susceptible rice varieties using Ethyl Methane Sulfonate was also observed and these were then treated with 0.2% (v/v) glufosinateto to determine induced glufosinate-resistance in seed-derived calli. Findings: Two traditional varieties (Pachchaperumal, Ma Wee) and fi fteen inbred varieties (At362, Bg250, Bg300, Bg352, Bg357, Bg358, Bg359, Bg360, Bg366, Bg369, Bg379/2, Bg403, Bg450, Bg454, and Bg94-1) were resistant to glufosinate. Hardly any distinct yield penalty in Bg94-1, Bg403, Bg454, Bg379-2 and Ma Wee was observed under all glufosinate concentrations. Visual symptoms and chlorophyll damages caused by glufosinate for all varieties recovered within 14 days of treatment. Higher glufosinate-resistance was observed in EMS-mutated calli derived from seeds of naturally glufosinatesusceptible varieties. Molecular (AFLP) analysis confirmed in vitromutation and theM31E10 primer combination was a potential AFLP marker to identify glufosinate-resistance in rice varieties. Research Limitation: The study reports the results of screening natural and induced glufosinateresistance in Sri Lankan rice. Inheritance of glufosinate-resistance is to be tested through several generations in Sri Lankan rice varieties. Original Value: Study provides a screening method applicable to Sri Lankan Rice varieties in identification of herbicide-resistance to permitted concentrations of glufosinate. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Early duration rice variety, VL Dhan 158 was developed by ICAR-Vivekananda Parvatiya Krishi Anusandhan Sansthan(VPKAS),Almora, Uttarakhand for cultivation under rainfed upland conditions of Uttarakhand and Himachal Pradesh during Kharif season. This variety was notified and released in 2017 by the Central Sub-Committee on Crop Standards Notification and Release of Variety for Agricultural Crops.VL Dhan 158 is derived from the cross RCPL 1-45 x VL 3861 with maturity duration of 110- 120 days. This has intermediate plant height, semi-erect panicle mostly exerted and plants are nonlodging. This variety has recordedaverage grain yield of 2,386 kg/ha in comparison to national check, Vivek Dhan 154 (1,722 kg/ha); regional check, Sukradhan1 (2,115 kg/ha) and Local check (1,905 kg/ha) with yield advantage of 38.53, 12.78 and 25.26 per cent, respectively, over these checks. It has exhibited high head rice recovery of 66.2%,intermediate ASV (4.0) and amylose content of 24.44%.It has shown resistance to brown spot(Cochliobolus miyabeanus) and blast(Magnaporthe grisea), the most serious disease of upland rice in Northern hill. [ABSTRACT FROM AUTHOR]

Abstract In order to help mitigate widespread cadmium (Cd) and arsenic (As) co-contamination in paddy soils in China, screening and breeding of low-accumulating rice ( Oryza sativa L.) cultivars (excluders) have been widely adopted. However, the performance of rice cultivars for grain Cd and As accumulation may vary in different growing environments. The inability to identify stable low-accumulating cultivars has largely hindered their application. In this study, 51 rice cultivars were evaluated at four Cd- and As-contaminated paddy sites in two crop seasons in northern Guangdong Province, China. The aim was to investigate the effects of cultivar, environment and their interactions in determining grain Cd and As concentrations, and so to identify stable low-accumulating cultivars. Results showed that environment effects dominated the Cd and As concentrations in rice grains, explaining 87% of the total variations. The crop season played a vital role; compared to early season, grain Cd levels increased and As levels lowered significantly in late season. Large variations in grain Cd, total As, inorganic As concentrations and the percentage of inorganic As were observed between different cultivars. Conventional japonica cultivars exhibited lower Cd levels but higher As levels in the grains than did indica cultivars. The cultivar × environment interaction (CEI) was significant, and its importance was comparable to the cultivar effect. By measuring and interpreting such an interaction, stable Cd and As excluder cultivars were identified based upon the yield, grain Cd and As levels as well as the stabilities of cultivars across the trial environments. Two stable Cd and As co-excluders were found among the hybrid indica cultivars. These results demonstrated that the variations in grain Cd and As concentrations could mainly be attributed to the environment effects and cultivar selection practices should include the analysis of CEI to identify stable low-accumulating rice cultivars. Graphical abstract Unlabelled Image Highlights • The environment and crop season are crucial in determining grain Cd and As. • Two hybrid indica cultivars exhibited stable Cd and As co-exclusion. • Stable excluders could be identified by analyzing cultivar × environment interaction. [ABSTRACT FROM AUTHOR]

In this study, we estimate increases in producer revenue, total exports, and welfare effects from the genetic gains of the rice breeding program at the University of Arkansas System (UofA) Division of Agriculture from 1983 to 2016. Rice producers are paid based on both the quantity and quality of rice. Therefore, we implement a cluster‐specific fixed‐effects model based on location and year to identify the contributions of the UofA breeding program for both paddy yields (quantity) and head rice yields (quality attribute) over time. Additionally, the estimated increased yield was imputed into the RiceFlow trade model to estimate price and export effects. Including spillover benefits from UofA varieties, we find that on average U.S. rice producers gain 30.9 million USD annually. The expansion of U.S. long grain rice exports facilitated by the UofA is estimated to be 53,000 milled metric tons annually, which is enough to lower rice prices by over 1% in low‐income countries such as Haiti, Panama, and Nicaragua. Overall, the public breeding program at the UofA contributes to (1) positive genetic gains, (2) additional revenue in the Mid‐South, and (3) increased trade between the U.S. and rice‐consuming countries. [ABSTRACT FROM AUTHOR]

IRGA 431 CL is an early rice variety, and its main characteristic is the resistance to Imidazolinones herbicides. The variety stands out for its excellent plant architecture, strong stems, high yield potential, good grain quality, and resistance to blast and high levels of toxic iron in the soil. It is recommended for exploitation in the rice fields of Rio Grande do Sul, Brazil. [ABSTRACT FROM AUTHOR]

The eefects of soil moisture content, pot seedling buried depth, and pot seedling height on the survival rate and growth of dry planted seedlings were researched by field experiment. The results showed that the seedling survival rate and growth were enhanced with the increase of soil moisture content after pot seedling transplanting, but there was no significant difference in the survival rate and growth of seedlings with 85 V and 100 V of soil moisture content. Pot seedling buried depth was one of the important factors affecting the survival rate, and when the pot seedlings were buried 2 cm deep, the seedlings showed high survival rate and excellent growth. Under the same condition of soil moisture content and buried depth, seedlings with pot seedling height of 15 cm had the best survival rate and growth. Therefore, the optimized conditions for dry-cultivated rice seedling planting were soil moisture content of 85V, pot seedling buried depth of 2 cm, and pot seedling height of 15 cm. [ABSTRACT FROM AUTHOR]

In the present study, 45 simple sequence repeat (SSR) markers distributed throughout the 12 chromosomes of rice and a gene-specific co-dominant marker for the fragrance (fgr) gene of rice were used to characterize 13 landraces collected from the adjoining areas of Bhagalpur in Bihar and 3 released rice genotypes. The number of alleles generated by each marker ranged from 2 to 4 with an average of 2.41 alleles per locus. Marker RM 489 generated maximum number of alleles (4). Polymorphic information content (PIC) varied greatly for all SSR loci ranging from 0.08 to 0.49 with average of 0.25. The highest PIC value (0.49) was obtained for RM 431, which suggests the utility of this marker for analyzing genetic diversity in rice. The constructed dendrogram showed two distinct clusters, where the major cluster (cluster I) contained 14 out of the 16 rice genotypes under study. Dice similarity coefficient was maximum between Malida and Burma Bhusi and minimum between Kalanamak and Gutraj. By using gene-specific marker for grn gene, 11 genotypes showed amplification of fragrance allele-specific band. Thus, the present study suggests that there is scope for exploitation of genetic diversity of landraces available in Bihar for future rice breeding programmes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha−1 (B1), soil application of 2 kg B ha−1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results suggest that the exogenous application of boron had a substantial effect on cell membrane stability, sugar mobilization, pollen viability, and spikelet fertility, hence the yield. The cultivars due to their variation in the tolerance level for high temperature stress behaved differently, and at high temperature stress, more response of the application of boron was seen in susceptible cultivars. [ABSTRACT FROM AUTHOR]

A set of differential isolates of Magnaporthe oryzae is needed for the postulation of blast resistance genes in numerous rice varieties and breeding materials. In this study, the pathotypes of 1,377 M. oryzae isolates from different regions of China were determined by inoculating detached rice leaves of 24 monogenic lines. Among them, 25 isolates were selected as differential isolates based on the following characteristics: they had distinct responses on the monogenic lines, contained the minimum number of avirulence genes, were stable in pathogenicity and conidiation during consecutive culture, were consistent colony growth rate, and, together, could differentiate combinations of the 24 major blast resistance genes. Seedlings of rice cultivars were inoculated with this differential set of isolates to postulate whether they contain 1 or more than 1 of the 24 blast resistance genes. The results were consistent with those from polymerase chain reaction analysis of target resistance genes. Establishment of a standard set of differential isolates will facilitate breeding for blast resistance and improved management of rice blast disease. [ABSTRACT FROM AUTHOR]

Tolerance to low temperature is an important factor affecting the growth and development of rice (Oryza sativa L.) at an early growing season in the temperate region, and at high altitudes of tropical regions. In this study, a backcross inbred line (BIL) population derived from an interspecific cross between Xieqingzao B (O. sativa L.) and an accession of Dongxiang wild rice (O. rufipogon Griff.) was used to identify quantitative trait loci (QTLs) associated with cold tolerance at the seedling stage. Seedlings were treated with a temperature of 6°C for 2 days and seedling mortality was measured for QTL mapping. QTL analysis was performed on the whole BIL population and on one subpopulation that showed Xieqingzao B homozygous at QTL detected in the whole population. One major QTL, qSCT8, and one QTL, qSCT4.3, with smaller effect was found in the whole population. The QTLs qSCT8 and qSCT4.3 were mapped on chromosome 8 and 4, explaining 60.96% and 8.83% of the phenotypic variance, respectively. In the subpopulation, three QTLs, qSCT4.1, qSCT4.2 and qSCT12, accounting for 56.22%, 57.62% and 53.09% of the phenotypic variance, respectively, were detected on chromosome 4 and 12. At all five loci, the alleles introduced from the Dongxiang wild rice were effective in decreasing seedling mortality. Our results provide a basis for fine mapping and cloning of QTLs associated with cold tolerance, and the markers linked with QTLs could be used to improve the cold tolerance of rice varieties by marker-assisted selection. [ABSTRACT FROM AUTHOR]

Key message: Shuhui498 (R498) is an elite parent of heavy panicle hybrid rice by pyramiding the rare gn1a and null gs3 alleles. This finding reveals the genetic basis and great potential application in future breeding of R498.Abstract: The heavy panicle trait, defined as 5 g or more of grain weight per panicle, is one of the target traits in super-high-yield rice breeding programs. The use of heavy panicle-type hybrid rice has been shown to be a successful strategy for super-high-yield breeding programs, particularly under the environmental conditions of high humidity and deficient solar radiation in southwestern China. However, the genetic components of the heavy panicle trait in hybrid rice remain elusive. Here, we report that the combination of loss-of-function mutations in Grain number 1a (Gn1a) and Grain Size 3 (GS3) is responsible for the heavy panicle phenotype of the elite hybrid rice restorer line Shuhui498 (R498). The null gn1a allele is the determinant factor for heavy panicles through increased grain number, while gs3 is associated with grain size and weight. R498 pyramided the two major null alleles, resulting in heavy panicles with a high grain number and large grains. Clustering analysis revealed that the null gn1aR498 allele is a rare haplotype which has been innovatively utilized in R498, underscoring the great potential of R498 for breeding purposes. Our research thus sheds light on the distinct genetic compositions of heavy panicle-type rice and may potentially facilitate super-high-yield rice breeding. [ABSTRACT FROM AUTHOR]

Abstract: Rice breeding in West Africa has been largely skewed toward yield enhancement and stress tolerance. This has led to the variable grain quality of locally produced rice in the region. This study sought to assess variations in the agronomic and grain quality traits of some rice varieties grown in this region, with a view to identifying sources of high grain yield and quality that could serve as potential donors in their breeding programs. Forty‐five varieties were grown under irrigated conditions in Benin and Senegal with two trials in each country. There were wide variations in agronomic and grain quality traits among the varieties across the trials. Cluster analysis using paddy yield, head rice yield, and chalkiness revealed that 68% of the total variation could be explained by five varietal groupings. One group comprising seven varieties (Afrihikari, BG90‐2, IR64, Sahel 108, WAT311‐WAS‐B‐B‐23‐7‐1, WAT339‐TGR‐5‐2, and WITA 10) had high head rice yield and low chalkiness. Of the varieties in this group, Sahel 108 had the highest paddy yield in three of the four trials. IR64 and Afrihikari had intermediate and low amylose content, respectively, with the rest being high‐amylose varieties. Another group of varieties consisting of B6144F‐MR‐6‐0‐0, C74, IR31851‐96‐2‐3‐2‐1, ITA222, Jaya, Sahel 305, WITA 1, and WITA 2 had high paddy yield but poor head rice yield and chalkiness. The use of materials from these two groups of varieties could accelerate breeding for high yielding rice varieties with better grain quality for local production in West Africa. [ABSTRACT FROM AUTHOR]

Grain size is important for brewing-rice cultivars, but the genetic basis for this trait is still unclear. This paper aims to identify QTLs for grain size using novel chromosomal segment substitution lines (CSSLs) harboring chromosomal segments from Yamadanishiki, an excellent sake-brewing rice, in the genetic background of Koshihikari, a cooking cultivar. We developed a set of 49 CSSLs. Grain length (GL), grain width (GWh), grain thickness (GT), 100-grain weight (GWt) and days to heading (DTH) were evaluated, and a CSSL-QTL analysis was conducted. Eighteen QTLs for grain size and DTH were identified. Seven (qGL11, qGWh5, qGWh10, qGWt6-2, qGWt10-2, qDTH3, and qDTH6) that were detected in F2 and recombinant inbred lines (RILs) from Koshihikari/Yamadanishiki were validated, suggesting that they are important for large grain size and heading date in Yamadanishiki. Additionally, QTL reanalysis for GWt showed that qGWt10-2 was only detected in early-flowering RILs, while qGWt5 (in the same region as qGWh5) was only detected in lateflowering RILs, suggesting that these QTLs show different responses to the environment. Our study revealed that grain size in the Yamadanishiki cultivar is determined by a complex genetic mechanism. These findings could be useful for the breeding of both cooking and brewing rice. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight (BLB) is a major disease of rice, limiting production throughout the world. Xanthomonas oryzae pv.oryzae is highly virulent pathogen, causing major losses in Rice. Present scenario needs development of disease resistant variety through marker assisted selection is the most promising way to improve their performance. Safri-17 is high yielding most popular rice variety of Chhattisgarh but it is highly susceptible to BLB disease. In the present investigation molecular markers were used to introgressed three major BLB resistance genes i.e xa5, xa13 and Xa21 into Safri-17 from a donor line RP-Bio226. Genetic analysis was used to confirm the F2 population for the presence of BLB resistance genes with the help of SSR and STS markers (RM6765, RM13, and pTA248, xa5R/S respectively). Breeding lines with two or three resistance genes were developed and tested for resistance to the BLB. They showed a wider spectrum and a higher level of resistance as compared to lines with only a single gene. The BLB resistance genes in homozygous condition (Xa21Xa21/xa13xa13/xa5xa5) showed resistance disease reaction whereas in heterozygous condition (Xa21xa21/Xa13xa13/Xa5xa5) showed moderate resistance reaction. Similarly two gene combinations gave more resistance reactions as compare to progenies have single gene. [ABSTRACT FROM AUTHOR]

The All India Coordinated Rice Improvement Project of ICAR-Indian Institute of Rice Research, Hyderabad organizes multi-location testing of elite lines and hybrids to test and identify new rice cultivars for the release of commercial cultivation in India. Data obtained from Initial Hybrid Rice Trials of three years were utilized to understand the genotype × environment interaction (GEI) patterns among the test locations of five different agro-ecological regions of India using GGE and AMMI biplot analysis. The combined analysis of variance and AMMI ANOVA for a yield of rice hybrids were highly significant for GEI. The GGE biplots first two PC explained 54.71%, 51.54% and 59.95% of total G + GEI variation during 2010, 2011 and 2012, respectively, whereas AMMI biplot PC1 and PC2 explained 46.62% in 2010, 36.07% in 2011 and 38.33% in 2012 of the total GEI variation. Crossover interactions, i.e. genotype rank changes across locations were observed. GGE biplot identified hybrids, viz. PAN1919, TNRH193, DRH005, VRH639, 26P29, Signet5051, KPH385, VRH667, NIPH101, SPH497, RH664 Plus and TNRH222 as stable rice hybrids. The discriminative locations identified in different test years were Coimbatore, Maruteru, VNR, Jammu, Raipur, Ludhiana, Karjat and Dabhoi. The AMMI1 biplot identified the adaptable rice hybrids viz., CNRH102, DRH005, NK6303, NK6320, DRRH78, NIPH101, Signet5050, BPH115, Bio452, NPSH2003, and DRRH83. The present study demonstrated that AMMI and GGE biplots analyses were successful in assessing genotype by environment interaction in hybrid rice trials and aided in the identification of stable and adaptable rice hybrids with higher mean and stable yields. [ABSTRACT FROM AUTHOR]

The study aims at identifying some submergence-tolerant rice genotypes through morphological and molecular characterization and their genetic variability analysis. Ten rice genotypes including two submergence-tolerant checks, two susceptible varieties and six advanced lines were evaluated for submergence tolerance in the laboratory and in the field during January–December 2015. The experiment was conducted in the field following randomized complete block design in a two-factor arrangement using five replications. Ten characters, viz. days to flowering, plant height, tiller number plant −1 , effective tiller plant −1 , and yield plant −1 etc. were studied for four treatments. A significant genotype × environment interaction was observed for all traits studied in this experiment. The yield was reduced for all genotypes at a different level of submergence stress compared to control. Binadhan-11, Binadhan-12, RC 249 and RC 251 showed tolerance, whereas RC 192, RC 193 and RC 225 showed moderate tolerance in submerged condition. The phenotypic coefficient of variance (PCV) was higher than the genotypic coefficient of variance (GCV) in all the studies traits. High heritability (75–97%) was found for all traits. High heritability along with high genetic advance was found for days to flowering (45.55) and plant height (40.05). Molecular characterization of the used genotypes was done with three SSR markers viz. RM 24, and submergence specific SC3 and SUB1. SC3 was found reliable for detection of submergence tolerant genotypes due to the highest gene diversity (0.840) compared to others. The banding pattern of the submergence specific markers SC3 and SUB1 identified in Binadhan-11, Binadhan-12, RC 192, RC 193, RC 225, RC 227, RC 249, and RC 251, which possess the SUB1 gene. Finally, clustering also separates the tolerant genotypes from the susceptible by dividing them into different clusters. The identified genotypes might be useful for the breeding programme for the development of submergence tolerant as well as resistant rice variety in Bangladesh. [ABSTRACT FROM AUTHOR]

The reduction in rice productivity as a result of elevated daily temperature due to climate change is a major concern for Thailand. This study aimed to investigate hydrogen peroxide and malondialdehyde (MDA) content and electrolyte leakage of rice seedlings grown from seeds exposed to different temperature (25°C, 35°C and 40°C) treatments over a short (one week) and long (two weeks) period before germination. Three rice cultivars were investigated, Dular, KDML105 and Riceberry. The experiment was designed in RCBD with six replications. The results indicated that Riceberry seeds produced a greater percentage of normal seedlings after both short- and long-term heat treatment (40°C). By contrast, KDML105 seeds exposed to 40°C for one and two weeks gave rise to the highest percentage of abnormal seedlings. The highest oxidative stress indicated by the accumulation of hydrogen peroxide was found in abnormal seedlings of cvs. KDML105 and Riceberry after short- and long-term heat (40°C) exposure, respectively. The effect of heat stress on membrane stability was indicated by MDA content and electrolyte leakage. MDA content was the highest in abnormal seedlings of cv. Riceberry after heat exposure for two weeks. High electrolyte leakage due to both shortand long-term high temperature treatment was found in abnormal seedlings of all the rice cultivars. Heat exposure to rice seeds at 40°C for one week induced the highest percentage of abnormal seedlings in KDML 105 coinciding with the highest hydrogen peroxide content and membrane damage. These results provide crucial information for consideration in breeding programmes for heat-tolerant rice cultivars. [ABSTRACT FROM AUTHOR]

The adoption of ordinary hybrid rice and super hybrid rice significantly increased the grain yield under non-limited nitrogen (N) fertilizer condition, however, the information on direct comparison of grain yield and nitrogen use efficiency (NUE) among the high-yielding super hybrid, ordinary hybrid, and inbred rice under low and moderate N rates is limited. Therefore, field experiments with two representative cultivars of each these types were conducted under N0 (0 kg N ha −1 ) and N90 (90 kg N ha −1 ) treatments in 2014 and 2015 in Wuxue County, Hubei Province, China. Grain yield of the super hybrid rice was higher than that of the inbred rice by 3.33-7.41% at N0 and 5.94-10.87% at N90. Similarly, the ordinary hybrid rice outyielded the inbred rice by 4.53-6.17% and 4.35-4.69% at N0 and N90, respectively. The yield advantage of the ordinary hybrid rice over the inbred rice was mainly due to higher aboveground total dry weight (TDW), while for the super hybrid rice, higher grain yield was mainly attributed to higher harvest index (HI) at N0, and both high HI and TDW at N90. Larger leaf area index (LAI) at heading stage and higher crop growth rate (CGR) contributed to higher TDW of the ordinary hybrid rice. Total N uptake at maturity was consistently higher in the ordinary hybrid rice, while the super hybrid rice had significantly higher nitrogen use efficiency for grain production (NUEg) than the inbred rice, which was associated with higher N harvest index (NHI) and lower leaf N concentration of the super hybrid rice. In conclusion, it was found that the super and ordinary hybrid rice exhibited higher yield over the inbred rice at low and moderate N rates, but the physiological mechanisms underlying the yield advantage were different. [ABSTRACT FROM AUTHOR]

The identification of the highest yielding cultivar for a specific environment on the basis of both genotype (G) and genotype x environment (GE) interaction would be useful to breeders and producers since yield estimates based only on G and environment (E) effects are insufficient. The objective of this study was to demonstrate the usefulness of additive main effects and multiplicative interactions (AMMI) model analysis. Replicated grain yield data of rice (Oryza sativa L.) genotypes at three locations in Coimbatore (E1), Bhavanisagar (E2) and Aliyar Nagar (E3) were obtained and used for this purpose. Through AMMI model analysis, the magnitude and significance of the effects of GE interaction and its interaction principal components relative to the effects of G and E were estimated. Among the three, E3 environment was far away from the origin. The environments E2 and E3 condition were exhibiting high interaction effect, whereas the environment E1 had moderate interaction effect with the other two environments. The parent TP 1021 R and the hybrids viz., IR 80559 A X RR 286 R, APMS 6 A X IR 62037 R, IR 75601 A X IR 72865 R, IR 75601 A X RR 347 R, IR 75596 A X MDU 5 R, IR 75596 A X ASD 06-8 R, CRMS 32 A X IR 62037 R, CRMS 32 A X TP 1021 R and IR 75608 A X ASD 06-8 R showed IPCA 1 score close to zero with high main effects indicating that these varieties were less influenced by environments. Hence, the above said hybrids were stable and had general adaptability for all the environments. Since, the environments E3 had positive IPCA 1 score and high mean, it had positive interaction with these genotypes and this environment was considered as the stable environment for these hybrids. [ABSTRACT FROM AUTHOR]

There are many rice characteristics that contribute to the grain yield. This study aimed to characterize relationships of yield and yield components into direct and indirect effects, and to estimate the magnitude of genotypic and phenotypic variation, heritability and genetic advance. The study was conducted with 232 recombinant inbred lines (RILs) derived from a cross between low yield but good cooking quality, KDML105, and new plant type with high yield, CH1 rice variety. These lines were planted in RCBD with 3 replications. Data were collected for agronomic traits, yield components and yield. The results indicate that path coefficient analysis elucidated a positive direct effect on the number of panicles per plant (0.540) and the number of filled grains per panicle (0.510). Percentages of their direct effect were 62.11 and 74.68 %, respectively. These 2 traits demonstrate high significant value which could be used as selection criteria for yield improvement. Moreover, high values of heritability along with high genetic advance were observed for plant height, grain yield and the number of filled grains per panicle. Thus, these characters may serve as selection criteria combined with flag leaf length for improved high yield potential of rice. [ABSTRACT FROM AUTHOR]