Rice Breeding

In general, the PCV was higher than GCV for all the characters and small differences between GCV and PCV were recorded for physical quality characters studied which indicated less influence of environment on these characters. High heritability was observed for traits like plant height, number of grains per panicle, spikelet fertility percent, Kernel length, breadth and L/b ratio, whereas, high genetic advance as per cent of mean observed for plant height, productive tillers, number of grains per panicle, head rice recovery and kernel L/b ratio.

The cultivated rice (Oryza Sativa L.) belongs to the tribe, Oryzeae under the sub family Pooideae, in the grass family Gramineae (Poaceae). It is classified into two broad species; the Asian (sativa L.) and African (glabberima Steud) rice. The crop is considered the world’s most diverse and versatile with reference to its wide adaptability to variable ecologies. The plant usually takes 3–6 months from germination to maturity, depending on the variety and the environment under which it is grown. Rice has been cultivated world-wide for more than 10,000 years. FAO in 2000 classified it as the most important food crop depended on by over 50% of the world population for about 80% of their food need.
Consequently, rapid population growth and economic development are creating high pressures on food production, and to meet the global food demands, rice yield is expected to increase at a minimum rate of 1.2% annually over the next 10 years. In limited cultivated farmland, it is critical to ensure food security through continuous grain yield improvements, thus intensive rice breeding over the past 50 years has dramatically increased productivity especially in the indica sub species. A number of breeding programs have since developed ambitious strategies to increase grain yield; one of such being the manipulation of tiller numbers.
The present study sought to determine and compare tiller productivity and survival dynamics, relative to grain yield. A set of 12 genotypes was used; ten (10) lowland hybrid lines (16KH09010053, 16KH09010003, AFRUG6020041, 16KH09010044, DU 363-2, 16KH09010005, 16KH09010022, 16KH09010072, AFRUG6020058 and KIMNY), and two (2) upland inbred lines (NAMCHE 5 and ENTRY 20). The experiment was set up in one of the agronomy fields based at the NaCRRI Irrigation Facilities (Trial Farms), a typical irrigated lowland ecosystem. Sowing was done on 15th February, 2017, in a nursery bed. 21 day old seedlings were then transplanted to well-prepared experimental plots on 8th March, 2017. DAP was applied at transplanting, and Urea 7 WAT, both as top dressings.
The field was well managed for weeds and water distribution. Data was collected on various aspects, including numbers of tillers, productive and surviving tillers for 10 random plants per plot, at weekly, and fortnight intervals on some occasions. The data was then processed using MS Excel, while ANOVA and Correlations were performed using Genstat.
The results showed that the genotypes varied appreciably for both productive and surviving tillers. Maximum tillers ranged from 9 (NAMCHE 5) to 18 tillers hill-1 (16KH09010044) with 1, 9 and 2 genotypes attaining ceiling number of tillers at 10, 11 and 12 WAT respectively. Productive tillers hill-1 varied from 7 (DU 363-2) to 16 (16KH09010022), whilst surviving tillers hill-1 ranged from 7 (NAMCHE 5) to 18 surviving tillers hill-1 (16KH09010022). The highest percent of productive and surviving tillers was recorded for the genotype 16KH09010022 (91.03 and 101.12% respectively) and the lowest for DU 363-2 (51.62%) and ENTRY 20 (71.48%) respectively.
Panicles m-2 were highest in 16KH09010022 (256.3) and lowest in 16KH09010072 (153.3). The highest grain yield was produced by DU 363-2 (6.04 tha-1) and the lowest by AFRUG6020041 (3.75 tha-1). The maximum tillers were positively correlated with the productive tillers (0.793), and panicles m-2 (r=0.689) which Panicles m-2 also showed strong correlation with surviving tillers (r=0.739), though weak and insignificant with grain yield (r=0.254). In the correlation matrix it was observed that neither the maximum tillers, nor productive tillers had positive influence on grain yield.

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"Background and aims
Basmati rice grown in the Indian subcontinent is highly valued for its unique culinary qualities. Production is however, often constrained by diseases such as bacterial blight (BB), blast and sheath blight (ShB). The present study developed Basmati rice with inbuilt resistance for BB, Blast and ShB using molecular marker assisted selection (MAS).

Methodology
Rice cultivar ‘Improved Pusa Basmati 1’ (carrying BB resistance genes, xa13 and Xa21) was used as the recurrent parent and cultivar ‘Tetep’ (carrying blast resistance gene, Pi54 and ShB resistance QTL, qSBR11-1) was the donor. Marker assisted foreground selection was employed to identify plants possessing resistance alleles in the segregating generations along with stringent phenotypic selection for faster recovery of the recurrent parent genome (RPG) and phenome (RPP). Background analysis with molecular markers was used to estimate the recovery of RPG in improved lines.

Principal results
Foreground selection coupled with stringent phenotypic selection identified plants homozygous for xa13, Xa21, and Pi54, which were advanced to BC2F5through pedigree selection. MAS for qSBR11-1 in BC2F5 using flanking markers identified seven homozygous families. Background analysis revealed that RPG recovery was up to 89.5 %. Screening with highly virulent isolates of BB, blast and ShB, showed that the improved lines were resistant to all the three diseases and were on par with Improved ‘Pusa Basmati 1’ for yield, duration, and Basmati grain quality.

Conclusions
This is the first report of marker assisted transfer of genes conferring resistance to three different diseases in rice wherein genes, xa13 and Xa21 for BB resistance; Pi54 for blast resistance and a major QTL qSBR11-1 has been combined through marker assisted backcross breeding (MABB). In addition to offering the potential for release as cultivars, the pyramided lines will serve as useful donor of gene(s) for BB, blast and ShB in future Basmati rice breeding programmes."

Rice production needs to increase in the future in order to meet increasing demands. The development of new improved and higher yielding varieties more quickly will be needed to meet this demand. However, most rice breeding programmes in the world have not changed in several decades. In this article, we revisit the evidence in favour of using rapid generation advance (RGA) as a routine breeding method. We describe preliminary activities at the International Rice Research Institute (IRRI) to re-establish RGA on a large scale as the main breeding method for irrigated rice breeding. We also describe experiences from the early adoption at the Bangladesh Rice Research Institute. Evaluation of RGA breeding lines at IRRI for yield, flowering time and plant height indicated transgressive segregation for all traits. Some RGA lines were also higher yielding than the check varieties. The cost advantages of using RGA compared to the pedigree method were also empirically determined by performing an economic analysis. This indicated that RGA is several times more cost effective and advantages will be realized after 1 year even if facilities need to be built. Based on our experience, and previous independent research empirically testing the RGA method in rice, we recommend that this method should be implemented for routine rice breeding in order to improve breeding efficiency.

Background and aims
Food production has to increase to meet the demand of a growing population. In light of high energy costs and increasingly scarce resources, future agricultural systems have to be more productive and more efficient in terms of inputs such as fertilizer and water. The development of rice varieties with high yield under low-nutrient conditions has therefore become a breeding priority. The rapid progress in sequencing and molecular-marker technology is now beginning to change the way breeding is done providing new opportunities.

Scope
Nitrogen (N) and phosphorus (P) are applied to agricultural systems in large quantities and deficiency of either nutrient causes yield losses and triggers complex molecular and physiological responses. The underlying genes are now being identified and studied in detail and an increasing number of quantitative trait loci (QTLs) related to N and P uptake and utilization is being reported. Here, we provide an overview of the different aspects related to N and P in rice production systems and apply a breeder’s perspective on the potential of relevant genes and pathways for breeding applications.

Main Points
For the development of nutrient-efficient rice, a holistic approach should be followed combining optimized fertilizer management with enhanced nutrient uptake via a vigorous root system leading to increased grain filling and yield. Despite an increasing number of N- and P-related genes and QTLs being reported, very few are actively used in molecular breeding programs. The complex regulation of N and P related pathways challenges breeders and the research community to identify large-effect genes/QTLs. For this it will be important to focus more on the analysis of tolerant genotypes rather than model plants since tolerance pathways may employ a different set of genes.

Rice as the major staple food of the world although is high in calories but deficient in essential micronutrients. This deficiency can be tackled by biofortification of rice grains with enhanced micronutrient content. Field experiments were carried out across three locations involving 17 genotypes, with the objective of assessing the genotype × environment interaction for native soil micronutrient assimilation in rice kernels and the influence of intrinsic soil variables on micronutrient content in rice grains. Contents of Fe, Zn, Cu and Mn in the milled kernels were found to vary significantly among genotypes and locations. There was significant genotype-by- environment interaction (GEI) for all the nutrients. Further, it was found that soil pH and soil available P had significant influence towards grain Fe content. Soil Zn availability and the electrical conductivity of the soil solution were found closely associated with grain Zn content. The two factors that regulated Cu and Mn content of rice grains were soil organic carbon content and soil Cu availability. The factorial regression (FR) approach to assess the role of significant intrinsic soil factor (s) on enrichment of specific micronutrient in the milled rice kernels showed differential genotype responses that ultimately determined grain micronutrient accumulation in each genotype. These determinants enabled prediction of genotypes suited to different environments. In certain cases, further examination of environmental co-factors is advocated to bring out a comprehensive picture of the micronutrient assimilation in milled rice grains.

Distinctness, Uniformity and Stability test are now become a important tool for cataloguing the germplasm and utilization of differentials for breeding programme. A total of 83 indigenous rice germplasm were characterized to test the divergence and related qualitative difference present among the lines. Thirty one morphological characters were observed. Basal leaf sheath colour, colour of tip of lemma, lemma & palea colour found highest variation in germplasm. Straw coloured sterile lemma found in 78 lines whereas purple colour found in 04 lines and most unique gold colour found in 01 line. On the basis of pigment distribution in 13 plant parts, the entire germplasm was classified into 23 groups as per DUS guideline. Last XXIII group included four germplasms R-652, R-671, R-714, Shymla which has pigmentation in overall 10 parts (colour of tip of lemma, colour of awns, anthocynin coloration of apex, lemma & palea colour, basal leaf sheath colour, leaf sheath anthocynin coloration, color of stigma, auricle colour, ligule colour, sterile lemma colour). The unique germplasms were found; chhatry germplasm has purple colour of tip of lemma, black colour of tip of lemma has rani kajar, surajone and white colour of tip of lemma has lakna. More study required on those germplasms for pointing out which are the traits that may be particularly referred to as indicators to determine an unstable expression of the phenotype of candidate variety.

The rice variety Ratnagiri 6 (RTN 65-1-2-2-2) was evolved from the cross between IR64 and Paras Sona using former parent as female through pedigree method of selection. The above variety is midlate in duration (118-125 days in Kharif), Semi-dwarf (100-110 cm plant height), medium slender and translucent kernel type. The variety showed 36.57, 19.96, 9.11, 23.53 and 26.38 per cent higher yield over the respective checks in station, state, national, agronomical and adaptive trials, respectively. It showed excellent milling (70.30 %), head rice recovery (66.19 %) and good cooking qualities (Amylose content 25.43 %). Ratnagiri 6 rice variety showed moderately resistant to leaf blast and bacterial leaf blight diseases and moderately resistant to stem borer, leaf folder and gall midge at endemic sites. It recorded an average yield of 4.0 to 4.5 t/ha. Therefore the rice variety Ratnagiri 6 recommended for release for commercial cultivation in Konkan region of Maharashtra in the year 2017.

ARTICLE INFO ABSTRACT The recent approach for rice production includes the improvement of yield is necessary to cater for consumer demand and Training Center, Egypt during 2014 and 2015growing season to estimate combining ability, heterosis and genetic parameters in and Sakha105 were recorded highest mean values for most traits. The crosses (Giza177 × Sakha106, Sakha101 × Sakha104 and Sakha101 × Gz7576 grain yield plant evident from the result, plant-1 as well as, to heading, number of filled grains panicle cross Sakha 101/Sakha 104, Sakha 104/Sakha 106, Sakha 105/BL1 and Sakha 106/BL1 were identified as themost promising cross for developing benefits to isolate superior transgressivesegregants for breeding programs in r

In the present study, we tested rice genotypes that included un(der)exploited landraces of Tamil Nadu along with indica and japonica test cultivars to ascertain their genetic diversity structure. Highly polymorphic microsatellite markers were used for generating marker segregation data. A novel measure, allele discrimination index, was used to determine subpopulation differentiation power of each marker. Phenotypic data were collected for yield and component traits. Pattern of molecular differentiation separated indica and japonica genotypes; indica genotypes had two subpopulations within. Landraces were found to have indica genome, but formed a separate subgroup with low linkage disequilibrium. The landraces further separated into distinct group in both hierarchical clustering analysis using neighbour-joining method as well as in the model based population structure analysis. Japonica and the remaining indica cultivars formed two other distinct groups. Linkage disequilibrium observed in the whole population was considerably reduced in subpopulations. Low linkage disequilibrium of landforms suggests their narrow adaptation in local geographical niche. Many population specific alleles could be identified particularly for japonica cultivars and landraces. Association analysis revealed nine marker–trait associations with three agronomic traits, of which 67% were previously reported. Although the testing landraces together with known cultivars had permitted genomewide association mapping, the experiment offers scope to study more landraces collected from the entire geographical region for drawing more reliable information.

http://dx.doi.org/10.1007/s12041-012-0146-6

Background
Rice is staple food for more than half of the world’s population including two billion Asians, who obtain 60-70% of their energy intake from rice and its derivatives. To meet the growing demand from human population, rice varieties with higher yield potential and greater yield stability need to be developed. The favourable alleles for yield and yield contributing traits are distributed among two subspecies i.e., indica and japonica of cultivated rice (Oryza sativa L.). Identification of novel favourable alleles in indica/japonica will pave way to marker-assisted mobilization of these alleles in to a genetic background to break genetic barriers to yield.

Results
A new plant type (NPT) based mapping population of 310 recombinant inbred lines (RILs) was used to map novel genomic regions and QTL hotspots influencing yield and eleven yield component traits. We identified major quantitative trait loci (QTLs) for days to 50% flowering (R2 = 25%, LOD = 14.3), panicles per plant (R2 = 19%, LOD = 9.74), flag leaf length (R2 = 22%, LOD = 3.05), flag leaf width (R2 = 53%, LOD = 46.5), spikelets per panicle (R2 = 16%, LOD = 13.8), filled grains per panicle (R2 = 22%, LOD = 15.3), percent spikelet sterility (R2 = 18%, LOD = 14.24), thousand grain weight (R2 = 25%, LOD = 12.9) and spikelet setting density (R2 = 23%, LOD = 15) expressing over two or more locations by using composite interval mapping. The phenotypic variation (R2) ranged from 8 to 53% for eleven QTLs expressing across all three locations. 19 novel QTLs were contributed by the NPT parent, Pusa1266. 15 QTL hotpots on eight chromosomes were identified for the correlated traits. Six epistatic QTLs effecting five traits at two locations were identified. A marker interval (RM3276-RM5709) on chromosome 4 harboring major QTLs for four traits was identified.

Conclusions
The present study reveals that favourable alleles for yield and yield contributing traits were distributed among two subspecies of rice and QTLs were co-localized in different genomic regions. QTL hotspots will be useful for understanding the common genetic control mechanism of the co-localized traits and selection for beneficial allele at these loci will result in a cumulative increase in yield due to the integrative positive effect of various QTLs. The information generated in the present study will be useful to fine map and to identify the genes underlying major robust QTLs and to transfer all favourable QTLs to one genetic background to break genetic barriers to yield for sustained food security.

http://dx.doi.org/10.1186/1471-2229-12-137

The study of genetic variation (GV) in 20 Philippine traditional rice varieties (TRVs) were
determined in grain morphology such as length (Gl), width (Gwd), and weight (Gwt), grain yield
(Gy), and grain micronutrients such as copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn). Analysis
of variance obtained highly significant GV among TRVs in all traits. The mean for Gl, Gwd,
Gwt, Gy, Cu, Fe, Mn, and Zn contents was 8.56mm, 2.8mm, 20.01g, 2.13t/ha, 8.64ppm, 14.56ppm,
20.79ppm, and 30.26ppm, respectively. The micronutrients in TRVs followed an order as Zn > Mn
> Fe > Cu. For the correlation in traits, 11 pairs were significantly correlated; however, only Mn and
Zn content in grains was positively and strongly correlated. Other significant pairs were either in
positive or negative and moderately correlated. Cluster analysis, on the other hand, revealed five
clusters and showed distinct TRV in two clusters. In conclusion, the presence of higher grain micronutrient
content in TRVs indicatesa better opportunity for breeders to determine parental genetic
resource in breeding rice with high grain micronutrients.

Nine lines and three testers were crossed in Line × Tester mating design during kharif season 2017 in Norman E. Borlaug Crop Research Center, GBPUAT, Pantnagar. In kharif season 2018, field experiment with 39 genotypes comprising 12 parents and 27 F1s was laid down in randomized block design with three replications. Sixteen characters including yield and quality parameters were taken under study. Among lines UPR-3716-27-1-1 emerged as a good general combiner for the maximum number of traits. Among the testers, Taraouri Basmati and Lal Basmati was found good general combiners. UPR-3709-11-1-1 ×Lal Basmati, Pusa Sugandh Dhan 4 ×Sugandhmati and Hariyana Basmati ×Sugandhmati was identified as the best specific combination for most of the traits and Pusa Sugandh Dhan 4 ×Sugandhmati was identified as the best specific combination for grain yield plant-1. Relative heterosis, heterobeltiosis and standard heterosis was estimated for all the characters among which for grain yield Hariyana Basmati ×Sugandhmati and Basmati 370 ×Taraouri Basmati excelled over maximum levels. Basmati 370 ×Sugandhmati and UPR-3506-7-1-1 ×Taraouri Basmati was identified as best heterotic combination at different levels for maximum traits like, days to 50% flowering, hulling recovery, grain yield plant-1 etc.

We report comprehensive information about genetics of diverse characters in a set of somaclones developed from a salt tolerant indica cultivar-Pokkali for the first time, which are novel, unique and deemed to be useful to devise breeding strategies to exploit somaclonal variation. 2 nd degree statistics, correlation and path coefficient analyses were performed involving 31 most productive somaclones, evaluated for 3 consecutive years (SC6-SC8 generation). By adjudging the results appropriate breeding strategies are envisaged to improvise Pokkali rice. A wide range of variations for all major agronomic characters was observed. Phenotypic coefficient of variation (PCV) was higher than Genetic coefficient of variation (GCV) for all characters, indicating substantial influence of the environment for major characters. Plant height, flag leaf area, leaf dry weight; harvest index had high-moderate heritability with high genetic advance, indicating predominance of additive gene actions. Plant height, panicle length, flag leaf area, biomass yield and harvest index had significant positive associations with grain yield at genetic level convey their predominant role in governing grain yield. Leaf area, leaf dry weight, panicle length and number of productive tillers per plant had direct effect on grain yield. Direct selection is advocated for improving panicle length and restriction selection is recommended to enhance leaf area, leaf dry weight, and number of tillers per plant. Biomass yield bore maximum negative effect on grain yield. Maximum 81.08% of the variability was contributed by grain yield/plant. Amongst all somaclones, BTS 24 was found to produce maximum of 3.7 tonnes per hectare, which is recommended for large-scale cultivation. Key findings: Quantification, interrelationship and contribution of component characters on grain yield, accrued from in vitro culture-induced variations in a set of Pokkali somaclones.

Rice is the principal food crop for majority of the global population and its production is frequently affected by drought. The objective of this study was to have improved understanding on drought resistance as a trait, study its molecular genetics and also to identify the potential drought resistant segregants. The genetic material used in this study comprised of near-isogenic lines of IR64 (BC2F7 generation) with random introgression from drought resistant land race Norungan. There was a significant reduction of 25 per cent and 75 per cent in mean plot yield under moderate and severe stress conditions respectively from that under irrigated control which reflected the varied stress intensities between the treatments. The genetic material exhibited significant phenotypic variation for 16 traits studied under three experimental conditions. Marker - trait association was assessed by single marker analysis. Totally 121 markers were used out of that eighteen markers showed putative association with at least one of the investigated trait. A candidate gene based marker for DREB 1 positioned in chromosome 8 was associated with yield under severe stress whereas SSR markers viz, RM 256 in chromosome 8; RM 245 in chromosome 9 were linked with yield under moderate stress. These markers were also linked with other associated traits viz, harvest index, leaf senescence and leaf rolling. These might be useful for marker assisted selection for rainfed rice improvement.

The way of life in Bastar continues to be dictated by ritual. Even today, agricultural practices are traditional. Use of wooden ploughs is massive while the number of iron ploughs is stumpy. The same is true of improved rice cultivation. The number of rice varieties and hybrids are truncated while the local landraces and germplasm are privileges. The usage of traditional agricultural implements has lowered the production of agriculture but the sustainability is maintained and crop biodiversity protected. The kharif crops grown here are paddy, millets, urad, arhar, jowar and maize. Sustainable agriculture, in terms of food security, rural occupation, and environmentally sustainable technologies such as soil conservation, sustainable natural resource management and biodiversity protection, are essential for holistic rural development. The research was carried out S.G. College of Agriculture and Research Station, Jagdalpur, Chhattisgarh. The materials was used ninety four local landraces of rice and three standard checks during Kharif 2016 in RBD Design, 16 qualitative and 20 quantitative characters observations was recorded. Analysis of variance showed significantly differences for all characters; out of 20, only seven principal components (PCs) exhibited more than 1.00 eigen value, and showed 77.42% variability among the traits studied. The PC1 was related to quality characters while PC2, PC3, PC4, PC5, PC6 and PC7 associated with quantitative traits. Introduction Rice (Oryza sativa L.) (2n =24) is the most significant food crops in the world and feeds over half of the overall population. Rice has played a central role in human nutrition and culture for the past 10,000 years. However, increase in global population, projected to be 9.2 billion by 2030, predicted increase in water scarcity and decrease in arable land, the constant battle against new emerging pathogens and pests and reduced quality due to possible adverse effects from climate change will pose greater challenges for rice breeders and agricultural Scientists (Khush, 2005) [5]. The total area under rice cultivation is globally estimated to be 162 million hectares with annual global production for 2016 at 745.5 million tonnes (495.2 million tonnes, milled basis) (Anonymous, 2016). Rice is life, for most people living in Asia Rice is one of the most important staple foods for more than half of the world's population and influences the livelihoods and economies of several billion people. (Pandey and Kar, 2017) [8] Being staple food, improving productivity and quality traits of rice always remains crucial. The quality of rice is a complex trait involving many physicochemical properties, and thus it has been a challenge to accurately evaluate quality for selection in rice breeding programs. To accomplish this, crop improvement programmes should necessarily aim at broadening the genetic base of the breeding stock (Vanaja and Babu, 2004) [12]. India has tremendous biodiversity for the landraces of rice. The number of landraces cultivated locally is rapidly replaced by improved varieties, which is causing narrowing of genetic base (Guei, 2000) [4]. Thus, reduced genetic variability underscores the need to collect landraces for ex-situ conservation and to characterize them for future rice breeding programmes based on agro-morphological traits because the evaluation of phenotypic diversity usually reveals important traits of interest to plant breeders. India is a primary centre of origin of rice and has many local landraces available in the remote tribal areas. Most of the land races are not in cultivation while many are lost and few are still cultivated by resource-poor traditional farmers in areas practising subsistence farming. They constitute an excellent reservoir of variability for several traits, resistance to biotic and abiotic stresses, quality and yield traits (Tanksley and Mc-couch, 1997) [11]. Keeping in view the above facts, the present investigation was undertaken to study the nature and degree of genetic divergence among the rice land races grown in Bastar plateau zone of

SCS124 Sardo is a medium-maturing cultivar with an upright growth habit; intermediate lodging tolerance; moderate blast resistance; high grain yield potential; and long, thin grains with excellent cooking and sensory quality, especially for white milled rice. It is suitable for parboiling and recommended for all regions of the state of Santa Catarina, Brazil.

Korean rice is a foreign genetic resources in the Philippines that has to be characterized for its proper germplasm utility. Ten Korean phenotypes were analyzed using correlation, clustering and principal component analyses (PCA) based on the 13 traits viz., culm length (CL), days to 50% flowering (D50F), days to maturity (DM), filled grains per panicle (FGP), flag leaf length (FLL), flag leaf width (FLW), grain length (GL), grain width (GW), grain yield (GY), plant height (PH), productive tillers (PT), spikelet fertility SF) and thousand grain weight (TGW) under different seasons of the Philippines. It was found out that Korean phenotypes had earlier D50F and DM, shorter CL and PH, more FGP, PT and SF, and higher GY under dry season than wet season. Each season had three groups based on the clustering analysis with a pattern. Group 1 had phenotypes with heavy TGW, early D50F and DM, short PH and FLL; and more FGP, SF and GY; group 2 had long CL, wide FLW, light TGW; and late D50F and DM; and group 3 had short CL, narrow FLW and low PT. Correlation in FGP, PT and SF to GY was consistently high positive (r≥0.68) in two seasons. Also, PCA consistently showed that GY, PH and PT were the highest contributors of variation with an average of 21.42% in two seasons. Korean GY therefore was highly variable but attaining higher GY can be possible by utilizing grain-filling (FGP and SF) and productive tillering (PT) traits as selection indices in the breeding program.

A major QTL for seedling stage salt tolerance, Saltol has been mapped on chromosome 1 in rice. The present study was carried out to characterise the haplotype diversity in the Saltol region using 20 simple sequence repeat markers, and it association with seedling stage salt tolerance under controlled condition (ECe of 12 dSm−1) in 23 diverse rice germplasm including land races, wild germplasm and improved varieties. Genotypes from kaipad ecosystem of Kerala showed salt tolerance and haplotypes of Saltol similar to Pokkali, whereas salt tolerant wild rices possessed different haplotypes and therefore may be novel sources for salt tolerance. Altogether, 14 different haplotypes were observed in 23 rice genotypes based on critical markers linked to Saltol QTL using Pokkali as the reference. The haplotypes possessing Pokkali alleles at both the markers, RM8094 and RM3412 could discriminate the salt tolerant genotypes from the susceptible genotypes and hence could be useful in marker-assisted selection.

Hot water emasculation is one of the methods in rice hybridization to deactivate pollen which mostly applied by Japanese researchers. This present experiment was aimed to determine the appropiate temperature for high success in emasculation by hot water. Field experiments were carried out during December 2009 until December 2010 in green house at Jatinangor, West Java, Indonesia. Experiments were arranged in completely randomized factorial design using three combinations of hybridization between three low land rice varieties ssp. indica (IR-64, Ciherang and Ciapus) as female with one ssp. Japonica, Kitaake as male parent combined with three temperature regimes replicated three times. Hot water emasculation method with temperature from 43°C - 45°C during 7 min. could be applied in three cultivars: IR 64, Ciherang, and Ciapus. An interaction was found between emasculation temperatures and genotype, in which temperature 43°C was very effective only for Ciapus. Three indica cultivars differed in their response to emasculation temperature. There was no interaction between temperature and genotype to the number of filled grains. Each cultivar had different sensitivity to the temperature of emasculation.

Key words: hot water emasculation, hybridization, pollen sterility, seed-set, rice

The parasitic weeds Striga asiatica and Striga hermonthica cause devastating yield losses to upland rice in Africa. Little is known about genetic variation in host resistance and tolerance across rice genotypes, in relation to virulence differences across Striga species and ecotypes. Diverse rice genotypes were phenotyped for the above traits in S. asiatica-(Tanzania) and S. hermonthica-infested fields (Kenya and Uganda) and under controlled conditions. New rice genotypes with either ecotype-specific or broad-spectrum resistance were identified. Resistance identified in the field was confirmed under controlled conditions, providing evidence that resistance was largely genetically determined. Striga-resistant genotypes contributed to yield security under Striga-infested conditions, although grain yield was also determined by the genotype-specific yield potential and tolerance. Tolerance, the physiological mechanism mitigating Striga effects on host growth and physiology, was unrelate...

The present investigation was carried out at the experimental farm of Rice Research and Training Center, Sakha, Kafer El-Sheikh, Egypt during 2008 and 2009 seasons to study the physio-morphological behaviour of some rice genotypes under lowand high nitrogen application. Twenty one genotypes were tested under three different nitrogen levels viz, 0, 75 and 150 kgN/ha for ten traits viz, flag leaf area, chlorophyll content, days to heading, panicle weight, , no. of filled grains/panicle, no. ofpanicles/plant ,1000-grain weight, grain yield t ha-1, grain yield efficiency index (GYEI) and agronomic nitrogen use efficiency(ANUE). The genotypes were divided into three groups i.e., japonica/japonica (J/J), japonica/indica japonica (J/IJ) and indicajaponica/indica japonica (IJ/IJ). GZ6296 x Giza178-1 and GZ6296 x Giza 178-3 gave the highest values of no. of filledgrain/panicle and no. of panicles/hill under low input of nitrogen. Giza177/Sakha101 and Giza176/GZ6944 (J/J) gave thehighest grai...

The present study was conducted in two consecutive seasons (2014 and 2015) at Agriculture College, Warrangal (India) to assess the combining ability of hybrid rice (Oryza sativa) for various cooking quality parameters. The genotypes involved in the study comprised of 45 F1 hybrids generated from 10 parents and two promising check varieties viz., BPT 5204 and Chittimuthyalu. In present study, the magnitude of specific combining ability variances was found higher than general combining ability for all the quality characters studied, except for kernel length, kernel length/breadth ratio and kernel elongation ratio. This indicated the greater role of non-additive gene action in controlling most of these traits. The best specific crosses for cooking quality traits were WGL-32100 x RP-Bio-5478-185 (high x low), Ramappa x RP-Bio-5478-176 (high x low) and Ramappa x RP-Bio-5478-185 (high x low) and interestingly these crosses involved parent Ramappa. These crosses were highly promising for cooking quality traits.

The present investigation was undertaken with 33 coloured and white rice genotypes to estimate genetic divergence of the genotypes for yield and quality traits. The study involved seven red pericarp, eight black pericarp and 17 white rice genotypes, in addition to the check, BPT 5204. The diversity was evaluated using multivariate analysis technique of Mahalanobis [4] D 2. The 33 rice genotypes studied were grouped into seven clusters. Cluster I was observed to be the largest with 18 genotypes, followed by Cluster III with nine genotypes and Cluster II with two genotypes. The clusters, IV, V, VI and VII were monogenotypic. The pattern of distribution of genotypes into various clusters was observed to be at random with no relation to geographical diversity. Results on inter-cluster distances revealed maximum diversity between genotypes of cluster I and cluster VII, while intra-cluster distance was noticed to be maximum for cluster III. Cluster II had recorded maximum grain yield per plant, in addition to test weight and plant height along with hulling percentage. The cluster II had also recorded intermediate amylose content and alkali spreading value (ASV) in addition to protein content more than 10 per cent and zinc more than 20ppm along with iron more than 10ppm. Further, maximum contribution towards genetic divergence was noticed by total phenol content (28.45%), followed by Total antioxidant activity (16.67%) and minimum by length/breadth ratio (0.10%).