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 BC 1 f 5 and Bc 2 f 4 populations by markerassisted 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.Rice (O. sativa L.) is the most important staple food crop for more than half of the world's population and it is cultivated in an area of 44.5 million hectare in India with the production of 106.5 million tonnes during the year 2016 1 . After the advent of high yielding semi-dwarf rice varieties, hybrid rice technology has been touted as a major strategy for enhancing the genetic yield potential of rice. The success of hybrid rice technology has been very well demonstrated in China, which produces 146.5 million tonnes of rice from 30.32 million hectares 1 . This significant increase in production in China is mainly due to cultivation of hybrid rice (with >50% area and production under rice hybrids). Several technical challenges, market and policy constraints has limited the development and diffusion of hybrid rice outside China 2 . In India, hybrid rice is cultivated in an area of ~3 million hectares 3 , which is about 6.7% of total area of rice cultivation. Hybrid rice accounts for less than 10% of the area under rice cultivation in Bangladesh, Indonesia, and the Philippines and just 10% in Vietnam.Hybrid rice technology aims to increase the yield potential of rice by exploiting the phenomenon of hybrid vigour or heterosis. Cytoplasmic male sterility coupled with fertility restoration controlled by nuclear genes is a very useful tool in exploiting heterosis in self pollinated crops. In rice, three CMS systems viz. Wild Abortive (WA), Boro II (BT) and Honglian (HL) are deployed for commercial hybrid rice seed production 4,5 . The most widely used CMS system in rice is based on wild abortive (WA) cytoplasm derived from Oryza sativa f. Spontanea 6,7 . The WA-CMS system is highly stable with compl...

Background Species belonging to the genus Trichoderma are considered as one of the most potential biocontrol agents which can be readily collected from soil and found effective against various fungal and bacterial diseases. In rice-growing areas, the major fungal pathogens affecting rice production include Rhizoctonia solani causing sheath blight and Sclerotium oryzae causing stem rot disease of rice. Due to the lack of resistant varieties and detrimental effects of chemicals, biocontrol gives a good opportunity to manage the diseases efficiently in a sustainable manner. Main body Trichoderma spp. from native rice rhizosphere soil were examined for their antagonistic efficiency to supress the two soil-borne rice pathogens, viz., R. solani and S. oryzae. Morphological, biochemical and molecular characterisation of the isolates led to the identification of species as T. asperellum. The isolates of Trichoderma spp. were found to be positive to IAA release and phosphate solubilisation and were screened against R. solani and S. oryzae in vitro and in vivo in pots under glass house conditions. Regression analysis indicated a positive correlation between the amount of chlamydospores produced by T. asperellum and their antagonistic potential against the two pathogens. Exposure to external stimuli, viz., light, injury and nitrogen sources in culture media triggered increased conidiation in Trichoderma isolates. Among the four isolates studied, Trichoderma asperellum IIRRCK1 (TAIK-1) was found to be the most effective in improving plant growth in rice and highly antagonistic against R. solani and S. oryzae. Sorghum grain was found to be the most suitable among different organic substrates studied to provide better growth and viability of TAIK-1 and improved the efficiency of the seed treatment and soil application. External stimuli in the form of near UV blue light, mechanical injury to the colonies and nitrogen source added to the culture media help in faster conidiation of Trichoderma. Conclusion Strain TAIK-1 showed strong competitive and antagonistic activities against fungal soil-borne pathogens, in addition with promoting healthy growth and development of rice plants. This can be a suitable and safe alternative to chemical management in the rice fields for long-term scenario.

Hybrid rice technology offers a great promise to produce 15% to 20% more yield than pure line varieties. The success of hybrid rice hinges on developing superior parental lines. To improve the blast resistance of hybrid rice parental line RP5933-1-19-2R, crosses were made with donors of two major blast resistance genes namely, Pi54 (Tetep) and Pi9 (IR71033-121-15) and the resulting F 1 s were confirmed for their hybridity by using Pi54MAS and NMSMPi9-1 genic markers. The confirmed F 1 s were intercrossed to obtain ICF 1 s and selected positive plants by markers were backcrossed to the recurrent parent, as well as selfed for advancing further to BC 1 F 3 and ICF 4 generations. The segregating plants were phenotyped for blast resistance at Uniform Blast Nursery. The identified complete restorers namely, RP 6619-1, RP 6616-26, RP 6619-3 and RP 6619-11 with Pi9 and Pi54 genes would serve as donors for broad spectrum blast resistance. This could ultimately lead to the development of new rice hybrids with improved resistance to blast disease, which is crucial for sustainable rice production and food security.