~ 3224 ~ Journal of Pharmacognosy and Phytochemistry 2018; 7(3): 3224-3226 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2018; 7(3): 3224-3226 Received: 04-03-2018 Accepted: 08-04-2018 Jignesh R Balat Department of Genetics & Plant Breeding, N.M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat, India Ranjit P Thakor Department of Genetics & Plant Breeding, N.M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat, India Indrajay R Delvadiya Department of Genetics & Plant Breeding, College of Agriculture, Junagadh Agricultural University, Junagadh, Gujarat India Sahadev R Rathva Department of Genetics & Plant Breeding, College of Agriculture, Junagadh Agricultural University, Junagadh, Gujarat India Correspondence Jignesh R Balat Department of Genetics & Plant Breeding, N.M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat, India Heterosis and inbreeding depression in F 2 population of rice ( Oryza sativa L.) for yield and related traits Jignesh R Balat, Ranjit P Thakor, Indrajay R Delvadiya and Sahadev R Rathva Abstract This study was conducted to evaluate genetic variation among eight parents and their six F2 populations for various morphological attributes at the Regional Rice Research Station, N.A.U., Vyara during Kharif – 2015. For grain yield per plant all the six crosses were displayed highly significant average heterosis in desired direction. Whereas, significant heterobeltiosis in desired direction was exhibited by the crosses NVSR 2031 x GAR-13, IR-28 x GAR-13, Gurjari x Varalu and GR-7 x GAR-13. The significantly negative relative heterosis for days to flowering was depicted by the crosses Gurjari x Varalu and GR-7 x GAR-13, respectively. Which indicates the chances of desired transgressive segregants for this trait. In plant height three out of six viz., NVSR 2031 x GAR-13, IR-28 x GAR-13 and Gurjari x Varalu expressed significantly positive inbreeding depression. These crosses might be useful for getting dwarf stature in segregating generations. Keywords: heterosis, inbreeding depression Introduction Rice (Oryza sativa L., 2n = 2x = 24) is second most widely grown cereal crop and the staple food for more than half of world’s population, providing two thirds of calorie intake for more than three billion people in Asia and one -third of calorie intake of nearly 1.5 billion people in Africa and Lat in America. Global production of rice (Rough rice-paddy) is 685 million tons from 158 million hectares area and its productivity is 4.3 t/ha. In India, rice is cultivated in 44.13 million hectares during 2015 with production of 106.19 million tones and productivity of 2416 kg per hectare (Anon., 2015) [2] . In Gujarat, rice is cultivated in 7.88 lakh hectares with product ion of 16.36 lakh tones and productivity of 2076 kg per hectare (Anon., 2015) [2] . The heterosis expresses the superiority of F 1 hybrid over its parents in term of yield and other traits. On the other hand, the inbreeding depression reflects on reduction or loss in vigour, fertility and yield as a result of inbreeding. The magnitude of heterosis helps in the identification of potential cross combinations to be used in conventional breeding programme to enable create wide array of variability in segregating generations. The knowledge of heterosis accompanied by the extent of inbreeding depression in subsequent generations is essential for maximum exploitation of such heterosis by adopting appropriate breeding methodology. Materials and Method Experiment was conducted in non-replicated trial as it was segregating material. Each row consisted of 20 plants with spacing of 20 cm x 15 cm inter and intra row spacing. Each F 2 was raised with minimum of 500 plant population and individual plant observations were recorded from 100 randomly selected plants. While, each parent and F 1 consisted of 50 plants and observations were recorded from 20 randomly selected plants. The experiment was planted in the month of July, 2015 at Regional Rice Research Station, N.A.U., Vyara. Data were recorded on days to flowering, days to maturity, plant height (cm), panicle length (cm), productive tillers per plant, no. of grains per panicle, 100 grain weight (g), kernel length (mm), kernel breadth (mm), kernel L/B ratio, grain yield per plant (g), straw yield per plant (g), harvest index (%) and leaf area (cm 2 ). Statistical analysis Heterosis: Heterosis, expressed as per cent increase or decrease in the mean value of F1 hybrid over the mid and bet ter parent (Heterobeltiosis) was computed for