Figure 5. Do not be afraid to leave plenty of white space around your figures. If you use someone else’s figure, always acknowledge the source. Figures cut and pasted from .pdfs of papers do not look good on posters. It is possible to make a statement of a result in a figure caption e.g. ‘X increases Y in Z’ rather than ‘Effect of X on Y in Z’. Local Landraces of Rice from Sri Lanka : Variation in Alleles and Traits Related to Drought Resistance Genotypic differences showed 84% of significance in maximum shoot length, 62% in root length, 54% in root thickness, and 73% in total root mass and 74% in root angle at day 21. Genotypic differences showed 84% of significance in maximum shoot length, 62% in root length, 54% in root thickness, and 73% in total root mass and 74% in root angle at day 21. Mayuri Munasinghe , Adam H. Price Institute of Biological and Environmental Sciences (Biological Interactions in Soil), University of Aberdeen, Aberdeen, AB24 3UU, U.K.   Background Rice is cultivated all over Sri Lanka. Cultivars grown in dry areas often experience drought at some stage of growth. It is suspected that some rice landraces are better adapted to a drought prone environment due to their greater ability to extract water from deep soil levels. Results (continued) Hydroponic screening Root thickness and maximum root and shoot length in hydroponic screen showed significant genotypic differences explaining 30, 60 and 55% of the variation respectively. Fig. 1. Sri Lanka (area: 65 610Km2 )is an island in Indian Ocean. Aims A total of 135 rice landraces from different geo-climatic regions of Sri Lanka are tested in this study using 1. physiological screening methods for rooting characteristics. 2. molecular marker characterisation for population structure and allelic variation in candidate genes. Fig.5: Plants (5weeks old) in Yoshida nutrient solution Fig.6: A block of plants with maximum root length (5 weeks) Methods Physiological screening: 1. Buried herbicide to measure rooting depth All genotypes were tested with a layer of herbicide (TRIK, 100 mg /plant) buried at a depth of 30cm in a soil box and symptoms of herbicide toxicity observed. Each plant was assigned a herbicide score daily for 22 days. 2. Hydroponic screening From 135 landraces, 36 with diverse reactions to the herbicide were tested in a hydroponic set up for 5 weeks. 3. Rhizotron method From 36 landraces, 12 were then grown in glass fronted rhizotrons for 6 weeks. Molecular marker characterisation DNA of all landraces to be screened with 25 microsatellite markers. Alleles of candidate genes for drought resistance and root growth will be investigated. Fig.7: Root length variation (35 days) in hydroponic screen. Rhizotrons Fig.10: Root length variation (35days) in rhizotrons Fig.8 & 9: Plants(39days old) growing in rhizotrons Significant genotypic differences explains 84% of the variance detected in maximum shoot length, 62% in root length, 54% in root thickness, 73% in total root mass and 74% in root angle at day 21. Molecular marker characterisation All landraces are being screened with 25 microsatellite markers. Results Buried herbicide to measure rooting depth A total of 50% of the variation in toxicity symptoms observed in plants was explained by cultivar. This indicated that potentially deep rooted and shallow rooted genotypes could to be distinguished. The best subset regression suggests that 55% and 85% of the variation in herbicide score could be explained by variation in traits tested in hydroponics and rhizotrons respectively. Fig.11: 18 Genotypes with RM211 in the top row and 19 genotypes with RM221 in the bottom row. Fig.12: 16 Genotypes with RM 242. Conclusions The herbicide scores significantly correlated with the drought scores of early and late vegetative stages in International Rice Research Institute database and with hydroponic and rhizotron data. Rooting depth can be assessed using these three techniques. Three genotypes (Podi wee, Sinnavellai and Niyan wee) were revealed as the most deep rooting drought resistant landraces. Future work Based on molecular marker data ,the genetic diversity and population structure will be revealed. Alleles of candidate genes for drought resistance and root growth will then be investigated. Fig. 2: Soil box with a herbicide layer at 30cm depth. Fig.4: Genotypes with highest and lowest mean herbicide score. Fig.3: Plants showing leaf yellowing Presented at Post Graduate Research Day 09.12.2011 Contact details: r01mmsm@abdn.ac.uk