Project Number: 6225-21000-010-24
Start Date: Oct 01, 2012
End Date: Sep 30, 2015
Task 1: Determine the Genetic Response to Straighthead Induction Using Natural and Chemically Amended Soil Sites Two field testing sites will be used through the course of the project. The UAPB site has been observed to naturally induce straighthead symptoms, whereas the DBNRRC site has been used for many years for straighthead evaluation following amendment with an herbicide (MSMA). One hundred germplasm accessions including domestic and foreign cultivars will be tested in a Randomized Complete Block Design at both sites. Maturity will be measured by date when 50% of panicles emerge from the sheath. At the end of the season, grain yield and plant height will be measured and straighthead symptoms will be scored using a 0 - 9 rating scale as described by Yan et al. (2005). Task 2: Determine Soil and Water Factors Associated with Straighthead Resistance Cultivars that are resistant, intermediate, and susceptible to straighthead from Task 1 will be grown in large plots at both field sites using a Completely Randomized Block Design. Soil and water samples will be collected from each plot every month from planting until harvest. Plant height, grain yield, and straighthead will be recorded at the end of season. Soil samples (0-15 cm) will be characterized for major/minor/trace elements, organic content, texture, pH, and cation exchange capacity using the USDA standard procedures. Water samples will be analyzed for major/minor/trace elements. Task 3: Determine Plant Factors Associated with Straighthead Resistance In the experiment for the Task 2, a main tiller and the most recently emerged (top) two leaves will be collected from each plot every month, and panicle samples will be collected every week from heading to maturity. The elemental (P, K, Ca, Mg, Na, S, Fe, Mn, Zn, Cu, and B) composition in the tissue will be determined using the ICP-AES. Task 4: Identification of Resistant Germplasm for Straighthead Improvement Germplasm accessions that had statistically similar straighthead symptoms in both the sites will be selected from year 1 for verification in large plots in year 2. In year 3, the most resistant germplasm accessions will be tested in farmer fields where straighthead has frequently occurred. Meanwhile, the most resistant accessions will be evaluated for agronomic characteristics in both the sites. The resulting information will be used by breeders for parental selection. Throughout these stages of operation, UAPB undergraduate and graduate students will be trained in scientific methods, experimental design, soil and plant sampling, field operations for rice farming and research, evaluation methods for screening for straighthead resistance, breeding techniques, making scientific presentations, and assisting in manuscript drafting.