Morpho-agronomic characterization and evaluation for drought tolerance of selected Philippine traditional rice (Oryza sativa L.) varieties

Assessment of agro-morphological diversity among conserved rice germplasm is an important endeavor in any genetic resources management and crop improvement. Discovery of desirable traits from traditional rice varieties (TRVs) and incorporating those traits in rice breeding efforts would greatly benefit rice farmers to instigate effect and better manage rice production in changing environmental conditions. The study provides information on morphological characterization and drought tolerance of TRVs used to assess the extent of genetic diversity of the collection and possibly identify some varieties with desirable traits for direct utilization. Fifty TRVs were planted during the 2011 wet cropping season for morphoagronomic characterization using 58 traits following the standard descriptors list for cultivated rice. Same set of germplasm were grown under soil bed imposed with either continuously flooded and progressive drought stress conditions to determine drought tolerance of our traditional rice varieties. Morpho-agronomic traits were analyzed using multivariate statistical analysis. The mean Shannon-Weaver diversity indices were H1=0.55 for all qualitative traits and H1=0.83 for quantitative traits. An overall genetic diversity of 0.65 was gathered indicating a medium level of genetic variation among these cultivars. The results obtained in the study revealed that drought had caused considerable morphological changes in plant growth during vegetative drought imposition. The severity of the drought affects the plant growth and it was measured by reduction in shoot length and shoot dry weight. Top five genotypes, PILIT TAPOL, SINADUGAN, KAMOROS, AZUCENA and MINALINIS showed less reduced shoot dry weight under drought condition, Several traditional rice germplasm collections have drought tolerance and should be further explored to support utilization of these germplasm for varietal improvement programs.