Evaluation of Morphological Traits, Dowdy Mildew Tolerance and Phytochemical Contents of Sweet Basil Germplasm Collected by Tropical Vegetable Research Center, Kasetsart University in Rainy Season

Abstract

Sweet basil is an important vegetable as domestic consumption and export due to high nutrition and medicinal properties. There is not much an information in breeding program and less diversity in sweet basil. Another problem of sweet basil is susceptible to downy mildew, especially in a rainy season. Therefore, the objective of this study was evaluation of sweet basil germplasm collected by Tropical Vegetable Research Center, Kasetsart University by investigating their morphological characteristics, tolerance to downy mildew in the rainy season and phytochemical content. Fifty three accessions were evaluated in leaf shape, leaf length, leaf width, inflorescence type, corolla color and phytochemical contents such as beta-carotene, chlorophyll A and chlorophyll B. The results showed that there were 10 accessions of sweet basil germplasm those were resistant to downy mildew. They were OC015, OC142, OC145, OC145-A, OC145-C, OC145-D, OC153, OC159, OC161 and OC161-A. Most of the leaf characteristics were ovate shape, serrate leaf margin, medium leaf margin depth and leaf length was between 4.1 and 6.8 cm, leaf width was ranging from 2.0-3.1 cm. There were 2 types of inflorescence characteristics that were group inflorescences (8 accessions) and verticillate cyme (40 accessions). Additionally, there were 5 accessions those had both inflorescence characters. The beta-carotene, chlorophyll A and chlorophyll B contents of resistant germplasm were 2.322-3.047, 8.408-11.564 and 2.588-3.819 mg/100 g FW, respectively. There were 13 selected sweet basil accessions those recovered from downy mildew and were grown in greenhouse and outside greenhouse conditions. The beta-carotene content of those were ranging from 1.814-2.253 mg/100 g FW. Furthermore, there were 2 selected accessions (OC058 and OC071) those could be grown in both greenhouse and outside greenhouse conditions, with no differences in beta-carotene, chlorophyll A and chlorophyll B contents.