SURVEYING THE ORIGIN AND BIOLOGICAL CHARACTERISTICS OF STEPHANIA BRACHYANDRA (DIELS) GENE SOURCES IN THAI NGUYEN

Abstract

This study focuses on the biological characteristics of the genetic resources of the Stephania brachyandra in Thai Nguyen, one of Vietnam's valuable medicinal plants currently at risk of extinction. Investigation results indicate that Stephania brachyandra is commonly found at an average density of 32.57 plants per square kilometer, with distribution density varying across districts, being highest in Vo Nhai district and lowest in Phu Luong district. This species primarily thrives in rocky mountain forests and regenerating land after extension exploitation. The plant is predominantly found above attitudes 250 m, followed by altitudes between 200-250 m, and is least common at altitudes below 200 m. The average shrub cover density in the Open Top Chambers (OTCs) with Stephania brachyandra populations surveyed across the districts is 18%, significantly lower compared to other plant species such as: Mua, Sim, Don nem, and Tu chau. The average ground cover density is 15.8%, mainly consisting of weeds such as grass, daisies, bamboo grass, pig bristle grass, and betel leaf. Regarding soil, the thickness of the A0 horizon varies from 1 to 4 cm. The A horizon has an average thickness of 30.3 cm, and is reddish-brown, moist and friable, with low rock content. The B horizon has an average thickness of 60 cm, and is yellow-brown, moist, slightly compact, with higher rock content. The chemical composition of the soil ranges from medium to nutrient-poor.