Growth and development, and genetic variation of Tin Hung Doi (Daiswa polyphylla (Smith) Raf.)

Abstract

Tin Hung Doi (Daiswa polyphylla (Smith) Raf.) is a rare medicinal plant mainly found growing in highland areas. This plant is at risk of extinction because its rhizome has been drastically dug up extensively for sale. There is very little information known about this plant. The objectives of this research were to study the following; 1) growth and development of Tin Hung Doi, including an investigation of habitat and outside environmental affects to highland areas of Chiang Mai, 2) genetic variations of Tin Hung Doi plant. The results showed two kinds of growth and development, flowering and non- flowering plants. The environment where Tin Hung Doi grows showed an average air temperature of 24.64cC with relative humidity of 67.40 percent, and average light intensity at 237.66 Lm m2. Moreover, Tin Hung Doi was found mainly in sandy loam soil which is a slightly acidic. The average organic matter of the soil was 8.01 g 100 g', with cation exchange capacity of 20.57 cmol(t) kg' at altitude 1,046 - 1,394 msl. Tin Hung Doi flower is a single flower sprouting at the top of the stem in the center of a whorl of leaves, comprising of a pedicel, 4-8 sepals or leafy bracts, 3-8 petals which reduce to a filiform structure. There are 10-22 stamens and a pistil with one ovary containing 2-38 ovules. The flowering plants normally emerge from April onwards, followed by shoot growth and young leaves. The flower emerges from the middle of a leaf whorl in April to May. Leaves open from May to June, the flowers bloom from May to July, then fruit setting and seed mature during July to December. The plants enter dormancy from September to January until resuming growth in the next growing season. The anatomy of the Tin Hung Doi flower is not so complicated. Cytology revealed 5 pairs of chromosomes (2n = 10). Root tips collected at 7 a.m. and 12 a.m. had many mitotic cells, 24 and 25 percent, respectively. Plant samples in Wat Chan, Galyani Vadhana district and Pa Kluay, Chom Thong district showed different arm ratios and chromosome types. The genetic variation study by RAPD technique with 18 primers on 30 samples from the same and different areas showed that they can be classified into 4 groups. Reproductive biology of Tin Hung Doi showed stigma viability approximately 35 days after bloom, pollen was viable approximately 15 days after bloom, and pollen germination at 25.90 percent in 1 percent medium supplemented with 5 percent sucrose. Seed viability was 100 percent tested by dying with 0.1 and 1 percent tetrazolium. The seeds germinated approximately 45.71 percent after 12-16 months from sowing. The information from this study can be used for Tin Hung Doi cultivation, breeding, and conservation.