No abstract

This study reports the in vitro germination of self-pollinated pod of Vanilla siamensis, native to Thailand. The aim of the present work is to determine the effect of culture media and plant growth regulators on seed germination and plantlet regeneration. The vanilla seeds were asymbiotically germinated on different culture media under aseptic conditions. The results showed that, New Dogashima medium (NDM) supplemented with 2% (w/v) sucrose, 15% (v/v) coconut water (CW) and 0.7% (w/v) agar gave the highest levels of seed germination at 10.1%. The fastest and highest percentage seed germination was achieved using NDM supplemented with 2 mg/l gibberellic acid (GA 3). Seeds on this culture medium germinated within 7-8 weeks in comparison with 10-11 weeks on culture medium without plant growth regulators. Protocorms were transferred to different culture media with various concentrations of 6benzyladenine (BA) to assess the protocorm development. The results revealed that ½ Murashige and Skoog (½ MS) medium gave the higher result in survival rate of protocorm than NDM. ½ MS medium with 0.5 mg/l BA was suitable for shoot formation. Plantlet development was completed after subculturing on ½ MS medium supplemented with 0.5 mg/l α-naphthaleneacetic acid (NAA) for 8 weeks and successfully acclimatized at 91.7%. The protocol outline here can be used for mass propagation of this endangered species and used as a guideline for improvement of V. siamensis and its in vitro conservation.

Viability of Grammatophyllum speciosum seeds was evaluated by a TTC (2,3,5-triphenyl tetrazolium chloride) test. The seeds were then asymbiotically germinated on different agar media under aseptic conditions. The results showed that keeping the seeds in the dark at 30°C for 1 day gave 99% of red staining embryos (referred to as viable). After sowing the seeds on half-strength Gamborg's B5 medium supplemented with 0.1% activated charcoal (AC) for 30 days, germination of those seeds was observed. Half-strength MS medium (½ MS) supplemented with 1 mg/l 6-benzylaminopurine in combination with 0.5 mg/l α-naphthalene acetic acid, 15% coconut water, 0.2% AC, and 0.7% agar gave the highest percentage of protocorm-like body (PLB) induction and proliferation. The PLBs could be regenerated into complete plantlets with vigorous shoot and root formation on ½ MS medium without any plant growth regulators. The survival rate of plantlets was 70% after hardening off in the greenhouse for 1 month.

Oil palm is an oil crop that produces the highest oil yield throughout the year. Repeated application of fertilizer in oil palm orchard results in severe salinity of planting areas. Therefore, the objective of this study was to determine growth, physiochemistry and re-growth of calli as effected by sodium chloride (NaCl). The calli were cultured in liquid oil palm culture medium (OPCM) supplemented with different concentrations of NaCl (0, 50, 100, 150, 200, 300 and 400 mM), 0.1 mg/l dicamba and 200 mg/l ascorbic acid for 4, 8 and 12 weeks. The results showed that increase in concentrations of NaCl and exposure times decreased growth rate of cells in suspension culture. The concentration of NaCl which inhibited growth rate at 50 % (IC50) was 166.73 mM after culture for 12 weeks. Increase in concentrations of NaCl and exposure times increased electrolyte leakage (EL), changing of electrical conductivity (EC) medium and proline content. NaCl at concentration of 400 mM gave the highest EL, changing of EC medium and proline content at 82.22 %, 3.77 mS/cm and 64.93 µg/gFW, respectively. Over 200 mM NaCl oil palm cells cannot survive. After transfer treated callus clumps to OPCM without NaCl for 8 weeks, the clumps treated in 50 mM NaCl gave the highest fresh weight at 416.5 mg while 100 mM gave the highest average number of nodules per tube at 84 nodules. This result suggests that cells of oil palm in vitro could not stand to NaCl at concentration higher than 200 mM.

This study was conducted to determine the optimum concentrations of 2, 4-D, L-proline and casein hydrolysate (CH) for efficient callus induction and plantlet regeneration from culturing mature embryos of Sangyod, an economically important indica rice variety in Thailand. The highest frequency of callus induction (73.08 ± 2.65 %) was obtained from MS medium supplemented with 2 mg/L 2,4-D, 750 mg/L CH and 200 mg/L L-proline. The combination of 1 mg/L BA, 0.5 mg/L Kn and 0.5 mg/L NAA containing solidified MS medium gave the maximum mean fresh weight of callus (938.9 ± 44 mg), green spot formation (64.17 ± 7.08 %), shoot induction frequency (66.25 ± 6.80 %) and mean number of shoots/explant (6.12 ± 0.36 shoots). The greatest mean number of shoots/explant (14.93 ± 0.97 shoots) and root formation percentage (82.71 ± 3.03 %) was observed in liquified MS medium supplemented with 0.5 mg/L NAA and 1 mg/L BA.