Study on the In Vitro Propagation and Encapsulation of Triploid Watermelon ‘新一號’ Shoot Tips

• Main Authors: Putri Santika, 山蒂卡
• Other Authors: Jong-Yi Fang
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/4m433w

碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作系 === 105 === Watermelon (Citrullus lanatus) is one of the most widely cultivated crops in the world for its fruit consumption. Excessive seed numbers in watermelon fruit, however, is fast becoming undesirable in the markets and has given rise to the popularity of seedless or triploid watermelon variety in the past several years. Nevertheless, the seed production of triploid watermelon has some difficulties, such as time consuming, laborious and poor seed germination rate. Synseeds, which are the analogues of true seeds, make a promising alternative for the propagation of triploid watermelon. This study aims at producing synseeds of triploid watermelon ‘新一號’ using shoot tips as the propagules, and examining different sowing substrates and medium formulations for synseed germination and growth under both in vitro and ex vitro conditions. The study included seed pre-treatment for germination, seed sterilization, shoot proliferation, synseed production and synseed sowing using different substrates, medium formulations and propagules, in in vitro andex vitro conditions. It was observed that the best pre-treatment for triploid watermelon ‘新一號’ germination is seed coat detachment. As for seed sterilization, 0.75% sodium hypoclorite (NaOCl) immersed for 10 min had the highest normal seedling percentage with 0% contamination. Shoot proliferation using seedling shoot tip explants produced the highest number of shoot per explant with the supplementation of 1 mg/L benzyladenine (BA) in the multiplication medium. Although root development was delayed by the presence of BA in the medium, BA addition did not affect acclimatization survival of the proliferated shoot tips. Synseeds were produced using shoot tips from aseptically germinated seedlings and BA-multiplicated explants, both having comparable performance. In synseed sowing in vitro, different substrates, as well as indole-3-butyric acid (IBA) addition, influenced the performance of synseed. Agar was observed to show superiority among other substrates tested. However, the study demonstrated the possibility of using vermiculite as alternative medium sowing susbtrate to agar. The addition of IBA in both gelling matrix and sowing medium, in general, gave positive effects on rooting rate, root number conversion and acclimatization success of triploid watermelon ‘新一號’ synseed. On the other hand, Hyponex medium, as well as sucrose-free medium failed to produce normal growth intriploid watermelon ‘新一號’ synseed which resulted in 0% conversion. Plant preservative mixture (PPM) at 0.5% was a better microbial agent than 100 mg/L mancozeb for synseed sowing ex vitro, as it achieved 0% contamination and maintained the synseeds growing potential with 65% rupture, 85% survival and 10% rooting rate after 28 days of culture. The production and growth of triploid watermelon synseed made using shoot tip propagules was achieved. Although it might not be applicable yet in the industry, advanced studies regarding antimicrobial agents and medium formulations for sowing ex vitro, as well as storage potential may further increase the applicability of the system in the future.