DESICCATION SENSITIVITY OF RECALCITRANT SEEDS - A STUDY ON TROPICAL FRUIT SPECIES

Mangosteen (Garcinia mangostana L.) rambai (Baccaurea motleyana Muell. - Arg.) and jelentik (Baccaurea polyneura Hook. f.) are tropical fruit species believed to have recalcitrant seeds. The seeds showed no dorm ancy; they germinated easily. At harvest, the mean moisture contents ( fresh weight basis) were 53.54, 51.20 and 44.90% for G. mangostana, B. motleyana and B. polyneura, respectively. G. mangostana seeds lost vi ability when their moisture content fell to about 24% while B. motleya na seeds lost viability below 35.5% moisture content. However, for B. polyneura, the seeds could be dried to low moisture content with high survival. The viability was still high when the moisture content was r educed to 13.46%. At this moisture content, the percentage germination was 91.76% and it was found that the seeds survived cyopreservation w ith 8.3% viability. For B. motleyana axes, the loss of viability occur red when their moisture content fell to about 36% (15% viability with predominantly callus formation) while for B. polyneura axes, viability was reduced to 33-67% when the moisture was 27-30%. At various moistu re contents, the seeds of the fruit species studied were exposed for 4 8 h to 7 degrees C and -4 degrees C. G. mangostana seeds did not survi ve either temperature. Baccaurea seeds survived 7 degrees C but failed to survive -4 degrees C. No axes from B. motleyana seeds at various m oisture contents survived cryopreservation. However, some viability (2 0-30%) was observed in B. polyneura axes cryopreserved at a moisture c ontent of about 27%. At this moisture content no normal growth was obt ained; callus formation was observed. It appears that the seeds vary i n the degree of desiccation sensitivity. They also vary in size. Seeds of G. mangostana are larger than Baccaurea seeds and thus, more sensi tive to desiccation. Seed and embryonic axis structure may also play a role in desiccation sensitivity.