National Integrated Banana R and D [research and development] program: Project 1.2 Development of dwarf banana cultivars (saba and cardaba) by irradiation

One hundred sixteen accessions of Cardaba/Saba and other cultivars were collected from twenty six banana growing areas of the country during the period. Of these, 77 accessions were considered putative dwarf, with pseudostem height below 4 meters. These accessions are currently maintained in the field for evaluation and confirmation. From these collections, 32 bunches from different accessions have already been harvested, characterized and evaluated. Three promising cultivars have been selected based on short stature, early fruiting and high yield. These include: -9-063 (Luyluy/Dippig), 09-064 (Cardaba), and 10-009 (Saba). Sensory evaluation was conducted using 16 different accessions for both cooked and uncooked type. For the uncooked fruits, Dippig appeared to be mostly liked by the respondents while 09-011 (Cardaba) and Dippig were more preferred for the boiled banana. On the other hand, 7 accessions were used for banana chips evaluation. Based from the sensory, 09-044 (Cardaba) was preferred most while 09-061 (Tiparot) was the least liked by the respondents. Morphological characterization and photo documentation of all the collections was also conducted. A catalogue containing the passport, characterization and evaluation data was also prepared. Cardaba and Saba (Dippig) shoot culture were subjected to cobalt gamma radiation at varying dosages. Reduction in terms of increase in shoot weight, number of shoots regenerated and percent survival were observed both in Cardaba and Saba (Dippig) as radiation dosage was increased. One-hundred percent (100%) survival of shoot cultures was observed at 0-40 Gy for Cardaba while 0-20 Gy for Saba (Dippig). One hundred percent mortality was observed beyond 70Gy in both cultivars. In Cardaba, LD50 was assumed to be between 50Gy (80% survival) and 60Gy (35% survival) while in Saba (Dippig) was between 30Gy and 40Gy with 52% and 60% survival. LD50 was taken at 45 days after irradiation. A total of 705 Cardaba shoot culture were irradiated at 0Gy (control), 5Gy, 10Gy, 20Gy, 30Gy, 40Gy, 50Gy, 60Gy, 70Gy, 80Gy, 90Gy and 100Gy while 375 Saba (Dippig) shoot cultures were subjected to varying dosages 0Gy (control), 5Gy, 10Gy, 20Gy, 30Gy, 40Gy, 50Gy, 60Gy and 70Gy. Irradiated cultures were further micropropagated which were used for screening for dwarf genotypes in-vitro and in the field. At present, 1,568 irradiated Cardaba and 280 irradiated Saba plants were established in the field for further evaluation. Initial selection of dwarf lines was done at the in vitro level. Optimization of the protocol was done using different cultivars and different dosages of GA3. Results showed that the optimum concentration is at 3 ppm GA3. A total of 355 irradiated Cardaba were subjected to 3 ppm GA3 but only 188 plants expressed normal growth were established and will be further tested in the field for confirmation.