Developmental Variation among Improved Coffee Hybrids Propagated through Somatic Embryogenesis

A study was conducted to assess the response of improved coffee varieties to somatic embryogenesis and identify varieties that can be included in multiplication programme using this technique. Young fully expanded leaves from six varieties N39-1, N39-5, KP423-1, KP423-3, CVT1-2 and CVT2-1 planted at Lyamungu were surface sterilized for 30 minutes under agitation using calcium hypochlorite solution, cut in small explants approximately 1 cm2. Seven explants each were plated in 5 magenta jars (6.5cm diameter) per variety, cultured in Murashige Skoog medium with initiation additives (MS1) for 6 weeks, and embryonic callus development additives (MS2) for 6 months. The time required for callus induction was observed during the first six weeks. Callus formation continued to be monitored up to six months. Then callus weights were taken per jar and results expressed as percentage of the established average weight of calli per genotype, and were routinely managed afterwards. Each magenta jar was treated as a replication, allowing for RCD design, and individual weights were exposed to ANOVA using STAT statistical software. The results showed some difference in both callus formation time and callus weight among the genotypes tested, the latter being significant at P<0.05. Explants from varieties CVT1-2 and CVT2-1 were fastest developing (3 weeks) followed by KP423-3 and KP423-1 (4 weeks) while N39-1 was slowest (5 weeks). The highest mean weight and percentage of callus development was observed in explants obtained from variety KP423-3 (86.25%), KP423-1 (83.73%) followed by N39-3 (63.75%) and CVT1-2 (61.25%), while the least performers were N39-1 (46.25%) and CVT2-1 (43.75%). This study has shown that response to somatic embryogenesis differs with varieties, opening up avenue for future screening of the remaining 13 varieties. Varieties KP423-3 and KP423-1, with high percent callus per explant and average initiation time, are hereby recommended as pioneers for investors interested in massive somatic embryogenesis of Arabica coffee in Tanzania.