IN VITRO PROPAGATION PROTOCOL OF TWO ELITE SUGARCANE (Saccharum officinarum L.) GENOTYPES USING APICAL MERISTEM CULTURE

Abstract

Conventional propagation of sugarcane (Saccharum officinarum L.) is limited due to low propagation rates, its time demand and potential transmission of pathogens through seed cane from generation to generation. In vitro propagation is the best alternative to overcome such limitations of conventional propagation. Hence, the present study was initiated to optimize a protocol for rapid in vitro propagation of two sugarcane genotypes (B4906 and Pr1013) grown in Ethiopia. Multiplication of propagules were carried out in completely randomized design(CRD) with 2x5x5 and 2x6 factorial treatment arrangements of genotypes, BAP(0.5, 1.0, 1.5, 2.0, and 2.5 mg/l) and NAA(0, 0.2, 0.3 0.4, and 0.5 mg/l), and genotypes with sucrose(20, 30s, 30, 40, 50 and 60 g/l) in combination respectively. In vitro rooting was also carried out in completely randomized design (CRD) with 2x5 factorial treatment arrangements of genotypes and NAA(2.0, 3.0, 4.0, 5.0 and 6.0 mg/l) in combination. For shoot multiplication, the initiated shoots were cultured on a medium containing BAP in combination with NAA. The effect of table sugar concentration was also tested for multiplication. For rooting, separated shoots were cultured on 1/2 MS media supplemented with NAA. Number of shoots and leaves, shoot length, number and length of roots were recorded. The results showed that the interaction effects of genotypes and plant growth regulators significantly influenced in vitro sugarcane multiplication. The interaction of genotypes and table sugar concentration also significantly influenced in vitro sugarcane multiplication. The combination effects of NAA and genotypes significantly influenced in vitro rooting. On MS media with 1.5 mg/l BAP and 0.4 mg/l NAA, B4906 gave the highest (16.88±0.5) numbers of shoots with 5.94±0.17 cm shoot length and 6.33±0.29 leaves/shoot. Whereas 2mg/l BAP and 0.5 mg/l NAA resulted in a maximum of 11.70±0.28 shoots with 4.48±0.08 cm shoot length and 4.95±0.11 leaves/shoot for Pr1013. On MS medium with 50g/l table sugar, B4906 gave the highest (13.42±0.29) shoots with 4.09±0.08 cm shoot length and 8.92±0.14 leaves /shoot, whereas Pr1013 produced a maximum of 7.78 ± 0.19 shoots with 4.61±0.04 cm shoot length and 7.77±0.03 leaves /shoot at 60g/l table sugar. Half MS medium with 2mg/l NAA resulted in 91.67% rooted shoots with 12.58±0.23 roots and 2.54±0.04 cm root length in B4906 whereas 4mg/l resulted in 66.67% rooted shoots with 7.83±0.70 roots and 2.60±0.05 cm shoot length in Pr1013. Rooted plantlets acclimatized in greenhouse and 96.1% of plantlets survived successfully in 15days. It could be concluded that the optimized protocol is useful for rapid clonal multiplication of sugarcane planting materials. In vitro propagation through bioreactor using this optimized protocol could be recommended to increase multiplication rate and reduce agar cost. In addition, further studies will be required for protocol improvement using different hormone combinations with aim of increasing multiplication efficiency and cost reduction.