Varietal Improvement of Strawberry (Fragaria x ananassa Dutch.) Through Somaclonal Variation Using In Vitro Techniques

Strawberry is a valuable, nutritious, and economically important fruit all over the world including Bangladesh. Therefore, there is a demand to develop a suitable variety of strawberry. For this purpose, leaf explants from in vitro grown strawberry plantlets were cultured onto MS medium supplemented with different concentrations and combinations of 2,4-D, NAA and BA for callus induction. The most effective combination was 2.0 mg/L NAA with 0.5 mg/L BA. Then, the calli proliferated in this medium were cultured in MS medium containing different concentrations and combinations of BA, BA + NAA and BA + KIN + NAA for shoot regeneration. The best media combination was 1.5 mg/L BA + 0.75 mg/L NAA + 0.5 mg/L KIN. The regenerated shoots were cultured onto MS medium with different combinations of auxins or in MS and 1⁄2 MS medium without plant growth regulators (PGRs). The highest rooting performance was recorded in MS medium without PGRs. The plantlets were then gradually acclimated and successfully transferred to the field for evaluation. Somaclonal variations in different morphological characters such as plant height, no. of leaves/plant, petiole length, no. of stolon/plant, stolon length, no. of nodes/stolon, canopy size, no. of clusters/plant, fruit shape, no. of fruits/plant, average fruit wt. (g), fruit wt/plant (g), were noticed. Some of the somaclones exhibited better performances of the above mentioned characteristics than those of micropropagated mother plants and were well adapted to Bangladesh agro-climatic condition and were cultivated commercially in the winter season by many farmers.