Phenotypic characters of various off types identified in laboratory, primary and secondary hardening in tissue cultured banana var. <i style="">Grand naine</i>

Abstract

An integrated study was undertaken on micropropagation of Grand nain variety of banana (Musa paradisiaca) from elite plants to identify and segregate (i) 3 types of off plants at the end of growth room phase development, (ii) 5 types of off plants at the end of primary hardening phase and (iii) totally 9 types (which included common 5 types observed at the end of primary hardening) at the end of secondary hardening phase. The morphological profiles of normal and off type plants were studied as a function of the above mentioned growth phases. The 9 off types identified after secondary hardening were finally subjected to field trials along with normal plants to serve as control using an optimized protocol of fertilizer application and irrigation. Their outcome indicated that off types, regardless of the type, could not sustain either transplantation shock or survived for not more that 3-6 months, giving poor growth/ no fruiting/ poor yield in quality and quantity. The composite data indicated that these off types were somoclonal variants and were not the result of epigenetic factor(s), as ruled out from studies of factors likely to affect their growth. It is, therefore, prudent to segregate them rigorously at each developmental phase so that delivery of only healthy normal plants to farmers was assured, limiting to minimum, if any, inadvertent contamination of off type plants due to limitation in their identification.