Unravelling the cascade of differentials (ABA and GA) in corm dormancy release of gladiolus (Gladiolus grandiflorus L.)

Dormancy release is an important process in commercial flower production and procedures for breaking dormancy are often complex. Gladiolus is a representative bulbous plant with a deep innate dormancy (rest) in new corm buds for 3-4 months just after harvest. The present investigation was conducted to unravel the underlying cascade of differentials (Gibberellic acid, GA and Abscisic acid, ABA) in regulating corm dormancy release (CDR) in gladiolus corms under different storage temperature and durations. The per cent sprouting in Punjab Glance was 88% +/- 1.15 after 3 months of ambient storage and 100% +/- 0.00 after 2 months of cold storage and in Punjab Glad 3, the per cent sprouting was 43.33% +/- 0.87 after 3 months of ambient storage and 96.33% +/- 0.33 after 3 months of cold storage. The maximum spike formation was 91.67% +/- 1.67 in Punjab Glance and 70.67% +/- 1.67 in Punjab Glad 3 after 3 months of cold storage. The content of GA and ABA were found to be significantly correlated to sprouting and spike formation as the content of both GA and ABA varied with storage duration and temperature as observed through HPLC. The GA content was more in cold stored corms than ambient stored corms in both the cultivars and maximum (58.66 +/- 0.12 ng/g) was observed in Punjab Glance after 3 months of storage. The ABA content increased with increase in duration of ambient storage from 1 to 3 months and maximum content (347.50 +/- 0.83 ng/g) was observed in 3 months ambient stored corms of Punjab Glad 3. Thus, CDR is dependent upon endogenous content of GA and ABA that further is regulated by temperature and varied with cultivar.