Author

Poonam Chetry and Shanti S. Sharma*

Abstract

Sikkim, with a long tradition of rice cultivation, is endowed with many landraces that represent a unique genetic resource for multiple desired traits for crop improvement. Here, the seed germination and seedling growth aspects of fifteen rice landraces, including both low land and up land, from Sikkim Himalaya have been assessed. The freshly harvested seeds of eleven landraces exhibited nearly complete (96-100%) germination within 6 d with a mean germination time (MGT) ranging from 1.04 (Ruduwah and Mumpupzho) to 1.88 (Sano attey). In contrast, four landraces namely, Birinful, Doodhkatey, Dhansey and Dharmali exhibited much lower germination that ranged from 62% (Birinful) to 71% (Dharmali) after 6 d suggesting partial dormancy; the higher MGT values (2.83-4.07) imply slower rate of germination. Seed germination in these landraces further declined after 6 months of storage. The α-amylase activity, measured in germinating seeds through an agar plate assay as well as biochemically, was much lower in the landraces showing low germination (Birinful, Doodhkatey, Dhansey) than in those with high germination (Chinizho, Nepalzho, Tukmorzho). Exogenous GA3 stimulated the enzyme activity in both the groups but the magnitude of stimulation was much stronger in the former than that in the latter. GA3-induced stimulation of α-amylase activity in the low germinating landraces was accompanied by a correspondingly enhanced seed germination. Taken together, the germination ability of the tested landraces seems to be inter alia determined by endogenous GA3 levels that influence the α-amylase activity. The tested rice landraces also exhibited strongly variable seedling growth parameters. For example, the root and shoot length varied from 3.52 to 8.62 cm and 5.19 to 13.62 cm respectively. The seedling growth was stimulated by exogenous GA3 application. The findings have implications primarily for seedling establishment potential .

Pages: 156-162

Doi Number 10.5958/2455-7218.2023.00026.8

Keywords ?-amylase, GA3, Rice landraces, seed germination, seedling growth, Sikkim Himalaya.