Environmental Control of Flowering and Viviparous Proliferation in Seminiferous and Viviparous Arctic Populations of Two Poa Species

Abstract

Inflorescence initiation and development in viviparous Poa alpina L. and seminiferous and viviparous Poa alpigena (Fries) Lindman from Svalbard have been studied in controlled environments. A dual induction requirement was found in all plant types with pronounced effects of photoperiod and temperature. Floral primordia were initiated in short days (SD) at temperatures up to 18°C, while at low temperatures (3 to 6°C) long days (LD) were equally effective. Normal culm elongation and panicle development were dependent on LD (> 17 h), although a few abnormal or stunted panicles were formed in SD as well, with high temperature partially substituting for long photoperiods. In the seminiferous form of P. alpigena (ephemeral) proliferation was induced by marginal induction (primary and secondary) and it was especially stimulated by SD during inflorescence development. In the habitually viviparous plants mixed inflorescences with a high proportion of sexual flowers were induced by saturating induction, primary and secondary induction acting additively. Long days (LD) and high temperature during inflorescence development were especially conducive. Comparison with other temperate perennial grasses are made and the adaptive value of these responses in the arctic environment is discussed with the literature in the field.