Regenerative Potential of Barley Grass (Hordeum leporinum)

Abstract

(1) Delayed germination of seeds in barley grass (Hordeum leporinum Link.) did not follow a pattern consistent with the position of the seed in the inflorescence (head). (2) Seed weight variation in the head of barley grass showed a consistent pattern; the heaviest seeds in the head occurred in the earliest-flowering spikelets at the centre of the heads, with progressive decreases in weight towards the upperand lowermost spikelets. (3) Delayed germination in the seed population was related to absolute seed weight, with sharp increases in the % of non-germinated seed below a fresh weight of 0.004 g. The lower range of seed weight variation in 64% of the heads of a sampled barley grass population was below this weight. (4) Seed number and weight exhibited an inverse relationship amongst the heads of a barley grass population. This, together with the pattern of seed weight variation in the heads, indicates the likelihood that competition exists between the demands for seed number and weight in the allocation of photosynthate to the developing grain. (5) The significance of these findings is discussed in the light of the likely physiological demands made of seed to ensure high regenerative potential in an annual species.