The effect of growth retardant application on floret site utilisation and assimilate distribution in ears of perennial ryegrass cv. S.24
1985
HAMPTON, J. G. | Hebblethwaite, P. D.
Application of the growth retardant paclobutrazol (PP333), at 2 kg a.i. ha‐¹ at spikelet initiation to plots of perennial ryegrass cv. S.24 in 1981 and 1982 significantly increased the number of seeds per spikelet present at final harvest by reducing the number of seeds aborted during seed development. Distribution of florets and seeds per spikelet was altered by PP333, as both basal and penultimate spikelets contained more florets and seeds than did those of untreated plants. Seed weight and germination were increased in florets of penultimate spikelets, although PP333 application delayed maturity by 3–5 days. In untreated plants, assimilate recovery was significantly lower from the terminal section of the ear, whereas in PP333 treated plants, no differences were found between basal, intermediate or terminal sections of the ear. PP333 increased assimilate demand at all sections of the ear when the ear and leaves were fed. The implications of this are discussed.
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