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The effect of the growth regulator paclobutrazol (PP333) on the growth, development and yield of Lolium perenne grown for seed
Author(s) -
HAMPTON J. G.,
HEBBLETHWAITE P. D.
Publication year - 1985
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.1985.tb01724.x
Subject(s) - paclobutrazol , anthesis , lolium perenne , perennial plant , agronomy , biology , yield (engineering) , dry matter , growth rate , horticulture , cultivar , mathematics , materials science , metallurgy , geometry
Application at spikelet initiation of the growth retardant paclobutrazol (PP333) at a rate of 2.0 kg a.i. ha −1 increased the seed yield of perennial ryegrass cv. S24 from 139 to 180 g m −2 in 1981, and from 111 to 256 g m −2 in 1982. Yield increases were associated with an increased production of fertile tillers in both years and with an increased number of seeds per spikelet in 1982. Other yield components were not changed. Seed yield increased with increasing PP333 application rate in both years. No significant yield difference was recorded between application at spikelet and floret initiation in 1981. Lodging was prevented completely by the 2.0‐kg rate, delayed until after anthesis by the 1.0‐kg rate and began before anthesis with the 0.5‐kg rate. PP333 reduced stem internode length and strengthened the base of the stem; total stem dry matter (DM) was reduced, but root DM accumulation was increased at all rooting depths. Leaf area duration was significantly increased in both years. Vegetative regrowth after seed harvest was not significantly reduced by PP333 application, but soil residual properties were demonstrated.