The effect of date of closing cut on seed production of Andropogon gayanus cv. Kent was studied
in NE Thailand. Cutting in August, September or
October produced progressively lower pure seed
and pure live seed yields than the uncut control
(433.9 vs 285.2, 159.3 and 62.1 kg/ha; and 302.6
vs 206.7, 99.2 and 38.6 kg/ha, respectively).
Delayed peak flowering in association with
increasing moisture stress, and a reduced leaf
area at flowering may have led to decreased
yields. Thousand-seed weight was unaffected by
cutting date. Tiller density increased with later
cuts, but as inflorescence density remained similar, tiller fertility decreased. Seed purity was
unaffected by cutting date. Closing cuts had a
large, negative effect on inflorescence size, indicated by dramatic reductions in pure seed yield
per inflorescence with successive cuts. Seed germination percentage decreased following cutting
in September or October, resulting in lower pure
live seed yield. Closing cut dates between May
and August should be investigated.