Tropical Grasslands (2007) Volume 41, 3542
Seed production of two brachiaria hybrid cultivars in north-east Thailand. 2. Closing date defoliation
M.D. HARE, P. TATSAPONG AND
Faculty of Agriculture, Ubon Ratchathani
University, Ubon Ratchathani, Thailand
Two field trials were conducted during 2003–2004
in north-east Thailand to examine the effects of
timing of closing defoliation on: seed production;
forage production before closing to seed; and
yield and quality of stubble at seed harvest of
2 brachiaria hybrid cultivars, Mulato (Brachiaria
ruziziensis x B. brizantha) and Mulato II (B. ruziziensis
x B. decumbens x B. brizantha).
In Trial 1, second- and third-year Mulato seed
crops closed in early July and early August produced
more seed than crops closed in May and
In Trial 2, seed yields of first-year Mulato seed
crops closed in September were reduced by over
50% relative to crops closed in May–August.
Seed yields of first-year Mulato II seed crops
were reduced by 70% when closed in August
rather than May or July, and September closing
produced no seed at all. The highest seed yield of
Mulato II (258 kg/ha) was 60% higher than the
highest seed yield of Mulato (161 kg/ha), mainly
because it produced nearly twice the number of
From the results of our research, we would
recommend a final closing defoliation for brachiaria
hybrid cultivars in Thailand any time in July.
Forage production before closing to seed was
significantly higher in late-closed seed crops than
in early-closed seed crops. In contrast, stubble
DM yields at seed harvest increased progressively
as the date of closing was advanced earlier
into the wet season.
The difficulties of implementing closing defoliations
by smallholder seed producers and the
methods of harvesting are discussed.