Seed yield and its components of Brachiaria decumbens cv. Basilisk, Digitaria milanjiana cv. Jarra and Andropogon gayanus cv. Kent in north-east Thailand under different rates of nitrogen application
Nr. Gobius et al., Seed yield and its components of Brachiaria decumbens cv. Basilisk, Digitaria milanjiana cv. Jarra and Andropogon gayanus cv. Kent in north-east Thailand under different rates of nitrogen application, TROP GRASSL, 35(1), 2001, pp. 26-33
In a study of seed yields of pasture grasses in Thailand, pure seed yields
of Brachiaria decumbens cv. Basilisk. Andropogon gayanus cv. Kent and Digit
aria milanjiana cv. Jarra in one season were 81-123 kg/ha. 326-569 kg/ha an
d 48-97 kg/ha. respectively. Corresponding thousand-seed weights were 4.68,
3.35 and 0.42 g. Germination rates were 3h. 73 and 17% at 4-6 months post
harvest. In Thailand, low plant density and seeds per inflorescence. not mo
isture availability. are likely to be the most important factors causing lo
w seed yields of B. decumbens. Seed production and quality of A. gayanus we
re exceptionally high, while seed yields of D. milanjiana were: similar to
reported values. The nylon gauze seed collection bags facilitated full seed
retrieval. Nitrogen application increased seed yield and inflorescence den
sity but produced significant lodging in all species at 200 kg/ha N on this
sandy loam. However. it did not affect seed weight. purity. germination or
viability of any of these species. Seed yields of B. decumbens,ls in Thail
and are characteristically low and present results indicate that low plant
density and few seeds per inflorescence are contributing factors. The reaso
ns for this are unknown. Gamba grass (Andropogon gayanus), with its drought
-resistant characteristics, high dry matter production, high seed productio
n and quality and low nitrogen requirement for seed production is a useful
addition to pasture options for north-east Thailand.