Seed production of two brachiaria hybrid cultivars in - Tropical ...

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Seed production in brachiaria hybrids 33 crops established from tillers produced 60% (Trial 2 vs Trial 1) and 117% (Trial 3) more seed than seed crops established from seed. When the components of seed yield were examined, it appeared that the number of inflorescences and seeds/m 2 were the most critical components of yield. Crops planted with tillers produced approximately 20% more inflorescences and 90% more seeds/m 2 than crops planted with seed. Currently, 2 of the 3 most important grass seed crops in Thailand, Ubon paspalum and Purple guinea, are established by planting tillers. While the third crop, ruzi grass, has usually been established with seed, there has been a shift recently towards planting tillers, because vegetative plantings usually produce quick establishment. Farmers also prefer to plant tillers because it is similar to their traditional method of establishing rice, in which rice is first sown into nurseries and 4- to 6-wk-old seedlings are then transplanted into paddies. Identical practices are followed with first-year grass seed crops. For subsequent grass seed crops, plants in existing fields can be dug up and rooted tillers divided and transplanted into new seed fields. By planting grass seed crops with tillers, farmers can plant in wide rows, which facilitates weeding and harvesting and leads to increased seed yields (Loch et al. 1999; Souza 1999). Planting early in the wet season (May or June) produced the most brachiaria hybrid seed in 3 out of 4 trials in the current study. Trial 3 was severely affected by drought, with the wet season rains finishing 6 weeks early, in mid-September, 2004. May- and June-planted crops in Trial 3 were defoliated in early August and, because of the drought, regrowth was very slow, resulting in seed yields similar to July- and August-planted seed crops. Inflorescence numbers and seeds/m 2 were again the most critical seed yield components determining higher seed yields from early establishment. As planting date progressed through the wet season, inflorescence numbers declined, but raceme and spikelet numbers increased. However, increased raceme and spikelet numbers did not compensate for the lower inflorescence numbers and seed yields declined. Hare et al. (2001) also found that inflorescence and seed numbers were the most important seed yield components influencing seed yields of Ubon paspalum. When both components declined with later planting, seed yields also declined. Forage production from grass seed crops is extremely important for smallholder farmers in Thailand. Farmers either feed the forage to their own livestock or sell it as fresh grass to other farmers (Khemsawat and Phonbumrung 2002) for current (July 2006) prices of US$0.05–0.07/kg fresh weight. Planting early enables farmers to cut forage from their seed crops before closing in late July– early August (Hare et al. 2007a). The forage of the brachiaria hybrids cut before closing was of a very high quality in all trials, with a high proportion of leaf (55–60%) and a high leaf crude protein concentration that averaged over 15%. In addition, the harvest stubble of brachiaria hybrids in the trials remained green, the stems were not hard and woody and the overall stubble was of a good quality. Farmers have commented on how the harvest stubble of brachiaria hybrids is far more readily eaten by livestock than that of Ubon paspalum, Purple guinea or rice, which are generally very stemmy and fibrous. The stubble yields of up to 25 t/ha DM will provide a valuable feed resource for farmers in the dry season, when feed supplies are limited. While the low seed yields of Mulato have proved to be not commercially viable, the better seed yields of Mulato II in villages and in other trials (Hare et al. 2007a; 2007b) are commercially viable. To produce acceptable seed yields, brachiaria hybrid seed crops should be hand-planted with tillers early in the wet season. Early sowing also enables high quality forage to be produced before closing to seed. Acknowledgements We thank the Thailand Research Fund (TRF) for providing financial support to this research program and the Faculty of Agriculture, Ubon Ratchathani University for research facilities. References CIAT (2004) Annual Report 2004 Project IP-5: Tropical grasses and legumes: Optimizing genetic diversity for multipurpose use. CIAT, Cali, Colombia. HARE, M.D. and PHAIKAEW, C. (1999) Forage seed production in Northeast Thailand: A case history. In: Loch, D.S. and Ferguson, J.E. (eds) Forage Seed Production Volume 2: Tropical and Subtropical Species. pp. 435–443. (CAB International: Oxon, UK). HARE, M.D., KAEWKUNYA, C., TATSAPONG, P., WONGPICHET, K., THUMMASAENG, K. and SURIYAJANTRATONG, W. (2001) Method
34 M.D. Hare, P. Tatsapong and K. Saipraset and time of establishing Paspalum atratum seed crops in Thailand. Tropical Grasslands, 35, 19–25. HARE, M.D. and HORNE, P.M. (2004) Forage seeds for promoting animal production in Asia. APSA Technical Report No. 41. The Asia & Pacifi c Seed Association, Bangkok, Thailand. HARE, M.D., TATSAPONG, P., LUNPHA, A. and WONGPICHET, K. (2005) Brachiaria species in north-east Thailand: dry matter yields and seed production. Tropical Grasslands, 39, 99–106. HARE, M.D., TATSAPONG, P. and SAIPRASET, K. (2007a) Seed production of two brachiaria hybrid cultivars in north-east Thailand. 2. Closing date defoliation. Tropical Grasslands, 41, 35–42. HARE, M.D., TATSAPONG, P. and SAIPRASET, K (2007b) Seed production of two brachiaria hybrid cultivars in northeast Thailand. 3. Harvesting method. Tropical Grasslands, 41, 43–49. KOWITHAYAKORN, K. and PHAIKAEW, C. (1993) Harvesting and processing techniques of tropical grass and legume seeds for small farmers. Proceedings of the XVII International Grassland Congress, Palmerston North and Rockhampton, 1993. pp. 1809–1813. KHEMSAWAT, C. and PHONBUMRUNG, T. (2002) Thai government promotes fodder production and encourages marketing. (Southeast Asia Feed Research and Development Network). Seafrad News, 12, 9. LOCH, D.S., COOK, S.J. and HARVEY, G.L. (1999) Crop establishment. In: Loch, D.S. and Ferguson, J.E. (eds) Forage Seed Production Volume 2: Tropical and Subtropical Species. pp. 141–157. (CAB International: Oxon, UK). MILES, J.W., VALLE, C.B. do, RAO, I.M. and EUCLIDES, V.P.B. (2004) Brachiariagrasses In: Moser, L.E., Burson, B.L. and Sollenberger, L.E. (eds) Warm-Season (C 4 ) Grasses. Agronomy Monograph No. 45. pp. 745–783. (ASA, CSSA, SSSA: Madison, WI, USA). MILES, J.W., CARDONA, C. and SOTELO, G. (2006) Recurrent selection in a synthetic brachiariagrass population improves resistance to three spittlebug species. Crop Science, 46, 1088–1093. MITSUCHI, M., WICHAIDIT, P. and JEUNGNIJNIRUND, S. (1986) Outline of soils of the Northeast Plateau, Thailand. Their characteristics and constraints. Technical Paper No. 1. Agricultural Development Center in Northeast, Khon Kaen, Thailand. PHAIKAEW, C. and PHOLSEN, P. (1993) Ruzigrass (Brachiaria ruziziensis) seed production and research in Thailand. In: Chen, C.P. and Satjipanon, C. (eds) Strategies for suitable forage-based livestock production in Southeast Asia. Proceedings of third meeting of regional working group on grazing and feed resources of Southeast Asia held in Khon Kaen, Thailand, 31 January–6 February 1993. pp. 165–173. RISSO-PASCOTTO, C., PAGLIARINI, M.S. and VALLE, C.B. do (2005) Meiotic behavior in interspecific hybrids between Brachiaria ruziziensis and Brachiaria brizantha (Poaceae). Euphytica, 145, 155–159. SOUZA, F.H.D. de (1999) Brachiaria spp. in Brazil. In: Loch, D.S. and Ferguson, J.E. (eds) Forage Seed Production Volume 2: Tropical and Subtropical Species. pp. 371–379. (CAB International: Oxon, UK). (Received for publication July 21, 2006; accepted October 12, 2006)
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