Broadcasting at low seed rate as a performance technology for newly selected rice genotypes under wet direct seeding
2005
Pasuquin, E.M. (International Rice Research Inst., DAPO Box 7777 Metro Manila (Philippines)) | Manalo, S. | Cruz, R.T. | Lafarge, T.
Broadcasting is an attractive crop establishment technique in rice fields for its simple and fast operation, low labor cost, and short turnaround time between crops because of the absence of seedbed. Previous research showed that plants broadcast in irrigated paddy fields may have higher grain yield than transplanted ones. In direct seeding, however, land levelling is critical, weeds are problems, and seeding rate is high. At present, with the high demand for improved production and low labour cost, there is an urgent need to identify appropriate rice genotypes with weed competitiveness and low seed rate requirement under broadcasting and to adapt crop management to approach yield potential. Two field experiments analyzing the performance of four varieties (2 hybrids, 1 indica, and 1 new plant type) were set up on the IRRI farm under two seed rates (25 and 50 kg/ha for hybrids, 50 and 100 kg/ha for indica and new plant type) and two direct-seeding techniques (wet surface broadcasting and row seeding), and on the PhilRice farm with the same treatments as above plus a transplanting check. At the two test locations, SL-8, a hybrid, had a higher grain yield when broadcast than when row-seeded and transplanted and its grain yield at 25 kg/ha was comparable with that at 50 kg/ha. The same was observed for indica and new plant type for which performances were similar at 50 and 100 kg/ha and better than or similar to those in transplanted fields. IR75217H, another hybrid, performed better under transplanting than under direct seeding, with similar yields in all direct-seeding establishment techniques. The morphological and physiological performances of each variety under the different conditions are discussed in detail.
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