Effects of delayed harvesting after physiologigal maturity on corn seed quality of single and three-way cross hybrids
1997
Weerachai Sriyisoon
Study on the effect of delayed harvesting on hybrid corn seed quality of single cross, SX2, and Three-way cross, TX1, was carried out by producing their hybrid seeds in the rainy season of 1992 in corn seed production fields of Ciba-Giegy (Thailand) Ltd., in Takfah District, Nakornsawan province. Harvexting began at physiological maturity and was delayed every 10 days interval until 60 days after physiological maturity. Results showed that delayed harvesting increased percentages of lodging, rotten and rejected ears of the seed parents. Delayed harvesting decreased seed germination, viability and vigor of the freshly harvested seeds which were more prominent in the single cross than the three-way cross. Delayed harvest also increased percentages of fungi infection which were higher in the single cross than in the three-way cross. After seed storage at ambient condition for 7 months, field test was done in the 1993 rainy season at 3 locations. It was found that field emergences of single cross hybrid corn seed were decreased in the delayed harvesting seed lots when planted under rainfed condition in farmer's field and resulted in slow plant growth. But delayed harvesting did not affect field emergence and plant growth of three-way cross. Silking date and barren plant were not statistically different when delayed harvesting seeds. Finally, in the farmer's field under rainfed conditions, hybrid corn planted from the delayed garvesting seed lots produced lower grain yields than those planted from physiological maturity harvesting seeds. In conclusion, harvesting in the single cross and three-way cross hybrid seed production fields should be done at 30 days but not later than 40 days after physiological maturity. Since delayed harvesting resulted in low seed quality and decreasing grain yield of single cross and three-way cross hybrid corns.
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