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ARS Home » Southeast Area » Stuttgart, Arkansas » Dale Bumpers National Rice Research Center » Research » Publications at this Location » Publication #149128
Title: EFFECTS OF GIBBERELLIC ACID ON RICE GERMINATION AND SEEDLING EMERGENCE IN STRESS CONDITIONS

Author
item Yan, Wengui
item DILDAY, ROBERT - RETIRED ARS
item HELMS, RONNIE - STUTTGART SEED CO
item BOURLAND, FREDDIE - UNIV ARK

Submitted to: Arkansas Agricultural Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: 6/20/2004
Publication Date: 8/11/2004
Citation: Yan, W., Dilday, R.H., Helms, R.S., Bourland, F.M. 2004. Effects of gibberellic acid on rice germination and seedling emergence in stress conditions. Arkansas Agricultural Experiment Station Research Series 517. pp. 303-316.

Interpretive Summary: Inadequate stand establishment is a major problem in drill-seeded rice production in the southern US, especially for semidwarf cultivars. This problem is estimated to cost US rice producers about 67 to $163 million annually. This test found that gibberellic acid (GA3)improved germination and stand establishment, and resulted in faster germination and seedling emergence. The improvement was greater in stress conditions, such as germination at cold temperatures and emergence at deep planting. The taller cultivars germinated faster and also emerged faster than the semidwarf cultivars, but the semidwarfs responded more to GA3, especially for germination at cold temperatures and deep seeding. This demonstrates that the application of GA3, in general, will be more important to semidwarf than tall cultivars. The emergence speed and stand establishment were greater at the shallow planting than at the deep planting, but the cultivars responded more to GA3 at the deep seeding. As a result, GA3 can work as a buffer to maintain good germination and stand establishment within a certain range of environmental conditions. The problem of inadequate seedling stands in rice production can be solved by treating seed with GA3. The seed treatment is almost essential for semidwarf cultivars, especially when they are planted early and/or deeply. Based on these results, 30% of rice seed or 50% seed of semidwarf cultivars in the US are treated with GA3 at present.

Technical Abstract: Inadequate stand establishment is a major problem in drill-seeded rice production in the southern U.S., especially for semidwarf cultivars. A total of 21 cultivars including 9 semidwarfs and 12 talls were treated with gibberellic acid (GA3) at 25 mg.kg seed-1 and evaluated for germination at 10, 13, 16, 19, 22 and 25 C in 1991; and for seedling emergence at planting depths of 1.9 cm and 5.0 cm in two years. The tall cultivars Millie, Mars, Alan and Katy germinated rapidly, with Katy having the greatest emergence potential and consequently the best stand establishment in both years. GA3 improved germination and stand establishment, and resulted in faster gemination and seedling emergence. The improvement was greater in stress conditions. The taller cultivars germinated faster and also emerged faster than the semidwarf cultivars, gut the semidwarfs responded more to GA3, especially for germination at cold temperatures and deep seeding. This demonstrates that the application of GA3 in general will be more important to semidwarf than tall cultivars. The emergence speed and stand establishment w4ere greater at the shallow planting than at the deep depth, but the cultivars responded more to GA3 at the deep seeding. As a result, GA3 can work as a buffer to maintain good germination as well as stand establishment. Treating the seed with GA3 can be helpful for early and/or deep planting of semidwarf rice.