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Effect of Heat on Breaking Seed Dormancy in Rice 1
Author(s) -
Jennings Peter R.,
Jesus Jose
Publication year - 1964
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1964.0011183x000400050029x
Subject(s) - dormancy , library science , citation , biology , crop , original research , horticulture , agronomy , computer science , germination
S dormancy in rice, O~Tza saliva L., is considered to be a valuable trait, particularly in tropical areas where rains frequently occur during the harvesting period. The grain of nondormant varieties often germinates in situ under such conditions, especially when the crop lodges into standing water. Two plantings per year of experimental rice material are common i tropical breeding programs. The available time between harvest and sowing is frequently insufficient to allow dormancy to disappear naturally. Where freshly harvested seed is sown in nursery beds, dormant seed remains in the beds and only the less desirable nondormant seed germinates and is transplanted. Thus, unless segregating hybrid material is treated to break dormancy, dormant phenotypes will be lost. A rapid, safe, nonliquid technique which effectively breaks dormancy in all varieties is needed. Partial or complete removal of seed hulls is effective (2) but is impractical for large seed lots. Aqueous solutions of (NH4)2SO4, KNOa, DDT, H2SO4, NaOC1, and hot water as treatments showed slight or no effect on dormancy (4). It is doubtful that any liquid treatment would satisfactorily meet the needs of a breeding program because of the difficulty in handling large numbers of small samples. Exposure of seed to wood smoke for 84 to 168 hours effectively broke dormancy of the one variety ,tested (4). If large numbers of varieties were to be treated, this method would present procedural difficulties. Roberts (3) treated one variety of varying seed moisture content at temperatures ranging from 27-47° C. The higher temperatures caused loss of dormancy but also led to loss of viability at the higher moisture contents. He suggested that drying seed to 11% moisture content or less followed by incubation at 47° C. in open containers for 7 days would remove dormancy from most varieties. The experiments reported here were designed to test the effectiveness of high temperatures and varying treatment periods on breakiug dormancy in a wide range of rice grain types.