Changes in the Water Content and Germination Rate During Seed Desiccation and Their Inter-Specific Differences among Zizania Species

Wild rice (Zizania palustris) is a newly cultivated crop that is known for its quality compounds of human healts benefits. Zizania seeds are extremely sensitive to drought during the maturing and storage period. This study was conducted to examine the effect of seed water content on genomination in three Zizania species, Z.aquatica, Z.latifolia and Z. palustris that have different morphological grain characteristics. Grain water content in the range of 9 to 83% showed a positive correlation with germination rate and speed. It was greatly affected by humidity during seed desiccation period. Seed water content was higher in the varieties or strains of larger grains than in those of smaller grains , also, in unhulled than in hulled grains. Seed water content decreased rapidly within 2 weeks of desiccation. Decreased seed water content was closely related to the decreased rapidly within 2 weeks of desiccation. Decreased seed water content was closely related to the decreased germination rate and speed in most Zizania species. Seed germination rate was maintained over 80% in water content over 35% in all Zizania species except for Z. latifolia from Sunchon bay that showed very low germination. However, seed germination at water content belo 35% was significantly different by the seed size but not necessarily by the species. Seed viability of 50% was observed at 20% of seed water content in the small grain Z. aquatica from Virginia, while at about 10-13% of water contents in the large grain Z. aquatica Iowa and Z. palustris. Taken together, the results from this study indicate that water content of mature wild rice seeds is a critical factor in germination, and it is affected mainly by humidity during seed maturation. Post-harvest practices to maintain seed water content in the range of 20 to 50% should improve wild rice seed viability