Elucidation of Weed Seed Dormancy Mechanism and Application of Calcium Cyanamide Fertilizer, a Dormancy-breaking Agent for Ecological Control of Weeds

通过对水稻种子休眠的生理和分子生物学分析，探讨了水稻种子休眠的机理，并测试了一种有效的水稻休眠剂--氰化钙。研究结果表明：1.种子休眠机理。在颖果或颖果的外盖中存在一个休眠施加因子，这种因子在去掉外盖后很容易扩散出去或退化。两对等位基因，一对是强制休眠的等位基因，另一对是控制种子休眠的基因。该物种的杂草和栽培形式，分别有种子休眠和没有休眠，都有两个等位基因编码1-半胱氨酸过氧化还蛋白，已被报道为许多物种休眠特有的抗氧化剂。但栽培类型的种子在吸胀时不表达这些基因，而杂草类型的种子则表现出2.三年田间试验表明，在水稻收获后的处理下，即使在秋季，这种肥料也能促进稻纵卷叶蛾的出苗，并使出苗的幼苗被次年冬季的低温杀死。春季处理也会刺激植物的出现，由此产生的植物会因划桨练习而死亡。氰胺肥对埋藏在土壤中的杂草种子也有一定的杀种活性。

We conducted physiological and molecular biological analyses to elucidate mechanism of seed dormancy in Echinochloa oryzicola, and tested calcium cyanamide fertilizer, a potent dormancy-breaking agent to ecologically control weeds in flooded rice. The followings were suggested from results obtained:1. Seed dormancy mechanisma. A dormancy-imposing factor is present either in outer covers of the caryopsis or caryopsis in which the factor readily diffuses out or degraded upon the removal of the outer covers. Two pairs of alleles, one for dormancy-imposing and the other for its maintenance genetically control of seed dormancy in Echinochloa oryzicola.b. Both weedy and cultivated forms of this species, with seed dormancy and without dormancy, respectively, have two alleles coding 1-Cys peroxiredoxin that has been reported as a dormancy specific antioxidant in many species. But seeds of the cultivated form do not express the genes upon imbibition, while those of weedy form express.2. Ecological weed control with calcium cyanamide fertilizerThree year's field experiment revealed that with the post-rice harvesting treatment the fertilizer stimulates emergence of Echinochloa oryzicola even in autumn and the young plants emerging were killed by low temperatures of the succeeding winter. The spring treatment also stimulates the emergence and resultant plants were killed by paddling practice. The cyanamide fertilizer also had seedcidal activity against weeds seeds buried in soil.