(Adds all bylines at the top of the story) By Maurice Tamman, David Gauthier-Villars, Sarah McFarlane and Sarah El Safty (Reuters) – The Russian invasion of Ukraine threatens millions of tiny spring-time sprouts that should emerge from stalks of dormant winter wheat in the coming weeks. If the farmers can’t feed those crops soon, far fewer of the so-called tillers will spout, jeopardizing a national wheat harvest on which millions in the developing world depend. The wheat was planted last autumn, which, after a brief growing period, fell dormant for the winter. Before the grain returns to life…