Pressing for Union Minister Ajay Mishra's dismissal and arrest over Lakhimpur incident in Uttar Pradesh, in which his son has been arrested, the farmers' body has called for a six-hour long nationwide ''Rail roko'' agitation. The Samyukta Kisan Morcha, an umbrella body of farmers' unions, said it will hold a peaceful nationwide rail roko protest from 10 am to 4 pm for justice in Lakhimpur Kheri violence in Uttar Pradesh.