Paddy saplings turn burnt

Sowed two varieties of paddy (ADT 43 and Poongaar ) under direct seeding using drum seeder in well puddled land. Watering was done on alternate days during evenings and drained in the mornings. The saplings sprouted well but eventually died after 12 days . Villagers attribute hard water and extremely hot climate condition as reasons for this.
But in nearby nurseries the saplings are fine. Any pointers for this ?