Don't use drip irrigation, the seedlings are too small, the effect of the drip tube is similar to soaking in water.

The correct watering method, when the seedlings, do not sun at noon, watering see dry and wet, is a little drought drought seedlings, called squatting to promote the growth of roots, improve drought resistance.

Try to recover it, watering once thoroughly into a semi-shade environment, do not sun at noon.