Actualizar valor nulo desde dataset

hola mi pregunta es como poner un valor nulo en la base de datos desde el dataset mi código es el siguiente

dtset.Horario.AddHorarioRow(TextBox2.Text, 0, CheckBox1.Checked, tipohorario, 1, DateTimePicker1.Value, _
DateTimePicker14.Value, DateTimePicker28.Value, DateTimePicker21.Value, _
DateTimePicker42.Value, DateTimePicker35.Value, DateTimePicker2.Value, _
DateTimePicker13.Value, DateTimePicker27.Value, DateTimePicker20.Value, DateTimePicker41.Value, _
DateTimePicker34.Value, DateTimePicker4.Value, DateTimePicker12.Value, DateTimePicker26.Value, _
DateTimePicker19.Value, DateTimePicker40.Value, DateTimePicker33.Value, DateTimePicker3.Value, _
DateTimePicker11.Value, DateTimePicker25.Value, DateTimePicker18.Value, DateTimePicker39.Value, _
DateTimePicker32.Value, DateTimePicker7.Value, DateTimePicker10.Value, DateTimePicker24.Value, _
DateTimePicker17.Value, DateTimePicker38.Value, DateTimePicker31.Value, DateTimePicker6.Value, _
DateTimePicker9.Value, DateTimePicker23.Value, DateTimePicker16.Value, DateTimePicker37.Value, _
DateTimePicker30.Value, DateTimePicker5.Value, DateTimePicker8.Value, DateTimePicker22.Value, _
DateTimePicker15.Value, DateTimePicker36.Value, DateTimePicker29.Value)
SqlDataAdapter1.Update(dtset)

ya probé dbnull.value, nullable, convertir una cadena vacía, a date y nada ojala me puedan ayudar

muchas gracias

Saludos