title: small RNA library from switchgrass drought stresses root
design: Seeds were germinated in Magenta Box and after the radicles were growing by 1cm long, the seedlings were  transferred into seed cubes (Oasis  Growing Medium, Smithers-Oasis Company, 295 South Water Street, Suite 201, Kent, OH, 44240, U.S.A.). When seedlings grown to the three-leaf stage, they were transplanted into a  Sandwich  growth system in sPCP tubes where the top and bottom garden soil layers were separated with a perlite layer.  Drought treatment was initiated when the longest roots reached the perlite layer by   withholding watering in the drought treated tubes.  The control plants were watered regularly by giving three L water every three days.  The experiment was terminated when soil water tension   treated group at 20 cm depth reached 100 centibar MPa (severe drought stress). Root samples were collected from the 2 cm distal end section consisting of root tip and elongation zone.