This emitter (120) has a first valve seat part (174) provided around a hole (173) which forms a portion of a flow path between a reduced-pressure flow path and a discharge part. The first valve seat part (174) is formed by a three-step recessed circumferential surface, and is provided with one groove (175) which intersects said three-step recessed circumferential surface, and becomes shallower as said groove approaches the hole (173). As the external liquid pressure increases, a film (140) gradually bends towards the first valve seat part (174), and the open area of the groove (175) gradually decreases. The flow rate of an irrigation liquid is adjusted to an amount capable of passing through the opening of the groove (175).

A modular in-line drip emitter may include a flow restrictor and a replaceable attachment. The flow restrictor may provide fluid communication between an inlet and a fluid outlet chamber. The flow restrictor may include rate limiting fluid path producing a predefined range of flow rate over a predefined pressure differential range between the fluid inlet and the fluid outlet. The attachment may be sized and shaped to mount to the flow restrictor. In some embodiments the attachment includes an inlet opening oriented for receiving fluid from a conduit and a fluid outlet attachable to the fluid inlet of the flow restrictor. In some embodiments the attachment includes a sleeve fitting into a conduit with an annular outlet chamber attachable to the outlet chamber of the flow restrictor.

The disclosed container defines (i) an interior configured to interact with a fluid and/or developing plants, and (ii) an exterior that at least partially defines a perimeter around the interior. The disclosed container may further include stacking features/elements which allow one container to be stacked/nested one upon the other. The disclosed container may further include features/elements which enable one container to be connected adjacent to the other. The disclosed container may further include (i) features/elements for delivering fluid, (ii) features/elements for draining fluid, and (iii) features/elements for supporting developing plants that are conducive to their growing within the disclosed container.