Introduction to irrigation experiment

Dr Mark O'Connell introduces the Nectarine, Open Tatura trellis, irrigation experiments.

Video transcript - introduction to experiment

In this field experiment we have September Bright, 1 year old trees, trained in an open Tatura trellis, 2 metre tree spacing per side, one meter diagonally opposite, four and a half meter row spacing, and we're going to try and train these trees in at least four leaders per tree, up to six per tree. We have a north-south row direction, and again in year three, we will commence the field experiment and in this case we're going to look at irrigation management, and irrigation strategies, and deficit irrigation at different growth stages of the crop cycle. Stage 1 growth, early growth of the fruit, we will stress some of these trees. In stage 2, we will also stress these trees, and in stage 4, post harvest, we will also stress some of these trees, and look at the interaction of water stress and fruit yield and fruit quality, in particular sweetness, Brix.

The irrigation levels (% of tree evapotranspiration), applied using drip irrigation, are:

The experiment has four irrigation application timings and likely crop responses:

Stage I of fruit development: cell division (rapid fruit growth) - water stress restricts cell division, reduces fruit size and yield
Stage II of fruit development: pit hardening (slow fruit growth, maximum vegetative growth) - water stress reduces vegetative vigour
Stage IIIa of fruit development (early): cell expansion - water stress reduces fruit size and yield
Stage IIIb of fruit development (late): cell expansion (sugar accumulation, chlorophyll degradation) - water stress reduces fruit size and yield

Table 1: Irrigation experimental treatments

2016/17 irrigation experiment

Regulated deficit irrigation (RDI) occurs during stage 2 of development. See Graph below.

Shoot and fruit growth graph

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