Fruit tree change to double output

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Groundbreaking research in Clyde could double productivity and redesign how fruit trees are grown, New Zealand Institute for Plant & Food Research, Science Group leader Dr Jill Stanley says.

The target of the research was to at least double the productivity of orchards, Dr Stanley said.

“Most orchards don’t intercept all the light coming into the orchard, a lot of it goes to the grass in between the rows, so you’ve got a lot of the light that could be used by a crop used to grow grass, basically.”

Dr Stanley’s team members were trialling cherries and apricots using the Future Orchard Planting System (Fops) at their 58ha research orchard in Clyde.

“Our main innovation is we move the rows closer together, so that more of the light is captured by the crop, but in doing that you can’t have the standard tree structure.”

The solution was to develop a planar canopy, which meant trees were grown in the nursery to have two main branching cordons, and once planted in the orchard, six main uprights were allowed to develop per cordon, Dr Stanley said.

The shape of the tree created was narrow but evenly distributed, enabling sunlight to reach every part of the tree in a consistent manner.

“In the centre of standard centre leader or multi-leader trees the light received by fruit can be as low as 1% of full sunlight, so you get low fruit quality down there,” Dr Stanley said.

“So these new designs actually have the potential to reduce variation in fruit quality as well.”

The narrow design allowed for closer planting, increasing the total number of trees per hectare, but reducing space for agricultural machinery for irrigation, spraying and picking.

Dr Stanley’s approach was to begin with the way the trees grew, rather than considering the machinery.

“The key thing that we’ve done is we are redesigning this on physiological principles, so we’ve thrown everything out and said: ‘What if we didn’t worry about machinery, we can redesign machinery’ – because that’s totally possible these days.

“So we’re not worrying about that, but we are looking at how can we redesign it to get the best physiological conversion of light into fruit,” Dr Stanley explained.

But in the meantime, they had trialled a series of different spacings between the trees to find the best arrangement that maximised use of sunlight but still enabled the passage of necessary machinery in between.

Normally, the spacing of trees in an orchard was 3.5m to 4m, but the trial blocks were planted at a 2m and 1.5m spacing.

“In general, you can get machinery down the 2m rows and not down the 1.5m rows,” Dr Stanley said.

The design of the Fops trees was ideal for future robotic picking systems, she said.

“In the future, if we decided that 1.5m rows was the best option, then you could redesign machinery to do that.”