For 30 years of avocado orchard production, the biggest environmental costs may come not from how young trees are grown, but from the fertilizer and electricity used to care for them.
That is the finding of a University of Queensland study comparing two ways to produce avocado rootstocks in Australia: conventional seedlings and plants grown through plant tissue culture, or PTC. The lab-based method is sometimes assumed to carry an added environmental burden. But the researchers found that, across the full system they assessed, PTC did not cause greater environmental impacts than seedling propagation. Their results are published in Environmental Technology & Innovation.
The team, led by researchers from the Queensland Alliance for Agriculture and Food Innovation with industry partners, looked from the production of planting material through three decades of orchard production. Dr. Cresha Gracy Nadar said that orchard management, rather than the propagation method, largely shaped the environmental results. Fertilizer production and use, along with electricity for irrigation, accounted for most of the impacts whichever method was used to produce the rootstocks.
The finding shifts attention toward changes growers can make once trees are in the orchard. The researchers identified more efficient fertilizer use, better irrigation and a cleaner electricity grid as the main opportunities to reduce impacts. Renewable power at PTC facilities could also cut the method's relatively small impact during propagation. But the researchers said that change would make only a limited difference to the full system's contribution to global warming, because orchard production accounts for much more of the burden.
PTC may also offer practical advantages for a crop that can be difficult to propagate. Dr. Alice Hayward, a co-author, said the method can multiply selected plant types throughout the year. It can produce many plants from a small amount of starting material, reducing dependence on seasonal seeds, mother plants and traditional cloning methods. That could be useful for perennial crops such as avocados, which take time to grow and can be challenging to reproduce by conventional means.
There is still an important question to answer. Avocado seedlings are genetically variable, while PTC can produce selected genotypes. If those lab-grown rootstocks help orchards deliver steadier yields, that could strengthen the environmental case for the method, Associate Professor Sudhir Yadav said. But the researchers cautioned that this possibility has not yet been confirmed: long-term comparative field trials across multiple avocado genotypes do not yet exist.
The study does not claim that PTC has no environmental footprint. Instead, it shows that choosing a propagation method may matter less than improving how an orchard uses fertilizer and water and how its electricity is generated. Future field trials can test whether PTC rootstocks also bring reliable production benefits, while orchard improvements offer a clear place to focus now.