Aug 6, 2019
Key to good spring in tree crops is looking after the roots in the fall

{Sponsored} Harvest is the time when farmers finally get the benefit of a long hard season and reflect on how to prepare for the next one. Here we look at how to best prepare tree crops for the rigors of the next one.

Harvest removes significant resource from a plant

Plants invest resources in nutrients and energy into producing the harvested fruit. They do so at a time when the crops hormones are predisposed towards senescence leaving the crop vulnerable to stress and damage.

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Following harvest, a crop has a period to adjust and prepare for the next season, and while not much appears to be happening above ground, this is the time to ensure that the crop has a good functioning root system ready to supply growth in the spring.

Harvesting coincides with stress hormone buildup

When mechanical harvest equipment (tree shaking or other mechanical equipment) is used, the problems are exacerbated due to the need for soil to be dry before shaking. This can cause damage to bark during the harvest process. This predisposes the crop to produce ethylene creating stress damage in combination with ABA, which builds up during dry conditions.

The combination of ethylene production and ABA build up ceases root growth and development and drives senescence. Thus, leaving the crop going into the off season with depleted resources and a root system that needs to play catch up in the spring.

Re-establishing roots is not a simple process

To improve the roots post-harvest, we need to feed them, but this is not as straightforward due to the process of “growth partitioning.” When we apply nitrogen to crops, they grow, but they do not grow evenly. The plant allocates growth disproportionately, where the growth occurs is heavily influenced by the quantity and form of Nitrogen applied.

Growers of tree crops, and other woody perennial fruit are very aware that untimely N applications lead to excess vegetative growth, increasing pruning and disease susceptibility and often reducing yield by pulling resources away from developing fruit.

So, to fix the problem we need to get crops to allocate growth to roots, rather than vegetative growth. To understand how to do this we need to learn a little about how the form of nitrogen influences growth partitioning.

The majority of N taken up by crops is taken up as nitrate, regardless of what form it was applied. This is a result of environmental instability whereby nitrogen gets rapidly converted by microorganisms into nitrates, losing some along the way. As a rule of thumb, most crops take in a third of the N applied. Then they take it up largely in the nitrate form.

Nitrates drive vegetative growth. Nitrates have to be transported to leaves to be processed into usable proteins, and as nitrate levels build up in foliage the production of the growth hormone auxin increases, creating an emphasis on vegetative growth. This is why we can see excessive shoot growth when we apply late season N to tree crops.

Amine nitrogen (NH2) is processed differently. It can be processed locally (requiring no transport to leaves and requires less energy to convert to protein). Importantly amine nitrogen does not create increased auxin production and encourages disproportionate investment in vegetative growth. Instead, when plants process amine N they exhibit increased root development.

Stabilized Amine N improves root growth

Cell Power® SizeN®* is the product that supplies amine N. It is stabilized using LimiN technology (developed by UK scientists). This ensures the Amine N supplied to the crop is taken up as Amine (does not change to nitrate) and is a useful tool for promoting better growth partitioning.

Research published in the Journal of Horticulture and Post Harvest Research in 2018 demonstrates how use of stabilized amine formulations like Cell Power® SizeN® can be used to improve root development in a wide range of horticultural crops.

Use of Cell Power® SizeN® after harvest is a great way to re-establish roots, reset the crops balance and leave it in the best possible state to produce good yields in the following season.

*Cell Power® SizeN® is the registered trademark of OMEX® Agrifluids, Inc.

For more information on products please contact OMEX® Agrifluids, Inc. at [email protected], visit omexusa.com or call 559-661-6138.




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