Where almond trees store energy can affect yield
Perennial plants store carbohydrates to bridge carbon shortages. Like those in the winter for example. Now American researchers show that it matters where a plant creates those carbohydrate stores.
Trees, bushes, and other perennial plants create stores of sugars and starch to bridge times of shortage. This enables trees who lose their leaves in autumn can survive till in the next spring when their leaves start to grow again and produce sugars via photosynthesis. But also, in times of stress, like warm dry days during which plants prefer to keep their stomata close and slow down their photosynthesis. In both cases stored carbohydrates are essential.
But how the amount and location of carbohydrate reserves influence the future growth of plants was less clear. To find out, the researchers measured the reserves of almond trees. They also looked at the growth of the tree trunk and the almond yield. They did this both in autumn, when the trees entered a period of shortage, and in spring, just after the leaves started to unfold.
Higher yield
As expected, the reserves were at the beginning of spring lower than they were in autumn. The researchers noticed that when a tree had more reserves in its branches their almond yield was also higher. The researchers suggest that having a more reserves in the branches enabled the trees to use that energy for the development of flowers which bloom in early spring. And more flowers means a bigger chance for more almonds later in the year.
What surprised the researchers was that the growth of the tree trunk was negatively correlated with the reserves in the tree trunk. This was unexpected because the in the trunk stored carbohydrates were also not correlated to a higher almond yield. It therefore appears that almond trees have one or more other destinations for the stored carbohydrates.
Wild trees have more reserves
Another thing that caught the attention of the researchers was that during the winter the stored starch reduced, but that the free available sugars stayed more or less at a similar level, or in the case of branches even increased. This, say the researchers, suggest two things. Firstly, that the plant tries to keep the level of freely available sugars at a steady level, through digesting starch bit by bit into sugars. And secondly that a high level of freely available sugars in the branches at the start of spring are needed for the support of that first growth spurt.
Now is this research done with almond trees selected for a high almond yield, and not for having a good buffer during the winter. The researchers noticed that the reserves of the almond trees only took up 0.8 to 2.2% of their total mass. Trees that you come across in a forest put aside as reserve between 4 to 8% of their mass. Which is much more. This makes almond trees more vulnerable for stress. Although tree management practices can lessen the dependence on stored carbohydrates.
Literature
Veeravelli, S.S., McElrone, A.J., Wright, I.R. et al. Trees just go “nuts”: prioritizing carbon allocation to yield in almond trees. Planta 263, 142 (2026). https://doi.org/10.1007/s00425-026-05003-0
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