Trees just go “nuts”: Prioritizing carbon allocation to yield in almond trees

Authors: VEERAVELLI, SHREYA - Purdue University; McElrone, Andrew; WRIGHT, IAN - University Of California, Davis; MOMAYYEZI, MINA - University Of California, Davis; Knipper, Kyle; BAMBACH, NICO - University Of California, Davis; CASTRO BUSTAMANTE, SEBASTIAN - University Of California, Davis; GAL, ANDREW - University Of California, Davis; KHALSA, SAT DARSHAN - University Of California, Davis; KARUNAKARAN, RANJITH - University Of California, Davis; NGYUYEN, HUNG - Purdue University; FURZE, MORGAN - Purdue University

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2026
Publication Date: 4/28/2026
Citation: Veeravelli, S.S., McElrone, A.J., Wright, I.R., Momayyezi, M., Knipper, K.R., Bambach, N.E., Castro Bustamante, S., Gal, A.J., Khalsa, S.S., Karunakaran, R., Ngyuyen, H.T., Furze, M.E. 2026. Trees just go “nuts”: Prioritizing carbon allocation to yield in almond trees. Planta. 263. Article 142. https://doi.org/10.1007/s00425-026-05003-0.
DOI: https://doi.org/10.1007/s00425-026-05003-0

Interpretive Summary: Stored carbohydrate reserves are important for fueling respiration during winter dormancy in perennial crops. We conducted a study of four almond varieties in a commercial orchard and measured sugar and starch concentrations in branch, stem, and coarse roots when entering and exiting dormancy. We then assessed the correlation between these data and metrics of stem growth and yield in the following growing season. We explored trade-offs between stem growth and yield using historical grower data across 6 growing seasons to compare against tree ring data. As expected, carbohydrate concentrations significantly decreased during the dormant season in all organs, and their concentrations when entering dormancy were positively correlated with yield the next year. We found when yield increased across years, growth in the trunk tended to decrease, thus captured carbon was prioritized to yield.

Technical Abstract: Perennial tree crops store nonstructural carbohydrates (NSCs) as energy reserves that can be used to persist during both predictable periods of reduced activity like dormancy and more unpredictable periods associated with stress. For deciduous tree crops, which lose their leaves at the start of dormancy, the NSC reserves accrued by that time are critically important for fueling respiration but may also influence processes in the following growing season. To quantify the seasonal NSC fluctuation surrounding dormancy and its influence on downstream processes like growth and yield, we conducted a comparative study of four almond varieties in a commercial orchard (California, USA). Sugar and starch concentrations were quantified in branch, stem, and coarse root when entering and exiting dormancy. We then assessed the correlation between these NSC data and metrics of stem growth and yield in the following growing season. We further explored long-term trade-offs between stem growth and yield using historical data from 2017-2022. Overall, total NSC concentrations significantly decreased during the dormant season in all organs. When assessing the relationship between NSCs and yield, we observed a significant positive correlation between branch total NSC concentration when entering dormancy and yield the next year. However, when assessing the relationship between NSCs and stem growth, we unexpectedly found that stem total NSC concentrations when entering dormancy were negatively correlated with stem growth the next year, suggesting that stem reserves are primarily used to support wintertime respiration or translocated to other organs. Further, a trade-off between stem growth and yield was evident; as yield increased, basal area increment tended to decrease. Thus, carbon was prioritized to yield. Overall, these findings advance our understanding of crop tree carbon physiology and provide insight into the resilience of different almond cultivars under changing environmental conditions.