Articles
Pecan nut weight is dependent on local shoot carbon supply-demand balance
Article number
1420_13
Pages
95 – 102
Language
English
Abstract
Wide variation in local carbon balance among individual shoot terminals in pecan (Carya illinoinensis) tree canopies exists due to shoot-to-shoot differences in carbon supply (photosynthesis) or reproductive demand for carbon.
Our objective was to test how nut quality parameters relate to the apparent balance of carbon supply and demand of pecan shoots.
We used specific leaf weight (SLW) of two terminal leaflets as an indicator of apparent shoot carbon supply and the number of nuts per shoot (NPS) as an indicator of shoot reproductive carbon demand.
In 2021, ripe ‘Pawnee’ and ‘Western’ pecan nut clusters and leaflets were hand sampled from individual shoot terminals representing the whole range of NPS and SLW in the canopies.
Inshell nuts and shelled kernels were weighed and kernels were analyzed for total lipids.
There was a significant increase in average individual nut weight with increasing shoot SLW. There was also a significant interaction of SLW and NPS on total cluster nut weight, with the greatest magnitude of the positive effect of SLW on total nut weight at high NPS. On the other hand, there was no significant relationship of SLW with total and average shoot kernel weight.
Initial analyses did not indicate a relationship of total kernel lipids with either NPS or SLW. These data are consistent with the hypothesis that local shoot level carbon balance can limit pecan nut growth and that carbon imported from elsewhere in the canopy may not be sufficient to make up for a shoot’s shortfalls in carbon needed for nut development.
SLW is closely associated with cumulative leaf sunlight exposure, so these results highlight the need for maintaining good sunlight distribution in pecan canopies for development of high-quality nuts.
Our objective was to test how nut quality parameters relate to the apparent balance of carbon supply and demand of pecan shoots.
We used specific leaf weight (SLW) of two terminal leaflets as an indicator of apparent shoot carbon supply and the number of nuts per shoot (NPS) as an indicator of shoot reproductive carbon demand.
In 2021, ripe ‘Pawnee’ and ‘Western’ pecan nut clusters and leaflets were hand sampled from individual shoot terminals representing the whole range of NPS and SLW in the canopies.
Inshell nuts and shelled kernels were weighed and kernels were analyzed for total lipids.
There was a significant increase in average individual nut weight with increasing shoot SLW. There was also a significant interaction of SLW and NPS on total cluster nut weight, with the greatest magnitude of the positive effect of SLW on total nut weight at high NPS. On the other hand, there was no significant relationship of SLW with total and average shoot kernel weight.
Initial analyses did not indicate a relationship of total kernel lipids with either NPS or SLW. These data are consistent with the hypothesis that local shoot level carbon balance can limit pecan nut growth and that carbon imported from elsewhere in the canopy may not be sufficient to make up for a shoot’s shortfalls in carbon needed for nut development.
SLW is closely associated with cumulative leaf sunlight exposure, so these results highlight the need for maintaining good sunlight distribution in pecan canopies for development of high-quality nuts.
Publication
Authors
R.J. Heerema, C. Velasco Cruz, I. Apodaca, C. Galvan, F.O. Holguin
Keywords
Carya illinoinensis, nut reproductive physiology, specific leaf weight
Groups involved
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