Articles
Photosynthesis measurements in pecan tree in northwestern Mexico
Article number
1420_11
Pages
77 – 84
Language
English
Abstract
In northwestern Mexico, trees with high water requirements are grown.
One of them is pecan (Carya illinoinensis), which presents, like other fruit trees, alternation and vivipary.
This region is characterized by high temperatures in spring, and relatively high humid and warm summers.
In the search to understand if the high air temperatures are impacting the accumulation of reserves and therefore the production of the next crop cycle, monthly measurements of photosynthesis (Pn) and leaf water potential (ψleaf) were carried out in seven sites in the coast of Hermosillo, Mexico.
These measurements were made from May to November 2022. For that, the LI6400 (LI-COR) and the Sscholander pump (MPS) were used, respectively.
The first ones were carried out between 9:00 am and noon, while the second around 13:00. Pn measurements were made on the same branches, of the same trees, until the age of the leaves allowed it.
In the case of ψleaf, measurements were maintained on the same trees throughout the measurement cycle.
The results of ψleaf during fruit growth (May-July) varied from -0.57 to -1.02 MPa, with an average value of -0.71 MPa.
During the fruit filling period (August) the ψleaf varied from -0.56 to -0.86 MPa, with an average value of -0.69 MPa.
In the harvest period (September-October) the ψleaf increased due to the reduction of irrigation, varying from -0.50 to -1.94 MPa, with an average value of -1.09 MPa.
During the postharvest period to the beginning of senescence (November) some plantations managed to rehydrate the trees, varying the ψleaf from -0.79 to -1.22 MPa.
On the other hand, the Pn data varied from 8.93 to 15.34 µmol CO2 m‑2 s‑1, with an average value of 12.41µmol CO2 m‑2 s‑1 throughout the fruit growth stage (May-July). During the fruit filling period (August) the Pn varies from 7.73 to 16.18 µmol CO2 m‑2 s‑1, with an average value of 11.36 µmol CO2 m‑2 s‑1. In the harvest period (September-October) the Pn presented its greatest variation, due to the fact that some measurements were made prior to harvest, during and postharvest, ranging from 8.57 to 17.26 µmol CO2 m‑2 s‑1, with an average value of 12.32 µmol CO2 m‑2 s‑1. This greater variation is due to the fact that during the harvest period, hydration and drying periods alternate between each harvest.
In postharvest to the beginning of senescence (November), the Pn varies from 4.72 to 7.62 µmol CO2 m‑2 s‑1, mainly influenced by the early drop in air temperatures during this 2022 cycle.
Finally, it can be preliminarily concluded that the average values of Pn between the period of fruit growth, fruit filling and harvest did not vary significantly.
However, monthly events of high Pn rates (greater than 20.0 µmol CO2 m‑2 s‑1) occurred, which corresponded to the minimum ψleaf (less than -0.7 MPa).
One of them is pecan (Carya illinoinensis), which presents, like other fruit trees, alternation and vivipary.
This region is characterized by high temperatures in spring, and relatively high humid and warm summers.
In the search to understand if the high air temperatures are impacting the accumulation of reserves and therefore the production of the next crop cycle, monthly measurements of photosynthesis (Pn) and leaf water potential (ψleaf) were carried out in seven sites in the coast of Hermosillo, Mexico.
These measurements were made from May to November 2022. For that, the LI6400 (LI-COR) and the Sscholander pump (MPS) were used, respectively.
The first ones were carried out between 9:00 am and noon, while the second around 13:00. Pn measurements were made on the same branches, of the same trees, until the age of the leaves allowed it.
In the case of ψleaf, measurements were maintained on the same trees throughout the measurement cycle.
The results of ψleaf during fruit growth (May-July) varied from -0.57 to -1.02 MPa, with an average value of -0.71 MPa.
During the fruit filling period (August) the ψleaf varied from -0.56 to -0.86 MPa, with an average value of -0.69 MPa.
In the harvest period (September-October) the ψleaf increased due to the reduction of irrigation, varying from -0.50 to -1.94 MPa, with an average value of -1.09 MPa.
During the postharvest period to the beginning of senescence (November) some plantations managed to rehydrate the trees, varying the ψleaf from -0.79 to -1.22 MPa.
On the other hand, the Pn data varied from 8.93 to 15.34 µmol CO2 m‑2 s‑1, with an average value of 12.41µmol CO2 m‑2 s‑1 throughout the fruit growth stage (May-July). During the fruit filling period (August) the Pn varies from 7.73 to 16.18 µmol CO2 m‑2 s‑1, with an average value of 11.36 µmol CO2 m‑2 s‑1. In the harvest period (September-October) the Pn presented its greatest variation, due to the fact that some measurements were made prior to harvest, during and postharvest, ranging from 8.57 to 17.26 µmol CO2 m‑2 s‑1, with an average value of 12.32 µmol CO2 m‑2 s‑1. This greater variation is due to the fact that during the harvest period, hydration and drying periods alternate between each harvest.
In postharvest to the beginning of senescence (November), the Pn varies from 4.72 to 7.62 µmol CO2 m‑2 s‑1, mainly influenced by the early drop in air temperatures during this 2022 cycle.
Finally, it can be preliminarily concluded that the average values of Pn between the period of fruit growth, fruit filling and harvest did not vary significantly.
However, monthly events of high Pn rates (greater than 20.0 µmol CO2 m‑2 s‑1) occurred, which corresponded to the minimum ψleaf (less than -0.7 MPa).
Publication
Authors
J.A. Gamez-Lucero, J.C. Rodríguez, A.E. Castellaños-Villegas, S. Er-Raki, R.J. Heerema, F. Cruz-Bautista, A. Meddich, J.H. Nuñez-Moreno
Keywords
leaf water potential, leaf temperature, stomatal conductance, air temperature, arid lands, irrigation
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