Navigation Links
Sun or shade: Pecan leaves' photosynthetic light response evaluated
Date:11/3/2009

COLLEGE STATION, TXPecan, the most valuable nut tree native to North America, is native from northern Illinois and southeastern Iowa to the Gulf Coast of the United States, where it grows abundantly along the Mississippi River, the rivers of central and eastern Oklahoma, and Texas. Popularity and consumer demand for pecans has increased the cultivation of pecan trees to other areas, while commercial production has expanded into many regions of the United States and Mexico.

Effective management of the tree canopy is of vital interest to pecan growers. Pecan trees require careful canopy management to avoid self-shading and to maintain productivity. Leaves of pecan trees typically intercept 65% to 70% of available sunlight with up to 95% light interception in overcrowded, unpruned orchards; less light naturally affects photosynthesis. To improve the amount of light penetration, pecan growers commonly use pruning techniques to increase photosynthesis and flowering on trees. To date, however, little information has been available to growers about the change in photosynthesis activity of pecan leaves throughout the growing season.

Leonardo Lombardini, Hermann Restrepo-Diaz, and Astrid Volder of Texas A&M University's Department of Horticultural Sciences published the results of an experiment using pecan tree cultivars in a recent issue of the Journal of the American Society for Horticultural Science. According to Lombardini and collaborators, the objective of the experiment was to quantify the effects of differences in light intensity on the "morphological characteristics and seasonal physiological performance of sun and shade leaves of field-grown pecan trees".

The experiment was conducted during the 2007 growing season at Texas A&M University. The cultivars used for the research, 'Pawnee' and 'Stuart', were chosen because of their rank as two of the most important pecan varieties for commercial growers.

Treatments were established according to the leaf type (sun or shade leaves) and cultivar. Sun leaves were growing on exterior portions of the tree canopy and were exposed to full sunlight for most of the day (southern exposure). Shade leaves were growing in interior parts of the tree canopy.

The study revealed that pecan shade leaves exposed to saturating radiation are about half as effective as sun leaves in assimilating CO2. Light saturation points were lower for shade leaves and steadily increased as the season progressed for both leaf types. The research showed that late-season photosynthetic capacity was maintained in shade leaves, whereas it was reduced to about 60% in sun leaves.

The authors noted that the results of the research may explain why pecan trees can tolerate severe hedging-type pruning and still maintain high productivity in areas characterized by relatively high light regions (such as the southwestern United States and east-central Australia). The authors explained that "the reduction of canopy size caused by hedging likely increases the ratio of sun-exposed leaves to shaded leaves, thus boosting carbon gain per unit leaf area".

Especially noteworthy is the autumn assimilation drop in sun leaves, without a corresponding assimilation drop in shade leaves, which the authors call "a significant finding".

This study provides baseline information relevant to improving management of the orchard light environment, and can be used by commercial pecan producers for developing new, effective canopy and crop management practices.


'/>"/>

Contact: Michael W. Neff
mwneff@ashs.org
703-836-4606
American Society for Horticultural Science
Source:Eurekalert  

Related biology news :

1. Bird flu leaves the nest -- adapting to a new host
2. Why are autumn leaves red in America and yellow in Europe?
3. The hepatitis healing power of blueberry leaves
4. A win-win: U-pick pumpkin farms recycle urban leaves
5. When leaves fall, more is occurring than a change of weather
6. From Canada to the Caribbean: Tree leaves control their own temperature, Penn study reveals
7. Aquaculture concept leaves judges goggle eyed
8. Why do autumn leaves bother to turn red?
9. Orientation of antenna protein in photosynthetic bacteria described
10. Berkeley researchers identify photosynthetic dimmer switch
11. Researchers decode genetics of rare photosynthetic bacterium
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Sun or shade: Pecan leaves' photosynthetic light response evaluated
(Date:4/5/2017)... , April 5, 2017  The Allen Institute for ... Cell Explorer: a one-of-a-kind portal and dynamic digital window ... imaging data, the first application of deep learning to ... stem cell lines and a growing suite of powerful ... for these and future publicly available resources created and ...
(Date:4/4/2017)... , April 4, 2017   EyeLock LLC , ... that the United States Patent and Trademark Office (USPTO) ... covers the linking of an iris image with a ... and represents the company,s 45 th issued patent. ... is very timely given the multi-modal biometric capabilities that ...
(Date:3/30/2017)... The research team of The Hong Kong ... identification by adopting ground breaking 3D fingerprint minutiae recovery and matching ... and accuracy for use in identification, crime investigation, immigration control, security ... ... A research team led by ...
Breaking Biology News(10 mins):
(Date:9/20/2017)... ... September 20, 2017 , ... ... study examining the effects of exoskeleton-assisted walking on gait parameters and neuromuscular ... article, "Neuromechanical adaptations during a robotic powered exoskeleton assisted walking session" (doi:10.1080.10790268.2017.1314900) ...
(Date:9/19/2017)... ... 2017 , ... Participants of this educational webinar will learn ... with the advantages and disadvantages of ductless, filtered fume hoods, they will also ... , Attendees will learn from an industry expert about the different types of ...
(Date:9/19/2017)... , Sept. 19, 2017 ValGenesis Inc., the ... is pleased to announce the strategic partnership with VTI ... clients with validation services using the latest technology available ... will provide clients with efficient and cost-effective validation services ... partner for the ValGenesis VLMS system. ...
(Date:9/18/2017)... ... 18, 2017 , ... Transportable biomass conversion facilities and the ... is the topic of a September 27 webinar hosted by the ... transportable biomass conversion facilities for producing biochar, briquettes, and torrefied wood, biomass supply ...
Breaking Biology Technology: