Photosynthetic Efficiency of Older vs. Younger Malus Trees

Overview

Introduction

Photosynthesis involves plants absorbing carbon dioxide and releasing oxygen back into the atmosphere. Having photosynthetic efficient trees is important to the quality of the air we breathe. In a study conducted by Richardson (1957) it was concluded that photosynthesis of a plant varies with age and also on the type of plant or tree itself, by observing CO2 concentrations using an infrared gas analyzer. In a different study done by Bao et al (2015) there was significant evidence stating that there was age-related changes such as gas exchange, water use characteristics, decrease in photosynthetic rates, etc. with increasing age. These measurements were measured by the LI-6400XT portable photosynthesis system.

The hypothesis of the study was that younger 2014 Malus trees would be more photosynthetically (higher SPAD, Phi2 and LEF) efficient than the older 2003 Malus trees because the leaves are younger and more susceptible to growth. Younger trees have experienced fewer photosynthesis cycles and are therefore, less "used". The hypothesis was supported by Webster et al. (2003) who planted trees with only one year age difference and saw a significant growth rate difference between the two trees. They were planted in the same environment and location and experienced the same weather conditions and the younger tree grew more rapidly than the older tree. The length and width of the leaves were measured with a ruler, while the height of the tree and width of the trunk was measured with a tape measure. Webster et al. (2003) concluded that because the tree was younger, it was more susceptible to photosynthetic growth. This research project was chosen to observe if similar results would surface. The reason for this research was to learn if the age of a Malus tree affects its photosynthetic efficiency in order to take in more carbon dioxide and release more oxygen more efficiently.

Methods

Three Malus trees planted in 2003 (Donald Wyman) and three Malus trees planted in 2014 (Sutyzam) were chosen to be studied (Figure 2). These six trees are located northwest of the Natural Science Building on Michigan State University’s campus. This location was chosen because all of the trees are in the same habitat and in close radius to each other. This field study used a multispeq (124) to collect data and to determine photosynthetic efficiency. Variables measured include phi2, NPQ and LEF (SPAD). One hundred and twenty leaves were collected three times a week (twenty leaves per tree). As illustrated in figure 1, each tree was divided into four quadrants, with five leaf samples collected clockwise at random from each quadrant in the exact order: North, East, South and West. Data was collected from the outermost layer of the tree in the bottom third portion at the widest portion of the leaf. The data collected between the three 2003 Malus trees were biological replicates and the three 2014 Malus trees were also biological replicates. The data was collected three times a week for four weeks (technical replicates). The statistical analyses for this research project will be a t-test and an anova.

Results

https://docs.google.com/document/d/1vCZyUMgYRJATIiGFAbkD1SJnGI7B_JcqOA1dMdyo5xE/edit?ts=5772d269

The following is a list of the trees to be sampled: Malus ‘Donald Wyman’ 2003082209 Malus ‘Donald Wyman’ 2003082210 Malus ‘Donald Wyman’ 2003082207 Malus ‘Sutyzam’ 2014020219 Malus ‘Sutyzam’ 2014020201 Malus ‘Sutyzam’ 2014020207

Literature Cited

Bao, JT., Wang, J., Li, XR., Zhang, ZS., Su, JQ. (2015), Age-related changes in photosynthesis and water relations of revegetated Caragana korshinskii in the Tennger desert, Northern China. Tree Structure and Function, 29(6), 1749-1760.

Richardson, D. (1957). The effect of leaf age on the rate of photosynthesis in detached leaves of tree seedlings. Acta Botanica Neerlandica, 6(4), 445-457

Webster, A., Vaughan, S., Lucas, A., Spencer, J., & Atkinson, C. (2003).Effects of tree age at planting, root manipulation and trickle irrigation on growth and cropping of apple (Malus pumila)cultivar queen cox on M.9 rootstock. Journal of Horticultural Science & Biotechnology, 78(5), 680-688.

Protocols

Leaf Photosynthesis - MultispeQ Beta ONLY

Measures photosynthesis-related parameters in <15 seconds, including: Phi2, PhiNPQ, PhiNO, NPQt, qL, LEF, and SPAD. In addition, measures PAR (photosynthetically active radiation), ambient temperature and relative humidity.

Works with the MultispeQ Beta device only


Questions

  1. Are you measuring from Malus Donald Wyman (2003) or Malus Sutyzam (2014)?
  2. Which quadrant? (5 leaves per quadrant, bottom third of tree)
  3. Leaf count (5 leaves per quadrant, random bottom third of tree)

Locations

Discussions


Team

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