Effects of Mineral Nutrition and Iron Supply on Growth and Physiological Responses of Selected Boreal Plant Species to Root Zone pH

• Author / Creator

  Xu, Feng

• High soil pH can aggravate the effects of water deficit stress, inhibit root growth, and reduce the availability of essential elements to plants, especially iron. Iron deficiency can severely decrease plant growth and yield and result in plant mortality. In my study, I examined the effects of root zone pH and the supply of iron and other essential mineral nutrients on several species of boreal forest plants including trembling aspen (Populus tremuloides), red osier dogwood (Cornus sericea), jack pine (Pinus banksiana), white spruce (Picea glauca), black spruce (Picea mariana), tamarack (Larix laricina), paper birch (Betula papyrifera), green alder (Alnus viridis), blueberry (Vaccinium myrtilloides), and bearberry (Arctostaphyllos uva-ursi). Several studies were carried out through the controlled-environment experiments in sand culture and hydroponics. These studies were aimed at helping to understand the processes in plants that contribute to high soil pH tolerance and improve the revegetation success of oil sands reclamation areas. The results of Chapter 2 demonstrated that the responses to high pH varied between studied plant species, likely due to their different nutrient demands. In high-pH sensitive plants, the high root zone pH reduced the plant biomass, net photosynthetic rates, transpiration rates, leaf chlorophyll concentrations, chlorophyll a to b ratios, and tissue concentrations of essential elements. The increased supply of essential mineral nutrients had a beneficial impact, but only on the total dry weights in trembling aspen and when added at the lower pH levels. In Chapter 3, I found that the positive impact of increased iron supply was effective only when the pH of the growth medium was neutral (pH 7). Therefore, the increased supply of mineral nutrients can be effective in overcoming high soil pH stress when the conditions for nutrient uptake and utilization are maintained. In the split-root experiment of Chapter 4, the high pH stress could be alleviated when part of the root system was exposed to lower pH. This improvement may be attributed to acidified localized areas that increase the solubility and uptake of micronutrients. The results also demonstrated that high pH induced stress responses in plants through the part of the root system that was exposed to high pH and affected the responses of the other part of the root system that was exposed to low pH. Among the studied plant species, white spruce was found to be relatively tolerant to high pH and its tolerance mechanisms may be related partly to higher biomass allocation to the roots. Trembling aspen and dogwood also showed some degree of high pH tolerance and the results suggested that dogwood may have higher Fe utilization efficiency and trembling aspen may be able to allocate more root biomass to the part of the roots exposed to high pH conditions when supplied with high levels of mineral nutrients. These plants could be considered as desirable candidate species for the revegetation of oil sands reclamation sites.

• Subjects / Keywords

  • Mineral nutrition
  • Boreal forest plants
  • High pH

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3CR5NT49

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.