Responses of Reclamation Plants to High Root Zone pH: Effects of Phosphorus and Calcium Availability

Abstract

Low phosphorus (P) availability and high pH inhibit plant growth in calcareous soils and some oil sands reclamation sites in northeastern Alberta, Canada. In this study, we used a split-root hydroponic setup to test the effects of supplemental P with different calcium (Ca) concentrations and root-zone pH conditions on the growth and physiological response of trees commonly found in the region: paper birch ( Marsh.), trembling aspen ( Michx.), green alder [ (Chaix) DC.], and black spruce [ (Mill.) Britton, Sterns & Poggenb.] seedlings. Plant roots were divided and treated with different combinations of P (0.5 and 15 mmol L), Ca (2 and 50 mmol L), and pH (5.0 and 9.0) for 6 wk. After that time, we measured seedling height, net photosynthesis and transpiration rates, and the concentration of chlorophyll and different elements in the leaves. Plant responses varied between species; black spruce was most resistant to high pH and high Ca concentrations. We did not find any strong beneficial effects of adding P to plants subjected to high root zone pH and high Ca concentration. However, exposure of part of the root system to low pH alleviated the effects of high pH, likely through the improved supply of micronutrients. Because pH conditions are often not uniform in disturbed sites and reclamation soils, our findings may help improve potential reclamation and phytoremediation strategies for the oil sands, bauxite, and coal-combustion residue utilization industries.

Fertilizer Efficiency and Risk Assessment of the Utilization of AOD Slag as a Mineral Fertilizer for Alfalfa (Medicago sativa L.) and Perennial Ryegrass (Lolium perenne L.) Planting

“…The high soil pH also has some negative effects on the root and plant growth. The water flux of the root, the elongation of the root cell, and the formation of the lateral roots and root hairs are inhibited when the soil pH is high [43,44]. Plants absorb soil N, P, and K and other micronutrients mainly through root tips and hairs [45].…”

Effects of pH and Mineral Nutrition on Growth and Physiological Responses of Trembling Aspen (Populus tremuloides), Jack Pine (Pinus banksiana), and White Spruce (Picea glauca) Seedlings in Sand Culture

“…The main objective of the study was to compare the responses of the three boreal plant species to root zone pH in sand culture. In controlled-environment hydroponic studies, white spruce exhibited relatively high tolerance, while trembling aspen and jack pine were moderately tolerant to high root zone pH [7,16,21,22]. Due to higher growth rates and greater nutrient demand of trembling aspen compared with the two studied conifer species, we hypothesized that increased nutrient supply would be more effective in ameliorating the high pH effects on trembling aspen compared with white spruce and jack pine.…”

“…An inability of plants to maintain root apoplast acidification can affect cell elongation and impair root growth [13,[22][23][24]. High pH also reduces root water flux [14,25] and results in reductions in shoot water potential [13,21] and transpiration rates [7,14,20]. However, relative contributions of mineral nutrition and water relations to growth responses in plants affected by high pH are difficult to separate.…”

“…Since high pH decreases the availability of Mg, Ca, Fe, Mn, P, Zn, and other mineral nutrients in soil solution [ 6 , 7 ], the main effects of high soil pH on plants are frequently attributed to nutrient deficiencies [ 8 ]. Under nutrient deficiency conditions, plant response strategies include increased nutrient use and acquisition efficiencies [ 8 ].…”

Hydraulic Redistribution in Slender Wheatgrass (Elymus trachycaulus Link Malte) and Yellow Sweet Clover (Melilotus officinalis L.): Potential Benefits for Land Reclamation

“…The impacts of oil sands mining on the environment are mitigated through reclamation, reforestation and closure activities. Plants in the oil sands reclamation areas are commonly faced with high soil pH, soil compaction and drought conditions [16,17]. These soil factors commonly affect the establishment and growth of young seedlings following planting [18,19] and impact root colonization by mycorrhizal fungi, as well as water and mineral nutrient uptake by plants [20][21][22].…”