Contrasting growth responses of Melastoma malabathricum populations to aluminium addition

Do M. malabathricum seedlings respond positively to the addition of aluminium to the growth medium?

Aluminium present in soils can be toxic to many plants and is a major limitation to crop production on acidic soils. For this reason, understanding the mechanisms of aluminium uptake and toxicity has been a major focus of plant physiological research. Plants that are able to tolerate and even accumulate aluminium are particularly interesting as potential model organisms for understanding the physiological constraints to plant growth and productivity on acid soils. The tropical Southeast Asian shrub Melastoma malabathricum is emerging as a model species for ecophysiological studies on aluminium accumulation, and has in previous studies has shown enhanced growth in response to aluminium addition.

Flowers of Melastoma malabathricum on the Peninsular Malaysia. Image credit: Mahmud & Burslem.

In their new study published in AoBP, Mahmud & Burslem investigate whether differential growth responses to aluminium addition among populations of Melastoma malabathricum are related to their capacity for nutrient uptake. Their results showed that relative growth rates (RGR) were significantly greater for populations of M. malabathricum seedlings that had received aluminium in the growth medium than for control plants. The increase in growth rate in response to aluminium addition occurred despite a reduction in dry mass allocation to leaves, with a higher allocation to roots and stems. Foliar concentrations of phosphorus, potassium, magnesium and calcium increased in response to aluminium addition and foliar nutrient concentration among populations was correlated positively with seedling relative growth rate. The authors conclude that some populations of the M. malabathricum express a physiological response to aluminium which leads to a stimulation of growth up to an optimum value of aluminium in the growth medium, beyond which growth declines.

Researcher highlight

Khairil Mahmud grew up in Malaysia and in 2013 moved to Scotland, United Kingdom to conduct a PhD in ecology at the School of Biological Sciences, University of Aberdeen, UK. Khairil is currently working as a senior lecturer at the Department of Crop Science, Faculty of Agriculture, Universiti Putra, Malaysia (UPM).

Khairil is a plant ecologist and is interested in plant eco-physiological and crop science research. He is also interested in plant phytoremediation research which is useful for stabilizing the land and ecosystem from heavy metal pollution.

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