Assessment of Dust-Induced Changes in Leaf Morphology and Physiology of Roadside Plants in Kano City

Dust accumulation on leaf surfaces is a significant but poorly quantified environmental stress affecting roadside plants in arid North West Nigerian cities such as Kano, and professional assessment of its morphological and physiological impacts informs urban greening and plant selection policies. This study assessed dust-induced changes in leaf morphology, chlorophyll content, stomatal conductance, and photosynthetic efficiency in five common roadside plant species in Kano city: Azadirachta indica, Casuarina equisetifolia, Ficus benjamina, Terminalia mantaly, and Polyalthia longifolia. Leaf and dust samples were collected from high-traffic roadsides and compared with control specimens from the Kano State Ministry of Agriculture arboretum. Dust load per unit leaf area was quantified gravimetrically. Chlorophyll a and b contents were determined spectrophotometrically. Stomatal conductance was measured using a porometer. Photosynthetic efficiency was estimated by chlorophyll fluorescence (Fv/Fm ratio). Results showed that mean dust load ranged from 3.4 to 7.8 mg/cm2 across species and sites. Dust-loaded leaves showed significantly lower chlorophyll content (mean reduction: 28%), stomatal conductance (mean reduction: 34%), and Fv/Fm ratios compared to control leaves. Ficus benjamina was most sensitive to dust-induced physiological stress, while Azadirachta indica showed the smallest photosynthetic efficiency decline. Dust load was positively correlated with proximity to unpaved roads (r = 0.79, p < 0.01). The study recommends prioritising dust-tolerant species in Kano roadside greening programmes and implementing regular leaf washing during the dry season. Keywords: dust pollution, leaf morphology, chlorophyll content, roadside plants, Kano