www.tropicalplantresearch.com 161 Received: 27 December 2016 Published online: 30 April 2017 https://doi.org/10.22271/tpr.2017.v4.i1.023 ISSN (E): 2349 – 1183 ISSN (P): 2349 – 9265 4(1): 161–167, 2017 DOI: 10.22271/tpr.2017.v4.i1.023 Research article Impact of dust accumulation on three roadside plants and their adaptive responses at National Highway 37, Assam, India Bitopan Sarma 1,2 , Sanjay Kumar Chanda 2 and Mantu Bhuyan 2 * 1 Academy of Scientific and Innovative Research, CSIR-North East Institute of Science and Technology, Jorhat, Assam, India 2 Biological Science and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat, Assam, India *Corresponding Author: mantubhuyan@gmail.com [Accepted: 13 April 2017] Abstract: Roadside plants are consistently exposed to dust. Deposition of dust on roadside plant and its impact on leaf epidermal traits as well as leaf pigment concentration, the percentage of carbon and nitrogen has been studied of three roadside plants i.e. Cassia alata, C. tora and C. sofera at National Highway - 37, Assam. Significant variation in terms of dust deposition with species specific result observed during the study. Declination of leaf pigment concentration, leaf area and nitrogen percentage along with increased leaf thickness indicate the dust pollution impact. Above findings may be helpful to find out some representative species for developing some model to cope with automobile generated dust pollution in future. Keywords: Dust pollution - Roadside plant - Chlorophyll - Leaf epidermal traits - Cassia spp. [Cite as: Sarma B, Chanda SK & Bhuyan M (2017) Impact of dust accumulation on three roadside plants and their adaptive responses at National Highway 37, Assam, India. Tropical Plant Research 4(1): 161–167] INTRODUCTION Dust is an important abiotic factor and has a key influence upon the organism. Sever pressure of dust may be responsible for altering bio-chemical as well as morphological setup of an organism which further initiated adaptive evolution to cope with the changing environment. Based on the source of generation as well as the structure of road, the role of dust may be variable (Farmer 1993, Anthony 2001). In an urban area, road dust contains a mainly huge amount of different metals as well as a small amount of clay and minerals too (Beckett et al. 2000). Vehicles are the prime source of dust generation for roadside plants. Poor road infrastructure, the frequency of running vehicles in terms wheel determine the rate of dust generation. Therefore, adaptive evolution of roadside plant species is more visible in poor road infrastructure with more running vehicles. The response of the plant to dust accumulation may vary according to different species, as dust deposition fluctuates with plant species due to leaf orientation, leaf surface geometry, phyllotaxy, epidermal and cuticular features, leaf pubescence, height and canopy of roadside plants (Davison & Blakemore 1976, Chaphekar et al. 1980, Farmer 1993, Chaturvedi et al. 2013) With the accumulation of dust, the roadside plant may exhibit adaptive response by changing morphological and physiological attributes. A number of registered motor vehicles in India have reached from 0.3 million to 159.5 million from 1951 to 2012 (Report: Road Transport Year Book 2011–12, Government of India, Ministry of Road Transport and Highways Transport Research Wing, www.morth.nic.in). In Assam, vehicles are increased from 53, 4885 in 2000–01 to 1,98,4880 in 2013–14 indicating 73.05% boost of the growth of motor vehicle in the state. But the roads are limited and poor in condition (Source: Office of the Commissioner of Transport, Assam and Directorate of Economics and Statistics, Assam). National Highway - 37 (NH-37) is the backbone of road transport in Assam and the road starts from Panchatantra of Goalpara district of Assam to Roing of Arunachal Pradesh with a length of 740 km and considered one of the busiest road connecting all the major cities of the south of the Brahmaputra river. In the present study, we emphasised the impact of dust deposition in terms of epidermal traits of leaf, chlorophyll contents, carbon and nitrogen percentage upon roadside plant and their adaptive responses to cope