Alteration of macronutrients, metal translocation and bioaccumulation as potential indicators of nickel tolerance in three Vigna species

Shabnam Ishtiaq , Seema Mahmood , Mohammad Athar

Abstract

Macronutrients (Na+, K+, Ca2+, Mg2+), yield and yield components, bioaccumulation and translocation of metal in plant parts of three Vigna species (V. cylindrica, V. mungo, V. radiata) were evaluated at 0, 50, 100 and 150 mg kg-1 soil of Nickel (Ni). A marked inhibition (p < 0.001) in the distribution of various macronutrients was noticed in these Vigna species except for Mg2+ content of the shoot and leaves. Similarly, all species retained more Ca2+ in their roots (p < 0.05) as compared to the aerial tissues. Ni induced a drastic decline (p < 0.001) for various yield and yield attributes except for 100 seed weight. Toxicity and accumulation of Ni in plant tissues considerably increased in a concentration dependent manner. Vigna species signify an exclusion approach for Ni tolerance as both bioaccumulation factor (BF) and translocation factor (TF) were less than 1.0. The Ni content of plants being root > shoot > leaves > seeds. Scoring for percentage stimulation and inhibition (respective to control) at varying levels of Ni revealed tolerance of the species in an order of V. radiata > V. cylindrica > V. mungo. The acquisition of Ni tolerance in V. radiata seems to occur through an integrated mechanism of metal tolerance that includes sustainable macronutrients uptake, stronger roots due to greater deposition of Ca2+in the roots, restricted transfer of Ni to above ground tissues and seeds as well as exclusion capacity of the roots to bind appreciable amount of metal to them. Thus, metal tolerant potential of V. radiata could be of great significance to remediate metal contaminated soil owing lesser impact of Ni on macro-nutrients, hence the yield.

Key Words

macronutrients; yield; metal excluders; nickel tolerance; Vigna species

Address

(1) Shabnam Ishtiaq and Seema Mahmood — Institute of Pure and Applied Biology, Botany Division, Bahauddin Zakariya University, Multan-60800, Pakistan
(2) Seema Mahmood — Division of Experimental and Evolutionary Biology, University of Glasgow, Glasgow, Scotland, G12 8QQ, UK
(3) Mohammad Athar — California Department of Food and Agriculture, 3288 Meadowview Road, Sacramento, CA 95832, USA
(4) Mohammad Athar — Department of Food Science and Technology, University of Karachi, Karachi-75270, Pakistan.

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