Abstract
Arsenic (As) is a toxic metalloid. Arsenic phyto-toxicity is manifested by its accumulation in
different tissue types and subsequent growth inhibition in plants. Despite the vital role of
leguminous crops in providing proteins to human diets, a little is known about the As
accumulation in lentil (Lens culinaris), mung bean (Vigna radiata) and pea (Pisum sativum). This
research is focused on the growth and As uptake in the root, shoot, and grain of the three crops
grown in high As soil amended with arbuscular mycorrhizal fungi (AMF), selenium (Se), Si-gel,
sulfur (S) and biochars (BC). The effects of AMF, Se, S, Si-gel and BC on photosynthetic
pigments and antioxidant enzyme activity were also studied in pulse crops. Arsenic phytotoxicity was dose-dependent as evidenced by relatively higher shoot length, fresh and dry
weights of root and shoot in low As treated soils (5 and 15 mg kg-1) than that in high As soils
(100 mg kg-1). Biomass of lentil genotypes pardina, red chief and precoz drastically decreased
when treated with As at 6 mg kg-1 concentration in comparison with 0 and 3 mg kg-1 As. Arsenic
content in grains of red chief genotype was found significantly lower than pardina and precoz.
AMF effectively reduced the As concentrations in roots and shoots of lentil plants grown at 8
and 45 mg As kg-1 soils. Arsenic concentration in mung bean grains was reduced 57% by AMF
and 59% by Se on average. The As in root, shoot and grain was also affected by genotypes. In
control treatment, grains of BARI mung 3 or 5 had 53% lower As concentration than that of
BARI mung 8. The choice of variety and soil amendment could reduce human As intake
through mung bean by 79%. Root, shoot and pod mass were generally higher in pea crops
grown in soil amended with AMF, Se, Si- gel and S. AMF, Se and Si- gel all were found more
effective than BC for the reduction of As uptake in pea crop. Arsenic in grains of pea crop was
reduced 77% by AMF, 71% by Se and 69% by Si- gel on an average. The choice of variety and
soil amendment could reduce human As intake through pea by 80%. Catalase (CAT) activity
increased due to the application of BC, AMF and Se in comparison with the control in mung
bean crop. However, proline was found significantly lower in AMF, BC and Se-treated mung
bean. Likewise, CAT activity was increased 24%, 38%,40%, 38% and 46% by BC, AMF, Se, Si-gel
and S treated pea, respectively. Ascorbate peroxidase (APX) and guaiacol peroxidase (POD)
activities were also found to be increased with the treatment of BC, AMF and Se. In contrast,
malondialdehyde (MDA) and proline contents were found to be significantly lower than that of
control in pea genotypes. It indicates that AMF, Se, Si-gel, S and BC reduced As uptake in root,
shoot and grain of lentil, mung bean and pea crops grown in high As soil as well as enhanced
biomass growth and nutritional quality. Oxidative damage and osmotic stress were potentially
minimized in As-stressed pulse crops due to application of specially AMF and Se as well. It is
concluded that choosing of variety and soil amendment with AMF and Se have great potential
for improving the nutritional quality of lentil, mung bean and pea crops grown in As
contaminated soil, thereby reducing As transfer to human bodies through food chains.