ABSTRACT
This study examined the impact of various types of amendments (farmyard manure (FYM), cow dung (CD), biogas slurry (BGS), biomaterial (Biom), gypsum (GYP) and lignite (LIG)) on arsenic (As) accumulation by the two contrasting rice genotypes in a pilot-scale experiment. Arsenic-contaminated irrigation water (i.e., 45 mg/L) was applied at three distinct growth stages of rice plants at transplanting, tillering and milking stages for both the genotypes, i.e., Kainat and Basmati-385 (fine and coarse, respectively). Results showed that a significant increase in shoot, root and grain dry weight, plant height, number of tillers per plant where organic amendments were added with maximum grain weight yielded for FYM, CD and Biom treatments. Arsenic concentration in shoot and grain significantly reduced compared to the control for the respective genotypes. The shoot As concentration ranged from 3.1–28 mg/kg DW for Kainat as for Basmati-383 it was 1.7–16 mg/kg DW for all amendments and minimum was found where CD and Biom was applied. The average grain As concentration for Kainat genotype was higher in plants with GYP and LIG treatments compared to CD and Biom treatments (0.29 and 0.04 mg/kg DW). In the case of Basmati-385, the mean average grain As concentration was 0.24 and 0.09 mg/kg As DW for CD and Biom treatments, respectively. mean grain As concentration for both the rice genotypes in CD and Biom amendments was below safe limit of As in rice grain (0.2 mg/kg DW) set by WHO/FAO. This study highlights that organic amendments, CD and Biom, could bind As from soil and decrease As contents in rice shoot and grain, and CD and Biom could possibly enhance the growth and yield of two contrasting rice genotypes.
