Iqbal et al. 2015 — Lead accumulation in rice varieties under combined Pb and salt stress, Pakistan
Iqbal et al. examined lead (Pb) accumulation and growth responses in two Pakistani rice varieties (Super Basmati and Irri-6) grown in pots with soil spiked at 0, 50, 100, and 200 mg Pb/kg under varying salt (NaCl) concentrations (0, 50, 100, 150 mM). The study is primarily a phytotoxicity investigation using artificially contaminated soil at concentrations considerably above ambient field levels; its relevance to natural-occurrence surveillance is limited. However, it provides data on differential Pb accumulation between cultivars and between plant organs (straw vs. grain) under controlled conditions in Pakistan, a country with significant rice cultivation and soil Pb contamination concerns.
Key numbers
- Soil Pb spike levels: 0, 50, 100, 200 mg/kg
- Pb in rice grain: substantially lower than straw at all treatment levels (consistent with the general translocation barrier for Pb in rice)
- Salt stress generally reduced Pb uptake and accumulation in both varieties at moderate NaCl concentrations, with effects reversing at higher salinity
- Super Basmati accumulated less Pb in grain than Irri-6 under most treatment conditions
- Exact grain Pb values reported in tables (values given as µg/g dry weight) — at 200 mg/kg soil Pb, grain Pb in Irri-6 exceeded that of Super Basmati
Methods (brief)
Pot experiment; two rice varieties; factorial design crossing Pb dose (4 levels) and NaCl concentration (4 levels); FAAS for Pb determination; Pakistan.
Implications
Certification: Provides cultivar-level differentiation for Pb accumulation in basmati vs. non-basmati rice — useful context for sourcing guidance, though soil spike levels far exceed ambient. Courses: Illustrates the general principle that straw accumulates far more Pb than grain (the plant excludes Pb at the grain-filling step), which is relevant to animal feed vs. human food exposure discussions. App: B-tier; controlled contamination study not usable for ambient concentration estimates.