Lead (Pb) distribution and accumulation in different plant parts and its associations with grain Pb contents in fragrant rice

Abstract

Lead (Pb) affects the growth and productivity of rice negatively through soil-Pb-plant interactions. A pot experiment was conducted to assess the Pb uptake and its distributive pattern in different fragrant rice cultivars i.e., Meixiangzhan-2 (MXZ-2), Xiangyaxiangzhan (XYXZ), Guixiangzhan (GXZ), Basmati-385 (B-385), and Nongxiang-18 (NX-18) and relationship of Pb uptake with grain Pb-contents and rice yield and related traits i.e., productive tillers hill^-1, spikelets panicle^-1, filled grain percentage, and 1000-grain weight. Lead as Pb(NO₃)₂ was applied at 0 (control), 400 (Pb1), 800 (Pb2) and 1200 mg kg^-1 (Pb3) of soil in solution form. Results showed that all rice cultivars accumulated different concentration of Pb, with the highest in roots and the lowest in grains. The translocation factors (TF) from stems to leaves were higher than root to stems and leaves to ears/grains. The grain Pb contents have significant positive associations with ear Pb contents and TF of Pb from leaves to ear at reproductive stage. Moreover, relative changes (RC) in grain yields have significant correlations with the RC in some yield attributes i.e., productive tillers per hill, spikelets per panicle, and filled grain percentage under Pb toxicity. Overall, grain Pb contents are affected mainly by the transference of leaves Pb contents to ears/grains (an index to determine final grain Pb contents) whereas RC in rice yields suggested its relationships with some agronomic attributes of fragrant rice under Pb stress.

Keywords: Fragrant rice; Grain; Lead uptake; Translocation factor.