Effect of Zinc application on Arsenic Dynamics in Contaminated Soil and Agronomic traits of Three Rice (Oryza sativa L.) Cultivars

Arsenic as aheavy metal, is one of the most important pollutant in the environment that has a detrimental effect on the morphological, physiological and biochemical properties of rice. Zinc application is one of the way to reduce negative effects of arsenic. For this purpose, an outdoor experiment was performed in the form of three-factor factorial experiment based on complete randomized design with three replications at the Rice Research Institute of Iran (Rasht) during growing season in 2019. The proposed factors were zinc at three levels (0, 10 and 20 mgkg-1) as zinc sulfate, arsenic at three levels (0, 1 and 2 mg kg-1) as Arsenic oxide, and three  rice cultivars (Hashemi, Gilaneh, Ghodsi). The results indicated that all factors had significant effect on the amount of zinc uptake in the soil, straw and grain, amount of arsenic in the soil, straw and grain, plant height, total and fertile tiller number, panicle length, 1000-seed weight, biomass and grain yield.   The uppermost increase in plant height, total tiller number, fertile tillers, panicle length, 1000-seed weight and grain yield were recorded 1.5, 68.4, 85.05, 31.5, 6.6 and 58.5 percent, respectively due to soil application of 20 mg zinc per kg-1. In terms of zinc uptake by straw and grain, Hashemi cultivar> Ghodsi cultivar> Gilaneh cultivar  showed the highest zinc content, respectively, which Hashemi and Ghodsi cultivars are more efficient in terms of zinc uptake and are more tolerant to arsenic. The highest amount of arsenic in straw and grain was observed in Gilaneh> Ghodsi> Hashemi cultivars, respectively. Therefore, due to the interaction of zinc with arsenic, the use of zinc and cultivars with high zinc uptake capacity might be a good way to reduce arsenic toxicity in rice plants.