Effect of Zinc on Growth, Yield and Zinc Use Efficiency of Rice in Rice–Wheat Cropping System

A four year rice-wheat cropping (2012-15) was developed on Nursery Jhilli area of Rajendra Agricultural University, Pusa, Bihar, where zinc applied in four different doses (2.5, 5.0, 7.5 and 10.0 kg ha-1) and 3 modes of application under rice – wheat cropping system, to investigate the effect of different doses of Zn and modes of application on rice growth parameters, yield and Zn use efficiency. Results reveled that among the different growth and yield attributing characteristics of rice the highest of number of tillers m-2, number of productive tillers m-2 and number of filled grain panicle-1 were observed in 7.5 kg Zn ha-1 at alternate year applied plot. Root weight were highest in 7.5 kg Zn ha-1 every year applied plot. The grain and straw yield data clearly indicated that application of zinc significantly increased both yields. The highest grain yield was found in 5 kg Zn ha-1 applied every year (40.20 q ha-1) and 7.5 kg Zn ha-1 in initial year application was the lowest dose for optimum rice grain yield in the fourth year. Highest Agronomic Efficiency was found in 7.5 kg Zn ha-1 (101.33 kg grain/ kg Zn) and the order of apparent Zn recovery efficiency was in the order of, 2.5 kg Zn, alternate year (3.72%) > 2.5 kg Zn, initial year (3.70%) > 7.5 kg Zn, every year (3.61%) > 2.5 kg Zn, every year (3.58%). A suitable dose (5 kg Zn ha-1) of Zn found more efficient in term of yield and recovery efficiency than high or low doses, this can be helpful to farming communities for better earning and reduce excessive application.