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A field experiment was conducted during 2004-05 on wheat and rice to study the response of Zinc application in wheat-rice system. Two levels of zinc 5 and 10 kg ha(-1) with control were studied with the basal dose of N, P2O5, K2O as 120-90-60 kg ha(-1) in the form of urea, TSP, SOP and zinc sulphate during both the crops. Wheat variety Naseer 2000 and rice variety IRRI 6, both were planted in R.C.B design with three replications. Zn application, significantly affected wheat grain yield, ranged from 2.7 to 3.5 t ha(-1), giving highest increase of 31.6% over control from 5 kg Zn ha(-1). The number of tillers, spike m(-2), spike length, plant height and 1000 grain weight of wheat were also significantly affected over control with the same treatment. Paddy yield was also significantly affected by Zn levels ranged from 3.9 to 5.9 t ha(-1). The highest yield was obtained from 10 kg Zn ha(-1) each applied to both crops. Similarly Zn application also affected significantly to the yield parameters of rice like the number of spike m(-2), number of spike/plant, spike length, plant height and 1000 grain weight over control from the above said treatment of 10 kg Zn ha(-1). The concentration of zinc in soil and leaves was significantly affected by the application of zinc in wheat and rice, ranged from 0.47-1.37, 22.6-367.37 mg kg(-1) in wheat and 0.45-1.18; 29.32-40.67 mg kg(-1) in rice, respectively (soil and leaves). The highest concentration in soil and leaves was recorded by the cumulative application of 10 kg Zn ha(-1) while lowest from control. The direct application of 5 and 10 kg Zn ha(-1) gave an increase of 39 and 45% while residual effect 30.0 and 43.0%, cumulative effect of 38 and 50% over control, respectively. The residual application of 10 kg Zn ha(-1) can be recommended for economical production in wheat rice system.

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To cite this paper: Khan, S.U., A.R. Gurmani, Jalal-Ud-Din, A. Qayyum, K.S. Abbasi, M. Liaquat and Z. Ahmad, 2016. Exogenously applied gibberellic acid, indole acetic acid and kinetin as potential regulators of source-sink relationship, physiological and yield attributes in rice (Oryza sativa) genotypes under water deficit conditions. AbstractRice is one of the important cereal crops drastically affected by water scarcity in rice ecosystems. In a pot study, the impact of externally applied gibberellic acid (GA3), indole acetic acid (IAA) and kinetin was investigated on assimilates mobilization and yield parameters of rice under water stress. Twenty five days seedlings of two rice genotypes KS-133 and Basmati-2000 were transplanted in soil filled pots and sprayed with GA3, IAA and kinetin each of 10 -5 M concentration at panicle initiation stage. Water stress was imposed to plants 80 days after transplanting for 10 days. Water stress (p≤ 0.05) reduced leaf chlorophyll content and yield of rice but increased the concentration of proline, leaf soluble protein and enhanced mobility of assimilates from leaves to grains. Application of GA3 and kinetin significantly (p≤ 0.05) increased chlorophyll content, growth and yield attributes in both genotypes under water stress conditions. However, IAA application did not improve the grain yield in rice genotypes under water stress. The positive impact of GA3 and kinetin spray was imitated in the form of enhanced solute accumulation; enhanced growth and greater grain assimilate deposition. This may be concluded that GA3 and kinetin can be applied exogenously prior to flower initiation in rice to reduce panicle sterility by increasing assimilates mobility under water deficit for optimal economic yield.