Response of summer fodder sorghum as influenced by preceding rabi sorghum varieties, residual effect of zinc, iron and varied fertilizer levels directly applied to fodder sorghum

A field experiment was conducted at ICAR- Indian Institute of Millet Research, Rajendranagar, Hyderabad during summer seasons of 2022 and 2023 to assess the performance of fodder sorghum (CSV 21f) as influenced by preceding rabi sorghum varieties, residual response to zinc, iron and to varied levels of fertilizers directly applied to fodder sorghum in a split-split plot design. The results indicated that the preceding rabi sorghum varieties did not have any significant effect on growth parameters, or on zinc and iron content and uptake of fodder sorghum. Similar results with no effect on growth parameters were also obtained by the residual effect to zinc and iron, although numerical supremacy was shown by S₁+ nano Zn @ 2.5 kg ha^-1 + Fe @ 5 kg ha^-1 (soil application). However positive enhancements in zinc content and uptake was observed due to residual effect of zinc and iron, with maximum content at 40 DAS (25.4 & 21.9 ppm), 55 DAS (30.9 & 29.3 ppm) and for uptakes at 40 DAS (242.7 & 240.7 g ha^-1) and 55 DAS (351 & 377.6 g ha^-1) was also achieved with S₁+ nano Zn @ 2.5 kg ha^-1 + Fe @ 5 kg ha^-1 (SA) and it was comparable to S₁+ nano Zn @ 2.5 kg ha^-1(SA). Similar results were noticed for iron content at 40 DAS (195.0 & 190.5 ppm), 55 DAS (219.5 & 212.0 ppm) and for uptakes at 40 DAS (1884.0 & 1792.9 g ha^-1) and 55 DAS (2498.3 & 2300.4 g ha^-1) was also achieved with S₁+ nano Zn @ 2.5 kg ha^-1 + Fe @ 5 kg ha^-1 (SA) and it was comparable to S₁+ Fe @ 5 kg ha^-1 (SA). Control and residual response of foliar applications were comparable indicating that soil application of micronutrients were preferable for residual effect on succeeding crops. In case of varied fertilizer levels, maximum growth, zinc, iron content and uptakes were resulted with 50% dose of fertilizers compared to zero level of application.