Synergistic Action of Iron and Phytohormones on Enzyme Activity, Chlorophyll and Grain Yield of Rice in Iron-Deficient Soil

To study the effect of foliar application of gibberellic acid (GA3) and cytokinin on antioxidative enzymes, chlorophyll content and grain yield of rice, experiment was laid out in 3-factor completely randomized design in Fe-deficient soil. The factors were i) Fe-efficient (RAU-759) vs. inefficient cultivar (Rajendra Suwasini); ii) ‘control’ (no Fe spray) vs. one soil application (20 kg/ha) + two foliar spray of Fe as 0.5% ferrous sulphate at pre-flowering and 7-days after flowering; and iii) foliar application of phytohormones GA3 @10 and 20 ppm; cytokinin @10 and 20 ppm and their combinations. The results revealed that combined application of cytokinin + GA3 @10 ppm enhanced the activity of catalase and peroxidase from 220.0 to 232.3 μmol/min/g fresh protein, and 86.2 to 98.8 Units/mg fresh protein, respectively in ‘RAU-759’. The maximum chlorophyll content was recorded in RAU-759 (39.2 SPAD value) with Fe application plus cytokinin + GA3 @10 ppm each. Grain yield increased significantly from 25.2 to 26.6 g/plant in ‘RAU-759’ provided with Fe application and GA3+cytokinin @10 ppm each compared to control. It is concluded that foliar application of GA3 and cytokinin significantly enhance the activity of catalase and peroxidase, and increase chlorophyll content in leaves leading to higher grain yield