Effects of foliar application of macronutrients (K, P) and micronutrient (Fe) on the growth of okra (Abelmoschus esculentus (L.) Moench) and Pangasius (Pangasianodon hypophthalmus) in a recirculating aquaponic system
Lakan Lal Meena, Ajit Kumar Verma, Kishore Kumar Krishnani, Dhalongsaih Reang, M.H. Chandrakant, Venisza Cathy John
Abstract
A 90-day study was conducted to investigate the combined effect of foliar application of macronutrients (phosphorus and potassium) and micronutrient (iron) on the performance of okra (Abelmoschus esculentus) with pangasius (Pangasianodon hypophthalmus) in an aquaponic system. A total of four treatments with variable phosphorus dosages of 2.7, 5.4, 8.1 and 10.8 g.l−1 as T1, T2, T3, and T4, respectively, in combination with 5 g.l−1 potassium and 1.0 g.l−1 iron in all treatments was compared with control. The water quality parameters were within the favourable limit for optimal aquaponic production. The foliar application of macro and micronutrients increased the vegetative growth of okra resulting in higher plant height, leaf number, length, and width in the treatments than in control, particularly in T3. A remarkable increase (p<0.05) in pod weight per plant and production of okra was observed in treatments, particularly in T3 (38.49±0.99 g per plant and 513.26±9.28 g.m−2) than the control (24.32±1.08 g.plant−1 and 324.30±18.71 g.m−2). No significant difference (p>0.05) was observed in the proximate and mineral composition of okra leaves and pods except for higher phosphorus levels in the treatment groups. The growth, haematological, biochemical and antioxidant enzyme parameters of P. hypophthalmus exhibited no significant variation (p>0.05) between the control and treatments. Thus, the study manifested that the combined foliar application of 8.1 g.l−1 of phosphorus with 5 g.l−1 of potassium and 1 g.l−1 of iron could significantly improve okra production in aquaponics.