Potassium fertilization for improving water relations, photosynthetic pigments and antioxidant defence system in intercropping system of Gossypium hirsutum L. and Cajanus cajan (L.) Millsp. under different irrigation regimes

Abstract

The present study evaluated the impact of potassium chloride (KCl) on growth, physiology, photosynthetic pigments and antioxidant enzymes under intercropping system of Gossypium hirsutum L. (RCH-773 variety) and Cajanus cajan (L.) Millsp. (Manak variety). The intercropping was operated in randomised complete block design under different irrigation schedules. The treatments were given as control (full irrigation), early water stress (no irrigation at vegetative stage), late water stress (no irrigation at flowering stage) and stress (no irrigation) along with three potassium concentrations K0, K1 and K2 (0, 20, 60 kg/acre respectively).The sampling was done at flowering stage (120 days after sowing). A long progressive water stress significantly reduced plant height, fresh and dry weight, leaf area, leaf area index, relative water content, membrane stability index and photosynthetic pigments. But application of potassium fertilizer enhanced all these parameters at a great value. The other parameters i.e. electrolyte leakage, superoxide dismutase and catalase increased in stress conditions. However, under potassium application, electrolyte leakage showed a remarkable decrease while the activity of superoxide dismutase and catalase was increased in control as well as in water stressed plants. It clearly shows that potassium is a strong osmo-regulator, maintains cation-anion balance, acts as co-factor for enzymes and helps plant withstanding drought stress conditions.