Effect of proline, humic acid and potassium nitrate foliar sprays on photosynthetic pigments, ionic ratio and relative water content under salt stress in maize (Zea mays L.)

A green house experiment was conducted at Agricultural College, bapatla during kharif, 2017 to study the effect of supplementation of 25 per cent extra nitrogen through maize stover or its compost along with foliar spray of humic acid/proline/KNO₃ on properties of maize grown on saline soil. Plants grown in saline soil showed that nitrogen deficiency contributed to the dominance of non-essential ions in exchange complex and denitrification losses at higher soil salinity. Foliar sprays were given in the form of conc. humic acid 0.2%, Proline @50 mM L⁻¹, KNO₃ @ 10 g L⁻¹ at 20 and 40 days after sowing. Release of nutrients from organic supplements and osmoregulatory role of foliar sprays were analyzed at critical stages of knee high, tasseling and at harvest. Nutrient content of raw maize stover and its compost were analyzed and based on nutrient content they were added to the respective pots. The experiment was conducted in CRD with thirteen treatments and three replications. Results indicated that plants which received exogenous sprays resulted in higher chlorophyll a and b, K⁺/Na⁺, Ca²⁺/Mg²⁺ ratio and relative water content which resulted in better plant performance. Favorable effect of crop residue on decreasing EC of soil could be contributed to the improvement of the soil structure and porosity, thus increasing salt leaching and reducing surface evaporation which inhibits salt accumulation in the surface layers.