The effects of irrigation water salinity, potassium nitrate fertilization, proline spraying and leaching fraction on the growth and chemical composition of corn grown in calcareous soil

Two pot experiments were conducted to study the effect of irrigation with saline water in relation to KNO3 fertilization, proline spraying and leaching fraction on the growth and Na+, K+, Cl-, NO3 - and proline contents of corn (Zea mays L.) plant grown on a nonsaline calcareous soil. The treatments included irrigation waters of different salinity (0.54, 3.36, 5.88 or 7.95 dS/m), three rates of KNO3 (0, 4 and 8 g/pot) fertilizer and foliar application with three rates of proline (0, 100 and 200 mg/L). The first experiment was irrigated with the water to the field capacity with leaching fraction and the second without leaching fraction. The experimental design was a split split plot with three replications. Also, the effect of these parameters on salt accumulation in soil was discussed. The obtained results showed that the dry weight of shoots was decreased as salinity of irrigation water increased. The highest decreases were attained with waters of 5.88 and 7.95 dS/m as compared with dry weight due to irrigation with 0.54 or 3.36 dS/m water salinity. High salinity of water increased the shoot contents of Na+, Cl-, proline and decreased NO3 - contents with or without leaching fraction, but the values without leaching fraction were higher than those of without leaching fraction. Also, increasing the salinity of irrigation water decreased K content in shoot which was higher with leaching than without leaching. On the other hand, KNO3 fertilization or proline spraying decreased Na+, Cl- contents and increased K+ or NO3 - contents in plant shoot and their values without leaching were higher than with leaching. The EC values of soil were increased with both increasing salinity of irrigation water and KNO3 fertilization. The decreased plant growth due to water salinity was partially offset by KNO3 fertilization, proline spraying and leaching fraction application. Also, KNO3 fertilization was more effective than proline for reducing the adverse effect of water salinity