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

摘要

Two pot experiments were conducted to study the effect of salinity of irrigation water in combination KNO₃ fertilization, proline foliar spraying and leaching fraction on the growth and Na+, K+, Cl-, NO₃- and proline contents of corn (Zea mays L.) plant grown in a nonsaline calcareous soil. The treatments included irrigation waters of different salinity (0.54, 3.36, 5.88 or 7.95 dS/m), three levels of KNO₃ fertilizer (0, 4 and 8 g/pot) and foliar application with three levels 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 replicates. 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. However the values without leaching fraction were higher than those of with 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+ and Cl- contents and increased K+ and 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 with increasing 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 salinity of irrigation water.