Integrated Application of Proline or Potassium in Alleviating the Adverse Effects of Irrigation Interval on Wheat Plants

Drought stress is one of the most harmful factors of plant growth and productivity.  Two pot experiments were carried out at greenhouse of agriculture botany department, faculty of agriculture, zagazig university, Sharkya Governorate, Egypt, during two successive winter seasons (2014/2015 and 2015/2016), to study the role of proline or potassium in mitigation the harmful impact of drought stress conditions on wheat plants c.v Misr 2 grown in Egypt. Growth parameters, yield and biochemical constituents were evaluated.Results show that all plant growth characters studied (shoot dry weight, leaf area and plant height) as well as yield and its components (dry weight of grains /plant, number of spikes/plant, number of grains/plant, number of grains/ spike, and1000-grains weight) were decreased with increasing irrigation intervals (irrigation every 10, 20 and 30 days) during the two successive growing seasons.The most effective treatment was Irrigation every 30 days in decreasing yield and its components. Integrated application of proline or potassium at rate of 0.1 and 0.2 % alleviated these negative effects by enhancing the growth and productivity. However, these increases were less than the control treatment. Moreover, it was found that drought stress decreased RWC, ELWR, RWL, photosynthetic pigments contents, whilst increasing, total phenol, proline as well as peroxidase and catalase activities in the leaves of wheat plants during the two growing seasons. However, application of proline or potassium increased all these parameters and decreasing total phenols. Treatment of proline at rate of 0.2 % was the most effective in this respect.  It is recommended that application of proline or potassium can fully or partially counteract the adverse effect of drought stress on growth, and productivity of wheat plants through their effects on biochemical constituents