MITIGATION OF EXCESSIVE SOLAR RADIATION AND WATER STRESS ON ‘KEITT’ MANGO Mangifera indica TREES THROUGH SHADING | MITIGATION OF EXCESSIVE SOLAR RADIATION AND WATER STRESS ON ‘KEITT’ MANGO Mangifera indica TREES THROUGH SHADING

anglais. Excessive solar radiation “global warming” and water scarcity are consider the main environmental constraints for plant growth and production under arid and semi-arid regions. The current research was aimed to study the effect of irrigation levels (100%, 85%, 70% of irrigation requirements), and shading levels (60%, 40%, 0%) on the growth and productivity of ‘Keitt’ mango trees. This experiment was conducted during two growing seasons (2016/2017 and 2017/2018) at El Behera Governorate, Egypt. Decreasing irrigation level (IR) decreased leaf area, malformed panicle, powdery mildew infection, final fruit set, fruit numbers, yield but it increased chlorophyll content, proline content, leaf water content. While, increasing shading levels (SH) increased leaves number, leaf area, fruit set, powdery mildew infection, malformed panicle but it decreased fruit sunburn damage, proline content, chlorophyll content and relative water content. Moreover, accumulative effects of 85% IR + 40% SH significantly increased leaf area, fruit set, fruit number, yield, chlorophyll content, WUE, proline content, relative water content, leaf water content while decreasing powdery mildew and sunburn damage. Results suggest that shading at 40% increased the yield up to 20% and decreased sunburn damage up to 0% under irrigation level of 70%. Shading may be a new technique to alleviate the adverse effects of water stress beside their role in avoiding excessive solar radiation on ‘Keitt’ mango trees.

polonais. Excessive solar radiation “global warming” and water scarcity are consider the main environmental constraints for plant growth and production under arid and semi-arid regions. The current research was aimed to study the effect of irrigation levels (100%, 85%, 70% of irrigation requirements), and shading levels (60%, 40%, 0%) on the growth and productivity of ‘Keitt’ mango trees. This experiment was conducted during two growing seasons (2016/2017 and 2017/2018) at El Behera Governorate, Egypt. Decreasing irrigation level (IR) decreased leaf area, malformed panicle, powdery mildew infection, final fruit set, fruit numbers, yield but it increased chlorophyll content, proline content, leaf water content. While, increasing shading levels (SH) increased leaves number, leaf area, fruit set, powdery mildew infection, malformed panicle but it decreased fruit sunburn damage, proline content, chlorophyll content and relative water content. Moreover, accumulative effects of 85% IR + 40% SH significantly increased leaf area, fruit set, fruit number, yield, chlorophyll content, WUE, proline content, relative water content, leaf water content while decreasing powdery mildew and sunburn damage. Results suggest that shading at 40% increased the yield up to 20% and decreased sunburn damage up to 0% under irrigation level of 70%. Shading may be a new technique to alleviate the adverse effects of water stress beside their role in avoiding excessive solar radiation on ‘Keitt’ mango trees.