The production of high quality seedlings is crucial for successful afforestation efforts, particularly in arid and semi-arid regions where drought stress is a major ecological challenge. Light and water stress are interrelated and have a major impact on seedling growth and development. The combined effects of light (25, 50, 75 and 100% of full sunlight) and water stress (field capacity of 100, 75 and 50%) on the morphophysiological characteristics of Cercis siliquatrum seedlings were investigated in a controlled nursery experiment. Additionally, the effect of zeolite on seedling quality was evaluated. The amount of proline greatly increased with water stress, whereas light had no effect. The highest values of morphological traits were obtained in conditions without water stress and light intensity of 50% and above whereas water deficit had the most negative effect on seedling quality in low light (L25). The use of zeolite reduced the negative effects of drought stress on seedlings and increased the seedling quality index by 15%. Additionally, zeolite increased the number of leaves (+13.5%), leaf dry matter (+7.9%), leaf area (12.1%), stem diameter (13.4%), stem length (+12.6%) and stem dry matter (+%), root length (+21.7%) and root dry matter (+12.3%). The results support the interplay hypothesis, which predicts stronger drought effects under both full light and heavy shade conditions compared to moderate shade. Our results also suggest that Cercis siliquastrum is a heliophyte species that thrives in moderate to high light conditions. We also recommended the application of Zeolite amendment to reduce the negative effects of drought stress and promote seedling growth and quality.
