Morphological characteristics of Fraxinus rotundifolia Mill, Morus alba and Acer negundo saplings under water stress in greenhouse and field in Robat Karim

2022. Morphological characteristics of Fraxinus rotundifolia Mill, Morus alba and Acer negundo saplings under water stress in greenhouse and field in Robat Karim. Environmental Sciences. 20(2): 117-134. leaf numbers, leaf size, seedlings height, collar diameter, dry leaf weight, and stem dry weight as well as two qualitative characteristics of seedlings, which are leaf freshness and seedling health, were measured. Results and discussion: The results showed that the number of MAD period times in the greenhouse for Fraxinus rotundifolia Mill species was 29, Acer negundo 28 and Morus alba 32 and in the field for Fraxinus rotundifolia Mill . species was 20, Acer negundo 20, and Morus alba 17 period times. Generally, in all three studied species, in May, as the first month of the research, the seedlings were in very good condition. In other months, after being under different water stress (two, four and six days), the number of leaves and leaf size always decreased over time. In the case of ash leaved maple, the number of leaves in the greenhouse area in August was zero (absolute defoliation). Conclusion: Generally, by increasing water stress, leaf number, leaf size, dry leaf weight, dry stem weight, leaf freshness, and health of the saplings were reduced. It seems that six days after reaching MAD point is the suitable time to irrigate the saplings according to their morphological characteristics. Considering the appearance of seedlings during irrigation, it helps to use water efficiently, prevent over-irrigation and under-irrigation of seedlings and save the relevant costs.