Interactive effects of salinity and drought stresses on the growth parameters and nitrogen content of three hedge shrubs

Abstract

The effect of salinity and drought stresses on three hedge shrubs was studied in a factorial experiment based on a Randomized Complete Block Design with three replications. The studied treatments included salinity at four levels (tap water, 100 mM NaCl, 150 mM NaCl, and Sea water), irrigation at three levels (irrigation intervals of 3, 7 and 10 days), and three hedge shrubs (Buxus hyrcana, Euonymus japonicus var. microphylla and Euonymus japonicus var. aureo-marginatum). It was found that the increase in salinity and drought negatively affected the studied traits so that the maximum Na concentration (719.9 mg kg−1) was obtained for irrigation with Sea water at the intervals of 10 and 7 days. All three shrubs irrigated with Sea water had higher Na concentration than other treatments. The lowest N content (0.393%) was obtained from the treatment of E. japonicus var. microphylla × tap water × 10-day irrigation interval and highest one (0.873%) was obtained from B. hyrcana × 100 mM NaCl × 7-day irrigation interval. The highest plant and root fresh weight (37.86 g) were related to E. japonicus var. microphylla irrigated with tap water. The highest plant dry weight of 18.77 g was related to E. japonicus var. microphylla × tap water and the lowest one (11.47 g) was related to E. japonicus var. microphylla × caspian Sea water. The highest and lowest number of axillary branches was related to irrigation with tap water and Sea water (7.29 and 0.59), respectively.