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Morphological and Physiological Changes of Kale (Brassica oleracea Acephala Group) Seedlings as Affected by Ion and Salt Stress

The aim of this study was to determine the effect of salt stress on morphological and physiological changes of kale seedlings. Seedlings of kale cultivar ‘Red Russian’ (RR)and Croatian kale population Konavle2 (K2) were grown in a passive hydroponic system in a greenhouse in Tifton, Georgia, USA. Seedlings were treated with seven different nutrient solutions (NS). The control NS (EC 2 dS m-1) was concentrated to achieve 4, 6 or 8 dS m-1. Three additional salt treatments included addition of NaCl solution to the control NS to achieve EC 4 (2+2 NaCl), EC 6 (2+4 NaCl) or EC 8 (2+6 NaCl) dS m-1. Seedlings treated with 2 dS m-1 had the greatest (187 cm2) leaf area (LA) ; seedlings treated with 8 dS m-1 and 2+6 NaCl dS m-1 had the smallest LA and specific LA. RR had greater LA (131 cm2) than population K2 (84 cm2). Seedlings treated with 2+4 NaCl and 2+6 NaCl dS m-1 had lowest leaf relative water content (less than 59%). Increased percentage of shoot (14.1%) and root (10.4%) dry weight (DW) was recorded in seedlings treated with EC 8 dS m-1. Population K2 had highest shoot (10.9%) and root (10.4%) DW compared with RR. The lowest number of stomata and epidermal cells was observed in seedlings treated with EC 2+2 NaCl. RR had reduced number of stomata and epidermal cells. Leaf gas exchange variables substantially decreased with increasing EC, regardless of the source of salinity. In conclusion, concentration of nutrient solution affected vegetative growth and physiology of kale seedlings.

dry weight, leaf area, leaf gas exchange, nutrient solution, relative water content

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