Mineral composition of 'Selva' strawberry as affected by time of application of nitric oxide under saline conditions

The objective of present study was to evaluate the impact of time of application of nitric oxide (NO) on mineral composition of strawberry 'Selva' plants under saline conditions. Well-rooted daughter plants were planted in 3L plastic pots filled with 1:1 (v/v) ratio of peat moss and perlite and grown under the greenhouse conditions (21 +/- 2/17 +/- 2A degrees C and RH = 60 +/- 5% under natural sunlight). After full establishment of plants they were divided into 10 groups: control, plants sprayed with distilled water and exposed to 40 mM NaCl salinity stress, plants sprayed with 50 or 75 mu M NO solutions under non-stress conditions, and plants sprayed with 50 or 75 mu M NO solutions at three different application times, one week before, at the beginning, and one week after initiation of 40 mM NaCl salt stress. Results indicated that concentrations of macro-nutrients, Fe and Zn in shoots and roots were decreased due to salinity stress. The NO application, regardless of time of application and level, mitigated the deleterious effect of salinity on minerals uptake. Time aspect of NO application was important as plants received 75 mu M NO solution, one week before initiation of salt stress had higher shoot N, K, and Ca concentration, productivity and leaf relative water content as compared with those received NO solution at the same concentration, one week after exposure to salt stress. Higher K/Na ratio of shoot was also observed in plants treated with 75 mu M NO solution one week before start of salinity compared with salt-stressed, non-NO-treated plants. It seemed that time of NO application could change the strategy of plant against stress.