Effect of Salinity on the Growth and Biochemical Profile of <i>Hedypnois cretica</i> and <i>Plantago coronopus</i> Plants in Relation to the Cropping System and Growth Environment

Abstract

The aim of the present work is to study the impact of salinity (i.e., 2 dS/m without addition of NaCl (control); 5 dS/m (EC-5); and 10 dS/m (EC-10) with the addition of 30 and 80 mM NaCl, respectively) on yield, organoleptic quality and the content of antioxidant compounds in Plantago coronopus and Hedypnois cretica plants in relation to different cropping systems and environmental conditions during growth (i.e., pots or floating hydroponics systems in the greenhouse and pots in the field (GPs, GH and FPs, respectively)). Almost all the growth parameters of the H. cretica plants in the greenhouse were impaired by both moderate (EC-5) and high (EC-10) salinity levels, especially in the floating hydroponics system, where, compared to EC-2, a reduction was observed of 33% in EC-5 and 76% in EC-10 in leaf area and of 24% and 75%, respectively, in fresh weight. On the contrary, the growth of the P. coronopus plants was negatively affected by salinity only in the GP system. However, salinity had no effect on most growth characteristics of both species grown in the field, suggesting a strong environmental effect on the impact of salinity in the tested species. On the other hand, the content of pigments, proline and total phenolics in the P. coronopus leaves, as well as their antioxidant capacity, were not affected by salinity in most cases, whereas in H. cretica the salinity effect was significant even at moderate levels (EC-5) in relation to the cropping system and growth environment. Moreover, both salinity levels reduced the nitrate content of P. coronopus plants in all cases (up to 61% in GP plants at EC-10) and of H. cretica GH plants (up to 67% in EC-10). Finally, regardless of the salinity level, the field-grown plants of both species showed a considerably higher content of total phenolics (by 59% in H. cretica and 58% in P. coronopus) and antioxidant activity (by 63% in H. cretica and 53% in P. coronopus, FRAP values), compared to the greenhouse ones. In conclusion, our results indicate that the tested combinations of cropping systems and growth environments could be used as an eco-friendly and sustainable agronomic tool to mitigate the negative effects of salinity and to regulate the organoleptic and biochemical properties of the tested species, allowing small-scale farmers in the affected areas to cope with the ongoing climate change and the environmental pressures they currently face through the exploitation of alternative/underexploited species of high added value.

Keywords

• wild edible species
• sustainable farming systems
• salinity stress
• scaly hawkbit
• buck’s-horn plantain
• antioxidant activity