KNO3, Nano-Zn, and Fe Foliar Application Influence the Growth and Physiological Responses of Aloe vera under Salinity

Aloe vera L. is a perennial drought-tolerant plant that is commonly used in the pharmaceutical, food, and cosmetic industries. To evaluate the effects of the foliar application of KNO3, nano-Zn, and Fe (0 and 2 mgL(-1)) on Aloe vera plants under NaCl salinity stress (0, 50, 100 mM), a factorial experiment was conducted based on a completely randomized design. The results revealed that foliar applications influenced the root dry weight. The chlorophyll b content was affected by the salinity plus the foliar application. The total soluble solids content, chlorophyll a, phenolics, and flavonoids of the leaves, the gel content, catalase and superoxide dismutase activity, malondialdehyde, proline, and mineral nutrients content were impacted by the treatments as well. The highest values for the gel content (0.37 g per leaf) and plant dry weight (13.1 g per pot) were recorded at 0 mM NaCl + KNO3 + nano-Fe. The top K/Na ratio (35.2), and the largest K (69 g kg(-1)), P (6.6 g kg(-1)), Ca (31 g kg(-1)), and Mg (2.5 g kg(-1)) contents were recorded after the 0 mM NaCl + KNO3 treatment. The highest Fe content (383 g kg(-1)) was observed with 0 mM NaCl + nano-Fe treatment, and the maximum Zn content (37.6 mg kg(-1)) was measured after the 0 mM NaCl + nano Zn treatment. One hundred mM NaCl increased the malondialdehyde and Na contents. The largest amount of catalase activity was measured after the 50 mM NaCl + KNO3 + nano-Zn treatment. Salinity stress had adverse effects on the growth and physiological responses of Aloe vera. However, the foliar application of KNO3, nano-Zn and Fe mitigated the damaging effects of salinity. The results from more detailed studies would be advisable for pioneer farmers and the agricultural sector.