The Effectiveness of Safe NPK Alternatives on the Growth, Productivity, and Essential Oil Content of Fennel Plants under Semi-Arid Saline Soils

Abstract

Production of safe agri-food products is the main target of the agricultural industry particularly with the detection of the unsafe effects of chemical fertilization. Using alternatives to mineral NPK-fertilizers during fennel cultivation, as a medicinal plant, was investigated during the current study. The selected alternatives to NPK-fertilizers were included the foliar application of active yeast (5gL-1), compost tea (2mlL-1),humic acids(2mlL-1), seaweed extract (0.5 g L-1), and vitamin C or ascorbic acid (0.5 g L-1), comparing with the negative control (tap water) and positive control as NPK (19:19:19)at 1.5gL-1.Applied active yeast recorded increase in many studied parameters such as number of branches per plants, dry weight, seed yield per fed, crude protein and total carbohydrates in seeds by 88 and 156%; 137 and 133%; 115 and 129%; 111 and 46%; 16.2 and 11.3% in both seasons, respectively comparing with the negative control and other applied treatments. The main components in fennel oil were α-pinene, followed by sabinene, then β-pinene under such saline conditions. The results of this study can support the farmers to reduce the applied NPK-mineral fertilizers with supplying the cultivated fennel under such saline soil conditions. Further studies are needed and more evaluations are required to know the best biostimulants can be applied under such salinity stress.