Influence of foliar fertilisers on biochemical and physiological properties in Nepeta racemosa Lam.

Abstract

The purpose of this study was to evaluate some elements of physiology and biochemistry in Nepeta racemosa Lam. in the pedo-climatic conditions of the Moldavian forest steppe. The parameters were quantified under conditions of differentiated fertilisation with three foliar products (KSC 1, KSC 2, and Corona K). Biochemical analysis by GC/MS revealed the highest concentration of the following components: nepetallic acid (Untreat - 54.33%, KSC 1 - 55.50%, KSC 2 - 56.90%, Corona K - 53.77), eucalyptol (Untreat . 9.87%, KSC 1 - 10.70%, KSC 2- 12.80%, Corona K - 10.78%), 3-hydroxy- (4S, 4aS, 7S, 7aS)-dihydronepetalactone (Untreat - 5.87%, KSC 1 - 5.37%, KSC 2 - 4.87, Corona K - 3.67%), and (4aS, 7S, 7aS)-trans, cis-nepetalactone (Untreat - 4.30%, KSC 1 - 5.00%, KSC 2 - 4.20%, Corona K - 5.23%). Polyphenols were present in large quantities in the Corona K variant, with 33.1 mg GA/g dw at the first harvest and 27.88 mg GA/g dw at the second harvest. The highest concentration of flavonoids was identified in the Corona K variant (26.34 mg QE/g dw - first harvest and 56.77 mg QE/g dw - second harvest). The antioxidant activity was between 14.76 and 38.54% at the first harvest, and from 12.18 to 22.95% at the second harvest. Chlorophyll pigments ranged from 13.12- 17.68 μg/ml-1 for chlorophyll a, 5.43-9.66 μg/ml-1 for chlorophyll b, and 2.07-3.34 μg/ml-1 for carotenoids. The highest grass production per m2 was achieved in the version fertilised with KSC 1 for both crops, with 986.66 g/m2 for the first harvest and 861.33 g/m2 for the second. Iridoids are a class of substances that are commonly used for pesticide role. The study aims to highlight these substances and determine whether differentiated fertilization influences. The presented data confirm the results in the literature for polyphenols and flavonoids, but also present chemotypic novelties in terms of chemical composition and represent a direction to follow for future research.