Effect of NPK fertilizer rates on secondary metabolites of pepino melon (Solanum muricatum Aiton)

Abstract

Secondary metabolites are bioactive compounds which are synthesized naturally in all plant parts. The quality and quantity of secondary metabolites produced by plants differ depending on the plant and environmental conditions under which they are produced. The purpose of the study was to investigate the effects of nitrogen, phosphorous and potassium (NPK) fertilizer (17:17:17) rates (0, 100, 200, 300 and 400 kg ha-1) on the production of secondary metabolites in field and greenhouse grown pepino melons (Solanum muricatum Aiton). The experimental design was randomized complete block design with five NPK fertilizer treatments replicated three times. Results indicated that an increase in NPK fertilizer rate led to an increase of carotenoids (lutein, lycopene and β-carotene) up to a maximum at 200 kg NPK ha-1 after which the contents decreased in both growing environments and trials. The control (no fertilizer application) favored the accumulation of total phenolic content (TPC) in both growing environments and trials. Greenhouse grown pepino melon fruits which were not supplied with fertilizer (control) had a TPC content of 174.3 and 145.5 mg GAE 100g-1 fresh weight (FW) in trial one and two, respectively. Fertilizers could not enhance production of TPC in pepino melon fruits and application of 200 kg NPK ha-1 is recommended for maximum accumulation of carotenoids (lycopene, lutein and βcarotene).

Effect of combined NPK fertilizer on polyphenol contents and antioxidant activity in methanol extract of Curcuma xanthorhiza

“…The combination of three NPK increased the polyphenol content and affected the antioxidant potential of C. xanthorrhiza (except for DPPH and FRAP analysis). However, Our findings tend to be different to other experimental results [30] reported that the phenolic content in the control (untreated) treatment of Pepino melon was remarkably higher than in the NPK treatment.…”

“…First, although the research results of Radušienė et al [38] stated a decrease in the levels of phenolic compounds due to nitrogen treatment, on the other side, there was a significant increase in naphtodianthrones and emodin, both of which are derivatives of anthraquinone. It is in line with Carol et al [30] which stated a decrease in the amount of TPC Pepino melon due to NPK treatment, but a drastic increase in lutein, lycopene, and β-carotene. Furthermore, the research of Narvekar and Tharayil [46] stated that the nitrogen supply increased the quantity of proanthocyanidins in strawberries, one of the phenolic oligomers.…”

“…Ahmed et al [28] reported an increase in the content of flavonoids and carbohydrates due to the modification of the dose of fertilization of Daucus carota L. Sun et al [29] found an increase in polyacetylene and volatile sesquiterpene oils of the Atractylodes chinensis as a result of the application of phosphorus in high doses. Gradually increasing the dose of NPK fertilization can improve the content of carotenoid metabolites in Solanum muricatum [30]. The former findings provide an insight that optimization of the production of plant endogenous secondary metabolites can be achieved through modifying the fertilization techniques.…”