Effects of different nitrogen fertilizer levels on yield, leave color, and content of bioactive compounds of Pouzolzia zeylanica L. Benn

Abstract

The study was carried out to investigate the effect of 4 levels of nitrogen fertilizer (10, 15, 20 and 25 kg urea/1000 m2) applied on the color of leaves (chlorophyll index SPAD and the red-purple color by a* value in Hunter’ color system), yield and bioactive compounds content (anthocyanin, flavonoid, polyphenol and tannin) of Pouzolzia zeylanica plant. The results showed that different nitrogen fertilizer levels had significant effects (P ≤ 0.05) on leave color, yield and content of bioactive compounds of this plant. At the level of 20 kg urea/1000 m2, the leaves had red-purple color and the obtained a* value was 8.06; the index of chlorophyll SPAD was 38.36; the yield was 1.64 ton/1000 m2, and the content of bioactive compounds was higher than other nitrogen fertilizer levels. The contents of anthocyanin, flavonoid, polyphenol and tannin were 0.296 mg CE/g dried material (DM), 5.03 mg QE/g DM, 15.54 mg GAE/g DM and 10.05 mg TAE/g DM, respectively.