The effects of two organic fertilizers on morpho-physiological traits of Marigold (Calendula officinalis L.)

Abstract

This experiment was carried out under greenhouse conditions to investigate the effects of vermicompost (VER) and humic acid (HA) on some traits of Marigold (Calendula officinalis), Mandarin cultivar. Treatments included VER (0, 10, 20, and 30%) and foliar application of HA (0, 200, 400, and 600 mg/l) at four levels. Chlorophyll content, relative water content, ion leakage in leaves and flowers, carotenoid, flavonoid, and protein content in flowers, number of flowers, and flower yield were measured. According to the results, higher levels of VER increased ion leakage while decreasing the relative water content of the leaves. Chlorophyll b, total chlorophyll, and leaf ion leakage were not affected by VER. The results revealed that the VER treatment had significant effects on petal flavonoids, carotenoids, petal electrolyte leakage (PEL), chlorophyll a, and relative water content. The use of HA did not affect the flower protein and reduced relative water content. All physiological traits, including petal carotenoid, chlorophyll a, total chlorophyll, ion leakage of leaves and flowers, and relative water content were significant under the influence of HA treatment at the probability level of 1%, while petal flavonoids and chlorophyll b were significant at the probability level of 5%. Investigate the interaction effect revealed the 10% VER + 600 mg/l HA allocated the highest amount of several flowers per plant, whereas this amount in flower protein with a mean of 661.1 mg fresh weight (FW), observed in 10% VER + 400 mg/l HA. In general, the use of HA at a concentration of 600 mg/l and 10% VER is recommended.