Effect of foliar application of different zinc sources on yield and phytochemical characteristics of basil (Ocimum basilicum L.)

Zinc is an essential micronutrient element and has a number of vital roles in plants. In the recent years, zinc nano-fertilizers have received considerable attention due to their increased uptake by plants as they are small in size and have high rate of penetration through plant cell membrane. To study the effect of foliar application of different zinc fertilizers on yield and phytochemical characteristics of basil (Ocimum basilicum L.), a pot experiment was conducted using a factorial based on a randomized complete block design with four replications during 2014 at the experimental greenhouse of the Horticultural Sciences Department of Urmia University. The treatments were three different zinc sources (zinc sulphate, zinc chelate and nano-zinc chelate) in four concentrations (0, 1, 2 and 3g/l). The results showed that foliar application of zinc had significant effect on evaluated parameters. Fresh and dry herb yield, zinc and phenol content of leaves, essential oil content, and yield increased with zinc application and in this regard, foliar application of nano-zinc chelate was more effective than two other zinc fertilizers. The lowest and the highest evaluated parameters were observed at concentrations of 0 and 3g/l, respectively. The results of essential oil analysis by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) showed that 20 components were identified in the basil essential oil. Linalool and eugenol were the main components of essential oil and they showed little variation under zinc application. Overall, the findings of this study showed that the effect of nano-zinc chelate application (especially at a concentration of 3g/l) was more effective than zinc sulphate and zinc chelate in increasing herb yield and active substances of basil.