Effects of Persian walnut leaf extracts on seed germination, seedling growth, and some physiological characteristics of the basil (Ocimum basilicum L.) cultivar 'Genovese'

SummaryThis study was conducted to elucidate the allelopathic effects of a series of dilutions of Persian walnut (Juglans regia) leaf extracts [i.e., undiluted, 1:2 (v/v), 1:4 (v/v), or 1:8 (v/v) dilutions] and distilled water (control) on the characteristics of seed germination, seedling growth, and subsequent physiological changes in the basil (Ocimum basilicum L.) cultivar, ‘Genovese’. The results indicated that all aqueous leaf extracts of walnut had statistically significant inhibitory effects on the germination of basil seeds and on seedling growth characteristics. Seed germination percentages, the lengths and fresh weights (FWs) of the plumule and the radicle, the FWs and dry weights (DWs) of the shoots and roots, and leaf areas decreased significantly with increasing concentrations of aqueous walnut leaf extract. The DWs of the plumules and radicles were increased by the undiluted walnut leaf extract. Moreover, it was found that the yields of essential oils and total phenolics, and the anti-oxidan...