Exploring the Effects of Medicinal Plant Extracts on Tomato (Solanum lycopersicum L.) Morphology, Biochemistry, and Plant Growth Regulators under Greenhouse Conditions

The irresponsible use of chemical fertilizers and pesticides in agricultural production has caused significant environmental impacts and damages to human health. This study aimed to explore the effects of extracts from several Iranian medicinal plants on tomato growth under greenhouse conditions. A completely randomized design was used and the treatments included methanolic extracts of Taraxacum officinale L., Conocarpus erectus L., Allium jesdianum L., Rheum ribes L., Dorema aucheri L. and Juniperus sabina L. at three concentrations of 1000, 5000, and 8000 mg/L. The measured variables were stem length (SL), internode distance (ID), branch number (BN), auxin content (AC), cytokinin content (CC), auxin/cytokinin ratio, total protein, total phenol content (TPC), total flavonoid content (TFC), and anti-oxidant potential (FRAP). Under greenhouse conditions, foliar spraying with Dorema aucheri plant extract (8000 mg/L) significantly increased the stem length by 15% compared to the control. Rheum ribes extract (8000 mg/L) resulted in an increase (19%) in internode distance. However, the number of branches decreased by 34% in response to the plant extracts. Compared to the control, the amount of cytokinin decreased after spraying, whereas the auxin content showed a sinusoidal trend of change. In response to all treatments, the auxin/cytokinin ratio increased, with the highest value observed in plants treated with Allium jesdianum extract (5000 mg/L). According to the results, the plant extracts proved effective and assisted in tomato growth. Future research may aim to identify the effective biological compounds in these extracts.