Allelopathic Effect of Cryptomeria japonica (L.f.) D. Don on Seed Germination of Zea mays L.

The allelopathic effects of Cryptomeria japonica (L.f.) D. Don leaf and bark extracts on the germination and early growth of Zea mays L. (maize) were investigated. Aqueous extracts of C. japonica (L.f.) D. Don leaf and bark were prepared at concentrations of 0% (control), 15%, 25%, 50%, and 75%. Maize seeds were treated with the extracts and incubated for 14 days. Germination percentage, root and shoot lengths, and biochemical parameters (protein, carbohydrate, phenol, and amino acid contents) were measured. Both leaf and bark extracts exhibited significant dose-dependent inhibitory effects on seed germination, growth, and defense biochemical composition of maize seedlings. Germination percentage and root and shoot lengths decreased progressively with increasing extract concentrations. The bark extract showed a stronger inhibitory effect on root growth, while the leaf extract more severely affected shoot length. Protein, carbohydrate, and amino acid contents declined with increasing concentrations, indicating disrupted metabolic activities. In contrast, phenol content increased, suggesting a stress-induced response. The bark extract caused more pronounced reductions in protein and carbohydrate contents and higher accumulation of phenols compared to the leaf extract. These findings demonstrate the strong allelopathic potential of C. japonica (L.f.) D. Don, and due to the presence of allelochemicals, it influences the early growth and development of maize seedlings, with implications for agroforestry practices and weed management strategies.