Evaluation of trichoderma isolates as potential biological control agent against soybean charcoal rot disease caused by Macrophomina phaseolina

Macrophomina phaseolina (Tassi) Goid remains the prevailing causal agent of charcoal rot disease that significantly suppresses the yield of a variety of oilseed crops. Its wide host range and ability to survive under arid conditions, coupled with the ineffective use of fungicides against it, have spurred scientific endeavours for alternative avenues to control this phytopathogen. Hence, the present study aimed to provide empirical evidence of the efficacy of three fungal isolates (T2, T10 and T12) of Trichoderma harzianum as biological control agents against charcoal rot in soybean (Glycine max L.). The results of the in vitro studies revealed that all three fungal isolates significantly inhibited the growth of M. phaseolina phytopathogen, with T12 showing considerably higher inhibition effect than T2 and T10 isolates. T12 inhibited the growth of M. phaseolina in the dual culture (72.31%) and volatile production (63.36%) assays, and the hyperparasitism test indicated cell lysis following the interactions with T12 mycelia. T12 isolate was mostly effective in field experiments, observable in the attained minimum plant disease indices both in the soil incorporation (11.98%) and seed inoculation (5.55%) treatments, in comparison to isolates T2 and T10. Moreover, the stem and root lengths, as well as the seed weight, were considerably increased, as compared to the control. Hence, the findings reported in the present study supported the applicability of T12 isolate as possible alternative to fungicides for the control of charcoal rot in soybean

Exogenously applied glycine betaine regulates some chemical characteristics and antioxidative defence systems in lettuce under salt stress

We investigated the effects of exogenous glycine betaine (GB) applications on antioxidant enzyme activity, dry matter, and the contents of organic acids, amino acids, total antioxidants, and total phenolics in lettuce, Lactuca sativa, under salt stress. The treatments included four concentrations of GB (0, 5, 10, and 25 mM) and two levels of salinity (0 and 100 mM of NaCl). The 25 mM GB treatment increased dry matter and the content of total phenolics in lettuce plants compared to the non-GB-treated plants under salt stress. Salinity (100 mM NaCl without GB) significantly reduced dry matter, total phenolic content, and total antioxidant content in the plants. However, the lettuce plants grown under salt stress generally had higher amino acid and organic acid contents than those grown under non-salinity conditions. GB treatments had different effect on amino acid and organic acid contents under salinity conditions. Superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities were elevated under the 100 mM NaCl and 0 mM GB treatments, whereas higher concentrations of GB decreased them under salt stress. The 25 mM GB treatment mitigated the negative effect of salt stress and increased the dry matter by 44% compared to the plants that were treated with 100 mM NaCl and 0 mM GB. The results suggested that exogenous GB treatments could ameliorate the tolerance of lettuce to salt stress by increasing the total antioxidants and total phenolics, and regulating antioxidant enzyme activity, and altering the contents of organic acids and amino acids