Data Sheet 1_Evaluation of potent Trichoderma strains against anthracnose-twister disease and enhancement of crop health and bulb yield in kharif onion.xlsx

In India, the productivity of onions during the kharif season (June-October) is quite low compared to the Rabi season (December-April). The yield losses in kharif onion are primarily attributed to the increased incidence of anthracnose-twister disease, which is often exacerbated by concurrent monsoon rains and high relative humidity during the kharif. To address this issue, a field study was conducted over three consecutive years (2021–2023) to assess the performance of eleven different Trichoderma strains in managing anthracnose-twister disease and improving plant growth and bulb yield in kharif onion. The strains were initially selected based on their ability to inhibit the growth of the anthracnose pathogen Colletotrichum gloeosporioides (in vitro confrontation assay) and HCN production; amylase, and protease production. The selected strains were also screened in vitro for PGPA traits (IAA and siderophore production; ability to grow in N2 free media, PO42-, Zn, and K solubilization). The antagonistic activity of Trichoderma strains against C. gloeosporioides ranged from 18.8% to 70.0% with T. longibrachiatum (OGRDT2) recording the highest inhibition (70%). Application of GRDT2 and OGRDT2 reduced the PDI to 36.00 ± 0.98 and 37.06 ± 1.38, respectively, compared to 62.77 ± 0.14 in the untreated control. The T. longibrachiatum (OGRDT2) and T. harzianum (GRDT2) treated plots registered an increased plant height (54.97 ± 0.80 and 53.29 ± 0.79 cm) and pseudostem diameter (13.96 ± 0.18 and 13.76 ± 0.20mm) compared to the control (42.68 ± 1.90 and 10.55 ± 0.04 mm), respectively, under field conditions. Additionally, these treatments supported higher biomass, as reflected in the increased normalized dry weights of the shoot (10.82 ± 0.89% and 10.39 ± 1.76 %), root (12.27 ± 0.11 % and 11.86 ± 2.67 %), and bulb (12.90 ± 0.65 % and 12.21 ± 0.81 %). The chlorophyll contents were again higher (4.1 ± 1.44 and 4.1 ± 0.83 mg/ml) in OGRDT2 and GRDT2 treated plants than 3.3 ± 0.80 mg/ml in the untreated control. The GRDT2 and OGRDT2 treated plots supported higher bulb yield of 20.66 ± 1.42 t/ha and 19.21 ± 0.87 t/ha compared to control (16.52 ± 0.69 t/ha). Our study demonstrated that T. harzianum (GRDT2) and T. longibrachiatum (OGRDT2) effectively reduced anthracnose severity and therefore can be explored for management of Anthracnose-twister disease of onion.

在印度，与凉季（Rabi season，12月-次年4月）相比，雨季季（kharif season，6月-10月）的洋葱产量普遍偏低。雨季季洋葱的产量损失主要源于炭疽扭曲病（anthracnose-twister disease）发病率上升，而雨季同期的降雨以及高相对湿度往往会加剧该病害的发生。为解决这一问题，本研究于2021-2023年连续三年开展田间试验，评估11株不同木霉菌（Trichoderma）菌株对雨季季洋葱炭疽扭曲病的防治效果，以及对植株生长和鳞茎产量的改善作用。供试菌株最初通过以下指标筛选：抑制炭疽病病原菌胶孢炭疽菌（Colletotrichum gloeosporioides）生长的能力（体外对峙试验）、产氰化氢（HCN）能力、产淀粉酶和蛋白酶能力。此外，还通过体外试验对筛选出的菌株开展植物促生性状（PGPA traits）筛查，包括产吲哚-3-乙酸（IAA）和铁载体能力、在无氮培养基上的生长能力，以及溶磷（PO₄²⁻）、溶锌（Zn）和溶钾（K）能力。11株木霉菌菌株对胶孢炭疽菌的拮抗活性介于18.8%至70.0%之间，其中长枝木霉菌（T. longibrachiatum）OGRDT2的抑制率最高，达70%。施用GRDT2和OGRDT2菌株后，病害严重度指数（PDI）分别降至36.00±0.98和37.06±1.38，而未处理对照组的PDI为62.77±0.14。田间试验条件下，施用长枝木霉菌OGRDT2和哈茨木霉菌（T. harzianum）GRDT2的试验小区，植株株高分别达54.97±0.80 cm和53.29±0.79 cm，假茎直径分别为13.96±0.18 mm和13.76±0.20 mm，均显著高于对照组（株高42.68±1.90 cm，假茎直径10.55±0.04 mm）。此外，这两个处理组的植株生物量更高，具体表现为地上部、根部和鳞茎的标准化干重分别提升：地上部10.82±0.89%、10.39±1.76%，根部12.27±0.11%、11.86±2.67%，鳞茎12.90±0.65%、12.21±0.81%。OGRDT2和GRDT2处理组植株的叶绿素含量分别为4.1±1.44 mg/ml和4.1±0.83 mg/ml，同样高于未处理对照组的3.3±0.80 mg/ml。GRDT2和OGRDT2处理组的鳞茎产量分别为20.66±1.42 t/ha和19.21±0.87 t/ha，显著高于对照组的16.52±0.69 t/ha。本研究表明，哈茨木霉菌GRDT2与长枝木霉菌OGRDT2可有效降低洋葱炭疽扭曲病的发病程度，因此可用于开发洋葱炭疽扭曲病的防治方案。