Evaluation of microbial consortia for the management of corm rot of saffron

Abstract

newline In order to develop the microbial consortiafrom biocontrol agents for the management of corm rot of saffron.Compatibility between various biocontrol agents viz. Pseudomonas fluorescens, Bacillus subtilis, Trichoderma asperellum/ Trichoderma harzianumwere assessed.The combination of Pseudomonas fluorescens, Bacillus subtilis and Trichoderma asperellum exhibited maximum growth on PDA (37.67±0.02 mm), NA (35.83±0.05 mm) and PDA:NA (20.27±0.10 mm) respectively, after 7 days of inoculation. Under field conditions, microbial formulation T12 (soil drenching and corm treatment with liquid formulation of microbial consortia at 1:1:2:1) exhibited minimum incidence of32.36±1.36 per cent (2022-23) and 35.11±2.57 (2023-24). Similarly, T12 exhibited minimum severities of 24.30±0.43 per cent in 2023 and 26.48±0.27per cent in 2024. Treatment T12also lowered the population ofFusarium oxysporum 4.88±0.18× 10and#8308;, 3.56±0.10 × 10and#8308;, 2.55±0.29 × 10and#8308; and 1.45±0.15 × 10and#8308; cfu/g at 30, 60, 90 and 120 DAS, respectively. Microbial consortia not only suppressed diseases but also promoted plant growth. During 2022-23, T12 (soil drenching and corm treatment with microbial consortia at 1:1:2:1) recorded the maximum of 35.67 corm sprouts, 6.00 flowers per corm, 16.66 leaves, a leaf length of 39.43 cm and a stigma length of 46.80 mm, with a yield of 2.18 kg ha-1. In 2023-24, T12 showed the maximum of 32.45 sprouts, 5.47 flowers, 36.67 leaves, a leaf length of 13.32 cm, and a stigma length of 44.61 mm, with a yield of 1.96 kg ha-1. It also produced the maximum number of daughter corms (6.48), weight (2.24 g) and diameter (3.02 cm).During 2022-23, biochemical analysis using HPLC of treatments T12, T9, and T11 revealed significant variations in safranal, picrocrocin, and crocin concentrations. T12 (soil drenching and corm treatment with microbial consortia at 1:1:2:1) exhibited the maximum concentrations of safranal (5.17 mg/g) and crocin (9.86 mg/g). T9 (soil drenching and corm treatment with microbial consortia at 1:1:1:2) recorded the maxi