Efficacy of jerangau merah (Boesenbergia stenophylla R.M. Smith) crude root extracts for suppressing Collectotrichum gloeosporiodes Penz. associated disease of chili (Capsicum annum L.)

2024-07-15T22:08:44+0530

Environmental pollution issues have prompted the exploration of biological control as a promising alternative for managing diseases in chili plants. However, the use of plant extracts and microbial inoculants to promote growth and control diseases in chili, particularly in Malaysia, especially Sarawak, is limited. The primary objective of this study was to assess the potential of Trichoderma and Boesenbergia stenophylla R.M Smith in suppressing Colletotrichum gloeosporioides Penz., a pathogen associated with chili (Capsicum annum L.) diseases. The efficacy of B. stenophylla in inhibiting C. gloeosporioides showed a maximum PIRG (Percent Inhibition Relative to Control Growth) value of 86.26% on day 8. The formulation of B. stenophylla (jerangau merah) demonstrated potential in suppressing chili anthracnose disease both in vitro and under field conditions. Two Trichoderma spp. isolated from the soil of rehabilitated forest floors were evaluated for their in vitro antagonism against C. gloeosporioides. T. harzianum gradually inhibited the growth of C. gloeosporioides starting from day 2, completely overtaking it by day 8 with a PIRG of 87.40%. T. harzianum inoculants proved effective in controlling the pathogen in vitro and enhancing the growth of chili seedlings, in addition to inhibiting C. gloeosporioides. Meanwhile, T. longibrachiatum also gradually inhibited the growth of C. gloeosporioides, achieving a PIRG of 56.02% by day 8. The presence of Trichoderma in the rhizosphere and on the roots generally improved the root growth of chili seedlings compared to controls inoculated with sterile distilled water (SDW) and those treated with B. stenophylla extracts. Chili seedlings responded better to T. harzianum inoculants than to T. longibrachiatum inoculants and B. stenophylla extracts. By week 8, seedlings inoculated with T. harzianum showed the highest root growth with 26.87 cm in root length and 9.48 g in root fresh mass. Disease assessment studies indicated that T. harzianum exhibited the greatest potential as a biocontrol agent (BCA), reducing disease incidence and severity by 53% and 51%, respectively. Similarly, application of B. stenophylla powder slowed down infection progression and improved chili plant growth, with disease incidence and severity values of 72% and 60%, respectively. Overall, the study demonstrated the efficacy of B. stenophylla in protecting and enhancing the growth of chili plants, potentially replacing harmful chemicals. Both B. stenophylla and T. harzianum inoculants showed effectiveness against C. gloeosporioides, suggesting their potential development as biocontrol agents. Assessment of plant-microbe interactions indicated that T. harzianum mediated induced resistance by producing inducible compounds such as peroxidase (PO). Single inoculation with T. harzianum was most effective, followed by a mixture of T. harzianum + B. stenophylla, delaying symptom onset and reducing disease incidence and severity. In conclusion, the findings suggest that Trichoderma inoculants and B. stenophylla extract powder are effective against C. gloeosporioides while promoting plant growth. Further research into formulation, application frequency, and techniques is essential to maximize their potential as BCAs against Colletotrichum diseases in chili plants.

Biochar soil application induces stress tolerance in Arachis hypogaea L. Varieties inoculated with stem rot fungus (Athelia rolfsii (Sacc.) C.C. Tu & Kim.)

2024-09-01T19:06:11+0530

This study aims to investigate the extent to which soil amendment with biochar can promote growth and induce biotic stress tolerance in Arachis hypogaea accessions (TAH-183, TAH-142, TAH-164, TAH-124 and TAH-134) inoculated with stem rot fungus (Athelia rolfsii). The experiment was set up in a complete block design. 5 seeds of A. hypogaea accessions were planted in 10 kg of sterilized soil in triplicates (control(C), A. rolfsii alone (T) and A. rolfsii+Biochar (A+T). Characterized pathogen A. rolfsii causing vine rot and wilt disease was obtained from Botany pathology laboratory and spawned with 300 g of millet seeds. 5 g of A. rolfsii colonized seeds were used to infect A. hypogaea accessions seedlings. Growth parameters and disease severity index (DSI) were taken using standard methods, while the total photosynthetic pigments (TPP) were determined using the atLeaf chlorophyll meter. All A. hypogaea accessions showed 100% germination across all treatments after 11 days except TAH-183 (80%) and TAH-134 (60%). TAH-142 and TAH-183 accessions inoculated with A. rolfsii were the most susceptible with disease severity index of 50% and 33.30% respectively. However, biochar application treatments recorded 0% DSI for all accessions. At 6 weeks after planting (WAP), it was observed that inoculation of A. hypogaea accessions with A. rolfsii significantly (p<0.001) reduced the growth parameters such as shoot length for TAH-142 and TAH-124 which recorded the lowest values; T=3.40±181 cm, C=15.50±1.45 cm, A+T=20.00±1.70 cm; and T=8.33±2.33 cm, C=15.20±1.20 cm, A+B=21.12±1.90 cm while TAH-183 and TAH-164 had the highest shoot growth (T=19.33±1.36 cm, C=20.00±1.54 cm, A+T=24.77±1.67 cm; T=16.83±1.76 cm, 17.00±1.13 cm, A+T=28.30±2.00 cm) when compared to their controls and biochar treatments. TAH-142 (T=30.00 mg/kg, C=37.90 mg/kg, A+B=40.00 mg/kg) recorded the least TPP contents, while TGM-183 (T=36.00 mg/kg, C=40.10 mg/kg, A+T=44.50 mg/kg) recorded the highest TPP. For postharvest parameters; TAH-142 (5.77±0.09 g) had the lowest fresh biomass yield while TAH-164 (58.70±1.56 g) had a better tolerance to A. rolfsii infection. However, TAH-183 showed greater fresh biomass yield when biochar was applied (89.67±4.53 g) while TAH-142 recorded the lowest (78.90±2.21 g). Amelioration of soil with biochar significantly (p=0.001) stimulated growth above the treatment and control. Similar trend was observed for leaf area, petiole length, leaf number, stem girth and internode length. This study has shown that A. rolfsii infection had a negative effect on the growth and biomass yield of A. hypogaea and soil amended with biochar conferred disease tolerance in all A. hypogaea accessions thus eliminating the need for the use of fungicides and additional fertilizer application.

Journal of Plant Stress Physiology

Efficacy of jerangau merah (Boesenbergia stenophylla R.M. Smith) crude root extracts for suppressing Collectotrichum gloeosporiodes Penz. associated disease of chili (Capsicum annum L.)

Biochar soil application induces stress tolerance in Arachis hypogaea L. Varieties inoculated with stem rot fungus (Athelia rolfsii (Sacc.) C.C. Tu & Kim.)