DefinePK

Research Objective

To evaluate twenty-five varieties/advanced lines of chilli against Fusarium wilt caused by Fusarium oxysporum f.sp. capsici (Foc.) under natural field conditions for two consecutive years (2017-18 and 2018-19) to find sources of resistance.

Methodology

Twenty-five chilli varieties/advanced lines were evaluated under Randomized Complete Block Design (RCBD) over two years (2017-18 and 2018-19). The pathogen (Foc) was isolated from symptomatic plants, purified on PDA medium, and identified based on colony color and macro/microconidia characteristics. A sick field was established by inoculating susceptible chilli varieties (Desi and Maxi) with Foc inoculum adjusted to $1\times10^6$ spores/mL via root zone injection. Seedlings at the three-leaf stage were transplanted into the sick field. Disease incidence was recorded regularly using a disease rating scale (0=Immune to 5=Highly Susceptible, 0% to 100% incidence). Disease incidence percentage was calculated using the formula: (Total number of infected plants / Total number of plants) $\times$ 100. Data were analyzed using ANOVA and Fisher's LSD test at the 5% significance level.

Methodology Flowchart

                        graph TD;
A[Collect 25 Chilli Varieties/Lines] --> B[Sow Seeds & Grow to 3-Leaf Stage];
B --> C[Transplant to Sick Field Inoculated with Foc];
C --> D[Monitor Disease Symptoms Over 2 Years 2017-19];
D --> E[Record Disease Incidence using 0-5 Rating Scale];
E --> F[Calculate Disease Incidence %];
F --> G[Statistical Analysis ANOVA, LSD];
G --> H[Identify Resistant/Susceptible Categories];
H --> I[Conclusion & Recommendations];                    

Discussion

Fusarium wilt caused by Foc is a critical soil-borne disease in chilli production. Chemical control is costly and non-eco-friendly, making screening for resistant cultivars the best long-term management strategy. Resistant plants often show elevated activity of defense-related enzymes (like peroxidase) and higher levels of secondary metabolites (tannins, phenolic compounds) compared to susceptible ones. The identified resistant and moderately resistant lines are recommended for incorporation into breeding programs to develop high-yielding, resistant cultivars.

Key Findings

None of the twenty-five evaluated chilli varieties/advanced lines expressed an immune response against Fusarium wilt across the two years.
Only one variety, BPVLC 14-1, was consistently categorized as resistant (R) with disease incidence below 20% (18.76% in 2017-18; 16.03% in 2018-19).
Nine varieties/advanced lines (including Uttal, Fengaio, Galaxy-2, Big daddy, GHHP 01, PH-275, Super sky AB, HPO33, and Super king) exhibited a Moderately Resistant (MR) response (21-40% incidence) in the second year.

Conclusion

The advanced line BPVLC 14-1 showed resistance, and nine other lines showed moderate resistance against Foc. These lines should be used in future breeding efforts to manage Fusarium wilt in chilli crops effectively and sustainably.

Fact Check

1. The study evaluated twenty-five varieties/advanced lines of chilli. (Confirmed in Abstract and Materials and Methods).
2. The resistant variety identified was BPVLC 14-1, showing 18.76% disease incidence in 2017-18. (Confirmed in Abstract and Table 1).
3. The study was conducted over two consecutive years: 2017-18 and 2018-19. (Confirmed in Abstract).

Mind Map