Screening for Powdery Mildew Disease Resistance in F4 Families of the Cross JNA1 and Byadgi Dabbi in Chilli (Capsicum annuum L.)

Abstract

Powdery mildew, caused by Leveillula taurica, is one of the major foliar diseases limiting chilli (Capsicum annuum L.) productivity. The present study investigated the progression of powdery mildew and evaluated resistance in F4 families derived from the cross JNA1 × Byadgi Dabbi during the late Kharif season of 2024-25 under natural epiphytotic conditions. Weekly disease monitoring was conducted from late December 2024 to February 2025. Initial symptoms were observed in the first week of January, with disease incidence gradually intensifying and peaking by the eighth week. Area Under Disease Progress Curve (AUDPC) values steadily increased from the first to the seventh week, while the highest apparent infection rate (r) was recorded in mid-February, indicating a rapid surge in disease severity. Resistance screening of F4 lines was performed at the fruit maturity stage using the 0-9 scale, none of the genotypes exhibited complete immunity (I). However, 11 genotypes displayed a highly resistant (HR) reaction and 9 were resistant (R), reflecting low levels of infection. The majority, 12 genotypes, were moderately resistant (MR), while 7 and 6 genotypes were classified as moderately susceptible (MS) and highly susceptible (HS), respectively. The wide distribution of resistance responses highlights significant genetic variability within the disease population. These findings emphasize the continuous and aggressive increase of powdery mildew in chilli and provide a valuable genetic base for selecting resistant lines in breeding programs aimed at developing powdery mildew resistance.