Vol. 11, Issue 12 (2022)

Author(s):
Raju Shyadambi, Sumangala Bhat, Jayant S Bhat, Venkatesh R Kulkarni and Edna Antony

Abstract:
Maize is one of the staple food crops globally and is affected by more than 61 diseases and of them 16 diseases are adversely affecting this crop. One among them is Turcicum (TLB) or northern corn leaf blight (NCLB) caused by the ascomycetes fungi Exserohilum turcicum. In India, the loss in grain yield due to TLB ranges from 25 to 90% depending on the disease severity. Early testing is one of the breeding methods advocated in maize breeding. An elite composite ADC-1 was selected for generating early segregating generations (selfed generations). One hundred S₁s were evaluated against TLB under artificial epiphytotics and for grain yield during kharif 2020. The spreader rows were planted at regular intervals to ensure buildup of sufficient TLB inoculums. The susceptible check, exhibited the disease score of 8, indicating the sufficiency of inoculums during the screening phase. Out of these, 30 lines were selected based on TLB reaction and grain yield and selfed to produce S₂s. These 30 lines along with checks were evaluated in randomized block design (RBD) during Kharif 2021. Among the thirty S₁ lines, 24 lines belonged to moderately resistant group and six lines were moderately susceptible. The lines S₁-23 (11.22 t/ha), S₁-32 (11.12 t/ha) and S₁-49 (10.84 t/ha) recorded highest grain yield with moderate resistance. Whereas, among the 30 S₂ lines, one line, S₂-3 recorded resistant reaction, while, 17 lines were moderately resistant and 12 moderately susceptible. The lines, S₂-55 (10.29 t/ha), S₂-74 (9.61 t/ha) and S₂-47 (9.33 t/ha) recorded highest grain yield with moderate resistance. There was a discernible decrease in yield from S₁ (8.28 t/ha) to S₂ (6.69 t/ha) generation. This was expected in allogamous crop like maize as a consequence of inbreeding. Among the potential top ten S₂ lines, S₂-55, S₂-23 and S₂-26 were also listed under potential top ten S₁ lines with moderately resistant reaction. This indicated the consistency of the lines over the selfing generation. Hence, there is further scope for selection and improvement of TLB and grain yield by accumulation of favourable alleles. Thus, the results suggested the possibility of improving resistance against TLB and grain yield further through population improvement approach, preferably by recurrent selection.