Turcicum leaf blight (TLB) resistance in field corn: Screening of early generation segregating lines coupled with higher productivity
Raju Shyadambi, Sumangala Bhat, Jayant S Bhat, Venkatesh R Kulkarni and Edna Antony
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.
How to cite this article:
Raju Shyadambi, Sumangala Bhat, Jayant S Bhat, Venkatesh R Kulkarni, Edna Antony. Turcicum leaf blight (TLB) resistance in field corn: Screening of early generation segregating lines coupled with higher productivity. Pharma Innovation 2022;11(12):64-70.