Breeding Field Corn for Higher Productivity with Turcicum Leaf Blight TLB Resistance in Early Segregating Generations

Abstract

The present study aimed to breed productive maize lines coupled with TLB newlineresistance in early segregating generations from a composite (ADC 1) through recurrent newlineselection with some modifications. To begin with, ADC 1 was self-pollinated to newlineproduce 450 S1 cobs and 100 S1 lines were selected and evaluated for TLB and grain newlineyield. The top 30 S1 lines were selected based on TLB reaction and yield per se and newlinesubsequently were selfed to produce S2s, S3s and S4s. These, except S4s were newlinesequentially crossed with three TLB resistant testers viz., LM13, P3304 and AH8323 to newlinegenerate 90 corresponding S1, S2 based-hybrids and 66 S3 based-hybrids for assessing newlineheterosis and heritability of combining ability in early segregating generations. Besides, newlinea marker-TLB resistance association study in two R x S F2 populations of the crosses newlineD1013 × PML68 (208 plants) and PDM4641 × PML68 (200 plants) using SSR markers newlinewas also carried out. newlinePer se performance of early segregating lines for grain yield was highest in S1- newline32 and S2-55 with moderate resistance in S1, S2 generations respectively. Similarly, S3- newline32 was identified as the best line in S3 generation for grain yield. The TLB resistant newlinehybrids, P3304 × S1-3 and LM 13 × S2-32 identified as the most potential hybrid in S1, newlineand S2 generations with significant heterosis over mid-parent. Likewise, P3304 × S3-34 newlinefor a grain yield in S3 generation. S1-17, S2-32 and S3-34 were found best combiners for newlineyield traits in each generation. The lines, S1-49, S1-17 and S1-32 were found best lines newlinefor TLB coupled with yield in S1 generation and the lines, S2-3, S2-55 and S2-32 in S2 newlinegeneration. Line S2-32 was found common in both generations and reported as the best newlinecombiner for TLB, grain yield and majority of the yield attributes. The A1, B1, C1 newlinesubgroup of S1 based hybrids; D1, E1, F1 subgroup of S2 based hybrids and G1, H1, I1 newlinesubgroup of S3 based hybrids consisted of the best combiner lines against the tester newlineutilized. The lines have a possible maximum number of favorable alleles and these newlinefa