Genetic Gains in Yield and Yield Related Traits under Drought Stress and Favorable Environments in a Maize Population Improved Using Marker Assisted Recurrent Selection

Abstract

The objective of marker assisted recurrent selection (MARS) is to increase the frequency of favorable marker alleles in a population before inbred line extraction. This approach was used to improve drought tolerance and grain yield (GY) in a biparental cross of two elite drought tolerant lines. The testcrosses of randomly selected 50 S₁ lines from each of the three selection cycles (C₀, C₁, C₂) of the MARS population, parental testcrosses and the cross between the two parents (F₁) were evaluated under drought stress (DS) and well watered (WW) well as under rainfed conditions to determine genetic gains in GY and other agronomic traits. Also, the S₁ lines derived from each selection types were genotyped with single nucleotide polymorphism (SNP) markers. Testcrosses derived from C₂ produced significantly higher grain field under DS than those derived from C₀ with a relative genetic gain of 7% per cycle. Also, the testcrosses of S₁ lines from C₂ showed an average genetic gain of 1% per cycle under WW condition and 3% per cycle under rainfed condition. Molecular analysis revealed that the frequency of favorable marker alleles increased from 0.510 at C₀ to 0.515 at C₂, while the effective number of alleles (N_e) per locus decreased from C₀ (1.93) to C₂ (1.87). Our results underscore the effectiveness of MARS for improvement of GY under DS condition.