Greenhouse screening of maize genotypes for deep root mass and related root traits and their association with grain yield under water-deficit conditions in the field

Plant roots play an important adaptive role in drought prone environments. Although there have been many efforts to improve root traits to develop drought tolerant maize varieties but significant progress has not yet made mainly due to difficulty in screening root traits. The aims of the study were to develop an easy and reliable screening method for deep root mass and related root traits of maize in greenhouse and evaluate their association with the grain yield under water-deficit field conditions. Twelve maize hybrids and their corresponding 12 female inbred parents were evaluated for phenotypic variation in deep root mass (dry weight of the root section below 45 cm from the root base), and related root traits, such as root length and total root mass in PVC tubes in greenhouse. The test hybrids were selected based on their grain yield under water-deficit conditions in the field. Plants were grown in three different growing media, and a mixture of sand, vermiculite, perlite and soil was found to be the best growing medium to study root growth. Deep root mass, total root mass and root length differed significantly among the genotypes, and these traits showed positive relationship with grain yield under water-deficit field conditions. The root screening system used is simple and inexpensive, making it suitable for evaluating large number of maize genotypes for root traits in greenhouse for selection for drought tolerance. Several diverse inbred lines for deep root mass have been identified and these could be used as parents to develop appropriate populations to study the genetic basis of deep root mass with a goal to manipulate drought tolerance.