Identification of New Sources for Earliness and Low Grain Moisture at Harvest through Maize Landraces’ <i>Test-Cross</i> Performance

Early maturity is a highly important factor in the interrelations between yield, grain moisture, and plant density, contributing to cost-efficient maize production. Landraces conserved in gene banks present a promising basis for enriching the diversity of early maize breeding material. To start and speed up the mobilization of the maize genetic resources maintained in the ex situ Maize Research Institute Zemun Polje gene bank collection, which are currently scattered, little studied, and underused, 63 landraces were selected as new potential sources of early maturity; their test-cross performance with two divergent early testers was evaluated. The majority of the landraces with a prevailed flint type (29) exhibited heterosis for yield when crossed with the Iowa Stiff Stalk Synthetic—Iowa Dent tester (102NS), out of which 20 top crosses expressed grain moisture below the defined threshold value (21.1%). The best performing landraces can be used as a starting point for a new pre-breeding programme for the broadening of flint maize breeding material. In parallel, nine landraces expressed simultaneous heterosis when crossed with the flint tester (14NS), exhibiting grain moisture above the threshold value. A simultaneous heterotic effect with two divergent inbred testers implies the existence of an independent heterotic pool. These findings will contribute to the broadening of maize breeding material for early maturity and low grain moisture at harvest, which are important goals in maize breeding