Investigation of the chilling tolerance of maize (Zea mays L.) hybrids at emergence and in the seedling stage

The emergence date and emergence percentage of seeds of 5 maize hybrids and the dry mass of individual shoots were examined in a pot experiment sown on three dates (April 3, 10, 17) in three types of soil (sand, sterilised maize soil, maize soil infected with fusarium), with seed treatment using two types of dressing agents (Captan, Carboxin+TMTD) and an untreated control. The emergence time changed considerably as a function of the sowing date. In the earliest sowing date treatment the seeds emerged after an average of 24.5 days, while in the latest treatment they emerged after 12.8 days. The dressing agent caused a slight but significant (0.8 days) reduction in the time required for emergence. The emergence percentage was slightly less in the earliest sowing date treatment compared with the laboratory germination percentage. In the earliest treatment less than 50% of the undressed seeds emerged. In this sowing date treatment seed dressing more than doubled the emergence percentage. As the result of seed dressing there was an average increase of almost 50% in the shoot dry mass. Among the hybrids the earliest maturing (FAO 200) hybrid, Nart 150, proved to be the best for all the traits tested. The three-way cross My TC 287 exhibited a sensitive response not only to early sowing, but also to pathogens in the undressed treatments.