Evaluation of Phenotypic Variation among Turkish Maize (Zea mays L.) Hybrids for Tolerance to Chilling Stress

Abstract

Maize (Zea mays L.) is a tropical crop and chilling temperatures (below 15 ºC) cause growth retardationand yield losses. The development of chilling-tolerant maize varieties is one of the goals of plantbreeders growing maize in cool climates. Hybrids are more vigorous than their parents, including beingmore tolerant to diverse stresses. However, stress screening is a problematic. This study aims toevaluate chilling stress tolerance of Turkish maize hybrids and to determine suitable indicators forselecting the most tolerant hybrid. Nine hybrids were subjected to low night-time temperaturesfollowing germination until the third leaf was fully enlarged. Hybrids were evaluated at themorphological, cellular and physiological levels by comparison with control seedlings. The data weresubjected to kinematic analysis and statistical tools. The findings showed that all indicators differedsignificantly among the hybrids. Indicators such as leaf elongation rate, mature cell length and cellproduction increase our understanding of stress tolerance by establishing connections betweenphenotype and cellular functions. Shoot fresh and dry weight emerged useful indicators for revealingassociation between growth and the physiological stress response of seedlings. In conclusion, this studyidentified beneficial indicators for breeding studies at early seedling screening of maize hybridsexhibiting genetic variation in terms of chilling stress tolerance.