Evaluation of physiological characteristics as selection criteria for drought tolerance in maize inbred lines and their hybrids

Improvement for maize drought tolerance has always been a significant objective for breeders and plant physiologists. Nowadays, climate change sets new challenges to major crop adaptation at stressful environments. For such a purpose, the measurement of physiological traits related to maize response to drought might prove to be useful indices. The objective of the present study was to establish whether the physiological traits can be used as reliable physiological markers to evaluate the performance of parental genotypes and their hybrids under both dry and normally watered conditions, and under two densities an ultra-low density (ULD) and a normal dense stand (DS). Thirty (30) maize inbred lines and 30 single-crosses among them were evaluated across three diverse locations in Greece. The ULD was 0.74 plants/(m-2), while the DS comprised 4.44 plants m(-2) in the water deficit regime, and 6.67 and 7.84 plants m(-2) in the normal water treatment for lines and hybrids, respectively. There was a very good association between the physiological characteristics studied and grain yield under the ultra-low density and especially for inbred lines. It was shown that the physiological characteristics can facilitate the selection of stress-adaptive genotypes under the low-density conditions and may permit modern maize to be grown at a wider range of environments. At the normal densities such a possibility was not evidenced since physiological parameters and yield did not correlate for either parents or hybrids