Drought tolerance in sunflower: two phenotyping methods

Drought conditions can be significant constraint is sunflower cropping. Determination of variability in sunflower drought response is necessary step in breeding effort to select tolerant genotypes. Experiments were conducted to compare two approaches aiming to isolate drought stress from other sources of stress, control water availability to plants and to determine impact of drought on plant growth. Two inbred lines, HA-26-PR and IMI-AB-14, were selected based on their response to drought. In the first experiment plants were grown for period of 14 days in rhizotrons and in the second for period of 60 days in pots. Both experiments were placed in growth chamber. Drought conditions in rhizotron experiment were on constant level compared to pot experiment where plants were gradually exposed to drought at one stage of development. Plants were phenotyped during and at the end of rhizotron experiment and only at the end of pot experiment. Growing plant in rhizotrons gave insight in root morphology and growth, but for the limited duration of time and only for early stages of sunflower growth. Pot experiment enables one to monitor plant growth and development over longer time and to impose drought at selected moment making it closer to the drought scenarios in field conditions. Both methods are reliable for drought stress induction and determination of drought impact and can be considered as complementary. Further research will aim the comparison of methods in controlled conditions with field drought experiments.