Endogenous auxins and branching of wheat roots gaining nutrients from isolated compartments

The auxin content in roots of hydroponically grown wheat (Triticum durum Desf.) plants was affected by imbalanced distribution of nutrients when the root medium fed to plants from isolated compartments. One day after the transfer of seedlings on the nutrient medium with uneven ion distribution, the IAA content in roots contacting concentrated nutrient solution became significantly higher than in roots bathed with a dilute solution. The IAA content reached the peak on the second day and remained steadily high later on. The lateral root primordia developed in these roots were more numerous; the largest difference in this parameter was observed in 1–2 days after the increase in root content of auxin. One day later, numerous lateral roots appeared on the parent roots contacting the concentrated nutrient solution. Thus, the increase in concentration of the nutrient solution bathing a part of root system raised the IAA content in the affected roots prior to the enhanced root branching. This hormonal response of plants might play an important role in changes of root growth rate and root branching, thereby improving plant nutrition.