Abstract
This study was conducted to test the impact of the nutrient solution temperature and the application of different stress treatments at tuberization on several growth variables for two potato cultivars grown in an aeroponic system. At 25 days after transplanting, low pH level, wilting stress and nitrogen withdrawal under warm (24 A degrees C) and cool (18 A degrees C) root-zone temperatures were applied to potato plants cv. Mystere and Chieftain. Significant differences in mini-tuber production, stolon number and length and root length were observed among root zone temperatures, stress treatments and cultivars. Cooling the nutrient solution temperature to 18 A degrees C significantly increased most growth variables and tuber yield for both cultivars. Plants subjected to nitrogen withdrawal at tuberization out-performed plants of the other treatments as well as the control and exhibited faster tuberization, higher mini-tuber number and weight as well as significantly higher root length, stolon number/plant and number of stolon branches/plant. The low pH and wilting treatments reduced plant growth and mini-tuber number/plant. They dramatically increased the number of stolon branches/plant and stolon number respectively. However, this increase did not counteract the negative effects on the other variables. The results of this study demonstrate that a judicious use of these stresses can effectively promote tuberization in aeroponics.