Document Type: Research Paper
Irrigation Department, Faculty of Agriculture, Shiraz University
Irrigation scheduling is important in irrigation water management. In this study, full (FI),
deficit (DI) and partial root drying (PRD) irrigation strategies were applied in Agria and Ramos
potato cultivars. Canopy temperature (CT) and leaf water potential (LWP) were assessed as the
potential tools for irrigation scheduling during the vegetative and productive growth stages.
LWP varied between ca. -1.4 and -1.6 MPa and was not significantly different between FI, DI
and PRD irrigation treatments. The LWP and CT values were not significant between the two
potato cultivars during the measurements, but CT was frequently significant between the
irrigation treatments such that the PRD treatments were significantly 5 and 2 oC warmer than FI
and DI treatments, respectively. Higher CT in PRD caused significant yield penalty such that DI
and FI produced almost two times higher fresh tuber yield. Analysis revealed that CT had
significantly higher correlation (r=0.66) with water productivity (weight of fresh tuber yield
divided by volume of applied irrigation water) than LWP, which its correlation was not
significant (r=0.40). This showed that crop water productivity could be better controlled by CT.
Moreover, it was realized that the seven-day irrigation interval was far longer than required and
potatoes in all irrigation treatments were under water stress, especially in PRD, that might
partially explain the 50% yield penalty of PRD compared to DI. The reason was that due to high
atmospheric demand, soil water in the wet part of the root system would be completely depleted
earlier by the time of next irrigation event. Conclusively, the CT is recommended as a more
reliable crop water status and irrigation scheduling indicator than LWP in response to different
water-saving irrigation managements.