A. OVCHAROVA1 and N. NEDKOV2
1 Agricultural University, Department of Melioration and Land Surveying, BG - 4000 Plovdiv, Bulgaria
2 Research Institute for Roses and Aromatic Plants, BG-6100 Kazanlak, Bulgaria
OVCHAROVA, A. and N. NEDKOV, 2005. Relationship between canopy air temperature differences of peppermint (Menta piperita L.), irrigation requirement and crop yield. Bulg. J. Agric. Sci., 11: 415-422
This study has been carried out to evaluate the different irrigation treatments on canopy temperature of peppermint (Menta piperita L.), cultivar Sofia and to investigate the relationship between canopy air temperature differences versus vapor pressure deficit for irrigation scheduling. Field experiments were conducted at the Research Institute of Roses and Essential Plants, Kazanlak (elv.382m,lat.42°37'N., 25°24'E.) during 1989-1990 with three treatments: 1.Drip - surface irrigation at 100% of field capacity; 2. Drip - surface irrigation at 70% of field capacity; 3.Non-irrigated with water stress, as a control. The measurements of the canopy of the peppermint were made by infrared hand-held remote thermometer Raynger (AG II model, Raytek Corporation, Santa Cruz, CA). It was defined the non-water stressed baseline of peppermint derived from canopy-air temperature differences (TC-TA) versus the air vapor pressure deficit (VPD). The relationship for peppermint was described by a linear equation as: dT = -1.96VPD + 1.32 with R2=0.78. The lower baseline of peppermint with an intercept +1.32 and slope -1.96 shows that on this line crop water stress index CWSI is 0. The upper limit line with stress index 1 at which peppermint does not transpire is at 3.8°C temperature differences when VPD is closed to zero. It were calculated the coefficient of irrigation water use efficiency (IWUE) and coefficient of water use efficiency (WUE) for irrigation and non-irrigated treatments.