Determining the infrared thermometer technique utilization possibilities for crop water stres index (CWSI) evaluation and irrigation scheduling of bermudagrass (Cynodon dactylon L.)under Antalya conditions

ABSTRACT DETERMINING THE INFRARED THERMOMETER TECHNIQUE UTILIZATION POSSIBILITIES FOR CROP WATER STRESS INDEX (CWSI) EVALUATION AND IRRIGATION SCHEDULING OF BERMUDAGRASS (Cynodon dactylon L.) UNDER ANTALYA CONDITIONS Yaşar EMEKLİ M. Sc. Thesis in Farm Structures and Irrigation Advisor : Prof. Dr. Ruhi BAŞTU? January 2005, 118 pages The aim of this research was to determine the infrared thermometer technique utilization possibilities for crop water stress index evaluation and irrigation scheduling of bermudagrass under Antalya conditions. The experiment was conducted at Akdeniz University Agricultural Faculty Research and Application Field and it's arranged in randomized complete blocks desing with three replications as open field bermudagrass plots. The experiment consisted of four irrigation treatments: 100, 75, 50 and 25% of class A pan evaporation (Si, S2 S3 and S4) and also an unirrigated plot during the experiment. Irrigation water was applied every other day and the amounts of applied water were measured by a watermeter. The treatments were irrigated by basin irrigation method. Irrigation water was delivered to each treatment by PVC and PE pipelines. Soil moisture changing in 0-30 and 30-60 cm soil profile was monitored by a neutron probe and sometimes neutron readings were checked gravimetrically. On the other hand, soil moisture tension changing in the root zone was monitored by tensiometers which were placed at 10 cm depth. During the experiment, 1168.20, 877.18, 584.10 and 292.08 mm total amount of irrigation water was applied for Sı, S2, IVS3 and S4 treatments, respectively. Evapotranspiration from those treatments was computed as 1 185.58, 900.39, 614.39 and 353.22 mm, respectively. Crop and site specific baselines which are necessary for calculation of C WSI, was determined with infrared thermometer measurements which have taken under open field conditions. The CWSI was determined using the emprical method of Idso (Idso et al. 1981). Crop surface temperature was measured daily during the solar noon period at 1 100, 1200, 1300 and 1400 h from all cardinal directions of plots. Infrared thermometer measurements for non-water-stressed baseline determination were made in middle of the experiment at four different days from 900 to 1600 h at 30 min intervals from Si treatment. Water-stressed baseline was determined using daily measurements from unirrigated plot. Munsell Color Chart was used for evaluation of turfgrass quality changing as regarded by treatments and period of time. Turfgrass color and density was evaluated by visually rating turf plots on a scale of 1 to 9. The research results showed that during the growing season, bermuda turfgrass was maintained at an acceptable quality and color with every other day application of water equivalent to 75% of class A pan evaporation. In the case of infrared thermometer technique based irrigation scheduling, seasonal mean CWSI value can be taken consideration as 0.102 and the technique can be used for irrigation scheduling for bermuda turfgrass under Antalya conditions. On the other hand, in the case of tensiometer based irrigation scheduling, the turfgrass can be irrigated in the region by keeping the soil water tension about 10-13 cb. KEYWORDS : Bermudagrass, infrared thermometer, crop water stress index (CWSI), irrigation scheduling, crop surface temperature COMMITTEE : Prof. Dr. Ruhi B AŞTU? Prof. Dr. Feridun HAKGÖREN Prof. Dr. Sadık ÇAKMAKÇI