Determination of Water Use and Water Stress of Cherry Trees Based on Canopy Temperature, Leaf Water Potential and Resistance

Abstract

This study was carried out in sub-humid climate conditions of Bursa, Turkey during the 21st-22nd of August, 2004. The main objectives were to develop baselines of graph, which is necessary for the calculation of crop water stress index (CWSI) and estimation of evaporation (E) from cherry trees to the air based on crop monitoring data. Two different irrigation water levels (T<inf>1</inf> water stressed and T<inf>2</inf> fully irrigated) were used. Besides canopy temperature, canopy resistance (r<inf>c</inf>) and leaf water potential (LWP) were measured. Diurnal measurements were made from 6:50 a.m. (sunrise) to 7:40 p.m. (sunset). Experimental lower base lines and theoretical upper base lines of the basic graphic of CWSI were determined. Instantaneous E values were calculated and cumulative daily E (E<inf>cum</inf>) and daily E (E<inf>d</inf>) calculated by converting only one instantaneous E to the daily E were defined. Although CWSI values of T<inf>1</inf> were raised from sunrise to midday, CWSI values of T<inf>2</inf> were close to zero throughout the measurement days. E<inf>cum</inf> and E<inf>d</inf> values were very similar, thus converting instantaneous E values to daily basis could be used. Significant relationships were determined between CWSI - E and CWSI - LWP for T<inf>1</inf> treatments. Relationships of CWSI - E, and CWSI - LWP were non-significant or poor for T<inf>2</inf> treatment due to the non-fluctuated trend of CWSI. According to the statistical analysis, linear relationships between E and LWP were significant for both water stressed and fully irrigated conditions.