Yield and quality response of drip-irrigated pepper under Mediterranean climatic conditions to various water regimes
This study examines the effects of different irrigation regimes on yield and water use of pepper irrigated by a drip system under field conditions during the 2004 growing season at the Soil and Water Resources Research Institute in Tarsus, Turkey under Mediterranean climatic conditions. The field trials consisted of three irrigation intervals (IF1:20±2, IF2:40±2 and IF3:60±2 mm of cumulative pan evaporation) and evaluated by three irrigation levels (DI1=0.50, DI2=0.75 and DI3=1.00). Both the irrigation levels (DI) and intervals (IF) had significantly different effects on pepper yields. The maximum and minimum yields were obtained from the IF1DI3 and IF3DI1 treatment plots as 35920 and 21390 kg ha-1, respectively. The yields and yield components decreased as irrigation levels decreased for each irrigation interval. However, the larger irrigation interval (IF3) resulted in lower yields with all irrigation levels. Pepper seasonal evapotranspiration varied from a low 327 mm in the more stressfull treatment (IF3DI1) to a high 517 mm in the well irrigated control (IF1DI3). Significant linear relations were found between the pepper yield and the total water use for each irrigation interval. Irrigation intervals resulted in similar water use in the treatments with the same irrigation level. Water use efficiency (WUE) and irrigation water use efficiency (IWUE) values were significantly influenced by the irrigation intervals and levels. WUE ranged from 6.0 kg m-3 in IF3DI2 to 7.8 kg m-3 in the IF1DI1. The maximum IWUE was observed in IF1DI1, and the minimum IWUE was in IF3DI3 treatment. Both irrigation levels and frequencies had significantly different effects on quality parameters such as the first and second quality yield, number of fruit, mean fruit weight, pepper length and width, as well as plant height at harvest. In conclusion, the IF1DI3 irrigation regime is recommended for field grown pepper in order to attain higher yields with improved quality. Economic evaluation revealed that full irrigation treatment (IF1DI3) generated the highest net income. However, under water scarcity conditions, IF1DI2 treatment can provide an acceptable net income.
Key words: Pepper, deficit irrigation, water use efficiency, yield response factor, economic evaluation.