Effect of drip irrigation regimes on yield and quality of field grown bell pepper

This study examined the effects of different irrigation regimes on yield and water use of bell pepper (Capsicum annuum sp. 1 1-B-14) irrigated with a drip irrigation system under field conditions in 2002 and 2003 growing seasons in the Mediterranean region of Turkey. Irrigation regimes consisted of three irrigation intervals based on three levels of cumulative pan evaporation (Epan) values (I1, 18–22 mm; I2, 38–42 mm; and I3, 58–62 mm); irrigations occurred on the respective treatments when Epan reached target values. Three plant-pan coefficients were evaluated as irrigation levels (Kcp1 = 0.50, Kcp2 = 0.75 and Kcp3 = 1.00). Irrigation intervals varied from 3 to 6 days in I1, 6 to 11 days in I2 and 9 to 15 days in I3 treatments. Combined variance analysis indicated that experimental years were not significantly different, but both Kcp and irrigation intervals (I) significantly influenced total pepper yields. Maximum and minimum yields were obtained from the I1Kcp3 and I3Kcp1 treatments: 33,140 kg ha−1 and 21,620 kg ha−1 in the first experimental year and 35,298 kg ha−1 and 21,010 kg ha−1 in the second experimental year, respectively. As the Kcp value decreased the total yields within each irrigation interval also decreased. However, with the lower irrigation frequency (I3), lower yields were obtained with all Kcp coefficients. Crop evapotranspiration (ET) values in the treatments varied from 365 mm in I2Kcp1 to 528 mm in I1Kcp3 in the first experimental year and 309 mm in I3Kcp1 to 511 mm in I1Kcp3 in the second experimental year. Significant second degree polynomial relations were found between pepper yield and total water use for each irrigation interval in 2002 and 2003 growing seasons. Different irrigation intervals resulted in similar water use in the treatments with the same Kcp value. Water use efficiency (WUE) and irrigation water use efficiency (IWUE) values were significantly influenced by the irrigation intervals, plant-pan coefficients and experimental years (Y1: 2002 and Y2: 2003) at 1% level of significance. WUE ranged from 4.7 kg m−3 in I3Kcp2 to 7.6 kg m−3 of ET in the I1Kcp1 in the 2002 growing season and ranged from 6.4 kg m−3 in I3Kcp3 to 7.9 kg m−3 of ET in the I2Kcp2 in the 2003 growing season. Maximum IWUE was observed in Y1I1Kcp1 (7.7 kg m−3), and minimum IWUE was in Y1I3Kcp3 treatment (4.8 kg m−3) in the experimental years. Kcp coefficients (irrigation amounts) and irrigation frequencies (I) and years had significantly different effects on quality parameters such as the first and second quality yield, and number of fruit. Both Kcp and I significantly influenced the mean fruit weight, pepper length and width, as well as stem diameter and plant height at harvest. In conclusion, I1Kcp3 irrigation regime is recommended for field grown bell pepper in order to attain higher yields with improved quality.