Scheduling Drip Irrigation for Bell Pepper Grown with Plasticulture

ABSTRACT

Producing economical yields of bell pepper (Capsicum annuum L.) while conserving water and nutrients requires an integrated approach to fertilization and irrigation. Detailed fertilization recommendations exist for bell peppers grown in Florida, but current irrigation recommendations are based on historical weather data and year-to-year adjustments. The objective of this study was to develop and test a crop factor (CF) for bell peppers grown with plasticulture and irrigated daily. Crop water use (ETc) was calculated daily by multiplying CF with Class A pan evaporation (Ep). Values for the proposed CF were 0.20, 0.40, 0.80, 1.00, and 0.80 for periods 1–2, 3–4, 5–11, 12, and 13 weeks after transplanting, respectively. Daily Ep values were converted, to irrigation volumes using 10 mm Ep = 835 L/100 m of bed length. ‘Brigadier’ bell peppers were established in a factorial combination of 75%, 100%, and 125% of the recommended 224 kg N/ha rate and 33%, 66%, 100%, and 133% of the reference irrigation rate (I3) based on the proposed CF. Soil water tension (SWT) was monitored twice weekly in all the plots receiving the 100% nitrogen (N) rate. The numbers of days SWT remained below the recommended 15 kPa increased quadratically in both years as irrigation rate increased. Only the 100% and 133% I3 irrigation rates maintained SWT within the 0 to 15 kPa range at 15 and 30 cm depths on most days in 2001 and 2002. In 2001, bell pepper yields tended to increase as N rate increased. For 125% N rate, total, marketable, and fancy bell pepper yields responded quadratically to irrigation rates. Highest yields occurred between 115% and 124% of I3. In 2002, bell pepper yield did not respond to irrigation rate, and responded quadratically and linearly for N rates of 75%, 100%, and 125%, respectively. Highest bell pepper yields occurred with 125% N rate and 133% I3 irrigation rate. These results suggest that highest yields of bell pepper grown in the spring with plasticulture may be achieved with a combination of 125% of the University of Florida recommended N rate and irrigation scheduled in real time using 1.25 × CF test values of 0.25, 0.50, 1.25, 1.00, and 1.00 for the periods 1–2, 3–4, 5–11, 12, and 13 weeks after transplanting, respectively, with 10 mm Ep = 835 L/100 m of bed length.

Keywords:

• Capsicum annuum
• drip irrigation
• nitrogen
• evaporation pan
• evapotranspiration

ACKNOWLEDGMENTS

This project was supported in part by the Florida Agricultural Experiment Station and approved for publication as Journal Series R-10987.

Notes

^z Based on 10 mm Ep = 835 L/100 m; assuming 100% delivery efficiency.

^y Growth stages used for irrigation scheduling and fertigation are the same (Simonne et al., 2004).

^x Based on two years of field work.