A closer look at mulch bell peppers

Bell pepper (Capsicum annuum L.) plants have a high demand for water and nutrients. Water stress on bell pepper is associated with reduced yields and incidence of blossom-end rot (BER). High irrigation rates are commonly applied to maximize yields. Excessive irrigation rates, however, may negatively affect bell pepper plants.

The objective of a new study was to evaluate the effects of irrigation rates and calcium fertilization on plant growth and fruit yield and quality. Trials were conducted in the spring of 2001, 2003, and 2005 at the University of Georgia, Tifton Campus. Drip-irrigated bell pepper (‘Camelot’ or ‘Stiletto’) plants were grown on black plastic mulch. Plants were irrigated with rates that ranged from 33% to 167% of the rate of crop evapotranspiration (ETc).

Results showed that irrigation at 70% ETc (2001), 67% ETc (2003), and 50% ETc (2003) were sufficient to maximize vegetative growth and fruit yield and provided yields similar to those at 100% ETc. Leaf net photosynthesis and stomatal conductance (gS) were reduced, and incidence of BER was increased with reduced irrigation rates (33% and 67% ETc). Incidences of soilborne diseases (Pythium spp. and Phytophtora capsici) tended to increase in plants receiving excessive irrigation rates (167% ETc). Irrigation rate also affected fruit quality; incidence of BER and fruit soluble solids were both increased at 33% ETc. Calcium fertilization had no effect on soil water content (SWC), plant growth, and incidence of soilborne diseases, and an inconsistent effect on fruit yield and incidence of BER.

In conclusion, there is potential for use of irrigation at rates below 100% ETc. Reduced irrigation diminished the volumes of water applied and provided fruit yields similar to those at 100% ETc. Excessive irrigation rates (167% ETc or above) wasted water and resulted in both higher incidences of soilborne diseases and reduced bell pepper yields.

Access the full study at HortScience.