Effect of irrigation level on plant growth, physiology and fruit yield and quality in bell pepper (Capsicum annuum L.)

The objective of this study was to evaluate the influence of drip irrigation level on plant growth, physiology, and fruit yield and quality in bell pepper. Bell pepper (‘Aristotle’) was grown on plastic film mulch in a sandy-loam soil in the spring of 2017 and 2018 in Tifton, GA. Four treatments with varying irrigation levels were applied: 33 %, 67 %, 100 % and 133 % - the rate of crop evapotranspiration (ETc). Irrigation level differentially affected plant growth, physiology and fruit yield and quality. Leaf water potential increased as the irrigation level increased. Leaf net photosynthesis (Pn), internal CO2 (Ci), electron transport rate (ETR), photosystem II efficiency (PSII), stomatal conductance (gs), and transpiration displayed a positive quadratic relationship with irrigation level. Plant height, stem diameter, leaf number per plant, shoot dry weight and stem fresh and dry weight also showed a positive quadratic relationship with irrigation level. Irrigation at 67 % ETc was associated with reduced plant water status, leaf gas exchange and plant growth, although marketable fruit yield at 67 % ETc was similar to that at 100 % ETc and 133 % ETc in both growing seasons. Fruit sunscald incidence decreased as the irrigation level increased while blossom-end rot incidence remained unaffected. After harvest, rates of fruit water loss, fruit transpiration and fruit skin permeance decreased at increased irrigation level. Elemental analyses indicated an increase in fruit mineral content with increased irrigation level. Overall, the present study showed that, compared to irrigation at 100 % ETc, deficit irrigation level at 67 % ETc had no impact on fruit yield and quality despite the reductions in plant water status, plant growth and leaf gas exchange. Irrigation above 100 % ETc did not result in increased plant growth and fruit yield, thus irrigating beyond this level may not be sustainable.