(25) Effects of Saline Irrigation Timing on the Physiology and Marketable Yield of Bell Peppers Growing in Mulch or Nonmulch Conditions

Abstract

The effect of applying saline water (2.5 dS·m-1) via a drip irrigation system at different growth stages of mulched or nonmulched bell peppers (Capsicum annuum L. var. Red Knight) was investigated under greenhouse conditions. The study 6 × 2 factorial was arranged as a randomized complete-block design. The six irrigation treatments were: 1) control—nonsaline water throughout growth; 2) saline irrigation throughout growth; 3) saline irrigation from transplanting until formation of the first fruit set; 4) saline irrigation from transplanting until appearance of the first flower and from first harvest to final harvest; 5) saline irrigation from appearance of the first flower until first harvest; and 6) saline irrigation from fruit set until final harvest. A measurement of stomatal conductance (gs), transpiration (E), and photosynthesis (A) rates was performed during vegetative growth, at flowering, at fruit set, and during fruit growth and development. Mulched plants had higher photosynthetic rates than nonmulched plants, although values were only significant for treatments 2, 3, 5, and 6. In addition, nonmulched plants were slower to recover after periods of saline irrigation than mulched plants. Mulched plants had significantly greater yields than nonmulched plants regardless of irrigation treatment. Saline irrigation when applied throughout growth or from fruit formation until harvest reduced marketable yields by 38% and 45% compared with the control plants.