Morpho-physiological responses of chili peppers (Capsicum annuum) to short-term exposure of water-saturated rhizosphere

Abstract

Chili pepper is frequently grown by local farmers at riparian wetland during dry season in Indonesia. However, during the last decade, unpredictable distribution and intensity of rainfall have increasingly threatened chili pepper production at the wetlands due to untimely water-saturated rhizosphere (WSR) occurrences. WSR is a condition when all pores within root zone were filled with water. This condition can be simulated by adding water into growing substrate until a thin layer of water was visible above substrate surface. Two Indonesian varieties (Laris and Romario) and one Japanese variety (Takanotsume) were used in this study. Aim of this study was to evaluate morpho-physiological effects of short-term (4 days) WSR exposure in chili pepper. Results of this study revealed that roots suffered more than aerial organs as indicated by the increase of shoot/root ratio from 4.56 at pre-exposure to 7.03 at end of the exposure. Total leaf area significantly reduced since larger older leaves were replaced by newly developed smaller leaves. Relative water content (RWC) in all organs was decreased, but did not reach a detrimental level. Leaf RWC was decreased from 83.6% at pre-exposure to 77.8% after the exposure; however, leaf RWC was able to rebound to 81.5% after 7 days of recovery. Photosynthetic and transpiration rates sharply decreased, associated with decrease in stomatal conductance during WSR exposure. Chlorophyll fluorescence also sharply declined. Gas exchange parameters did not significantly recover after 7 days of recovery in all varieties. Meanwhile, SPAD values were not affected by WSR exposure.