Physiological changes of sweet pepper under low irrigation regimes applied in three phenological stages of vegetative growth, reproductive growth, and fruit set

Abstract

ABSTRACT A factorial experiment based on a completely randomised design (CRD) with 10 replicates was planned to evaluate if commercially low irrigation reduced output and how physiologically low irrigation influenced yield at different plant growth stages. In three phonological phases of the vegetative stage (VG), reproductive stage (RP), and fruit set (FS), two irrigation regimes of 100% of field capacity (FC) and 80% field capacity (low irrigation = LI) were employed. The results demonstrated that the shoot's fresh weight did not vary between the VG and RP phases, but rose during the FC stage. In FS, both photosynthesis and transpiration were reduced. VG had the highest amounts of photosynthesis and transpiration. Nevertheless, fruit yield rose during the second and third weeks of FS. As starch dropped and glucose, sucrose, and fructose increased, plasma membrane aquaporins (PIP) gene expression and abscisic acid (ABA) levels climbed. In conclusion, it was proved that lowering water consumption to 80% FC did not impact yield at any development stage, including FS, due to the larger sink of fruit rather than maintaining ideal photosynthetic conditions. ABA and PIP expression increased, which may serve as a signal for the plant to overcome the moderate stress generated by LI.