Shrinkage and growth under water stress
As whole plants dehydrated from 0 to -3MPa, peduncles were observed to shrink by a mean 20% (±4.99%) of their original hydrated area, and petioles by an average of 46% (±3.39%) (fig. 2). At the same time, fruit continued to grow, showing a mean increase from original size by 26% (±4.17%). This growth stopped immediately after the vascular connection with the stem was severed by cutting when stem water potential reached -1MPa.
The treatment of girdling pedicels was observed to have no effect (P=0.711) on fruit growth compared with the ungirdled control (fig. 3). No interaction was observed between treatment (girdled vs ungirdled) and water potential (P=0.959), indicating fruit of each treatment were growing in the same way under water stress, despite the phloem of the girdled fruit being fully disrupted. Both girdled and ungirdled fruit continued to grow significantly at decreasing water potentials (4.26e-06***) with girdled fruit growing 4.25% (±0.4%) and ungirdled fruit growing 4.5% (±0.67%) over the 6 days of plant dehydration.