A group of researchers in the United Kingdom, has developed the Partial Root Drying technique. This is achieved by splitting the root system in two. In container production this can be achieved either by separation into two pots or using a plastic barrier between two halves of the root system in one pot. One side is allowed to dry the soil while the other half is irrigated. The treatment is then reversed, allowing the previously well-watered side of the root system to dry out while fully irrigating the the previously dry side. The researchers discovered that plants are capable of measuring the quantity of water available to them around the root system and demonstrated that dry roots release the stress hormone abscisic acid that signals the plant to inhibit shoot and leaf growth and close leaf stomata, thus maintaining a favourable water status. With leaf formation suppressed, sugars are also redirected to fruit sustaining fruit growth and improving flavour. PRD also enhances flowering and may beneficially effect the shapes of ornamental trees and other perennial crops keeping them compact and bushy. PRD also has the potential to change the length and/or timing of the flowering season and promises great saving in the use of water resources while at the same time improving plant performance. On trials in Australia, PRD halved the use of water in an area of grapevines. The yield was not reduced while the flavour and colour of the grapes was improved and there was a mucg reduced requirement for pruning side shoots. The research team is currently evaluating its use on a range of crops including Citrus, olives and cotton. Prof. W.J. Davies and M. Bacon. www.lancaster.ac.uk