Root water uptake by kiwifruit vines following partial wetting of the root zone

Abstract

Rates of sap flow and root-water uptake by two 7-year old kiwifruit vines (Acinidia deliciosa) were studied in an orchard with the aim of determining the ability of the vines to alter their spatial pattern of root-water uptake following differential wetting of the root zone. Time-domain reflectometry (TDR) was used to monitor changes in the soil's volumetric water content, 0. The heat-pulse technique was used to monitor sap flow not only in the stem but also in several large roots to see how root flow responded with local changes in soil water availability. Prior to irrigation there was a broad correspondence between the pattern of water uptake and the distribution of root-length density. However, following irrigation, we observed a preferential uptake of water from the wetter parts of the soil and a corresponding decline in water uptake from the drier parts of the soil. Observations of root uptake by TDR following irrigation also revealed the inordinate activity of near-surface roots. The vine would preferentially draw upon near-surface water if it were available. Kiwifruit vines are able to shift rapidly their pattern of uptake, in a matter of days, away from drier parts of the root zone and begin to extract water preferentially from those regions where it is more freely available. Upon full wetting of the root zone, previously inactive roots in the dry soil of the root zone were quickly able to recover their activity. Indeed their activity following rewatering was found to be greater than it had been prior to the period of soil dryness. A rapid flush of new root growth is considered to be the mechanism that leads to this enhanced activity.

Pattern of water extraction by grapevines on two soils in the Waikato, New Zealand

“…There were also isolated locations within the vertical cross-section where water extraction occurred at a faster rate than that of the surrounding soil. Similar water extraction behavoiur was reported by Green & Clothier ( 1995) for kiwifruit. They attributed this to the vines ability to preferentially extract nearsurface water, and water in the root zone that was more freely available.…”

“…Snow (1987) and Green & Clothier (1995) studied the pattern of water extraction for kiwifruit vines in the Manawatu, and Rahardjo (1989) studied the water extraction pattern of apple trees in Hawkes Bay. Such studies provide data on the depth and volume of soil which is supplying all or most of the plants' water requirements, as well as giving an indication of the quantity of water being extracted by the plant.…”

“…This information can aid decisions on the duration, volume, and frequency of irrigation. It is also useful to know which are the depths or horizons which are supplying water to the plant for a particular soil type, and how these depths vary with time (e.g., Green & Clothier 1995).…”

Water extraction and implications on soil moisture sensor placement in the root zone of banana

“…On the other hand, Nnyamah and Black (1977) claimed that the water extraction pattern of a crop was similar to the distribution of thin roots when the soil water was not limiting. However, Green and Clothier (1995) studied water extraction of kiwifruit vines and observed that root water uptake was more dependent on soil water availability than of thin roots distribution. Yet, there are other studies indicating that the diameter of lateral roots was also a highly variable factor in the soil (Yorke and Sagar, 1970;Cahn et al, 1989;Varney et al, 1993;Jordan et al, 1993;Thaler and Pagès, 1996).…”

Subsoil water available in suction and poor in amount under continuous grassland use

“…Eissenstat 1991;Klepper 1991;Green and Clothier 1995). Herbaceous plants are also likely to evolve their root systems into subsoil layers (e.g.…”