|Author:||Camposeo, S. ; Rubino, P.|
|Book Group Author:||NA|
A 2-year trial was performed on autumn-sown sugar beet grown in pots in order to study the influence of irrigation frequency on the water used by plants along the soil profile. The outdoor pots, containing one plant each, were 1.3 m high and had circular openings, through which Time Domain Reflectometry (TDR) apparatus wave guides could be inserted. Three irrigation intervals were compared and plants were watered whenever the soil layer explored by roots had lost 30% (SWD1), 50% (SWD2) and 70% (SWD3) of the total available water (TAW). During the irrigation season, the water extracted by the plants from each layer along the soil profile (RWU) was determined by monitoring volumetric soil moisture content (θ), by TDR. At harvest time, root length density (RLD) along the soil profile was assessed using the Tennant method. The applied irrigation frequencies significantly affected the RWU. With the SWD3 protocol, irrigation was at longer irrigation intervals (9 days) and watering volumes were as high as 84 mm. In this treatment, the plants lost almost 60% of total water from the lower soil layer (0.6-1.0 m). In treatment SWD1, the irrigation interval was very short (3 days), and water extraction from 0.0-0.6 m soil depth was 92.0%. In the intermediate treatment, the irrigation interval was 5.5 days and a more uniform water depletion was observed along the root zone, approximately equal between the 0-0.6 and 0.6-1.0 m soil layer. Water extraction of sugar beet plants at the deeper soil layers in response to long irrigation intervals was related to an increase in water uptake efficiency of the deeper younger roots and not to an increase in root length density, which, on the contrary, decreased. This morpho-physiological acclimatization to progressive soil water deficit was coupled with an increase of the root/shoot ratio.
|Pages:||301 - 309|
|Journal:||Plant and Soil|
acclimatization, available water, drought resistance,irrigation, irrigation scheduling, plant water relations, potexperimentation, root shoot ratio, roots, soil water content, sugarbeet,water deficit, water uptake, Italy, Beta vulgaris var. saccharifera,Beta vulgaris, Beta, Chenopodiaceae, Caryophyllales, dicotyledons,angiosperms, Spermatophyta, plants, eukaryotes, Southern Europe, Europe,Mediterranean Region, Developed Countries, European Union Countries,OECD Countries, drought tolerance, watering, Field Crops (FF005) (NewMarch 2000), Plant Water Relations (FF062), Environmental Tolerance ofPlants (FF900), Soil Physics (JJ300), Soil Water Management (Irrigationand Drainage) (JJ800) (Revised June 2002) [formerly Soil Water Management]