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. Termed either managed allowable deficits or regulated deficit irrigation, the concept is defined as a preset level that soil or substrate is allowed to dry before irrigation. Deficit irrigation has been successfully used in container production of red tip
’ perception of quality. An example is the study of Lopez et al. (2010) on deficit-irrigated ‘O'Henry’ peach. DI significantly increased SSC and TA with no effect on the SSC/TA ratio. Based on this ratio, no conclusion could be reached on how organoleptic
for SDI (0.22 and 0.31). Water savings were obtained using the deficit irrigation strategies: 35% in DI and 44% in SDI. Table 1. Total water applied in 2010, 2011 and 2012 cropping seasons and olive and oil yield for each irrigation treatment: control
deficit and evaporation rates during a long summer, need to be irrigated during part of their seasonal cycle. The limited water resources characteristic of this region have promoted the development of several strategies of deficit irrigation. In a deficit
the lack of water imposed by deficit irrigation, which is being implemented in many places worldwide ( Fereres and Soriano, 2007 ). Where the environment limits stand establishment, seeding success may be improved by applying a seedcoating before
cultivars. Cai et al. (2012) reported that container-grown roses could use partial closure of stomata to acclimate to drought stress in a greenhouse. A deficit irrigation treatment of 20% ET O resulted in a marginally acceptable visual quality of
deficit irrigation reduced biomass accumulation (Stone et al. 2000). Similarly, plant growth, development, and physiological processes of field corn ( Z. mays ) were negatively affected by water stress, which resulted in a significant reduction in biomass
-available water for container-grown woody shrubs ( Beeson, 2006 ), to study the effect of canopy closure on ET o ( Beeson, 2010 ), and to quantify daily water use for woody ornamentals ( Beeson, 2007 ). Deficit irrigation Mini-lysimeters were used to
Irrigation of container-grown ornamental crops can be very inefficient, using large quantities of water. Much research was conducted in the 1990s to increase water efficiency. This article examined water management, focusing on three areas: water application efficiency (WAE), irrigation scheduling, and substrate amendment. Increases in WAE can be made by focusing on time-averaged application rate and pre-irrigation substrate moisture deficit. Irrigation scheduling is defined as the process of determining how much to apply (irrigation volume) and timing (when to apply). Irrigation volume should be based on the amount of water lost since the last irrigation. Irrigation volume is often expressed in terms of leaching fraction (LF = water leached ÷ water applied). A zero leaching fraction may be possible when using recommended rates of controlled-release fertilizers. With container-grown plant material, irrigation timing refers to what time of day the water is applied, because most container-grown plants require daily irrigation once the root system exploits the substrate volume. Irrigating during the afternoon, in contrast to a predawn application, may increase growth by reducing heat load and minimizing water stress in the later part of the day. Data suggest that both irrigation volume and time of application should be considered when developing a water management plan for container-grown plants. Amending soilless substrates to increase water buffering and reduce irrigation volume has often been discussed. Recent evidence suggests that amending pine bark substrates with clay may reduce irrigation volume required for plant production. Continued research focus on production efficiency needs to be maintained in the 21st century.
To be useful for indicating plant water needs, any measure of plant stress should be closely related to some of the known short- and medium-term plant stress responses, such as stomatal closure and reduced rates of expansive growth. Midday stem water potential has proven to be a useful index of stress in a number of fruit tree species. Day-to-day fluctuations in stem water potential under well-irrigated conditions are well correlated with midday vapor-pressure deficit, and, hence, a nonstressed baseline can be predicted. Measuring stem water potential helped explain the results of a 3-year deficit irrigation study in mature prunes, which showed that deficit irrigation could have either positive or negative impacts on tree productivity, depending on soil conditions. Mild to moderate water stress was economically beneficial. In almond, stem water potential was closely related to overall tree growth as measured by increases in trunk cross-sectional area. In cherry, stem water potential was correlated with leaf stomatal conductance and rates of shoot growth, with shoot growth essentially stopping once stem water potential dropped to between −1.5 to −1.7 MPa. In pear, fruit size and other fruit quality attributes (soluble solids, color) were all closely associated with stem water potential. In many of these field studies, systematic tree-to-tree differences in water status were large enough to obscure irrigation treatment effects. Hence, in the absence of a plant-based measure of water stress, it may be difficult to determine whether the lack of an irrigation treatment effect indicates the lack of a physiological response to plant water status, or rather is due to treatment ineffectiveness in influencing plant water status. These data indicate that stem water potential can be used to quantify stress reliably and guide irrigation decisions on a site-specific basis.