Water Deficit


Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Acronyms.

Water Deficit

 

(biology), the incomplete saturation with water of plant cells, resulting from an intensive water loss by the plant that is not replenished by absorption of water from the soil. A water deficit is usually observed during the hottest hours of the day. The leaves of many plants, such as thorn-apple and pumpkin, lose their turgor at this time and droop. The external appearance of plants with a large amount of mechanical tissue (immortelles) does not change even when they die of water deficit. With the arrival of dry weather one can observe residual water deficit, when the plant cannot make up its lack of water during the night. Water deficit, especially residual water deficit, causes many physiological and biochemical changes in plants. Some plants (certain groups of xerophytes, the so-called euxerophytes) can with-stand a very large water deficit (up to 50-60 percent), while other plants (mesophytes) are harmed by a relatively small water deficit. Since there is no reliable method for determining water deficit, one must sometimes resort to determining the wilting coefficient. For plants that are raised without watering, one determines the amount of water in the soil at the moment when their leaves begin to wilt.

REFERENCES

Genkel’, P. A.“Ustoichivost’ rastenii k zasukhe i puti ee povysheniia.” Tr. In-ta fiziologii rastenii im. K. A. Timiriazeva, 1946, vol. 5, part 1.
Litvinov, L. S. O pochvennoi zasukhe i ustoichivosti k nei rastenii. L’vov, 1951.
Zholkevich, V. N. Energetika dykhaniia vysshykh rastenii v usloviiakh vodnogo defitsita. Moscow, 1968.

P. A. GENKEL’

Mentioned in ?
References in periodicals archive ?
Methods based on crop physiological response to water stress, such as leaf water potential, leaf water content and stomatal conductance are considered as the most reliable one in qualifying crop water deficit (Jones, 2004).
Water deficit showed positive result on the production bioactive compounds of various plant species especially medicinal and herbal plants.
The application of water deficit usually resulted in reducing diameters expressed in different genotypes.
Oliveira, "Mechanisms underlying plant resilience to water deficits: Prospects for water-saving agriculture," Journal of Experimental Botany, vol.
It is thus understandable that the current advice to dairy farmers irrigating pasture is that yield does not start to decline until the soil water deficit equals the critical value of half the total soil water-holding capacity of the root-zone, which has a default depth of 600 mm (Martin et al.
The water deficit of China would be about 200 billion cubic meters, while 21 percent of the surface water resources of the country are unfit even for farming, which consumes about 70 percent of the country's water.
Irrigation level positively influenced marketable yield of tomato, with tomato yield decreasing as the water deficit level increased.
As it was shown in the results of this study, water deficit stress had a negative effect on most of the chicory characteristics under study.
This global water deficit is the result of demand tripling over the last half-century.
As one of the 10 most water impoverished countries in the world, Jordan's water deficit exceeds 500 million cubic meters a year, according to the water ministry.
Ascorbate was elevated in the water deficit treatments relative to the full irrigation at all subsequent sampling dates, even on DOY 269, when differences in leaf water potential were no longer detected (Fig.