| 释义 |
echard Ecology.|ˈɛkɑːd|
[f. Gr. ἔχειν to hold, withhold + ἀρδεία irrigation.]
Water in the soil which is not available to plant roots.
1905F. E. Clements Res. Methods Ecol. ii. 32 The terms, physiological water-content, and physical water-content, are awkward... It is here proposed to replace them by short words which will refer directly to the availability of the soil water for absorption... The terms suggested..are respectively, holard..chresard..echard (ἔχω, to withhold). Ibid. 32 This is the non-available water, or the echard. 1926Tansley & Chipp Study of Vegetation vii. 127 When the plants show signs of permanent wilting..the amount [of water] which the soil then contains is called the echard (water held back by the soil from the plant). 1938Weaver & Clements Plant Ecology (ed. 2) viii. 203 The water retained in the soil at the time of permanent wilting is nonavailable for growth or the echard (to withhold). 1960N. Polunin Introd. Plant Geogr. x. 301 It is often necessary to distinguish between water which is available to plants..and that which is so strongly held as to be unavailable (echard). |