Resistance to Water Loss in the Mesophyll of Leek (Allium porruni)

Measurement of the rate of water loss and the gradient in water-vapour concentration from the evaporating surface to the air enabled calculation of the resistance to water loss from the leaf mesophyll of leek (Allium porruni) and from green blotting-paper. The additional resistance found in the case of mesophyll estimates the mesophyll cell-wall resistance (wall resistance). Wall resistance was, however, small, less than 0.09 sec cm−1 in turgid mesophyll and only 0.15 sec cm−1 greater when the mesophyll water deficit was 50 per cent. Results are discussed in relation to the evidence of other workers indicating greater resistances to water loss in the mesophyll.