EFFECTS ON PLANTS 



Effects of Various Degrees of Moisture upon the Structure of Tropaeohim majus 



(Kohl '86) 



The general effects of the second type of water-deficiency (increased exit 

 through transpiration) were summarized by Winkler ('13) as follows: 



"Werden Pflanzen in trockener Luft erzogen, so ist im allgemeinen das 

 Langenwachstum verzogert, auch werden die Internodien weniger lang, dafiir 

 aber dicker und ihre Zahl wird erhoht; die Festigkeit der Achsenorgane ist 

 grosser; die Haarbildung an Blattern und Stengeln erscheint gefordert; die 

 Wurzelbildung erfolgt reichlicher, der Blattfall, die Blute- und Fruchtbildung 

 eher; die Epidermis-, Rinden- und Markzellen bleiben kleiner; die Bildung von 

 Sekretionsorganen und Kristalzellen wird begiinstigt, die Entstehung von Kork 

 und Sclerenchym beschleunigt, die Gefassbildung gefordert. Kultur in feuchter 

 Luft hat gerade den umgekehrten Erfolg (Kohl, Eberhardt)." 



Dickson ('18) found that the water requirement in the oat plant varies 

 considerably according to the proportions of the various salts found in the 

 nutrient medium. The requirement is decreased by a deficiency of magnesium, 

 slightly increased by a deficiency of calcium, and greatly decreased by a defi- 

 ciency in potassium, phosphorus or nitrogen. 



CALCIUM DEFICIENCY 



That calcium is essential for the normal growth of the higher plants has long 

 been recognized (e.g. by Stohmann '62, in the maize plant), but its function is 

 not yet entirely clear. Loew ('92) considered calcium as one of the important 

 mineral bases entering into the constitution of the proteins in the cell-nucleus 

 and chlorophyll-bodies. Reed ('07) pointed out that calcium differs from 

 potassium and phosphorus in forming but a small proportion of the actual living 

 protoplasm; but it has varied and important functions, influencing processes and 

 products into which it does not itself seem to enter. True ('22) recently 

 concludes: 



