Physiologie. 3 



the sorghums. (Journ. agr. Research. Washington. VI. p. 473 — 

 484. 19160 



A physiological study was made by the writer of the water 

 relations of com and the nonsaccharin Sorghums. In connection 

 with other experiments it was thought advisable to determine the 

 water requirement of several varieties of these plants. The term 

 „water requirement" as used in this paper, means the ratio of the 

 weight of the water absorbed by the plant to the weight of the dry 

 matter produced. 



The plants were grown in large sealed galvanised-iron cans 

 which contained approximately 110 KG. of soil. The soil had a 

 wilting coefficient of 13, and under the conditions of the experi- 

 ment it had a moisture content of 20 to 21 per cent (dry basis). 

 This moisture content was kept approximately constant by replacing 

 every 48 hours the water that had been lost by transpiration. 



During both seasons (1914 and 1915) three plants of com were 

 grown in each can during both seasons; in 1914 six sorghum plants 

 to each can, in 1915 three plants of sorghum. The plants were 

 grown in a screened inclosure in order to protect them from the 

 hailstorm and severe winds that are prevalent in Western Kansas. 

 The rate of evaporation in such a shelter was found to be only 

 two-thirds as high as under field conditions. The season of 1915 

 was cooler and more humid, and the rate of evaporation much 

 lower than in 1914 As a consequence the water requirement of the 

 former year was only about 66 per cent of that of the latter year. 



Using the water requirement of Blackhull kafir as 1, the water 

 requirement of the plants grown in 1914 would be as follows: 

 Dwarf milo 1,04; hybrid com 1.09; Sherrods White Dent com 1.22 

 and Pride of Saline com 1.24. In 1915, if the water requirement of 

 Blackhull kafir be considered as 1, the water requirement of Dwarf 

 Blackhull kafir would be 1.02; Dwarf milo 1.12; feterita 1.14; hybrid 

 com 1.17; Pride of Saline com 1,23; Sherrods White Dent com 

 1.37; and Sudan grass 1.41. M. J. Sirks (Wageningen). 



Tiemann. Ueber Zuführung und sparsame Verwendung 

 der Feuchtigkeit in den Holzpflanzen. (Allgem. Forst- u. 

 Jagdzeitung. XCIII. p. 61—70. 1917.) 



Eine physiologische Arbeit, welche folgende Gruppierung zeigt: 

 I. Die direkte und indirekte Zuführung ausreichender 

 Feuchtigkeit zu den Wurzeln der Pflanzen und die möglichste Er- 

 haltung dieses Feuchtigkeitszustandes. 



1. Direkte Zufuhr des Wassers zu den Wurzeln geschieht 

 durch atmosphärische Niederschläge, Bewässerung und Begiessen 

 (letztere 2 Umstände kommen nur für Forstgärten und Saat- und 

 Pflanzenkämpen in Verwendung). 



2. Indirekte Zufuhr kann bewirkt werden durch das Lockern 

 der Zwischenräume zwischen den Pflanzreihen, durch das Anhäu- 

 feln und durch Bodenauflockerung um Pflanzenheister behufs He- 

 bung deren Wachstums, ferner durch Beimischung des Bodens der 

 Beete in Forstgärten mit hygroskopischen Stoffen, z.B. Humuserde, 

 Moorerde, Asche. Bei der Zersetzung der Humusstoffe bildet sich 

 auch Wasser. 



II. Möglichste Ausnutzung des im Boden vorhandenen Wassers 

 (mit den Nährsalzen) durch besondere Beschaffenheit des Wurzel- 



