186 



NATURE AND PROPERTIES OF SOILS 



98. Influence of water on the plant. 1 — As the amount 

 of water available to a crop is increased up to a certain point, 

 the vegetative growth also is usually increased, the plant be- 

 coming more succulent. The percentage of moisture in the 

 crop, even at harvest time, is usually high. Shipping qualities 

 are depressed with increased moisture, especially if the water 

 available is excessive. With an enlargement of the plant 

 cell a change probably occurs in the cell contents, tending 

 toward a greater susceptibility to disease. 



Ripening especially is delayed by large amounts of mois- 

 ture, tillering is diminished, and the percentage of protein 

 content of the crop is decreased. It is a curious fact that 

 many of the general and morphological effects of large quan- 

 tities of available water on plant growth are the same as those 

 caused by the presence of too much soluble nitrogen. In 

 cereals the stimulation from a large supply of water is 

 shown especially in the ratio of grain to straw. Widt- 

 soe 's 2 findings in this regard are representative of the data 3 

 available on this point: 



Table XXXIII 



DISTRIBUTION OF DRY MATTER BETWEEN GRAIN AND STRAW WITH 

 VARYING AMOUNTS OF WATER. 



Inches of water ap- 

 plied 



Grain in percentage 

 of dry matter of 

 entire crop 



5 

 44 



7% 

 43 



10 



43 



15 



41 



25 



38 



35 



37 



50 



33 



1 Mitscherlich, E. A., Das Wasser als Vegetations f aktor ; Landw. Jahr., 

 Band 42, Seite 701-717, 1912. 



a Widtsoe, J. A., The Production of Dry Matter with Different Quan- 

 tities of Irrigation Water; Utah Agr. Exp. Sta., Bui. 116, p. 49, 1912. 



8 Bunger, H., tJber den Einfluss Verschieden Eohen Wasser gehalts des 

 Bodens in den Einzelhen Vegetationsstadien bei Verschiedenem Nahr- 

 stoffreichtum auf die EntwicTclung des Haferpflanzen; Landw. Jahrb., 

 Band 35, Seite 941-1051, 1906. 



Also, Seelhorst, C, von, und Freckmann, W., Der Einfluss des Was- 

 sergehaltes des Bodens auf die Ernten und die Ausbilding V erschiedener 

 Getriedevarietaten ; Jour. f. Landw., Band 51, Seite 253-269, 1903. 



