INFLUENCE OF SHORTER LIGHT RAYS UPON ABSORPTION OF NITRATE BY THE YOUNG WHEAT PLANT

Abstract

Wheat seedlings 3 wks. of age were exposed to daily radiation periods in chambers under climatic control. Absorption of NO3 per unit of dry matter was determined as affected by supplementing the common mazda lamp with the carbon arc, the total intensity being constant. Combined lamps increased the violet to ultra violet region 4-5%. With the use of a low voltage arc lamp on nitrate-starved plants the results indicated benefit from the radiations of shorter wave length. KNO3 was a superior carrier to NaNO3 under both forms of radiation. Elimination of preparatory starvation gave much more positive responses to the carbon arc, as did also modification of the latter to increase rays characteristic of middle, solar ultra violet. With these beneficial modifications the absorptive effect became relatively independent of the basic element accompanying NO3.