ANNUAL REPORT, 1935 27 



used from geranium, tomato, primrose, and begonia. From fuchsia, the node 

 or above and below the node may be used. With Asparagus Sprengeri, old or 

 new shoots cannot be used. With the rose, the test should not be made on a 

 part where active growth is taking place. An actively growing plant part may 

 give a negative test because the nitrate is being utilized in growth. The test 

 is useful in determining misuse of fertilizers, as the resultant injuries are 

 frequently attributable to a high nitrate content of the fertilizer mixture. There 

 is considerable variation in results of tests when ammonium sulfate is used as a 

 source of nitrogen for nitrogen deficient plants. Indications sometimes point 

 to a photochemical effect in which the ammonium ion is transformed to the 

 nitrate ion. 



Slow Response of the Gardenia to Certain Stimuli. (L. H. Jones.) 

 Gardenias are relatively slow in responding to certain treatments. Fuchsia 

 and geranium responded to various forms of nitrogen in 8 to 10 days. Under 

 the same conditions the gardenia did not register a response for 23 days. Ni- 

 trate salts are not very effective on gardenias in small pots as the plant requires 

 such heavy watering that leaching quickly occurs. Urea or ammonium sulfate 

 are, perhaps, the most rapid in giving a response, but organic sources of nitro- 

 gen might be preferred on the basis of giving a slower, but sustained response. 



A concentration of hydrocyanic acid gas strong enough to kill all the leaves 

 on a geranium plant failed to injure a gardenia plant. The gardenia plant 

 responded by pointing its leaves more directly upward and the young leaves 

 curled in. The plant was again normal within 72 hours after exposure. 



There were considerably more abscised buds on gardenia plants exposed to 

 low temperatures than on plants kept at the normal greenhouse temperature. 

 The data are incomplete owing to the small member of plants and buds involved. 



Removal of the terminal shoots of plants stimulates formation of axillary 

 shoots. The order of macroscopic development of the bud in the axil of a leaf 

 is appearance, then swelling, and finally bursting of the bud. In these tests 

 the time was measured between the pinehing-back of the terminal shoot and 

 the bursting of the axillary bud. Healthy plants of geranium, petunia, and 

 rose required but 7 days; the gardenia required 20 days. 



The gardenia was found to be characteristically slow in its responses to the 

 treatments given. 



The Water- Holding Capacity of Mixed Soils. (L. H. Jones.) The 

 addition of peat to a soil increases the wilting coefficient as well as the water- 

 holding capacity. Such soils may feel moist when actually the moisture present 

 is not available for the plant. The use of large amounts of inorganic fertilizers 

 on such soils, particularly in the greenhouse, increases the osmotic concentration 

 of the soil solution to such an extent that heavy watering should be practiced 

 to avoid leaf injury from the concentrated soil solution. 



A formula for calculating the probable water-holding capacity of a mixture 

 of two or more soils by volume is fairly accurate if the final volume is equal to 

 the sum of the volumes mixed. However, it usually happens that the final 

 volume is less than the sum of the volumes because the smaller elements of a 

 fine soil fill the interstices of a coarser soil. This is particularly true when peat 

 is used. In such cases the formula gives a higher calculated value than is 

 found by an actual determination. 



Plant Containers. (L. H. Jones.) A plant container of paper designed 

 for tree nurseries has been in use for more than a year. No deterioration of 

 the paper has occurred. However, it is recommended that such containers be 

 insulated from a moist soil beneath the pot by thin boards or heavy asphalted 



