BOOKS AND CURRENT LITERATURE 



Limiting Factors and Plant Growth. — A most interesting con- 

 tribution to the subject of climatic conditions as related to plant growth, 

 and one that has apparently escaped the notice of many students of 

 this subject, is Smith's 1 study of the giant bamboo (Dendrocalamus 

 giganteus), carried out in Ceylon. Lock's 2 previous studies in the same 

 locality indicated that the growth of this plant is controlled by atmos- 

 pheric humidity, while other workers had secured contradictory 

 results, or ones indicating that temperature is the important control- 

 ling condition. In the study here considered Smith presents compari- 

 sons of the rates of growth of giant bamboo with both temperature and 

 humidity conditions, and shows that the one or the other of these two 

 conditions acted as the limiting factor, accordingly as one or the other 

 was more variable during the particular time period in question. The 

 veiy rapid growth rate of the plant here used, which exceeded two 

 centimeters per hour in some instances, made it possible to compare 

 the growth rates with the climatic conditions for relatively short time 

 periods. The rapid growth is supported by a large reserve food supply 

 and thus may not be compared directly with growth under conditions 

 where there is no such supply. 



The records of air temperature were obtained from shaded mercurial 

 thermometers and those of relative humidity from readings of wet and 

 dry bulb thermometers. Relative humidity does not, of course, fully 

 express the moisture conditions of the environment as they may affect 

 plant growth, but it may have been the most important factor influenc- 

 ing the moisture conditions in this case. The bamboos grew in moist 

 soil along the borders of "tanks" or reservoirs, where the water supply 

 was abundant. Large well-established clumps were selected for study 

 at each of three stations, in different climatic zones: at Anuradhapura, 

 in the hot, dry lowlands, 300 feet above sealevel; at Peradeniya, in the 

 warm, moist region, 1500 feet above sealevel; and at Hakgala, in the 

 cool, moist mountain region, 5600 feet above the sea. At each of 

 these stations observations were made upon the growth of young 



1 Smith, A. M., On the application of the theory of limiting factors to measure- 

 ments and observations of growth in Ceylon. Ann. Roy. Rot. ( rard. Peradeniya 

 3: 303-375. 1906. 



2 Lock, R. H., On the growth of the giant bamboos. Ann. Roy. Hot. Card. 

 Peradeniya 2 (Pt. II). 1904. 



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