1918.1 EXPERIMENT STATION RECORD. 627 



AGRICTJLTTJRAL BOTANY. 



Leaf product as an index of growth in soy bean, F. M. Heldebrandt 

 (Johns Hopkins Univ. Circ, n. ser., No. S {1011), pp. 202-205).— The author 

 emphasizes the statement that the relations established by McLean (E. S. R., 

 36, p. 809), first, that the leaf product (the sum of the products of length by 

 breadth of all the leaflets on a soy bean plant four weeks old) is approximately 

 proportional to the total leaf area of the plant ; and, second, that this leaf area 

 is itself nearly proportional to the total dry weight of stem and leaves, applies 

 generally to the soy bean data obtained at nine different localities in Maryland. 



In order to utilize the method proposed by Livingston and McLean (E. S. R., 

 35, p. 732) of employing the growth rates of standard plants as climatic 

 indices, and in order to keep the plants so utilized alive and uninjured, soy 

 bean leaflets were employed according to methods which are briefly described. 

 As these leaflets are approximately elliptical in form, and as the area of an 

 ellipse is proportional to the product of its axes, the sum of the individual 

 leaflet products of a soy bean plant (the total leaf product for that plant) 

 should be approximately proportional to its total leaf area. 



It is noted that this proportion does hold in case of soy bean plants four weeks 

 old. The dry weight of stem and leaves of this plant is found to be approxi- 

 mately proportional to the total leaf area. It is thus possible, by multiplying 

 the proper constant by the leaf area, to calculate the dry weight of the plant. 

 The soy bean may thus prove to be suitable for use as a standard plant for the 

 measurement of climate, as Its growth can be determined from easily obtained 

 leaf measurements. 



Seasonal variations in the growth rates of buckwheat plants under green- 

 house conditions, E. S. Johnston (Johns Hopkins Univ. Circ, n. ser.. No. 3 

 (1917), pp. 211-211). — The present study was undertaken with special refer- 

 ence to its applicability in physiological experimentation in plant growth, which 

 may show itself to be subject to puzzling variations due to changing conditions 

 in the greenhouse as the seasons change. 



Japanese buckwheat (Fagopyrum esculentum) was employed in connection 

 with Shive's three-salt nutritive solution (E. S. R., 34, p. 333; 36, p. 328). A 

 set of similar water cultures was started every two weeks, and each continued 

 for four weeks, so as to allow successive sets to overlap, several different 

 kinds of measurements being made each week. 



The data, as tabulated, show the growth rates to vary in general inde- 

 pendently from period to period, although increase of weight and increase of 

 area correspond rather closely, both giving high rates for summer and low 

 rates for spring and autumn. So far as these data may be taken as an indi- 

 cation, there is nothing in the usually uncontrolled conditions in a greenhouse 

 in this climate that might be expected to produce a regular march of growth 

 rates in height for buckwheat during spring, summer, and autumn. There is 

 a general agreement between increase of dry weight and of leaf area. 



It appears from the considerations as presented and discussed that by 

 employment of such a method as the present one the climatic plant-producing 

 power of any four-week period may be directly compared with that of any 

 other such period at any time or place, the standard plant being used as an 

 automatically integrating instrumont for the measurement of the effective 

 climatic conditions, as has been suggested by Livingston and McLean (B. S. R., 

 35, p. 732; 36, p. 809). 



The effect of aeration on the growth of buckwheat in water cultures, E. E. 



.Free (Johns Hopkins Univ. Circ, n. ser.. No. 3 (1911), pp. 108, 199). — Water 



cultures of buckwheat in the solution found by Shive (E. S. R., 34, p. 333) to 



