8 MASS. EXPERIMENT STATION BULLETIN 428 



Disinfection of Tobacco Seedbeds. (C. V. Kightlinger.) Fall and spring 

 steaming, chloropicrin, fall treatment with double strength formaldehyde, and 

 spring treatments with single and double concentrations of formaldehyde were 

 tested as soil disinfectants In tobacco seedbeds in 1944. The results were similar 

 to those obtained in previous >'ears. 



Fall and spring steaming and chloropicrin were highly effective in the control 

 of weeds. Fall and spring treatments with double strength formaldehyde were 

 somewhat more effective than the spring treatment with single strength formalde- 

 hyde, although none of the formaldehyde treatments gave satisfactory control 

 of weeds. 



No damping-off or bedrot occurred in the seedbeds during the season; there- 

 fore, the comparative effectiveness of the different treatments in preventing 

 seedbed diseases of tobacco could not be determined. 



The Absorption by Food Plants of Chemical Elements Important in Human 

 Nutrition. (Walter S. Eisenmenger and Karol J. Kucinski.) Both the type of 

 ion and the evolutional development of the plant seem to have a part in regulating 

 the intake of the various ions into the plant. The elements proportionately more 

 abundant in sea water than in land waters seem to be more easily introduced 

 into the plant. The more highly developed flowering plants seem to take up 

 elements applied to the soil less than do the less developed types. Under similar 

 conditions less calcium is taken up than potassium, sodium, and magnesium 

 when each is added separately at the rate of 250 p. p.m. Chlorides, bromides, 

 and iodides can be increased by larger percentages in plants than can phosphorus 

 and sulfur when the two last-mentioned elements are applied to soil as phosphates 

 and sulfates. The halides are more abundant in sea water than in land waters. 



The Intake by Plants of Elements Applied to the Soil in Pairs Compared to 

 the Intake of the Same Elements Applied Singly. (Walter S. Eisenmenger and 

 Karol J. Kucinski.) Whan 250 p. p.m. of calcium, magnesium, potassium, or 

 sodium were added singly to plots, the intake of each into plants was increased. 

 When two of these cations were added at the same rate to a single plot, the intake 

 of each was less than when either of the two was added singly. 



Preliminary experiments with seedlings of soybeans in water solution indicate 

 that the higher the copper content of the growing medium, the lower is the cal- 

 cium content of the aerial portion of the plant. These results may not necessarily 

 hold true under field conditions. In field tests 75 pounds of copper sulfate was 

 applied per acre. Plants grown on these plots will be analyzed to determine 

 the effect of copper on the intake of calcium within the plant. 



Magnesium Requirement of Plants. (Walter S. Eisenmenger and Karol J. 

 Kucinski.) During the past growing season, 1944, no heavy rains fell from the 

 time of planting to the time of harvest. This was conducive to conservation of 

 magnesium of the soil. Only a few species of plants showed the effects of slight 

 deficiency of the element in the soil. This was apparently true throughout the 

 State as no reports were available from extension and research men, or from 

 individuals who usually bring in samples of plants grown on soils deficient in 

 magnesium. 



The Ranunculus, Malvaceae, Ulmaceae, Geraniaceae, and Cruciferae showed 

 the deficiency only to a slight degree. No plants usually ascribed to the higher 

 orders gave evidence of the slightest deficiency of magnesium. 



Not all plants show the usual symptom of chlorosis. Among these plants are 

 some of the purslanes and a few of the roses — Portulaca oleracea, Rubus viUosis, 

 Potentilla canadensis; and the common strawberry shows only an eKceedinglj- 



