Salinity Effects with EPTC and CDEC in Tomato (Lycopersicon esculentum) and Lettuce (Lactuca sativa)

Abstract

The combination of salts at the approximate ratio found in saline irrigation water, (NaCl 41.9 mM, CaCl220.9 mM, and MgCl2.6H2O 10.5 mM), with either 1 mM EPTC (S-ethyl dipropylthiocarbamate) or 0.1 mM CDEC (2-chloroallyl diethyldithiocarbamate) induced a greater reduction of root length, shoot length, and fresh weight of tomato (Lycopersicon esculentumMill. ‘VF-315’) relative to either factor alone. The osmotic pressure of this salt solution is 0.40 MPa (mega Pascal), which is equivalent to 4.0 bar or ca. 4.0 atm. Similar results were found in lettuce (Lactuca sativaL. ‘Great Lakes–659’) using salts at 0.30 MPa (NaCl 31.4 mM, CaCl215.7 mM, and MgCl2.6H2O 7.3 mM) combined with either 0.75 mM EPTC or 0.2 mM CDEC. In tomato, the inhibition was additive for each parameter measured. In lettuce, however, the effect on fresh weight and shoot length was synergistic and the effect on root length was additive. Calcium chloride was the single salt component of the mixture, which when combined with either EPTC or CDEC, induced a significant reduction of root length, shoot length, and fresh weight in tomato relative to either factor alone. No additional reduction in growth was found in lettuce when each individual salt was combined with either EPTC or CDEC.

Reciprocal Effects of EPTC, CDEC, and Certain Ions on Their Absorption by Tomato (Lycopersicon esculentum)

“…In the mixture of salts used, calcium appears to be responsible for the increase in the absorption of EPTC and CDEC. Calcium has been shown to alter membranes and the absorption process (16,20,25,26,27) and increase the phytotoxicity of these two herbicides to tomato seedlings (1); whereas, sodium and magnesium do not appear to alter these phenomena (1,11). Therefore, we considered it prudent to evaluate the effect of calcium, but not sodium or magnesium, on the residual levels of these two herbicides.…”

“…The salinity-EPTC or -CDEC effect on tomato and lettuce tLactuca sativa L.) were studied previously (1). The combination of salinity at 0.40 MPa (NaCI 41.9 mM, CaCl2 20.9 mM, and MgCI 2• 6H 2 0 10.5 mM) with either EPTC or CDEC induced an increased degree of injury relative to either herbicide or salt alone in both species.…”

“…Absorption studies showed that total naprop• amide levels were 60% higher in corn root tissue than in tomato root tissue. The greater napropamide content in 1 Received for publication May 27, 1980. From a thesis by the senior author in partial fulfillment of the requirements for the Ph.D. degree at the Univ.…”