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

Abstract

Absorption experiments were conducted with tomato (Lycopersicon esculentumMill. ‘VF-315’) seedlings using salts at the approximate ratio found in saline irrigation water (NaCl 41.9 mM, CaCl220.9 mM, and MgCl2· 6H2O 10.5 mM) in combination with two herbicides. The osmotic pressure of this salt solution is 0.40 MPa (mega Pascal), which is equivalent to 4.0 bar or about 4.0 atm. EPTC (S-ethyl dipropylthiocarbamate) at 0.25 mM reduced the residual Na+, Ca2+, and Mg2+content relative to the treatment with salts alone. CDEC (2-chloroallyl diethyldithiocarbamate) at 0.1 mM produced similar effects for Na+and Ca2+. The addition of salts to either EPTC or CDEC induced significantly higher concentrations of total and residual herbicide in the tomato seedlings. The data suggest that salts reduce the tolerance of tomato to EPTC and CDEC by increasing absorption of the herbicides. The residual EPTC or CDEC in the tomato seedlings increased as the CaCl2concentrations increased in the incubation medium. A strong linear relationship was found between the calcium content and EPTC or CDEC content in the tomato seedling tissue.