Cyrus B. Munshi

Glycoalkaloid and nitrate content of potatoes as affected by method of selenium application

A comparison of two methods of selenium application, banding and foliar spray, of sodium selenite (Na2SeO3) on total glycoalkaloid (TGA) and nitrate nitrogen (NO3-N) was studied during each of two consecutive years. The levels of application used were 0.0, 1.6 (0.75), 3.36 (1.5), and 5.6 (2.5) kg/ha (ppm soil). Both TGA and NO3-N were significantly reduced by application of 1.5 and 2.5 ppm of sodium selenite. Tuber selenium levels were significantly increased at all levels of application, using either banding or foliar spray, but were well below the toxic range for human consumption. Banding resulted in greater uptake of Se, and greater decreases in TGA and NO3-N as compared to foliar spray.

Residue levels of isopropyl N-(3-chlorophenyl) carbamate (CIPC) in potatoes as affected by level of application, storage time and temperature, and method of cooking

Abstract Katahdin potato tubers were treated with 1 and 3% CIPC and the various tissue sections were analyzed for CIPC residue using a modified High Pressure Liquid Chromatographic method. Tubers were analyzed for CIPC residue immediately following the CIPC treatment as well as after 6 months of storage. Increasing CIPC concentration significantly ( p ≤ 0·001) increased residue level in tubers stored at both 5°C and 20°C for 6 months. CIPC residue was highest in the peel, followed by the cortex with peel and cortex without peel, with little or no residue in the pith. The CIPC residue level was higher in tubers stored at 5°C as compared to those stored at 20°C, and the residue level decreased during storage. Cooking resulted in decreased residue levels in all the sections of the tuber due to leaching of CIPC into the cooking water. The amount of residue in the cooking water was higher when tubers were boiled as compared to steaming.