Trigonelline concentration in field-grown soybean in response to irrigation

Trigonelline (TRG) is a conjugate of nicotinic acid, and is postulated to function as a compatible solute in response to salinity- and water deficit-stresses. TRG concentrations and several agronomic characteristics were measured under irrigated field and non-irrigated field conditions within 18 soybean (Glycine max) genotypes using leaves taken from different growth stages (vegetative, flowering and pod development). Under irrigation, relative water content (RWC) ranged from 90.0 to 99.6 %. Under non-irrigation, RWC ranged from 86.3 to 97.5 %. TRG concentration ranged from 364 to 555 mug g(-1)(d.m.) under irrigation, and from 404 to 570 mug g(-1)(d.m.) under non-irrigation. TRG concentrations increased in the majority of genotypes (15 of 18) under non-irrigation even though RWC did not significantly differ in many genotypes between treatments. TRG decreased as plants progressed to pod development and seed filling. Mean seed yield under non-irrigated conditions declined 55 % relative to the irrigated controls. TRG concentrations among all genotypes were significantly correlated with seed yield.