Optimizing exponential growth of Triticum aestivum by application of the relative addition rate (RAR) technique utilizing a computer-controlled nutrient delivery system

we conducted experiments designed to assess whether plants can be grown under conditions of low ionic strength simulating natural soil conditions. wheat (triticum aestivum, cv. atlas 66) plants were grown using ten different relative nutrient addition rates (rar) of nutrients (0.00, 0.06, 0.09, 0.12, 0.15, 0.18, 0.21, 0.24, 0.27, and 0.30 day-1) with a background solution containing 50 μmol.l-1 n and all other essential nutrients in optimal proportions relative to n. the relative growth rate (rgr) of plants over a 19-day experimental period responded directly to rar (from 0.06 to 0.21 day-1) with a linear slope of 0.56 and an intercept of 0.085 day-1. solution electrical conductivity (ec) values remained relatively stable over the experimental period. we examined the effect of varying nutrient concentrations in background solutions on growth of wheat plants at a rar of 0.20 day-1. plant dry mass production in the 50 μmol.l-1 n background solution was higher than the theoretical regression. on the other hand, plant dry mass production in the 0 μmol.l-1 n background solution was close to theoretical regression (considering a relative growth rate of 0.20 g.g-1.day-1) throughout most of the experimental period. minimal fluctuations in solution ec values were observed over the experimental period. with the use of the computer-controlled nutrient delivery system and the rar technique, it was possible to grow plants under conditions of low electrical conductivity simulating natural soil conditions.