Abstract
The present study was performed to characterize the interaction between nitrogen (N) form and availability with respect to growth, water relations, and mineral nutrition of wild swiss chard (Beta macrocarpa Guss). Plants were cultured hydroponically with two levels of N concentrations, high-N (2.5 mM) or low-N (0.5 mM), added as nitrate (NO-3) or ammonium (NH+4). At high N, growth was affected significantly by N form. If the NO-3 medium was considered as control, the use of NH+4 decreased dry matter production and leaf area by ca. 35%. Use of NH+4 led to water economy and did not affect the nutrient content of the plant tissues. Compared to growth with high N, plants growth fell in either low- NO-3 or low- NH+4 medium. In this case, the difference between the two N sources was not significant. Our results showed that the replacement of NO-3 by NH+4 as the N source decreased the NO-3 concentration in consumable leaves and increased the water use efficiency.