Effects of Salinity and Nitrate Nitrogen on Growth, Ion Accumulation, and Photosynthesis of Sugar Beet

摘要

Effects of salinity and nitrate nitrogen (NO_3~--N) on growth, ion accumulation, chlorophyll content, chlorophyll fluorescence, and photosynthetic characteristics of sugar beet cultivar KWS3418 were investigated in a greenhouse experiment. Seedlings were exposed to 0 and 1% NaCl in 0.5, 5 or 10 mM NO_3-N treatments for 25 days. The results showed that increasing NO_3~- supply improved shoot and root dry weights, decreased the Cl~- concentration in leaves and roots regardless of NaCl concentration. Higher NO_3~--N supply also increased concentration of chlorophyll, net photosynthetic rate (Pn), actual PSII efficiency (Φ_(PSII)) in leaves and soluble sugar concentration in roots. The results indicate that increasing NO_3~- supply can help sugar beet to mediate ion homeostasis, to increase the ability of photosynthesis, and subsequently to increase the growth under high salinity. The interactive effects of salinity and nitrate availability can significantly increase soluble sugar in roots of sugar beet.