The physiological effect of pre-soaking with tryptophan on sugar beet (Beta vulgaris L.) productivity under different levels of salinity stresses

Abstract

Abstract Background Salinity has a negative effect on the productivity of many crops. Therefore, the present study was conducted to investigate the effect of pre-soaking in different concentrations of tryptophan (0.0, 2.5, and 5.0 mM) on growth, yield and root quality of two sugar beet cultivars (DS-9004 and LP-15) under different salinity levels (320, 2000, 4000, 6000, and 8000 ppm) in an effort to reduce salinity damage on sugar beet. The data were collected at 2 stages of growth (75 and 180 days after sowing). Results The results revealed that the pre-soaking in tryptophan treatments (2.5 mM) were the most effective treatments under different salinity levels and caused significant increases in all tested parameters of this study. Moreover, increasing salinity levels decreased significantly the root purity parameters and increased impurity parameters of sugar beet. The DS-9004 cultivar gave the highest values of all studied parameters compared with the LP-15 cultivar under different salinity levels with tryptophan (2.5 mM). Chlorophyll a content and chlorophyll a/b ratio, as well as carotenoids content, were highest in DS-9004 cultivar, while chlorophyll b content was highest in LP-15 cultivar at 75 days. Conclusions Salinity level up to 320 ppm positively affected the growth yield of sugar beet while the highest significant reduction was associated with increasing salinity up to 8000 ppm. Thus, pre-soaking in tryptophan (2.5 mM) has a promotive effect on increasing sugar beet yield under water salinity conditions.

Keywords

• Salinity
• Sugar beet
• Pre-soaking
• Tryptophan
• Growth
• Yield