|KAWAKAMI, E - University Of Arkansas|
|OOSTERHUIS, D - University Of Arkansas|
Submitted to: Arkansas Agricultural Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: 3/31/2011
Publication Date: N/A
Interpretive Summary: Nitrogen is the most yield limiting nutrient in most agricultural soils, and high salt concentrations in the soil (salinity) can cause significant crop yield losses and may detrimentally affect nitrogen uptake and utilization within the plant. Incorporating additives to urea fertilizer to limit nitrogen losses may improve nitrogen use, but little is known about the interaction between fertilizer additives and salinity stress in cotton. The objectives of this study were to evaluate the effect of salinity on the growth and physiology of cotton and to determine if any benefits or toxic side effects might result from the incorporation of fertilizer additives. Cotton plants were grown under low, medium, and high salinity levels and different rates of urea fertilizer were applied with and without additives incorporated into the fertilizer. The results indicated that salinity stress reduced plant growth by negatively impacting plant physiological responses and a fertilizer additive was identified that improved N uptake at low salinity levels; however, this effect was not observed with increasing levels of salinity. In conclusion, fertilizer additives can be used to improve nitrogen uptake under low salinity levels, allowing farmers to obtain optimal productivity with decreased input costs. Higher salinity levels are detrimental to growth and no advantage is provided by including additives at high soil salinity levels.
Technical Abstract: Salinity is an abiotic stress factor that can cause significant crop yield losses. Nitrogen is an essential plant element that is usually limited in most agricultural soils. Recently, incorporation of additives such as NBPT and DCD into N fertilizers has been done with the purpose of increasing N use efficiency of crops. The objectives of this study were to evaluate the effect of salinity on the growth and stress physiology of cotton and to investigate if toxic effects of NBPT and DCD would occur in salt-stressed cotton plants. The treatments consisted of three levels of salinity: low (0.45 dS m-1), moderate (8 dS m-1), and high (16 dS m-1) and five N treatments: untreated control, full recommended N rate with urea, 80% of the recommended N rate with urea, 80% of the recommended N rate with urea plus NBPT and, 80% of the recommended N rate with urea plus NBPT and DCD. The results indicated that salinity stress reduced plant growth (low leaf area and plant dry matter), decreased N assimilation (low NR, GS and protein content), increased plant stress response (high GR and SOD), and decreased plant photosynthetic capacity (low chlorophyll, stomatal conductance, and chlorophyll fluorescence). Addition of NBPT to urea fertilizer improved N uptake at low salinity levels; however, this effect was not observed with increasing levels of salinity. No benefit of addition of DCD was observed and no evidence of NBPT and/or DCD phytotoxicity was observed in any of the salinity levels. In conclusion, salinity stress hindered the performance of the additive NBPT and negatively affected the growth and physiology of cotton.