|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. It is usually common in irrigated areas with arid climates. Cotton is classified as a moderately salt-tolerant species with a salinity threshold level of 7.7 dS m-1. However cultivation of cotton in high salinity soils is known to cause significant reductions in growth and yield. Nitrogen is an essential plant element that is usually limited in most agricultural soils. It is reported that cotton is able to recover only 20.5 to 30 % of the total N applied. Recently, incorporation of additives such as NPBT and DCD into N fertilizers has been done with the objective of increase 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 (<1 ds-m), moderate (8 ds-m), and high (16 ds-m) and five N treatments: untreated control, full recommended N rate with urea, 75% of the recommended N rate with urea, 75% of the recommended N rate with urea plus NBPT and, 75% of the recommended N rate with urea plus NBPT and DCD. The results indicated that high salinity levels significantly reduced N uptake, stomatal conductance, and protein content. On the other hand high salinity significantly increased leaf antioxidants GR and SOD activity. No toxicity of NBPT or DCD was observed; but addition of NBPT significantly increased cotton N uptake.