Document Type : Research Paper
Authors
1
Assistance Prof. in Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research Institute;
2
Professor in Faculty of Agriculture, Department of Agronomy, Ferdowsi University;
3
M.Sc in soil science, Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research Institute;
4
B.Sc. in soil science, Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research Institute;
Abstract
To determine the effect of different levels of nitrogen and salinity on yield and nitrogen use efficiency of two wheat cultivars, a field experiment was conducted at Salinity Research Station of Agricultural College, Ferdowsi University of Mashhad, in 2007-08 and 2008-09 growing seasons. A split plot layout within a randomized complete block design with three replications was used. Three levels of salt stress (1.3, 5, and10 dS/m) were assigned to the main plots and a combination of three levels of ammonium sulfate (50, 100, 150 kg N/ha) and 2 wheat genotypes, namely, Bam (resistant) and Toos (susceptible to salt stress) were allocated to subplots. In the second year, micro plots (1 by 1.5 m) were established within the main experiment to monitor uptake of 15 N-labeled fertilizers. Results indicated that the percentage of N derived from labeled fertilizer was significantly (P≤ 0.05) higher in 150 kg ha-1 at salinity level of 10 dS/m than the other N levels. The highest and lowest FNU were observed in 50 and 150 kg N.ha-1, respectively. Chlorophyll content, grain yield, and potassium concentration in the aboveground plant decreased significantly with increasing salinity treatment. There were also significant differences in grain yield, chlorophyll content, and potassium concentration between the various rates of N fertilizer. The Na concentration decreased significantly with the increase in nitrogen application up to 150 kg N.ha-1 and also increased significantly with the increase in salinity treatments up to 10 dS/m. The results showed that an increase in fertilizer-nitrogen absorption by plant had occurred when application of nitrogen fertilizer exceeded wheat requirements. It seems that this condition increases the tolerance against the ill effects of salt stress in wheat.
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