Studies on nitrogen uptake and accumulation of cold type wheat

Previous studies indicated that the canopy temperature of different wheat genotypes after anthesis was different.There were many reports about the physiological,anatomic and ecological characteristics of different wheat genotypes with lower and higher canopy temperature,but little about their nutritional traits.The objective of this study was to investigate the N uptake and accumulation characteristics of genotypes with lower canopy temperature.Field experiments were conducted from 2002 to 2004 at the Agricultural Experimental Station of Northwest AF University,Yangling,Shaanxi province,China.It is a sub-humid area susceptible to drought.The genotypes Xiaoyan 6(XY6) and Shaan 229(S229) were named cold type wheat(CTW) due to their lower canopy temperature and NR9405 and 9430 were named warm type wheat(WTW) due to their high canopy temperature.For each genotype,four fertilizer treatments were setup: CK(no fertilizer),P fertilization(P2O5 176.25 kg/ha),N fertilization(N 237.0 kg/ha),and NP fertilization(P2O5 176.25 kg/ha and N 237.0 kg/ha).The treatments(variety × fertilizer) were factorial arranged with a 4×4 randomized complete block design.Each treatment was replicated three times.The area of each plot was 2.1 m2. The soil is classified as Eum-Orthic Anthrosol,equivalent to an Udic Haplustalf in the USDA system.The soil had the following chemical properties: OM,9.564 g/kg;total-N,1.08g/kg;available N,17.50 mg/kg;available P,12.27 mg/kg;and available K2O,141.24 mg/kg.The results showed that CTW had a higher N accumulation rate in foliage before anthesis.Under the condition of single application P,single application N and NP combine,N accumulation rate of CTW after flowering were 168.6%,144.6% and 217.4% higher than that of WTW,respectively.N accumulate rate in grain and N residue in the functional leaf of CTW were also higher at maturity stage.The high N content in leaves of CTW established a good N nutritional foundation for maintaining a high photosynthesis rate.The high N accumulation rate after anthesis of CTW was close related to their high metabolic physiological activities at grain filling stage and their strong root N uptake capacity.