title: Effects of high NH(+) 4 on K(+) uptake, culm mechanical strength and grain filling in wheat.
abstract: It is well established that a high external NH(+) 4 concentration depresses many processes in plant development, but the underlying mechanisms are still not well understood. To determine whether the negative effects of high levels of NH(+) 4 are related to competitive cation uptake, wheat was grown in a field with moderate (18 g N m(-2)) and high (30 g N m(-2)) supplies of NH(+) 4 in the presence or absence of additional K(+) (6 g K2O m(-2)) to examine culm mechanical strength, the main components of the vascular bundle, nitrogen (N) remobilization and the grain-filling rate. The results indicated that an excessive supply of NH(+) 4 significantly decreased culm mechanical strength, the cellulose and lignin contents of vascular bundles, the N remobilization efficiency (NRE) and the grain-filling rate compared with a moderate level of NH(+) 4. The additional provision of K(+) considerably alleviated these negative effects of high NH(+) 4, resulting in a 19.41-26.95% increase in culm mechanical strength during grain filling and a 34.59% increase in the NRE. An assay using the scanning ion-selective electrode technique (SIET) showed that the net rate of transmembrane K(+) influx decreased by 84.62%, and measurements using flame photometry demonstrated that the K(+) content decreased by 36.13% in wheat plants subjected to high NH(+) 4. This study indicates that the effects of high NH(+) 4 on culm mechanical strength, cellulose and lignin contents, the NRE and the grain-filling rate are probably associated with inhibition of K(+) uptake in wheat.
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Lingan
authors.initials: L
authors.lastname: Kong
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Mingze
authors.initials: M
authors.lastname: Sun
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Fahong
authors.initials: F
authors.lastname: Wang
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Feng
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Jisheng
authors.initials: J
authors.lastname: Si
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Shengdong
authors.initials: S
authors.lastname: Li
authors.affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences Jinan, Shandong, China.
authors.forename: Huawei
authors.initials: H
authors.lastname: Li
keywords: K+ flux; N remobilization; ammonium (NH+4); culm mechanical strength; wheat (Triticum aestivum L.)