title: [Effects of combined application of nitrogen and phosphorus on diurnal variation of photosynthesis at grain-filling stage and grain yield of super high-yielding wheat].
abstract: Taking super high-yielding wheat cultivar Jimai 22 as test material, a field experiment was conducted to study the effects of combined application of nitrogen (N) and phosphorus (P) on the diurnal variation of photosynthesis at grain-filling stage and the grain yield of the cultivar. In treatments CK (without N and P application) and low N/P application (225 kg N x hm(-2) and 75 kg P x hm(-2)), the diurnal variation of net photosynthetic rate (Pn) was presented as double-peak curve, and there existed obvious midday depression of photosynthesis. Under reasonable application of N/P (300 kg N x hm(-2) and 150 kg P x hm(-2), treatment N2P2), the midday depression of photosynthesis weakened or even disappeared. Stomatal and non-stomatal limitations could be the causes of the midday depression. Increasing N and P supply increased the Pn, stomatal conductance (Gs), stomatal limitation value (Ls), and transpiration rate (Tr). Fertilizer P had less effects on the photosynthesis, compared with fertilizer N. When the P supply was over 150 kg x hm(-2), the increment of Pn was alleviated and even decreased. Among the fertilization treatments, treatment N2P2 had the highest Pn, Gs, and water use efficiency, being significantly different from CK. It appeared that fertilizer N had greater regulatory effect on the diurnal variation of photosynthesis, compared with fertilizer P, while the combined application of N and P had significant co-effect on the Pn, Gs, and Tr. A combined application of 300 kg N x hm(-2) and 150 kg P x hm(-2) benefited the enhancement of Pn and grain yield.
authors.affiliation: Key Laboratory of Dry Land Farming Technology, Qingdao Agricultural University, Qingdao 266109, Shandong, China. haibo1026@126.com
authors.forename: Hai-bo
authors.initials: HB
authors.lastname: Zhao
authors.forename: Qi
authors.initials: Q
authors.lastname: Lin
authors.forename: Yi-guo
authors.initials: YG
authors.lastname: Liu
authors.forename: Wen
authors.initials: W
authors.lastname: Jiang
authors.forename: Jian-jun
authors.initials: JJ
authors.lastname: Liu
authors.forename: Yan-ju
authors.initials: YJ
authors.lastname: Zhai
mesh_terms: D018533:Biomass; D002940:Circadian Rhythm; D005308:Fertilizers; D009584:Nitrogen / Q000494:pharmacology*; D010758:Phosphorus / Q000494:pharmacology*; D010788:Photosynthesis / Q000502:physiology*; D012639:Seeds / Q000254:growth & development; D014908:Triticum / Q000254:growth & development* / Q000502:physiology
chemical_list: D005308:Fertilizers; D010758:Phosphorus; D009584:Nitrogen