title: Leaf density explains variation in leaf mass per area in rice between cultivars and nitrogen treatments.
abstract: Leaf mass per area (LMA) is an important leaf trait; however, correlations between LMA and leaf anatomical features and photosynthesis have not been fully investigated, especially in cereal crops. The objectives of this study were (a) to investigate the correlations between LMA and leaf anatomical traits; and (b) to clarify the response of LMA to nitrogen supply and its effect on photosynthetic nitrogen use efficiency (PNUE).
  
  
  
  In the present study, 11 rice varieties were pot grown under sufficient nitrogen (SN) conditions, and four selected rice cultivars were grown under low nitrogen (LN) conditions. Leaf anatomical traits, gas exchange and leaf N content were measured.
  
  
  
  There was large variation in LMA across selected rice varieties. Regression analysis showed that the variation in LMA was more closely related to leaf density (LD) than to leaf thickness (LT). LMA was positively related to the percentage of mesophyll tissue area (%mesophyll), negatively related to the percentage of epidermis tissue area (%epidermis) and unrelated to the percentage of vascular tissue area (%vascular). The response of LMA to N supplementation was dependent on the variety and was also mainly determined by the response of LD to N. Compared with SN, photosynthesis was significantly decreased under LN, while PNUE was increased. The increase in PNUE was more critical in rice cultivars with a higher LMA under SN supply.
  
  
  
  Leaf density is the major cause of the variation in LMA across rice varieties and N treatments, and an increase in LMA under high N conditions would aggravate the decrease in PNUE.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China and Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km7·5, 07122 Palma de Mallorca, Illes Balears, Spain.
authors.forename: Dongliang
authors.initials: D
authors.lastname: Xiong
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China and.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China and.
authors.forename: Xi
authors.initials: X
authors.lastname: Liu
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China and.
authors.forename: Shaobing
authors.initials: S
authors.lastname: Peng
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China and.
authors.forename: Jianliang
authors.initials: J
authors.lastname: Huang
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
mesh_terms: D005838:Genotype; D058503:Mesophyll Cells; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000502:physiology*; D018515:Plant Leaves / Q000737:chemistry* / Q000166:cytology / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen
keywords: Leaf density; leaf mass per area; leaf photosynthesis; leaf thickness; photosynthetic N use efficiency; rice