Nuclear magnetic resonance relaxation characterisation of water status of developing grains of maize (Zea mays L.) grown at different nitrogen levels.
Changes in water status of developing grains of maize (Zea mays L.) grown under different nitrogen levels were characterized by nuclear magnetic resonance (NMR) spectroscopy. There were distinct changes in water status of grains due to the application of different levels of nitrogen (0, 120 and 180 kg N ha(-1)). A comparison of the grain developmental characteristics, composition and physical properties indicated that, not only the developmental characteristics like grain weight, grain number/ear, and rate of grain filling increased, but also bound water characterized by the T2 component of NMR relaxation increased with nitrogen application (50-70%) and developmental stages leading to maturation (10-60%). The consistency in the patterns of responses to free water and intermediate water to increasing levels of nitrogen application and grain maturity suggested that nitrogen application resulted in more proportion of water to both bound- and intermediate states and less in free state. These changes are further corroborated by the concomitant increases in protein and starch contents in grains from higher nitrogen treatments as macromolecules like protein and starch retain more amount of water in the bound state. The results of the changes in T2 showed that water status during grain development was not only affected by developmental processes but also by nitrogen supply to plants. This study strongly indicated a clear nutrient and developmental stage dependence of grain tissue water status in maize.
Laboratory of Biophysics, Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110012, India. Electronic address: pkrishnan@iari.res.in.
Prameela
P
Krishnan
Laboratory of Biophysics, Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110012, India.
Usha Kiran
UK
Chopra
Laboratory of Biophysics, Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110012, India.
Ajay Pal Singh
AP
Verma
Laboratory of Biophysics, Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110012, India.
Devendra Kumar
DK
Joshi
Laboratory of Biophysics, Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110012, India.
Ishwar
I
Chand
D009682:Magnetic Resonance Spectroscopy; D009584:Nitrogen / Q000378:metabolism* / Q000494:pharmacology; D010940:Plant Proteins / Q000032:analysis / Q000378:metabolism; D013213:Starch / Q000032:analysis / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D003313:Zea mays / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*
D010940:Plant Proteins; D014867:Water; D013213:Starch; D009584:Nitrogen
Grain filling; Grains; Maize; Nitrogen; Nuclear magnetic resonance relaxation; Water status