The Effects of N Nutrition on the Water Relations and Gas Exchange Characteristics of Wheat (Triticum aestivum L.)

Morgan, J.A.

Plant Physiology 80(1): 52-58


ISSN/ISBN: 0032-0889
PMID: 16664606
DOI: 10.1104/pp.80.1.52
Accession: 001484528

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Growth chamber grown wheat plants, supplied with nutrient solution containing 12mM N, had a greater photosynthetic capacity under adequately watered conditions and a greater sensitivity of CO2 exchange rate and leaf conductance to CO2 and to leaf water potential than did plants which received 1 mM N. Increased sensitivity of high-N plants was associated with greater tissue elasticity, lower values of leaf osmotic pressure and greater shoot FW. These N-related changes resulted in greater desiccation of high-N plants as leaf water potential fell and were probably related to the greater sensitivity of high-N leaf gas exchange to reductions in water potential. Water use efficiency, calculated as CO2 exchange rate/transpiration, increased from 9.1 to 13 and 7.9 to 9.1 mmol/mol for high- and low-N plants, resp., as water became limiting. Stomatal oscillations seen in the low-N treatment at low leaf water potentials and ambient CO2 concn disappeared as CO2 was lowered and the stomata opened.