Premium
Water Use Efficiency and Dry Matter Distribution in Nitrogen‐ and Water‐Stressed Winter Wheat
Author(s) -
Heitholt J. J.
Publication year - 1989
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1989.00021962008100030014x
Subject(s) - dry matter , transpiration , water use efficiency , chemistry , nitrogen , agronomy , gravimetric analysis , zoology , photosynthesis , irrigation , biology , biochemistry , organic chemistry
Water use efficiency (WUE) and the distribution of dry matter to the roots in wheat ( Triticum aestivum L.) are potential selection criteria for improving yield under water stress. The objectives of this research were (i) to compare methods of measuring WUE, and (ii) to determine the distribution of dry matter between shoots and roots in water‐ and N‐stressed wheat. Winter wheat was grown in a potting mixture for 6 wk in growth chambers with varying levels of N and water. Nitrogen applied to the mixture varied from 10 to 100 mg N per plant. Water supply was maintained at 15 to 35% of the mixture water holding capacity (stressed) to above 50% of capacity (well watered). Cumulative transpiration, steady‐state CO 2 and H 2 O exchange rates, and dry matter were determined. The ratio of dry matter production (mmol C) to transpiration (mol H 2 O) averaged 1.39 and 1.94 mmol C mol −1 H 2 O for the 10 and 100 mg N treatments, respectively. The ratio of the steady state CO 2 exchange rate to the H 2 O exchange rate was 1.97 and 4.24 mmol C mol −1 H 2 0 for the 10 and 100 mg N treatments, respectively. The gas exchange WUE values tended to be higher than the gravimetric WUE values, but the two were correlated ( r = 0.76**). Results supported the hypothesis that gas exchange WUE values could provide an accurate prediction of WUE values obtained from gravimetric analysis. Shootroot ratio was consistently reduced by N stress, but not by water stress. The results supported previous observations that optimal leaf N concentration promoted higher WUE. Mild water stress did not consistently affect WUE, but a more severe water stress consistently decreased WUE, especially under suboptimal N supply.