Effects of temporary drought on nitrate-fed and nitrogen-fixing alfalfa plants

Abstract The effect of temporary drought on growth, carbon exchange and solute accumulation has been examined in alfalfa plants dependent on either N2 or nitrate. Plants were subjected to cyclical moderate or severe drought (drought/recovery). Growth parameters, photosynthetic rate (Pn), leaf conductance to water vapour (gw), chlorophyll content, and solute accumulation were determined. Growth decreased markedly under water deficit, but no significant differences between either groups of plants were found. Nitrogen-fixing plants developed higher root/shoot ratios maintaining larger leaves with increased specific leaf area and greater chlorophyll content than nitrate-fed ones. Leaf conductance and net photosynthetic rate declined simultaneously with the drought treatments in both groups of plants; however, N2 fixing plants retained higher Pn and gw values than nitrate-fed plants at lower RWC. Upon rewatering, a considerable stomatal closure remained in nitrate-fed plants. Drought treatment induced an increase in solute concentrations, mainly potassium, especially important in nitrate-fed plants. The interactions between the type of N nutrition and drought tolerance in alfalfa plants during temporary drought are discussed.

[1]  Theodore T. Kozlowski,et al.  Water deficits and plant growth , 1968 .

[2]  Jianhua Zhang,et al.  Control of Stomatal Behaviour by Abscisic Acid which Apparently Originates in the Roots , 1987 .

[3]  J. Aguirreolea,et al.  Effect of water stress on photosynthetic activity in the Medicago-Rhizobium-Glomus symbiosis , 1990 .

[4]  B. Saugier,et al.  Effects of nitrogen deficiency on leaf photosynthetic response of tall fescue to water deficit , 1989 .

[5]  W. A. Brun,et al.  Water Stress Effects on CO2 Assimilation, Photosynthate Partitioning, Stomatal Resistance, and Nodule Activity in Soybean1 , 1980 .

[6]  P. Kramer,et al.  Behavior of Corn and Sorghum under Water Stress and during Recovery. , 1971, Plant physiology.

[7]  T. Carter,et al.  Field Drought Tolerance of a Soybean Plant Introduction , 1990 .

[8]  W. Kaiser.  Methods for studying the mechanism of water stress effects on photosynthesis , 1987 .

[9]  J. Aguirreolea,et al.  CO2 Evolution by Nodulated Roots in Medicago sativa L. under Water Stress , 1989 .

[10]  C. Sheaffer,et al.  Alfalfa Response to Soil Water Deficits. III. Nodulation and N2 Fixation 1 , 1983 .

[11]  T. Sinclair,et al.  Who Taught Plants Thermodynamics? The Unfulfilled Potential of Plant Water Potential , 1985 .

[12]  J. Sprent.  CHAPTER 7 – WATER DEFICITS AND NITROGEN-FIXING ROOT NODULES , 1976 .

[13]  E. Schulze,et al.  Adaptation to water stress of the leaf water relations of four tropical forage species. , 1980 .

[14]  W. R. Stern,et al.  Water Relations and Osmotic Adjustment of Leaves and Roots of Lupins in Response to Water Deficits1 , 1987 .

[15]  M. Sánchez-Díaz,et al.  Effects of Temporary Droughts on Photosynthesis of Alfalfa Plants , 1993 .

[16]  J. Morgan.  The Effects of N Nutrition on the Water Relations and Gas Exchange Characteristics of Wheat (Triticum aestivum L.). , 1986, Plant physiology.

[17]  J. Sprent,et al.  EFFECTS OF WATER STRESS ON GROWTH AND NITROGEN‐FIXING ACTIVITY OF TRIFOLIUM REPENS , 1973 .

[18]  S. Hobbs,et al.  Physiological responses of drought tolerant and drought susceptible durum wheat genotypes , 1989 .

[19]  S. Chapman,et al.  Methods in plant ecology , 1977 .

[20]  M. Sánchez-Díaz,et al.  Photosynthetic nutrient use efficiency, nodule activity and solute accumulation in drought stressed alfalfa plants , 1992 .

[21]  H. Nguyen,et al.  Leaf Water Content and Gas-Exchange Parameters of Two Wheat Genotypes Differing in Drought Resistance , 1990 .

[22]  R. E. Sharp,et al.  Growth of the maize primary root at low water potentials : I. Spatial distribution of expansive growth. , 1988, Plant physiology.

[23]  W. Kaiser,et al.  Effects of water deficit on photosynthetic capacity , 1987 .

[24]  P. F. Scholander,et al.  Sap Pressure in Vascular Plants , 1965, Science.

[25]  N. Turner,et al.  Leaf gas exchange and water relations of lupins and wheat. III: Abscisic acid and drought-induced stomatal closure , 1989 .

[26]  M. Sánchez-Díaz,et al.  Nitrogen fixation, stomatal response and transpiration in Medicago sativa, Trifolium repens and T. subterraneum under water stress and recovery , 1980 .

[27]  David C. Nielsen,et al.  Nitrogen Fertility Influence on Water Stress and Yield of Winter Wheat , 1991 .

[28]  Paul J. Kramer,et al.  Water Relations of Plants , 1983 .

[29]  M. I. Minguez,et al.  Responses of nitrate-fed and nitrogen-fixing soybeans to progressive water stress , 1989 .

[30]  W. Stout,et al.  Technique for simulating field drought stress in the greenhouse. , 1990 .

[31]  J. Sprent,et al.  Effects of NaCl on Growth, Nitrogen Incorporation and Chemical Composition of Inoculated and NH4NO3 Fertilized Vicia faba (L. ) Plants , 1983 .