References
- Böehm , W. 1979 . Methods of studying root systems , Berlin , , Germany : Springer Verlag .
- Helal , H. M. 1991 . Bodengefüge, Wurzelentwicklung und Wurzelfunktionen . Z. Pflanzenern. Bodenk. , 154 : 406 – 407 .
- Helal , H. M. 1992 . “ An index for estimating the living part of plant roots ” . In Root Ecology and its Practical Applications , Edited by: Kutschera , L. 739 – 742 . Klagenfurt , Austria : Verein für Wurzelforschung .
- Helal , H. M. and Al Niemi , S. 1992 . “ Damage and regeneration of maize roots under drought stress ” . In Root Ecology and its Practical Applications , Edited by: Kutschera , L. 97 – 100 . Klagenfurt , Austria : Verein für Wurzelforschung .
- Helal , H. M. , Müller , A. and Sauerbeck , D. 1994 . Auswirkungen von Bodenverdichtungen auf die Wurzelfunktionen und den Nährstoffhaushalt . Landbauforschung Völkenrode, Sh. , 147 : 167 – 177 .
- Helal , H.M. and Ragab , M. 1995 . Growth and nitrogen yield of Leucaena/ maize mixed culture as affected by salt stress and gypsum . Z. Pflanzenernähr. Bodenkunde , 158 : 121 – 122 .
- Helal , H. M. and Sauerbeck , D. 1989 . Carbon turnover in the rhizosphere . Z. Pflanzenern. Bodenk. , 152 : 211 – 216 .
- Keifer , D. W. and Spanswick , R. M. 1979 . Correlation of adenosine triphosphate levels in Chara corallina with the activity of the electrogenic pump . Plant Physiol. , 64 : 165 – 168 .
- Kutschera , L. , Huebl , E. , Lichtenegger , E. and Persson , H. 1992 . Root Ecology and its Practical Application , Klagenfurt , Austria : Verein fur Wurzelforschung .
- McLachlin , K. D. 1980 . Acid phosphatase activity of intact roots and phosphorus nutrition of plants . Aust. J. Agric. Res. , 31 : 429 – 440 .
- Mengel , D. B. and Barber , S. A. 1974 . Nutrient uptake rates per unit of root of corn grown under field conditions . Agron. J. , 66 : 399 – 402 .
- Mengel , K. and Helal , H. M. 1967 . Effect of exchangeable Ca of young barley roots on the flux of K and phosphate. An interpretation of the Viets‐Effect . Z. Pflanzenphysiol. , 57 : 223 – 234 .
- Murphy , J. and Riley , J. P. 1962 . A modified single solution method for the determination of phosphate in natural waters . Anal. Chim. Acta , 27 : 26 – 30 .
- Tennant , D. 1975 . A test of a modified intersect method of estimating root length . J. Ecology , 63 : 995 – 1001 .
- Soils and Water Department, Atomic Energy Authority (AEA), Cairo, Egypt.
- Nile Valley Regional Project, ICARDA, Cairo, Egypt.