02132naa a2200277 a 450000100080000000500110000800800410001910000200006024501320008026000090021252013740022165000160159565000090161165000160162065000220163665300100165865300110166865300200167965300120169970000180171170000180172970000170174770000160176470000170178077300570179710543591997-04-16       1987    bl ---       0--  u    #d1 aSINCLAIR, T. R.  aField and model analysis of the effect of water deficits on carbon and nitrogen accumulation by soybean, cowpea and black gram.  c1987  aIdentification of the key physiological traits that limit carbon and nitrogen accumulation in grain legumes is an important step in understanding how to improve their productivity in water-limited environments. A growth model was used to assist in the interpretation of two field experiments comparing the performance of soybean, cowpea and black gram under water deficits, and to assess the importance of  different physiological traits in determining productivity in these grain legumes. The coefficients of the relationships in the model describing leaf growth, carbon and nitrogen input, seed growth, and the water budget were obtained from the literature and from glasshouse and field experimentation. The principal differences in input variables to model the growth of soybean, cowpea and black gram were those describing leaf emergence rate, N fixation during seed filling, and the biochemical composition of the seeds. The relationship describing the response of leaf-area growth, radiation-use efficiency and N fixation to soil water content differed little among species. Similarly, those input variables associated with radiation interception and solar radiation-use efficiency were held constant for the three species. An important difference among the species was that N fixation continued during seed growth in soybean but did not in cowpea or black gram.  aGlycine Max  aSoja  aVigna Mungo  aVigna Unguiculata  aCaupi  aCowpea  aDeficit hidrico  aSoybean1 aMUCHOW, R. C.1 aLUDLOW, M. M.1 aLEACH, G. J.1 aLAWN, R. J.1 aFOALE, M. A.  tField Crops Researchgv. 17, n. 2, p. 121-140, 1987.