02404naa a2200241 a 450000100080000000500110000800800410001910000220006024501210008226000090020330000110021252015970022365000110182065000230183165000090185465300110186365300120187465300220188670000210190870000170192970000170194677301990196314616572004-10-15       1999    bl uuuu     u00u1 u    #d1 aNEPOMUCENO, A. L.  aPhysiological responses of brazilian soybean cultivars submitted to water deficit in different developmental phases.  c1999  ap.444.  aDrought alone has causing most of the breakage in soybean productivity in Brazil and in the world. The development of new cultivars more tolerant to water deficit is one of the possible solutions to reduce these losses. Therefore, the objective of this work was to study the physiological responses that some Brazilian soybean cultivars present to tolerate drought during different phases of the development. The experimental design used was randomized completely blocks with slip-plots. The plots received three treatments: Irrigated (I), water deficit (WD) during vegetative period (VP) and WD during reproductive period (RP). The sub-plots received five cultivars: Bragg, BR-4, BR-16, OCEPAR 4 e EMBRAPA 48. The rainfall was controlled, according to the treatments, by using mobile shelters (66 m2) constructed over the plots. Photosynthetic rate (A), stomatal conductance (g), relative water content (RWC), and air-leaf temperature difference () were measured in three different dates, at the end of the WD-VP treatment, at the middle of the WDRP treatments. In the average of the cultivars the water deficit decreased A, g, RWC, and BR-4, OCEPAR 4 and EMBRAPA 48 presented the highest A, g, RWC and in all treatments. Although the physiological responses of these cultivars, in theory, favor a possible higher yield, only EMBRAPA 48 did not reduced yield significantly in the treatments. However, based on the physiological characterization, it is possible to suggest that cultivars EMBRAPA 48, BR-4 and OCEPAR 4 have a higher tolerance to water deficit when compared to Bragg and BR-16.  aBrazil  asoil water deficit  aSoja  aBrasil  aSoybean  aTolerancia a seca1 aFARIAS, J. R. B.1 aNEUMAIER, N.1 aDELATTRE, N.  tIn: WORLD SOYBEAN RESEARCH CONFERENCE, 6., 1999, Chicago. Proceedings: invited and contributed papers and posters. Chicago: University of Illinois / Soybean Research & Development Council, 1999.