01957naa a2200217 a 450000100080000000500110000800800410001910000200006024500950008026000090017552013230018465000120150765000150151965000100153465000110154470000160155570000170157170000140158870000180160277301190162016541982008-01-29       2007    bl ---       0--  u    #d1 aALVES, A. A. C.  aEvaluation of drought tolerance contrasting cassava varieties under semi-arid environment.  c2007  aCassava varieties are being field evaluated under irrigation and rainfed conditions in the semi-arid environment of Petrolina, Brazil, where the annual average rainfall and potencial evapotranspiration are around 560 mm and 1500 mm, respectively. Plants has been submitted to two water treatment: irrigation and water deficit (irrigated only in the first 3 months after planting). Trials were evaluated in different periods using growth and physiological parameters, aiming to identify most contrasting traits that can be useful to select genotypes for drought tolerant attributes. From the preliminar analysisof the trials'data (not completed yet), the results have showed significant effect of water deficit treatment on production's parameters such as tuber roots fresh weight, number of tuber roots, dry matter and harvest index, with different responses among varieties. The most contrasting traits that have showed correlation to the varieties performance are leaf retention, leaf conductance, and early bulking. Additional analyses, such as abscisic acid, sugars and starch accumulation are currently undergoing. These results will be useful, not only for characterizing the varieties as tolerant or susceptible to drought, but also for defining the better traits for genotype selection in the breeding program.  acassava  airrigation  awater  aStress1 aDITA, M. A.1 aSILVA, A. F.1 aDUQUE, L.1 aSETTER, T. L.  tIn: ANNUAL RESEARCH MEETING, 2007, Benoni. Poster Abstrcts...Benoni: Generation Challenge Programme - CGIAR, 2007.