The main purpose of the study was to determine the amount of aminoacid "Prolina" in the leaf of Valencia orange (Citrus Sinensis) in relation with the water available in a soil Mollisols (Fluventic Haplustolls); the results are from the cycles 1993 and 1994. We work in orange Valencia graft on: madarin orange, Cleopatra (Citrus Reshssi), lemon Volkameriano (Citrus Volkameriano) and Citrange Carrizo (Poncirus trifoliata). The soil was a Fluventic Haplustolls, sandy loam the experimental design was aleatory, the irrigation was each 5-10 and 15 days. There is a significant difference at 0.01 P between different irrigations and the amount of proline during February and April 1994. In February Citrus Volkameriano presents the biggest amount of proline 15.83 micrograms/gr fresh material when the plants were under condition of moderate (10 days) to extreme (15 days) deficits of water. During April the citrus Volkameriano presents the proline in 89.20 microgram/gr fresh material in condition of moderate (10 days) deficit of water. The citange Carrizo present the lowest content of proline 5.75 microgram/gr fresh material under conditions of extreme hydric deficit.

Plantas jovens de acerola propagadas sexuada e assexuadamente foram submetidas a um déficit hídrico de 20 dias de suspensão da irrigação. No decorrer desse período, foram determinados a acumulação de prolina, o potencial da água na folha (psiw), o potencial osmótico, o teor relativo de água (TRA), a resistência difusiva (Rs), a transpiração (E) e a temperatura foliar (Tf), além de mensurados a radiação fotossinteticamente ativa (PAR) e o déficit de pressão de vapor (DPV) do ar na câmara do porômetro. O aumento da concentração de prolina para os dois tipos de plantas ocorreu a partir do 5º dia de suspensão de rega, sendo de 38,1 vezes mais que o controle para as plantas oriundas de sementes e de 26,4 vezes para as enxertadas, no 10º dia de suspensão da irrigação. Os valores mínimos de psiw nas plantas sob severo estresse hídrico variaram de -4,5 a -5,7 MPa, sendo o menor deles verificado nas plantas de origem sexuada. Estas apresentaram ainda os maiores valores para E (0,9 mmol.m-2.s-1) e para concentração de prolina (20,42 mg.g-1 MS), e os menores para o TRA (38,4 %) e para a Rs (940 s.m-1), no final do experimento. As aceroleiras desenvolveram estratégias de sobrevivência à seca, com características diferenciadas, em função do prolongamento do estresse, o qual influenciou significativamente os parâmetros avaliados, com exceção da temperatura foliar. | Young sexually and assexually propagated Barbados cherry plants were submitted to water deficit (20 days without irrigation). During this period the accumulation of proline, water potential of branches, osmotic potential, the relative water content of leaves, the leaf diffusive resistance, the transpiration rate and leaf temperature in the cuvette were determined. In addition, photosynthetically active radiation (PAR) and vapor pressure deficit (VPD) were measured in the porometer cuvette. The concentration of proline for both types of plants began to increase on the fifth day without watering, and reached 38.1 times the concentration in the control plants grown from seeds and 26.4 times the concentration in grafted plants on the tenth day without watering. The lowest levels of leaf water potential in the plants suffering from severe water stress varied from -4.5 to -5.7 MPa, the lowest values being observed in the sexually propagated plants. These plants also showed the highest values for transpiration (0.9 mmol.m-2.s-1) and proline concentration (20.42 mg.g-1 DM), the lowest for relative water content of the leaves (38.4%) and diffusive resistance (940 s.m-1) at the end of the experiment. The Barbados cherry plants developed strategies for surviving drought, with differences between various characteristics, resulting from prolonged stress, which significantly influenced the parameters evaluated, with the exception of leaf temperature.