ABSTRACT The water deficit is one of the main limiting factors to the yield of sweet oranges. The present study aimed to determine alternative rootstocks to ‘Rangpur’ lime for ‘Pera’ sweet oranges grown on tropical hardsetting soils with greater potential tolerance to water deficit. Six citrus scion/rootstock combinations were grown during eight years in an orchard established in Sergipe, Brazil. The tree height, number of fruits per plant, cumulated fruit yield, leaf proline content and survival rate of trees were evaluated between 6th and 8th year after planting. Greater rate of tree loss occurred among the sweet orange onto ‘Orlando’ tangelo, which also induced the lowest cumulative fruit yield. After prolonged water deficit, moderate to high proline content was found in trees grafted on Sunki of Florida mandarin × C13 citrange – 012° (TSKFL × CTC13-012), ‘Orlando’ tangelo, ‘Indio’ and ‘Riverside’ citrandarin. Conversely, after a short water deficit during the wet season, trees on ‘San Diego’ citrandarin and Rangpur lime clone of Centro Nacional de Pesquisa Mandioca e Fruticultura – CNPMF 03 ‘Rangpur’ lime showed higher proline content. Trees onto TSKFL × CTC13-012 and ‘Indio’ also induced the greatest accumulated fruit yield at the 8th year after planting. It is assumed that ‘San Diego’ and CNPMF 03 ‘Rangpur’ induce response more quickly to water deficit, whereas TSKFL × CTC13-012 and ‘Indio’ are less susceptible to prolonged deficit. Therefore, trees on ‘San Diego’ and Indio citrandarin, CNPMF-03 ‘Rangpur’ lime, TSKFL × CTC13-012 hybrid present greater potential to tolerate water deficit and produce more fruits on the hardsetting soils of the coastal tablelands of the Brazilian Northeast.

Resumo: O objetivo deste trabalho foi avaliar os teores de prolina em cultivares de girassol (Helianthus annuus), em condições de deficit hídrico natural na região do Semiárido brasileiro. Treze cultivares foram semeadas em experimentos estabelecidos em três áreas do Nordeste brasileiro. O teor de prolina foi determinado em folhas de plantas no estádio R4-R5. Diferenças significativas entre cultivares ocorreram apenas onde a disponibilidade de água foi menor. As médias de prolina variaram de 3,47 a 17,41 μg g-1. As cultivares de girassol BRS387, BRS323 e BRS324 apresentaram os maiores teores de prolina com 54,74, 46,27 e 35,16 μg g-1, respectivamente. Essas cultivares são as que acumulam mais prolina em condições de deficit hídrico severo.

Abstract: The objective of this work was to evaluate the proline content of sunflower (Helianthus annuus) cultivars, in the conditions of natural water deficit in the Brazilian semiarid region. Thirteen cultivars were sown in experiments set in three sites in the Brazilian Northeast. Proline content was determined on leaves from plants at the R4-R5 stage. Significant differences among cultivars occurred only where water availability was lower. Proline averages ranged from 3.47 to 17.41 μg g-1. The sunflower cultivars BRS387, BRS323, and BRS324 showed the greatest proline contents with 54.74, 46.27, and 35.16 μg g-1, respectively. These are the cultivars that accumulate more proline under conditions of a severe water deficit.