Introduction. The grapefruit tree has a long production period. In the Jordan Valley, harvest lasts from November to March. Many Jordanian farmers tend to harvest their fruit early to get high prices, regardless of its quality. Thus, the effect of the harvesting date on fruit quality of grapefruit cv. ‘Red Blush’ was evaluated under Jordan Valley conditions for two seasons, 2002 and 2003. Materials and methods. Fruit quality of uniform 25-year-old grapefruit cv. ‘Red Blush’ trees budded on sour orange rootstock was studied during the 2002 and 2003 seasons. Fruits were harvested from October 15 in both seasons with 15-day intervals with a total of eight harvests. The studied data were total soluble solids (TSS), titratable acidity (TA), the [TSS/TA] ratio and juice percentage. Results and discussion. Fruit total soluble solids and fruit juice percentages were at a minimal level during early harvesting dates and increased with time, reaching the maximum level on January 1 for TSS and January 15 for fruit juice percentage in the first season and on December 15 and February 1, respectively, in the second season, after that TSS decreased. Fruit titratable acidity values were at maximal levels during early harvesting dates (October 15) and decreased with time, reaching the minimum level on February 1 in the first season and on January 15 in the second season. The [TSS/TA] ratio ranged from 5.5 to 6.0 between January 1 and February 1 in the first season, and between December 1 and January 15 in the second season. Conclusion. Our study displayed that Jordan Valley growers are harvesting their grapefruits much too early to provide acceptable eating quality fruits to local markets.

Introduction. Generally, in Iran, citrus cultivars are grafted on Sour orange rootstocks. However, susceptibility of this rootstock to tristeza (CTV) has required a research program to replace Sour orange trees with other rootstocks. Materials and methods. Yield performance and fruit quality of Ruby Red and Marsh grapefruits were assessed for 5 years (1999 to 2003) in the Agricultural Research Station in Dezful (Southern Iran) according to the eight different rootstocks used: Carrizo citrange, Citrus amblycarpa, Cleopatra mandarin, King mandarin, Sour orange, Swingle citrumelo, Troyer citrange and Volkamer lemon. Results and discussion. For the 5 years studied, cumulative yields per tree and yield per trunk cross-section area were the highest on Cleopatra mandarin, Sour orange, Swingle citrumelo and Volkamer lemon, whereas trees on Citrus amblycarpa, Carrizo citrange, King mandarin and Troyer citrange were the least productive. The results showed that individual fruit weight, size and skin thickness were significantly higher for both cultivars on Volkamer lemon, compared with the other rootstocks. Fruits on the Cleopatra mandarin rootstock had the lowest weight and fruit diameter. The rootstock type also affected the fruit juice amount and soluble solid content. Fruits from cultivars which were grafted on Sour orange rootstock had total soluble solids of 9.93% and 51% of juice content, whereas on Volkamer lemon rootstock, they had 7.81% of total soluble solids and 45.3% of juice content. Total acid of the fruits from cultivars grafted on Volkamer lemon had the significantly smallest amount (1.33%). In both cultivars of grapefruits, no significant differences were observed except in the size of the fruit, fruit juice and vitamin C contents. Interactions between rootstock and cultivar were significantly different. Conclusion. Our results indicated that the yield and fruit quality of grapefruit are strongly influenced by the rootstock used. Also, the interaction between cultivars and rootstocks may be an interesting strategy for the adaptation of cultivars to different climatic areas.

Introduction. The Brazilian citrus industry is characterized by orange production for processing, with the Rangpur lime (Citrus limonia L. Osbeck) as the predominant rootstock. Grapefruit (Citrus paradisi Macf.) is cultivated on a small scale and represents one of the less studied citrus species. Using other rootstock alternatives to Rangpur lime could increase fruit production and quality. Materials and methods. Ten citrus (Troyer citrange, Swingle citrumelo, Cleopatra mandarin, Valencia Americana sweet orange, Volkamer lemon cv. Catania 2, Nacional and Florida rough lemons, Rangpur lime, Thornton tangelo and trifoliate orange) were evaluated as rootstocks for the Marsh seedless grapefruit in an experiment planted at the Citrus Experimental Station of Bebedouro (EECB), São Paulo State, Brazil, in January 1991. The spacing was 8.0 m between rows and 4.0 m between trees. The experimental design, randomized blocks, presented four replications with three trees per plot. Trees were grown without supplementary irrigation. Yield was evaluated from 1994 through 2000; fruit quality from 1994 through 1999; the tree size in May 2000. Results. For each studied characteristic, the various rootstocks showed significant differences, except for the average weight of the fruit. The data obtained were compared with the results already published in the Brazilian literature. Conclusion. Swingle, Troyer, Cleopatra and trifoliate orange could be used as alternative rootstocks for Marsh seedless grapefruit.

La phaeoramulariose des agrumes au Cameroun due à Phaeoramularia angolensis : expression parasitaire à différentes altitudes.Résumé – Introduction. La phaeoramulariose ou cercosporiose des agrumes due à Phaeoramularia angolensis (De Carvalho & Mendes) P.M. Kirk constitue une sérieuse contrainte de production en Afrique tropicale. L'expression parasitaire peut varier de façon notable d'une localité à l'autre. Matériel et méthodes. L'évolution de la maladie sur de jeunes plants de pomelo Marsh inoculés à l'aide d'une suspension conidienne a été étudiée sur huit sites d'altitudes différentes (80 m à 1250 m). Les données de température (T) et d'humidité relative (HR) maximales, moyennes et minimales ont été relevées sur les sites durant la période d'observation. Résultats et discussion. L'incidence de la maladie a varié de façon croissante en fonction de l'altitude. Sur les huit sites étudiés, celui de Nyombé à 80 m d'altitude (Tmoy > 25 $^{\circ}$C, Tmax > 30 $^{\circ}$C avec HRmoy < 80 %, HRmin < 60 %) s'est révélé très défavorable à la maladie. En revanche, l'expression des symptômes a été complète sur les autres sites qui présentent des conditions climatiques plus fraîches et plus humides (Tmin < 20 $^{\circ}$C et HRmin > 60 %). Conclusion. Ces résultats constituent les premières données de caractérisation des zones à risque d'invasion par P. angolensis. Ces résultats joints à d'autres travaux ultérieurs impliquant différents contextes écologiques permettront d'établir une cartographie du risque épidémique.