Genetic similarity of citrus fresh fruit market cultivars

The objective of this work was to assess the genetic similarity of the following citrus fresh fruit market seedless cultivars: Lane Late, Navelate, Navelina and Salustiana sweet oranges (Citrus sinensis (L.) Osbeck), Clemenules and Marisol mandarins (C. reticulata Blanco) and Okitsu satsuma mandarin (C. unshiu Marcovitch), and the hybrids Nova [C. clementina x (C. paradisi x C. tangerina)] and Ortanique (tangor probably derived from C. sinensis (L.) Osbeck x C. reticulata Blanco), utilizing isoenzymatic markers. Electrophoresis analysis of proteins extracted from leaf tissues was utilized to detect polymorphisms at ten isoenzymatic systems. Out of 30 alleles, 16 were polymorphic. The Jaccard coefficient was utilized to estimate the genetic similarity between the cultivars and the unweigthed pair-group method using an arithmetic average (UPGMA) was used to obtain the phenogram (NTSYS 1.7). The cultivars showed high genetic similarity (>72.5%), and were classified in five main groups: sweet oranges, 'Clemenules' and 'Marisol' mandarins, 'Nova', 'Ortanique', and 'Okitsu' satsuma mandarin.

Monitoring the viability of citrus rootstocks seeds stored under refrigeration

The citrus nursery tree is produced through the bud grafting process, in which rootstock is usually grown from seed germination. The objective of this research was to evaluate, in two dissimilar environmental conditions, the viability and polyembryony expression of five citrus rootstocks seeds stored in different periods under refrigeration. The rootstock varieties evaluated were: Rangpur lime (Citrus limonia Osb. cv. Limeira), Trifoliate orange (Poncirus trifoliata Raf. cv. Limeira), Citrumelo (P. trifoliata x C. paradisi Macf. cv. Swingle), Sunki mandarin (C. sunki Hort. ex Tanaka) and Volkamer lemon (C. volkameriana Ten. & Pasq. cv. Catania 2). The experimental design was the randomized blocks in a 11 x 5 x 2 factorial scheme, evaluating from time zero to the tenth month of storage, the five varieties of rootstock in two environments: germination and growth B.O.D type chamber (Biological Oxygen Demand - Eletrolab Brand Model FC 122) at 25 °C; and greenhouse seedbed with partial temperature control (22 °C to 36 °C) and humidity control (75-85%). The plot had 24 seeds in four replicates, using trays with substrate in greenhouse and Petri dishes with filter paper in B.O.D. chamber. The seed germination rate and polyembryony expression were evaluated monthly. It was concluded that Trifoliate and Citrumelo Swingle seeds can be stored for up to seven months, while Volkamer lemon, Rangpur lime and Sunki seeds can be stored for up to ten months. The polyembryony expression rate was slightly higher when measured in greenhouse than in B.O.D. chamber and remained stable in both environments until the seventh month, from which dropped sharply. Citrumelo Swingle seeds expressed the highest polyembryony rate (18.8%), followed by Rangpur lime and Volkamer lemon (average value of 13.7%), Sunki (9.4%) and Trifoliate (3.2%). Despite some differences among varieties, the viability of rootstock stored seeds can be monitored either in the greenhouse or in B.O.D. germination chamber, the latter being the faster and more suitable method.

Effect of trickle irrigation on root development of the wet bulb and 'pera' orange tree yield in the state of São Paulo, Brazil

The aim of this study was to evaluate the effect of different microirrigation designs on root system distribution in wet bulb region, orange orchard yield and quality of orange fruits. The experiment was installed as random blocks with five treatments and four replicates in an orchard of 'Pêra' orange trees grafted on 'Cleopatra' mandarin rootstock. The treatments consisted of: one drip line (T1), two drip lines (T2), four drip lines (T3) per planting row, microsprinkler irrigation (T4) and without irrigation (T5). Irrigation treatments favored yield and ºBrix. The treatment with a single drip line (T1) showed the greatest quantity of roots in relation to the treatments T2 and T3.