Lucica Mihalte

Dynamic Analysis of the Evolution of Cereus peruvianus (Cactaceae) Areas Attacked by Phoma sp.

Cereus Peruvianus (night blooming Cereus, or peruvian apple) is one of the sensitive species to Phoma attack. Photographic images can intercept a certain phytopathology, at a certain moment. The computerized analysis of such an image turns into a value the spread which the phytopathological process has at that moment. The purpose of this study is to assimilate the technique of achieving successions of digital photos of Cereus peruvianus f. monstruosa attacked by Phoma sp. Parallely with recording the images, with the help of Rhythm digital temperature humidity controller, were recorded data about the green house microclimate (air humidity-minimum and maximum, temperature-minimum and maximum). In the first stage of the study, the attack presents small fluctuations, reaching a high level in days with low temperatures. So, the most significant growths were recorded in the periods: 10. 02. 2005-20. 02. 2005 with an affected area of 10.97-8.82 = 2.15 and 11. 03. 2005-22. 04. 2005 with growth differences of 14.67-13.32 = 1.35. Generally, the affected areas grow in days with low minimum temperatures. The great advantage of this technique is represented by the possibility of using in situ in home areas of species or crop plants in fields. Repeated images, achieved in time, then overlapped, can provide important data on the evolution of affected areas.

THE SEGREGATION OF TREE HABIT ON PEAR SEEDLINGS IN SIX HYBRID COMBINATIONS

Trees habit is an important trait in pear breeding and pear culture (1, 2, 3). The segregation for trees habit of F1 pear hybrids belonging from six combinations was analysed. The seedlings originate in incomplete diallel cross, effectuated with four genitors (Comtesse de Paris, Milenium, Virgiliu Hibernal, Cluj 89-1-81 selection), were framed in six classes of growth (after UPOV Guidelines), respectively architectural ideotype: 1. Fastigiate; 2. Upright; 3. Semi-upright; 4. Spreading; 5. Drooping; 6. Weeping. In each combination, the majority of F1 hybrids had spreading habit (between 57% in Comtesse de Paris x Milenium and 81% in Milenium x Cluj 89-1-81). The occurrence of high percentages of spreading habit seedlings in all combinations (see the table) suggests that this ideotype of tree growth is easy to obtain in pear breeding. Because a valuable type of tree habit for modern plantation is with a spurred growth habit and strong apical control, it can be appreciated that Milenium (a relative new cultivar created at Fruit Research Station Cluj-Napoca) can be used as genitor for this trait. Especially used as mother genitor in cross with Virgiliu Hibernal (another new cultivar obtained at FRS Cluj), Milenium gave birth to the highest percentage of upright seedlings (16%), and with fastigiate habit (3%)