Compatibilidade reprodutiva e micropropagação de ameixeiras japonesas.

Abstract

The Japanese plum (Prunus salicina Lindl.) has an important role in the horticulture worldwide. It has great importance in Brazilian market and is gaining fans for its production, especially in Rio Grande do Sul and Santa Catarina where winter conditions are propicious to its cultivation. However, there are some problems faced by farmers and breeders, which limit the increase in domestic production of plum trees, among these, there are the gametophytic self-incompatibility, due to the presence of a codominant multi-site (containing the so-called S-alleles) and susceptibility to Xillela fastidiosa Wells, which affects quality of propagation material. In face of these problems, the objective of this work was to identify physiologically Salleles of six cultivars of Japanese plum and develop a micropropagation protocol for the cv. America. Thus, experiments of controlled pollination were carried out in experimental fields at Embrapa Clima Tempreado (Pelotas/RS) and the in vivo pollination were carried out in the laboratory of six cup cultivars of Japanese plum (America, Rosa Mineira, Pluma 7, Amarelinha, Reubennel and Santa Rosa), to evaluate the fruit set and pollen tube growth (CTP), respectively. Additionaly, were also performed experiments of micropropagation in the Laboratory of Plant Tissue Culture (UFPel/RS) to identify an appropriate protocol for micropropagation of cv. America. In studies of reproductive compatibility, the fruit set was very low for all crosses, with the larger value had occur in the autopollination of 'Reubennel' (8.41%). 'America' only formed fruit when pollinated with the cvs. Rosa Mineira, Amarelinha, Santa Rosa and Reubennel, these last one had mutual compatibility with cv. America. 'Amarelinha' and 'Rosa Mineira' proved to be compatible with the pollen of 'Rosa Mineira' and 'Reubennel'. There was significant interaction for CTP level and pollen used to pollinate each female parents, and the crosses between 'America' x 'Pluma 7' and 'Rosa Mineira' x 'Santa Rosa' were incompatible while cv. America is self-incompatible. Some crosses that showed no pollination and fruiting in the field, hit the egg (level 6) or ovary (level 5) during in vivo pollination, such as 'Reubennel' x 'Rosa Mineira', 'Rosa Mineira' and 'Amarelinha' x 'America' and 'Amarelinha' and 'Pluma 7', and 'Santa Rosa' x 'America'. These results, together with the molecular data of S-alleles, allow a better understanding of the reproductive biology of P. salicina. In the micropropagation experiments we found that the in vitro establishment of basal 11 explants of cv. America in MS medium is higher than the apical explants. BAP concentrations between 0.25 and 0.50mg dm-3 are more appropriate for the multiplication while MS medium supplemented with 1.0mg dm-3 GA3 and 2.0g dm-3 of vegetal charcoal is the most appropriate to in vitro elongation of their shoots. Half of concentration of salts and vitamins of MS medium with the addition of 1.0mg dm-3 of IBA is the most efficient for the in vitro rooting of Japanese plum, cv. America, during periods of less than 20 days, reaching 88% survival after 30 days of acclimatization.