Polinização e vingamento de ameixeira japonesa (Prunus salicina Lindl.). Avaliação da colocação sequencial de colmeias e de um bioestimulante

Mestrado em Engenharia Agronómica - Instituto Superior de AgronomiaRESUMO Durante o ano de 2008, estudou-se o vingamento da cultivar de ameixeira japonesa ‘Angeleno’ em Campo Maior, Bombarral e Setúbal utilizando a cultivar Fortune como polinizadora. Nas 3 regiões, a eficácia da colocação sequencial de colmeias (T1) nos pomares e da utilização de um bioestimulante Göemar BM86® (T2) para auxílio de vingamento foi comparada com a prática comercial (T0), que consiste na colocação da totalidade das colmeias a 10% da floração. Dada a ocorrência de geada em Campo Maior, a análise do vingamento e da produção apenas foi realizada para Bombarral e Setúbal. Nestas regiões, o vingamento inicial registou médias de 7,33% em T0, 7,38% em T1 e 14,31% em T2. O comportamento relativo das modalidades manteve-se até à colheita, verificando-se uma densidade de colheita de 19,7 frutos/cm2 em T2, de 10,5 frutos/cm2 em T0 e de 9,5 frutos/cm2 em T1. Este acréscimo de vingamento em T2 não teve reflexos negativos na qualidade dos frutos, já que as classes de calibres se mantiveram homogéneas e todas superiores ao calibre mínimo comercializável. As condições climáticas afectaram fortemente os resultados, evidenciando a importância da sua análise na escolha do local para instalação de pomares de ameixeira. EXTENDED ABSTRACT Plum productivity is directly related with pollination and fruit set. Japanese plums carry a gametophytic self-incompability system, that prevents self-pollination or cross pollination with cultivars that harbor the same haplotypes. Therefore, cross pollination with compatible cultivars is an important requirement to ensure a suitable yield. Insects have to be introduced to promote pollen transfer ensuring that fruit set is achieved. In commercial orchards, fruit growers normally introduce bee colonies when 10% of the flowers are open. In this study, we compared this practice with an alternative practice consisting in the introduction of half of the bee colonies at 10% of the flowers open and the remaining part at full bloom. In addition, we also studied the effect of the application of a biostimulant, the Göemar BM 86®. This product is obtained from seaweeds (Ascophyllum nodosum) and is considered to induce beneficial effects on the growth of the pollen tube. This study was conducted in 2008 in three distinct regions of Portugal, namely in Bombarral (in the Oeste region), in Setúbal (40km South from Lisbon) and Campo Maior, near the border with Spain, located at the same latitude as Lisbon. The three orchards were certified to integrated pest management and they were planted about 15 years ago. In the three orchards, the cultivar studied was Angeleno and the polliniser used was the cultivar Fortune. During the growth cycle, flower number, the length and the diameter of the branches and the fruit set, at beginning, in an intermediate stage and at harvest (final fruit set) were counted. After the harvest the size of all fruits was measured and the weight was estimated according to a previously established linear regression. In order to evaluate the impact of the climate conditions, climate data of the three regions during the period of flowering and fruit set was recorded. Concerning flower number, flowering was more abundant in Campo Maior than in the other regions. In Campo Maior, the trees subjected to the Göemar BM86® treatment were severely affected by frost, therefore results were not fully conclusive. In the other two regions, the sequential introduction of bee colonies did not increase significantly the fruit set or any production parameter (size or weight of fruits). Additionally, the interaction between the treatments and locals was significant, showing the influence of climate conditions. Considering only Bombarral and Setúbal, initial fruit set was 7.33%, 7.38% and 14.31% in T0, T1 and T2 respectively. Final fruit set was 3.38%, 3.59% and 8.74%, in T0, T1 and T2 respectively. The highest values of fruit set in T2 resulted in a significantly higher crop density in T2 (19.7 fruits/cm2), compared to T0 (10.5 fruits/cm2) and T1 (9.5 fruits/cm2). Furthermore, fruits derived from trees treated with Göemar BM 86® had homogeneous size classes and all above the minimum size that is used commercially. This assay suggests that this growth regulator may have a beneficial effect in fruit setting in plum. However, it has to be considered that the application of such product implies three sprays, which may represent an additional cost (although Göemar BM 86® spraying may be combined with other products). One last consideration relates to the fact that weather conditions are of extreme importance and can determine the success of plum production, no matter which cultural practices are carried out. In our experiment, we verified that the climate conditions were as influent as cultural practices