Metabolismo antioxidante e reconexão dos tecidos vasculares na compatibilidade de mudas enxertadas de pereira e marmeleiro

Abstract

The expansion of the cultivation of temperate fruit trees brought several problems of adaptation of the cultivars, especially the need for new rootstocks adapted to the new regions. The study of incompatibility in the grafting process is very complex and involves anatomical, biochemical and genetic components. Some authors believe that the incompatibility occurs due to a deficiency in the functioning of antioxidant metabolism, which leads to the accumulation of Reactive Oxygen Species (ROS) and, consequently, cell death. If there is no perfectly functioning antioxidant metabolism, cell damage will occur and vascular reconnection will be difficult. Thus, the objective of this study was to correlate the antioxidant metabolism and reconnection of grafting vascular tissues in the compatibility in incompatible intergeneric combinations of quince and pear. The experiment was conducted in the Fruit Sector belonging to the Department of Agriculture of The Federal University of Lavras (UFLA). The rootstocks were conducted with a single stem. The scions were grafted by the cleft grafting method when they had an average diameter of 7 mm to 15 cm in height. The cleft grafts were standardized to approximately 10 cm in length and 7 mm in diameter. Pyrus calleryana and Chaenomeles sinensis rootstocks were grafted with the pear cultivars Packham's Triumph, William's, Triunfo, Primorosa and Shenseri, with the quince cultivar Mendoza Inta 37 and also Pyrus calleryana and Chaenomeles sinensis. A completely randomized design was used with a 2 x 8 factorial scheme, with three replications and 15 grafts per plot. Percentages of graft sprouting, sprout length and diameter were evaluated. For biochemical evaluations, samples were collected in the grafting region at 5, 15, 25, 35 and 45 days after grafting. Samples of three plants were collected per treatment at each time of collection and the samples were separated into two, the scion portion and the rootstock portion. Hydrogen peroxide (H2O2) and lipid peroxidation (concentration of Malondialdehyde - MDA) were evaluated. Anatomical evaluations were also performed in the graft region at the same time of collection. Subsequently, the thickness of the graft bark and the rootstock bark and the area of the callus mass formed were measured. The rootstock Chaenomeles sinensis provides greater growth to quinces Cydonia oblonga and Chaenomeles sinensis. On the other hand, the Pyrus calleryana rootstock provides higher growth to the hybrid pears (Pyrus communis x Pyrus pirifolia) plants, Pyrus calleryana, and the Cydonia oblonga quince. Hydrogen peroxide concentration is higher in scions compared to rootstocks. Lipid peroxidation is higher in the rootstocks than in the scions. Hydrogen Peroxide concentration and Malondialdehyde concentration are similar in compatible and incompatible combinations. Callus formation is not a determinant of graft compatibility.