Alelopatia de Carya illinoinensis (Wangenh.) K. Koch na germinação e desenvolvimento de plântulas de Lactuca sativa L.

Abstract

With increasing interest in the cultivation of Carya illinoinensis (pecan), it has been noted the need to verify if aqueous raw extracts (EBAs) from different plant residues (RV) of pecan have allelopathic effect on germination and development of lettuce seedlings. The VR were collected in distinct phenological phases of this fruit, and correspond to the following plant materials: pruning remains, leaves, fruit epicarp and fruit mesocarp. Separately for each plant material, after collection of the RV, it was dried in a forced ventilation oven and then ground in a knife mill to obtain the powder, which was stored separately in glasses kept away from the light and at room temperature. To obtain the EBA, proceed as follows, separately for each RV, mixed with a blender, 10 g of powder with 90 ml of distilled water, then filtered with beaker gases. The experiment consisted of five treatments and five replicates, totaling 25 experimental units. Treatments used: Witness (distilled water), EBA (10%) epicarpo of the fruit, EBA (10%) mesocarp of the fruit, EBA (10%) pruning remains and EBA (10%) leaves. The lettuce achenes of the cultivar "Crespa Grand Rapis - TBR", from the line of seeds without defensive, remained previously for 3 days at a temperature of 10 ° C to overcome dormancy. Each experimental unit was composed of a box of the gerbox type, previously disinfested with 1.05% sodium hypochlorite, where two sheets of germitest paper were placed in each box, followed by addition of 25 lettuce achenes, previously maintained in 2-2.5% sodium hypochlorite for one minute and then washed in sterile distilled water. And on the germitest paper was poured the solution of each treatment, in the volume corresponding to 2.5 times the mass of the germitest paper. Subsequently, they were incubated in BOD (Biochemical Oxygen Demand) with photoperiod of 12h and temperature of 15 ° C, for seven days. Germination percentage, germination speed index, seedling length, root length, shoot length, and total fresh mass were evaluated. The EBA (10%) epicarp of the pecan fruit had the lowest germination and seedling development indexes, followed by EBA (10%) pecan leaves. It is concluded with the present work that walnut EBAs negatively affected the germination and development of lettuce seedlings.