Extrato de alga Ascophyllum nodosum (L.) Le Jolis e nitrogênio em mudas de Alibertia edulis (Rich) A. Rich

Abstract

Alibertia edulis (Rich) A. Rich. (Cerrado quince, Rubiaceae) is a tree whose fruits can be consumed fresh or processed. The leaves and fruits have medicinal properties that are widespread in communities in the Cerrado region. As it is a native species, unbridled extractivism becomes a threat, and there is a need for studies on the management and cultivation of the species ex-situ. The use of biostimulants has also been widespread in agriculture, as a way of obtaining quality seedlings. Among these, we can highlight the biostimulant based on seaweed extract (Ascophyllum nodosum - EAn) that increases plant growth, mitigates some biotic and abiotic stresses and improves plant defense by regulating physiological processes. Thus, the objective of this work was to evaluate the growth of Cerrado quince seedlings with EAn and N application. The experiment was carried out with the application of 5 doses of EAn (0, 5, 10, 15 and 20 mL L-1 of water), with and without addition of N (50 mg kg-1 ) to the soil. The experiment was carried out in 5 L plastic pots, under a nursery with 50% shading, and the height, diameter, number of leaves and chlorophyll were evaluated every 30 days, from 50 to 200 days after transplanting (DAT). After harvesting, plant biomass, leaf area, leaf area ratio, shoot-root ratio - RPAR, seedling quality, N content in plant tissue and efficiency of N uptake and use by the plant were evaluated. The experimental design used was randomized blocks, in a 5 x 2 factorial scheme, with three replications, and each experimental unit consisted of a pot with 2 plants in each. The highest seedling heights were 17.83 and 16.25 cm and diameters of 3.77 and 3.29 mm with 15 and 20 mL of EAn L -1 , respectively. The highest number of leaves was 13.4 leaves with N. The leaf area ratio and shoot/root ratio of the seedlings was influenced by the interaction between EAn and N doses, the highest being 0.62 cm²/g without EAn and without N. The highest RPAR was 1.52 in seedlings cultivated with a dose of 4.52 mL of EAn L -1 without N. The highest values of shoot and total biomass were in seedlings cultivated with 15.86 and 20 mL of EAn L -1 , both with N, while the seedlings that received 20 mL of EAn L -1 had higher MSR (1.92 g plant-1 ). The Dickson quality index showed linear adjustment with higher values (0.63 and 0.61) without and with N, both with 20 mL of EAn L -1 , respectively. It is suggested the application of EAn, independent of the addition of N, is a promising practice in the production of seedlings of A. edulis.