Ecofisiologia de sementes de Solanum lycocarpum (Lobeira) em função do mês de dispersão

Abstract

Solanum lycocarpum St. Hil., popularly known as lobeira or wolf fruit, is a tree or shrub belonging to the Solanaceae family. It presents great resistance to water deficit and excess water can delay its germination, which favors its development in stress regions, such as degraded areas and pasture areas, where there is rapid drying of the soil. The general objective of this work was to characterize physiological variations of S. lycocarpum seeds as a function of the month of dispersion, for a period of 12 months, and to associate them with possible variations in dormancy. As specific objectives, it was aimed to analyze, at each collection, the percentage of germination and germination speed index and to relate the results with the climatological data of the study location, in the same months, in order to understand how these factors may have influenced the depth of the dormancy. Ripe lobeira fruits were collected monthly, between July 2018 and June 2019, in a population located in the region of Lavras, MG. For the humidity test, after passing through the acclimatized room for two days, four replicates of five lobeira seeds were weighed and later placed in an oven at 105 ºC for 24 h. For germination test, four replications of 25 seeds were used, washed in sodium hypochlorite (1%; 10 min), placed in gerbox-type boxes on two sheets of germination paper, in germinators, under 8 temperatures, ranging from 15 to 40°C. In a BOD, germination was tested with photo and thermoperiod variation (12 h at 30 °C with light and 12 h at 20 °C without light). The radicle protrusion (2 mm) was evaluated daily and at the same time until 40 days. Germination tests were carried out in a completely randomized design (DIC), in a double factorial model 12 (collection months) x 8 (temperatures). The data obtained reveal that there was no significant difference between the humidity of the collected batches, after passing through two days of drying in an acclimatized room. Germination and IVG of Solanum lycocarpum seeds change according to the month of collection, at temperatures of 25, 30, 35 and 25-30 °C. Germination is higher at temperatures of 20-30 and 30 °C, regardless of the month of collection. For the use of seeds under conditions of thermal stress, the best months of collection are February and April, because they were where the response to the stress condition was better.