Germinação e armazenamento de sementes, produção de mudas e fenologia de Talinum triangulare (Jacq.) Willd., Cuiabá/MT

Abstract

The species Talinum triangulare (Jacq.) Willd. (Talinaceae) is often found in tropical environments. In Brazil it is used as food in the North and Northeast regions, due to its nutritional and cultural value. The objective of this study was to study the temperature, pre-soak and light condition in the germination to evaluate the seed performance during storage. Also, to evaluate the potential of rooting of cuttings in four seasons of collection, as well as, the production of seedlings in trays in three environments of shading. In addition, to describe the phenological BBCH scale and the duration of the main stages of development and the germination of the seeds in function of the climatic conditions in different times of evaluation of the species. For this, this work was divided in four chapters. In the first chapter, there are evaluations of five temperatures (15, 20, 25, 30 and 30/20 ºC) in the germination of the seeds. After four pre-soaking periods (0, 12, 24, 36 and 48 hours) and four germination conditions (constant light, constant dark, photo period of 8/16 and 12 / 12 hours light / dark, respectively). After these two tests, the seeds were stored in three environments (A1: 7 ± 2 °C and RH of 65 ± 4%, A2: 18 ± 2 °C and RH 63 ± 4% and A3: 25 ± 2 °C and UR of 51 ± 4%). Seed germination was evaluated every three months for 24 months of storage. The seeds of T. triangulare presented the best results for germination at 30/20 °C alternating temperature, with 24 hours of pre-soak in water and photoperiod of 12 hours. Storage at the condition of 7 ± 2 °C and RH of 65 ± 4% prolongs the viability of the seeds. In the second chapter, the rooting of the stakes was evaluated in four seasons of collection and installation of the experiment (summer/January, autumn/March, winter/July and spring/October), four types of stakes (underground: xylopodium, aerial: basal, medium and apical) and three substrates (commercial: Vivatto®, washed and sterilized sand and fine expanded vermiculite). The xylopodic cuttings have the best results for all analyzed variables, followed by the basal cuttings. Sand and vermiculite are efficient in maintaining the survival of the cuttings; there are no differences in the percentage of rooting of the cuttings in the different substrates, however, the commercial substrate provides the obtaining of more vigorous seedlings. In autumn, the highest percentage of rooting of the cuttings was observed (53.7%). In 10 the third chapter the treatments were composed by the factorial 3x5, with three levels of shading: no screen, 35 and 50% shading; and five doses of Bacillus subtilis (Serenade®), applied to the substrate (0, 2, 4, 6 and 8 mL L -1 of commercial substrate) before sowing. In the environment with 35% shading the seedlings are higher, with longer root length, greater stability of the clod and greater fresh mass of the shoot. The environment without shade screen favors chlorophyll content, Dickson quality index, height/diameter ratio, and fresh and dry root mass. The environment with 50% shading is not favorable to the production of T. triangulare seedlings. The doses of B. subtilis applied to the substrate do not generate significant increases in the characteristics evaluated in the seedlings. In the fourth and last chapter, the phenological evaluation of the T. triangulare species was carried out through the description and duration of the phenological stages during the years 2016 to 2018, in 12 growing seasons. In each evaluation period, phenophase changes were recorded according to the BBCH phenological scale, whose main scale is divided into ten distinguishable phases (0-9). The first (0) determines the germination phase, and the last one (9), refers to the senescence of the plant. These phases were subdivided into secondary (two-digit) and tertiary (three-digit) stages. At each growing season, plant seeds were harvested for the evaluation of physical and physiological attributes in the laboratory. Seven main stages were described for the species: germination (0); leaf development in the main branch (1); development of lateral branches (2); development of floral bud (5); flowering (6); maturity of seeds (8); senescence of plants (9). These stages were divided, giving a two- and three-digit code for each development phase. The time of cultivation influences the duration of the phenological stages. The seeds of T. triangulare harvested in plants conducted under milder climatic conditions present better germination results.