Physiological changes in Mimosa caesalpiniifolia Benth. seeds from different sources and submitted to abiotic stresses

Abstract

A B S T R A C TSeed germination of species that develop in arid and semi-arid soils can be altered by water deficit and abundance of salts in the soil. Knowledge on tolerance limits is fundamental to understand the adaptive capacity of species under such conditions. The objective of this study was to evaluate the physiological changes (germination and vigor) of Mimosa caesalpiniifolia seeds from different regions and submitted to water and saline stresses. To simulate water stress, the osmotic agent polyethylene glycol (PEG 6000) was adjusted to the potentials of 0, -0.2, -0.4, -0.6 and -0.8 MPa, whereas for the saline stress, NaCl solutions were adjusted to the potentials of 0, -0.1, -0.3, -0.5, -0.7; -0.9 and -1.1 MPa. The experimental design was completely randomized, in a 3 x 5 factorial scheme for water stress and 3 x 7 factorial scheme for saline stress, with four replicates of 25 seeds. The variables analysed were: germination, germination speed index and seedling shoot length, root length, shoot dry matter and root dry matter. M. caesalpiniifolia seeds, coming from different geographic regions, showed similar physiological responses to water stress; with respect to salt stress, their tolerance varies according to the region of harvest, and those from Vazante, MG, Brazil were more tolerant during germination and initial growth of seedlings.Alterações fisiológicas em sementes de Mimosa caesalpiniifolia Benth. de diferentes procedências e submetidas aos estresses abióticos R E S U M O A germinação de sementes de espécies que se desenvolvem em regiões áridas e semiáridas pode ser afetada por fatores como deficiência hídrica e excesso de sais no solo, desta forma, o conhecimento sobre os limites de tolerância a esses fatores, é fundamental para compreender a sua capacidade de adaptação. Objetivou-se neste trabalho avaliar as alterações fisiológicas (germinação e vigor) de sementes de Mimosa caesalpiniifolia provenientes de diferentes regiões brasileiras (Sudeste, Centro-Oeste e Nordeste) e submetidas aos estresses hídrico e salino. Para simular o estresse hídrico foi utilizado o agente osmótico polietilenoglicol (PEG 6000), ajustado para os potenciais de 0; -0,2; -0,4; -0,6 e -0,8 MPa, enquanto para o salino utilizou-se as soluções de NaCl nos potenciais de 0; -0,1; -0,3; -0,5; -0,7; -0,9; -1,1 MPa. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 3 x 5 para estresse hídrico e 3 x 7 para estresse salino, com quatro repetições de 25 sementes. As variáveis analisadas foram: porcentagem de germinação, índice de velocidade de germinação, comprimento da parte aérea e da raiz e massa seca da parte aérea e da raiz de plântulas. As sementes de M. caesalpiniifolia, provenientes das diferentes regiões geográficas, respondem fisiologicamente de maneira semelhante ao estresse hídrico; já com relação ao estresse salino, a tolerância das sementes é variável em função da região de colheita, sendo as provenientes de Vazante, MG, mais tolerantes durante a germinação e o crescimento inicial das plâ...

Environmental factors affecting germination of Mimosa ephedroides (Fabaceae), an endemic shrub from Monte Desert, Argentina

“…Nasr et al, (2012), pointed out that saline stress during germination affects cell division and elongation, and therefore, mobilization of essential reserves for this stage. Furthermore, under saline stress, seed reserves that could be used for growing embryonic axis are used to repair damaged cells (45). Saline stress increases MGT and reduces germination percentages, as shown by this study.…”

Physiological performance of Tabebuia aurea seeds subjected to abiotic stresses

“…The decrease in shoot dry mass with the use of PEG 6000, as a function of the reduction in the water potential of the solution, may be associated with the reduction in the speed of physiological and biochemical processes. In addition, under this condition of water deficit, hydrolysis and mobilization of reserves in the seeds during the germination process are usually difficult (SOUSA et al, 2018;LEAL et al, 2020). Similarly, the water stress simulated by PEG 6000 caused a reduction in the dry mass of roots and shoots of P. moniliformis seedlings (MATOS et al, 2021).…”

“…For this reason, plant production becomes dependent on adequate management, with irrigation and salinity correction practices to minimize the occurrence of water and salt stresses (SOUSA et al, 2018;LEAL et al, 2019). Tests with simulation of water and salt stress in the laboratory have been used to identify species that are capable of developing in stressful environments.…”