Germinação e crescimento de plântulas de genótipos de aveia branca submetidas ao estresse salino

Abstract

<p>A aveia branca é uma cultura de inverno utilizada em sucessão ao cultivo do arroz irrigado, estando sujeita ao estresse salino, devido ao acúmulo de sais no solo, principalmente na região sul do Rio Grande do Sul. O objetivo deste trabalho foi avaliar a germinação de sementes, o crescimento inicial das plântulas de nove genótipos de aveia branca, bem como identificar os genótipos contrastantes para o caráter tolerância à salinidade. Para isso, os genótipos foram submetidos a diferentes concentrações salinas (0, 25, 50, 75 e 100 mM de NaCl por litro de água), sendo analisadas as seguintes variáveis: porcentagem de germinação, primeira contagem de germinação, índice de velocidade de germinação, comprimento e massa seca da parte aérea e raízes das plântulas. As variáveis analisadas foram afetadas negativamente com o aumento da concentração de NaCl. O comprimento de raiz e o comprimento de parte aérea constitui em variáveis promissoras na separação dos genótipos em relação às diferentes concentrações salinas, permitindo selecionar dois genótipos contrastantes à salinidade, o URS 22 caracterizado como tolerante e o UPF 16 como sensível.</p>

Germination and vigor of soybean genotypes seeds under saline stress

“…A reduction in the GSI under saline stress in association with an osmotic potential ranging from 0.0 MPa to 1.2 MPa has been reported by other authors working with several species of agronomic interest, such as soybean (Chichanosk et al, 2019), sunflower (Rossetto et al, 2021), and oat (Timm et al, 2015). According to Leal et al (2020), this is because low osmotic potentials reduce the absorption of water by seeds and can prevent the sequence of events in the germination process from occurring, thereby reducing the germination speed and percentage.…”

EMERGENCE OF Megathyrsus maximus SEEDLINGS GROWN UNDER SALT STRESS

“…Silva et al (2020) observed that the chemical composition of the BRS Zuri cultivar of Megathyrsus maximus is negatively affected by increasing salinity levels, with a 9.46% reduction in crude protein (CP) content and a 1.34% increase in neutral detergent fiber (NDF). Timm et al (2015) observed a decrease of about 5.0% in seedling emergence percentage and 21.7% in the emergence speed index with increasing salt stress in all white oat (Avena sativa L.) cultivars, while in forage sorghum (Sorghum bicolor L. Moench), Coelho et al (2014) found no differences in seedling emergence percentage among the cultivars evaluated. Although studies evaluating these parameters in M. maximus are scarce, it was observed that increasing irrigation with saline water causes damage to the percentage and speed of germination, as well as to the chemical composition of forage cultivars.…”

“…In the present study, statistically differentiated behavior among cultivars for parameters related to seedling emergence was not observed at the salinity levels employed. Several studies have been conducted with other grass species, and the results show variation in the effect of salt stress among different species and cultivars (Coelho et al, 2014;Timm et al, 2015;Silva et al, 2020). Silva et al (2020) observed that the chemical composition of the BRS Zuri cultivar of Megathyrsus maximus is negatively affected by increasing salinity levels, with a 9.46% reduction in crude protein (CP) content and a 1.34% increase in neutral detergent fiber (NDF).…”