Abstract
Abstract: Seeds vigor can influence seed performance under stress conditions. The objectives of this study were to evaluate the effect of water and thermal stress on germination and performance of melon seedlings, and to verify if germination under stress conditions is an efficient parameter to evaluate the vigor of these seeds. Four lots of ‘Golden Mine’ melon had their initial quality characterized by germination, first count, accelerated aging and seedling emergence tests. Germination under water stress was performed on a paper moistened with PEG 6000 solution at 0.06, -0.3, -0.6 and -0.9 MPa. The percentage and speed of germination, length and dry mass of the seedlings were evaluated. For the thermal stress experiment, cold test and germination at sub- (15 ºC) and supra-optimal (35 ºC) temperatures were performed, as well as at the ideal temperature (25 ºC). The germination of melon seeds under water stress induced by PEG 6000 at -0.3 and -0.6 MPa is an efficient method to detect differences in the physiological potential of lots of melon seeds, but these differences disappear under severe water stress (-0.9 MPa). Germination under sub-optimal temperatures also allows to identify differences in seeds performance and to classify them according to the vigor level.
Highlights
Germination occurs with the resumption of the metabolic activity of the seed embryo in a coordinated and sequential way, which includes hormonal regulation, protein metabolism, reserves transportation, and other events (Rajjou et al, 2012)
Considering that the conditions that seeds face in the soil in order to germinate are not always ideal, the objective of this work was to evaluate the influence of water and thermal stress on the germination and performance of melon seedlings (Cucumis melo L.), and to verify if the germination under stress conditions can be used to estimate the vigor of these seeds
The same practically did not occur in the other lots. These results indicate a lower vigor of these seeds than the ones from the other lots, considering their performance under water stress at -0.3 MPa
Summary
Germination occurs with the resumption of the metabolic activity of the seed embryo in a coordinated and sequential way, which includes hormonal regulation, protein metabolism, reserves transportation, and other events (Rajjou et al, 2012). For these processes, seeds need to reach an adequate level of hydration, which allows the reactivation of the metabolism and, the growth of the embryonic axis (MarcosFilho, 2015). The responses to water stress vary according to the species, intensity and other factors, and in each situation there may be a water potential value in which the germination does not occur (Adegbuyi et al, 1981)
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