Thermal stress and physiological changes in watermelon seeds

Abstract

Given that watermelon is a crop widespread around the world, there is considerable interest in verifying how its seeds physiologically behave under unfavorable temperature conditions. This study aimed to evaluate the biochemical changes mobilization and reserves degradation, as well as the enzyme activity, during seed germination and initial growth of watermelon seedlings subjected to thermal stress, using temperature, germination percentage, germination rate and relative germination frequency over the incubation time as evaluation parameters. The experimental design was completely randomized, in a 5 x 3 factorial scheme, with five temperatures (17 ºC, 20 ºC, 25 ºC, 30 ºC and 35 ºC) and three cultivars (Charleston Gray, Fairfax and Crimson Sweet), with 4 replicates of 50 seeds. Germination, seedling growth, reserve degradation and stress protection system were evaluated. Thermal stress caused deleterious effects on watermelon seeds with germination capacity at well defined temperature limits, being 25 ºC the ideal temperature, with the highest percentage of normal seedlings. Sub- (17 ºC) and supra-optimal (30 ºC) temperatures presented more than 80 % of abnormal seedlings. The α-amylase enzyme activity is intense only at the beginning of germination. Under thermal stress, the proline contents increase mainly in the cotyledons.

Heat stress mitigation on the germination and initial development of carrot seedlings using plant growth regulators1

“…The negative effects of high temperatures during germination were also observed for carrot (Pereira et al 2007) and pepper (Diel et al 2019) cultivars, which showed a lower germination rate Heat stress mitigation on the germination and initial development of carrot seedlings using plant growth regulators when subjected to temperatures above standard ones for the species. In watermelon seeds, the temperature of 30 ºC caused a reduction of 80 % in germination (Silva et al 2018).…”

Physiological Effects of High Temperature Stress in Some Cucurbit Plants

“…Changes and responses to thermal stress induced in the plant occur at all functional levels of the organism, which are reversible at first, but may become permanent. Even if the stress condition is temporary, the plant vitality decreases according to the stress duration (Silva et al, 2018). Understanding the response of plants to high temperatures and the adaptation mechanisms they developed is important to maintain agricultural productivity.…”

Estresse térmico e tratamento químico no potencial fisiológico de sementes de Zea Mays L.

“…Nas sementes, a temperatura atua tanto na indução e quebra de dormência quanto no crescimento embrionário (SILVA et al, 2018). Cada espécie de semente possui uma faixa de temperatura ideal para ocorrer a germinação e emergência, e à medida que a temperatura aumenta acima do valor ótimo, a germinação fica mais lenta e as sementes menos vigorosas, não resistindo ao estresse imposto pelo ambiente (MELO et al, 2012).…”