Alternating temperature and accelerated aging in mobilization of reserves during germination of Carica papaya L. seeds

Abstract

-The aim of this study was to identify the phases of water absorption during germination of Carica papaya seeds and evaluate the influence of alternating temperature and accelerated aging on mobilization of reserves during germination. Weight gain was evaluated, obtaining the imbibition curve. Phase I of germination comprises the period from zero to five hours; phase II, from five to 120 hours; and phase III begins after 144 hours. Seeds were subjected to the germination test under temperatures of 25 ºC and of 20-30 ºC (16/8 h), and before and after accelerated aging (43 °C / 72 h). During the germination test, at initial time, after 4, 10, 120, and 240 hours of soaking, we determined the levels of soluble sugars, starch, lipids, and total proteins. Greater germination was observed under alternating temperature. Under this condition, there is reduction of carbohydrates, lipids, and proteins in phase I, and fluctuations in lipid levels, and an increase in protein levels during phases II and III. Mobilization of lipids in papaya seeds is not influenced by accelerated aging, but the seeds subjected to aging have lower protein content in phase III.Index terms: soaking, papaya, soluble sugars, starch, lipids, proteins.Alternância de temperatura e envelhecimento acelerado na mobilização de reservas durante a germinação de sementes de Carica papaya L.RESUMO -Objetivou-se, neste trabalho, identificar as fases da absorção de água durante a germinação de sementes de Carica papaya e avaliar a influência da alternância de temperatura e do envelhecimento acelerado na mobilização de reservas durante a germinação. Foi avaliado o ganho de peso, obtendo-se a curva de embebição. A fase I da germinação compreende o período entre zero e cinco horas; a fase II, entre cinco e 120 horas; e a fase III se inicia após 144 horas. Sementes foram submetidas ao teste de germinação sob temperaturas de 25 ºC e de 20-30 ºC (16/8 h), e antes e após o envelhecimento acelerado (43 °C / 72 h). Durante o teste de germinação, no tempo inicial, após 4, 10, 120 e 240 horas de embebição, foram determinados os teores de açúcares solúveis, amido, lipídeos e proteínas totais. Observou-se maior germinação sob alternância de temperatura. Nesta condição há redução dos carboidratos, lipídeos e proteínas na fase I, flutuações nos teores de lipídeos e aumento nos teores de proteínas durante as fases II e III. A mobilização dos lipídeos em sementes de mamão não sofre influência do envelhecimento acelerado, mas as sementes submetidas ao envelhecimento apresentam menor teor de proteínas na fase III.Temos para indexação: embebição, mamão, açúcares solúveis, amido, lipídeos, proteínas.

Mobilization of reserves and vigor of soybean seeds under desiccation with glufosinate ammonium

“…Within 24 hours of soaking, all treatments showed radicle protrusion, with water content in the seeds close to 60%, coinciding with Mengarda et al (2015) and Castro et al (2004) who have reported that at the end of phase II during germination, the seeds water content is close to 60%, starting phase III, when root protrusion starts. Han et al (2013) have defined that phase II is between 12 h and 24 h of soaking in soybean seeds.…”

Relationships between substrate and the mobilization of reserve with temperature during seed germination of Ormosia coarctata Jack.

“…Unfavorable temperature conditions can negatively affect reserve mobilization, thereby impairing germination (Mengarda et al, 2015). Ataíde et al (2016), however, observed no differences in reserve mobilization in seeds germinated at 15 or 25 °C.…”

“…Low germination temperatures were shown to decrease the concentration of linoleic acid in Helianthus annuus seeds (Belo et al, 2014), suggesting that the synthesis of this fatty acid was inhibited. Sugar, starch, lipid, and total protein concentrations were higher in Carica papaya seeds imbibed at constant temperature (25 °C) than at alternating temperatures (20 and 30 °C) (Mengarda et al, 2015).…”

Effect of mercury-treated soil on germination and growth of papaya (Carica papaya L.)

“…During field development, the papaya is considered a full-sun plant that is fairly resistant to salinity and water restriction. The plants are sensitive to salinity and intense irradiance during their early stages of development (Cavalcante et al, 2010;Mengarda et al, 2014). Extreme temperatures, drought, winds, injuries, and viral infections are all stressors that papaya is susceptible to, especially during the reproductive phase (Raza et al, 2019).…”

“…The photosynthetic mechanisms of papaya are influenced by several environmental variables (Campostrini and Glenn, 2007). The emergence of seedlings is affected by high irradiance, whereas the development of seedlings is affected by low irradiance (Mengarda et al, 2014).There is genetic diversity in papaya response to light conditions, including adjustments to leaf chlorophyll concentration that prevent photosynthetic photoinhibition (Campostrini and Glenn, 2007).…”