Effects of seed hydration memory on initial growth under water deficit of cactus from two populations that occur in different ecosystems in Northeast Brazil

Abstract

Discontinuity during the rehydration process of seeds that germinate in arid and semi‐arid ecosystems leads to the occurrence of hydration and dehydration cycles (HD cycles). HD cycles play an important role in the persistence and dynamics of plants in these ecosystems. Pilosocereus catingicola subsp. salvadorensis is a cactus that occurs in different ecosystems of northeast Brazil. This species is submitted to different environmental conditions, such as irregularity of soil water availability. This factor directly influences seed production, germination and establishment of new individuals in these ecosystems. The aim of this study was to evaluate the effects of HD cycles on the initial growth of P. catingicola subsp. salvadorensis seedlings from different ecosystems under water‐deficit conditions. Seeds collected in two different ecosystems were submitted to 0, 1, 2 and 3 HD cycles and seedlings from these seeds were submitted to water‐deficit treatments. HD cycles had effects not only during germination, but also in the initial growth and establishment of seedlings. Seeds from different populations had distinct responses to HD cycles and water‐deficit treatments. These effects, as acquisition of a greater tolerance of water deficit, were differentiated between populations of the same species that are established in different ecosystems. The effects of HD cycles interfere directly with seedling recruitment dynamics and the maintenance of these populations.

Seed discontinuous hydration does not benefit germination, but improves drought tolerance of Triplaris gardneriana seedlings

“…However, this adaptive response was only observed when exposure to the conditioning priming agent in seeds occurred moderately, with no positive response to a long-term condition (Singh et al, 2014;Thomas et al, 2020). Our results are partially in line with this statement, demonstrating that seedlings from seeds that have undergone two cycles of HD (moderate exposure), associated with moderate stress exposures, seem to accumulate greater acclimatizing stress responses, such as increased biomass production and leaf area, a behavior also observed by Lima and Meiado (2018b) in Cactaceae. In its turn, the benefits of exposure to the three HD cycles (long-term condition) manifest into greater regulation of RGR in stem diameter and leaf number, and maintenance of RWC even under the most severe stress.…”

“…However, some studies with plants from Caatinga, a Brazilian Tropical Dry Forest, have demonstrated that, sometimes, discontinuous hydration do not favor germination in adequate water availability, but it does benefit the process in drought or salt stress condition (Lima & Meiado 2017;Lima & Meiado 2018b). On the other hand, some observation has showed that, for some species, the benefit of discontinuous hydration has been recognized during plant initial growth (Lima & Meiado 2018a) or during stress environmental conditions conferring to drought or salt-tolerance (Lima & Meiado 2018b).…”

Hydropriming changes temperature thresholds for seed germination of tree species from the Caatinga, a Brazilian tropical dry forest

“…Other studies have already demonstrated the benefits of hydropriming in relation to the time required for seeds to germinate (Contreras-Quiroz et al, 2016;Lima and Meiado, 2017;2018a;2018b;Lima et al, 2018). In these works, carried out on species that also occur in the Caatinga seeds that ondergone HD cycles significantly decreased the germination time This acceleration of germination speed can be beneficial for seeds to germinate and for seedlings to establish themselves in more favorable times and not be exposed to other environmental adversities, such as water Journal of Seed Science, v.43, e202143004, 2021 scarcity, contamination by pathogens, predation, among others.…”

“…Hydropriming can be limited by the amount and time of exposure of seeds to water or conditioning agents. In natural conditions, seeds can undergo several short cycles of hydration and dehydration, which would lead to a greater tolerance to high temperatures at which seeds are exposed to germinate in this semiarid ecosystem (Lima and Meiado, 2017;2018a;2018b;Lima et al, 2018). Cycles of hydration and dehydration of seeds provide biochemical changes, such as mobilization of protein storage, mainly globulins and prolamins (Aragão et al, 2002), synthesis of stress proteins and late embryogenesis proteins (LEA) (Bray, 2004), and accumulation of organic solutes (Matias et al, 2015) allowing seeds to cope better with drought periods, such as the predicted by future climate scenarios (IPCC, 2014).…”

Promoção De Vigor E Germinação Em Sementes Da Caatinga Pela Utilização De Técnicas De Priming

“…Acerca dos resultados obtidos nesta pesquisa em relação a tecnologia do Hydropriming, descritos nas Tabela 1 -3, servem de base para a discussão sobre os seguintes pontos. Primeiro, sementes provenientes da Caatinga apresentam memória hídrica, com eventos de hidratação e desidratação sendo integrantes deste processo, segundo afirma Lima & Meiado (2018), sendo assim, a utilização de longos períodos contínuos de imersão em água poderiam não ser convenientes para algumas populações e espécies provenientes deste bioma. Também, fazendo um paradoxo sobre o escrito de Pereira (2011) e Ferreira et al (2021, pode ser percebido que sementes provenientes de populações vegetais do bioma Caatinga apresentam comportamentos diferentes em relação a promoção de germinação e vigor, em relação a utilização da imersão em água pelo período de 24h.…”