Diversidade de respostas de plântulas de cultivares de Psidium guajava L. sob estresses osmótico e salino in vitro
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Data
2024-06-24
Autores
Silva, Kaoany Ferreira da
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Universidade Federal do Espírito Santo
Resumo
Over the years, the occurrence of saline soils and low-quality water has increased in commercial crops, a problem that directly interferes with the productivity of several important crops, including guava (Psidium guajava L.). As the most important fruitful crop in the Myrtaceae family, guava presents great genetic variability and is cultivated in various regions in Brazil, suggesting its high potential for agroclimatic flexibility. The adoption of technologies like in vitro assays has been shown as powerful allies in this domain in front of benefits as high repeatability in small spaces, environmental control and several others. This study aimed to investigate the responses triggered by Psidium guajava L. seedlings under osmotic and saline stresses in vitro through the addition of active compounds, namely Mannitol and NaCl, to the culture medium. In the first chapter, morphological - shoot lenght (mm), root lenght (mm), leaf number and total fresh weight (mg) - and anatomical variables - cuticle and epicuticular wax production - were analyzed in P. guajava ‘Paluma’ under medium without active compounds (Ψos = 0 MPa), 12,26 g L-1 Mannitol (Ψos = -0,5 MPa), 24,52 g L-1 Mannitol (Ψos = -1 MPa), 5,9 g L-1 NaCl (Ψos = -0,5 MPa), and 11,8 g L-1 NaCl (Ψos = -1 MPa) in vitro culture medium. It was observed that P. guajava ‘Paluma’ seedlings exhibited responses such as a reduction in the number of leaves under stress, with a focus on osmotic stress in vitro, and an increase in cuticle and epicuticular wax on leaves under saline stress. In the second chapter, morphological - shoot lenght (mm), root lenght (mm), leaf number and total fresh weight (mg) - and biochemical variables - chlorophyll a (g kg-1 MS), chlorophyll b (g kg-1 MS), carotenoids (g kg-1 MS), phenolic compounds (mg g-1 MS), aminoacids (mM g-1 MS), proline (mmol kg-1 MS) e malondialdehyde (mmol g-1 MS) - of seedlings were analyzed under a factorial design, including the same treatments applied in the first chapter and three commercial cultivars of P. guajava, ‘Paluma’, ‘Cortibel Rugosa Média’, and ‘Cortibel Rugosa Grande’. The results showed differences between the brazilian commercial cultivars of P. guajava under osmotic and saline stress. These differences were noticeable through the responses triggered by their seedlings. All commercial cultivars showed an increase in plant biomass, albeit with distinct "preferences". While P. guajava ‘Paluma’ seedlings increased both fresh and dry mass under both stresses, P. guajava ‘Cortibel Rugosa Média’ seedlings increased their rates under higher Mannitol concentration in the culture medium and both NaCl treatments, and P. guajava ‘Cortibel Rugosa Grande’ seedlings increased under ionic stress in both treatments. It was concluded that P. guajava plants develop differently responses when subjected to osmotic and saline stress. These mechanisms extend to morphological, anatomical and biochemical levels, which varies also among cultivars. Therefore, characterizations of these responses are necessary to understand each cultivar particularities and its climatic aptitude, in order to stablish a correct and efficient handling for each one
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Palavras-chave
Goiabeira , Manitol , NaCl , Cultura de tecidos , Guava , Mannitol , Tissue culture