Physiology in Talisia esculenta seedlings under irrigation with saline water on substrate with hydrogel

Abstract

Salinity interferes in the physiology of seedlings from germination and seedling emergence, so it is necessary to adopt measures to mitigate its effects. The objectives of this research were to evaluate irrigation frequency, saline water, polymer, and container volume in the emergence and physiology of Talisia esculenta (A. St.-Hil.) Radlk. The treatments were obtained from the combination of polymer doses (0.0; 0.2; 0.6; 1.0; and 1.2 g dm-3), electrical conductivities of the irrigation water (0.3; 1, 1; 2.7; 4.3; and 5.0 dS m-1), and irrigation frequencies (daily and alternate), plus two additional treatments to assess the volume of the container. A randomized block design was used. Emergence and leaf indices of chlorophyll, fluorescence, and gas exchange were analyzed 100 days after sowing. The increase in electrical conductivity reduced and delayed seedling emergence. Decreasing irrigation frequency reduced the chlorophyll b index, stomatal conductance, transpiration, net CO2 assimilation, and carboxylation efficiency. The magnitude of the effects of electrical conductivity of water and polymer were associated with the frequency of irrigation. However, both salinity and polymer reduced practically all physiological variables. The reduction in container volume also affected the physiology of the seedlings, with more effects when irrigated on alternate days. The T. esculenta seedlings are considered sensitive to salinity, should be irrigated daily with water with less electrical conductivity than 1.0 dS m-1, as well as higher capacity containers used (0.75 vs 1.30 dm3).

Produção de mudas de Talisia esculenta sob irrigações com água salina em substrato com hidrogel

“…Under lower water availability, larger leaf area is required to sustain the same rate of biomass accumulation, as observed in seedlings of P. edulis, which obtained the highest leaf area ratio when the irrigation frequency was reduced from daily to alternate days or every two days (Carvalho et al, 2013). In addition, water restriction, caused by the lower frequency of irrigation, in addition to compromising growth and biomass Bezerra et al (2022) Production of Talisia esculenta seedlings... accumulation, also reduces the quality of T. esculenta seedlings (Figure 1), as also observed in A. squamosa seedlings (Silva et al, 2018a, b).…”

“…In component one, with 64.47% of the total variability, all variables except for leaf mass ratio were retained. Bezerra et al (2022) Production of Talisia esculenta seedlings...…”

“…Dispersion of growth and quality variables of T. esculenta seedlings and groups of treatments (Table 1) based on the scores of the first and second principal components (PC). Bezerra et al (2022) Production of Talisia esculenta seedlings...…”

“…Under water restriction, caused by the lower frequency of irrigation, biochemical and physiological processes in plants are altered (Moura et al, 2016;Felippe et al, 2020;Bezerra et al, 2022) in order to adjust to the conditions of the environment. Growth is partly governed by cell turgor pressure (Taiz et al, 2017) and, therefore, water limitation reduces both the synthesis and the growth of new cells, consequently altering morphology.…”

“…Salt stress reduces from the emergence of seeds (Bezerra et al, 2022) to the growth and quality of seedlings, as observed in Passiflora edulis (Bezerra et al, 2014(Bezerra et al, , 2019, Artocarpus heterophyllus (Oliveira et al, 2017), Annona squamosa (Silva et al, 2018a, b), Tamarindus indica (Lima Neto et al, 2018), Carica papaya (Nascimento Neto et al, 2020), as well as T. esculenta (Melo Filho et al, 2017), which is considered sensitive to salinity (Bezerra et al, 2022). This is because excess salts have the effect of reducing water potential, hindering water absorption, in addition to the specific toxicity of each ion (Taiz et al, 2017), resulting in physiological and metabolic changes (Bezerra et al, 2022). Since each species has a limit of salinity tolerance, it is necessary to check the limit and, mainly, associate measures that mitigate salt stress to enable the use of water that is restrictive for agriculture.…”