Tag Archives: photosynthesis

73-85 A. Karlsons and A. Osvalde
Effect of zeolite, clay and peat on salt stress tolerance of lettuce (Lactuca sativa L.)
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Effect of zeolite, clay and peat on salt stress tolerance of lettuce (Lactuca sativa L.)

A. Karlsons* and A. Osvalde

Institute of Biology, Faculty of Medicine and Life Sciences, University of Latvia, 4, O. Vaciesa Street, Riga, LV−1004, Latvia
*Correspondence: andis.karlsons@lu.lv

Abstract:

The present study aimed to investigate the effects of natural zeolite, clay and peat amendments on the growth and NaCl absorptions of lettuce (Lactuca sativa L.) under gradually increasing salinity. Four different growing media based on quartz sands with 10% additions of zeolite, clay and peat were tested. The worst effect of NaCl on plant biomass was evident at the highest salinity levels for zeolite applications. While adverse salinity impact on leaf and root biomass was least pronounced in treatments with peat additives. As expected, the lowest Na concentrations in plant tissues were found in the growing media supplemented with zeolite. In the case of Cl, however, it was the opposite – lettuce leaves accumulated significantly higher chloride concentrations in the zeolite variants in salinity treatments above 20 mM NaCl. In the control, clay and peat treatments, as the substrate salinity increased, the Cl level in the plant increased similarly. Adverse changes in leaf chlorophyll concentration (SPAD) and photosynthetic rate (µmol m^-2 s^-1) parameter appeared under salinity concentrations above 20 mM and were more pronounced in zeolite and sand substrate. According to the obtained results, peat additives can effectively mitigate the harmful effects of excessive salts by binding and immobilizing them as well as improving the water-holding capacity and nutrient availability. The study also concluded that natural zeolite successfully immobilizes cationic sodium, but the harmful effect of chlorine significantly reduced plant growth and photosynthetic performance. Clay additives to the growth medium showed the potential to reduce the adverse effects of salinity on lettuce, however, under the experimental conditions implemented, the effect was small.

Key words:

organic matter, photosynthesis, plant biomass, pot experiment, sodium chloride

317-328 L. Āboliņa, A. Osvalde, and A. Karlsons
Effect of substrate moisture level on cloudberry seedling growth and development after propagation
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Effect of substrate moisture level on cloudberry seedling growth and development after propagation

L. Āboliņa¹²*, A. Osvalde¹, and A. Karlsons¹

¹University of Latvia, Institute of Biology, O. Vaciesa street 4, LV-1004 Riga, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Agriculture and Food technology, LV-3001 Jelgava, Latvia
*Correspondence: laura.abolina@lu.lv

Abstract:

Experimentation of cloudberry cultivation has recently started in Latvia. Propagation is an essential part of cloudberry cultivation strategy, and it is an important step to ensure cloudberry survival and high vitality in field conditions. Optimal moisture conditions have to be determined for seedling development in the greenhouse. Potted cloudberries, cultivar ‘Nyby’, were grown at four different relative moisture levels of the substrate (in percent of the full water-holding capacity of the peat) – 50%, 60%, 70%, and 80%. Physiological measurements were taken once every week, including the concentration of total a and b chlorophyll in SPAD units and stomatal conductance in mmol m^-2s^-1. Morphological parameters, such as the number of leaves per pot, leaf size (cm), number of winter buds and visual score (from 1 to 5) were measured at the end of the vegetation season. Results revealed significant differences between the substrate moisture treatments for chlorophyll content in leaves, winter bud development and visual scoring. The authors note that slightly higher results were found for all parameters for the 80% treatment, following the tendency of increased plant vitality in higher moisture levels. This study indicates that a relative moisture of at least 70% of the full water-holding capacity of the peat is necessary for successful cloudberry growth and development under greenhouse conditions.

Key words:

cultivar Nyby, greenhouse, peat substrate, photosynthesis, Rubus chamaemorus, SPAD, transpiration, winter buds

685-702 M. del Rosario Jacobo-Salcedo, R. David Valdez-Cepeda, I. Sánchez-Cohen, L.Á. González-Espíndola, J.G. Arreola-Ávila and R. Trejo-Calzada
Physiological mechanisms in Ficus carica L. genotypes in response to moisture stress
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Physiological mechanisms in Ficus carica L. genotypes in response to moisture stress

M. del Rosario Jacobo-Salcedo¹³, R. David Valdez-Cepeda², I. Sánchez-Cohen³, L.Á. González-Espíndola¹, J.G. Arreola-Ávila¹ and R. Trejo-Calzada¹*

¹Universidad Autónoma Chapingo, Unidad Regional de Zonas Áridas, Carretera Gómez Palacio-Cd. Juárez, km 40, C.P. 35230, Bermejillo, Durango, México
²Universidad Autónoma Chapingo, Centro Regional Universitario Centro-Norte,
Apdo, Postal 196, C.P. 98001, Zacatecas, México
³Centro Nacional de Investigación Disciplinaria en Relaciones Agua Suelo Planta Atmósfera del Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, km 6.5 Canal Sacramento Zona Industrial, C.P. 35140, Gómez Palacio, Durango, México
*Correspondence: rtrejo@chapingo.uruza.edu.mx

Abstract:

The genus Ficus comprises cultivated and wild species that vary in phenotypic characteristics of both the plant and the fruit. This genus is considered to originate from Mediterranean regions and arid lands of Europe and Africa, known as the Fertile Crescent. Ficus carica L. (fig) is a globally emerging fruit crop due to its increasing production trends and capacity to produce in low water availability. Understanding the fig tree’s responses to water deficit is essential for adapting to sustainable production and climate change. In this study, we investigated the water deficit tolerance of native Ficus carica accession and the Black Mission commercial variety. This research aimed to define the relationship between resistance to water deficit and plant physiological and biochemical markers (physiological and biochemical). Those markers considered relative water content (RWC), photosynthesis (P_N), stomatal conductance (gs), intercellular CO₂ (Ci), transpiration (E), proline (Pro), and soluble sugar content (SSC). The results revealed that fig genotypes exhibit various adaptive mechanisms and physiological responses to water deficit, including osmotic adjustment, stomatal regulation, and proline accumulation. The water deficit condition was confirmed by measuring the soil water potential; the maximum values were in the range of -2.1 to -3.6 MPa. The ‘Guadalupe Victoria’ accession demonstrated significant water deficit resilience by maintaining higher P_N values in low water availability. Additionally, the study highlighted the role of osmotic adjustments in maintaining water balance and cellular function during stress periods. These findings will provide valuable insights for the selection process of genotypes with enhanced drought tolerance in water-limited environments.

Key words:

native accession, osmotic response, photosynthesis, proline

503-512 J.R. Oliveira, C.M. Hüther, R.A.K. Ricardo, G.K. Donagemma, I. Batista, M.E.F. Correia, M.D. Muller, P.S. Melo, G.M. Corrêa, N.F. Rodrigues and S.R.L. Tavares
Evaluation of photosynthetic variables of Brachiaria brizantha under eucalyptus canopies in a livestock-forestry integration system
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Evaluation of photosynthetic variables of Brachiaria brizantha under eucalyptus canopies in a livestock-forestry integration system

J.R. Oliveira¹*, C.M. Hüther¹, R.A.K. Ricardo¹, G.K. Donagemma², I. Batista¹, M.E.F. Correia³, M.D. Muller⁴, P.S. Melo¹, G.M. Corrêa¹, N.F. Rodrigues⁵ and S.R.L. Tavares²

¹Federal Fluminense University, Department of Agricultural Engineering and Environment, Street Passo da Pátria, n.156, São Domingos, Zip Code: 24210-240, Niterói- RJ, Brazil
²Brazilian Agricultural Research Corporation, Soils Research Unit, Zip Code: 22460-000, Rio de Janeiro-RJ, Brazil
³Brazilian Agricultural Research Corporation, Agrobiology Research Unit, Zip Code: 23891-000, Seropédica-RJ, Brazil
⁴Brazilian Agricultural Research Corporation, Dairy Cattle Research Unit, Zip Code: 36038-330, Juiz de Fora-MG, Brazil
⁵Federal Rural University of Rio de Janeiro, Soils Department, Zip Code: 23890-000, Seropédica-RJ, Brazil
*Correspondence: jroliveira@id.uff.br

Abstract:

Livestock sector generates significant environmental impacts despite its global economic importance. The current challenge is to find sustainable ways of boosting this sector, while mitigating the negative impacts of this activity. In Brazil, degraded pastures are common because of inadequate management, damaging the soil. Integrated livestock-forestry (ILF) systems combine forest species and pastures in the area, incorporating elements of sustainability. In this system, the tree species is related to the productivity of the pasture, as the shade generated by the canopy creates different light conditions, influencing the photosynthetic activity of the forage. The aim of this study was to evaluate the influence of the luminosity of the understory of an ILF system on the photosynthetic activity of the forage species Brachiaria brizantha in the Atlantic Forest region of Brazil. Transient chlorophyll a fluorescence and chlorophyll concentration were analysed in forage plants grown in consortium with Eucalyptus urograndis (Clone 1407), with spacing of 4m between trees and 24m between tree rows. Two treatments were established based on light conditions: the control treatment, corresponding to the condition with the highest light corresponded to the pasture row, and the treatment with the lowest light, corresponding to the area under the canopy. The results show that the low light supplied to the forage plant, during the experiment period, under eucalyptus canopies, promotes changes in the intensity of chlorophyll a fluorescence and chlorophyll concentration, indicating low efficiency of the electron transport chain and changes in leaf nitrogen content, due to a possible stress situation.

Key words:

cattle, forage, light stress, photosynthesis, silvopastoral system