Use of hydrogel in the irrigation management of white pitaya (Hylocereus undatus) seedlings: Biometrics and accumulation of organic and inorganic solutes

The initial development of pitayas may be limited by a few factors, among them, water deficit. Agricultural hydrogels can be used as an alternative to enhance the retention and availability of water and nutrients in the soil. Therefore, this study aimed to evaluate the influence of irrigation frequency and hydrogel doses on the development of white pitaya (Hylocereus undatus) seedlings to establish a time interval in days between irrigations that provides better seedling development and determine the hydrogel dose that provides a reduction of water consumption without damaging seedling development. The experimental design consisted of randomized blocks in a 4 x 4 factorial arrangement, in which the treatments corresponded to 4 hydrogel doses (0, 2, 4, and 6 g/plant of Biogel Hidro Plus) incorporated into the substrate and four irrigation frequencies (1, 3, 5, and 7 days of interval). The biometric characteristics, photosynthetic pigments, and organic and inorganic solutes of the plants were evaluated after 120 days. The use of daily irrigation negatively influenced the growth and biomass accumulation of the aerial part of the seedlings and, consequently, provided the lowest values of cladodes of the pitaya seedlings. Pitaya seedlings had greater development when using an irrigation frequency of around 3 days. The application of 6 g/plant of hydrogel provided the highest averages for accumulation of dry biomass, photosynthetic pigments, and organic and inorganic solutes at irrigation levels of 3.6, 4, and about 3.8 days of intervals, respectively. Hydrogel incorporation allowed increasing the interval between irrigations by 1 day without damages to the seedling development.

Dynamic Release of Solutes from Roof Bitumen Sheets Used for Rainwater Harvesting

Bitumen waterproof sheets are widely used to seal building roofs. Previous works have focused on the mechanical-physical properties of bitumen sheets, as well as their aging and degradation processes, and their impact on sealing properties of the buildings. Due to a growing need over recent years to use rooftops in urban environments for rainwater harvesting purposes, it is highly important to better characterize the quality of the harvested water from the bitumen covered roofs, and to shed more light on the impact of bitumen degradation processes on the release of various components to the harvested roof water. In the present study, the extracted organic and inorganic solutes from bitumen-covered roofs by water flow on the bitumen sheets were examined through a series of experiments, including measurements from the roofs of buildings in the center of Israel during the winter of 2019–2020. The results indicated high levels of organic and inorganic solute loads in the roof water during the first flush of the first rain of the winter, with maximal electric conductivity readings at the order of 4 dS/m. However, it was shown that following the first flush, a ~20 mm of cumulative rainfall was sufficient to wash off all the summers’ accumulated solutes from the roof. After this solute flushing of the roof, harvested rainwater along the winter was of good quality, with electric conductivity readings in the range of 0.04–0.85 dS/m. Moreover, it was shown that bitumen sheets which were exposed to direct sun radiation emitted greater loads of solutes, likely a result of elevated aging and degradation processes. The findings of the present research point to the need to find efficient ways to isolate roof bitumen sheets from direct sun radiation and to design rainwater harvesting systems that will not collect the water drained from the first flush.

Evaluation of Calcium Alginate-Based Biopolymers as Potential Component of Membranes for Recovering Biosurfactants from Corn Steep Water

Corn steep water (CSW) is a complex agro-food stream that is used as a source of cost-competitive biosurfactants, since they are produced spontaneously in the steeping process of corn, avoiding production costs. Nevertheless, the extraction of biosurfactants from CSW using sustainable processes is still a challenge. Consequently, the use of calcium alginate membranes could present a novel and sustainable technology for recovering biosurfactants from aqueous streams. Therefore, the aim of this work is to evaluate calcium alginate-based biopolymers, without and with the presence of grape marc as an additive, as a key component of membranes for the recovery of biosurfactants in corn steep water. Biosurfactants are present in CSW, together with other inorganic solutes and biomolecules, such as organic acids, sugars, cations, anions as well as metals. Hence, the competition of these mentioned compounds for the active sites of the calcium alginate-based biopolymers was high. However, they showed a good adsorption capacity for biosurfactants, recovering around 55 ± 2% and 47 ± 1%, of biosurfactants from CSW using both calcium alginate-based biopolymers, with and without biodegraded grape marc. Regarding adsorption capacity, it was 54.8 ± 0.6 mg biosurfactant/g bioadsorbent for the biopolymer containing grape marc, and 46.8 ± 0.4 mg biosurfactant/g bioadsorbent for the calcium alginate-based biopolymer alone. Based on these results, it could be postulated that the formulation of green membranes, based on calcium alginate-based polymers, could be an interesting alternative for the recovery of biosurfactants from aqueous streams including CSW.

ASPECTOS BIOQUÍMICOS E FLUORESCÊNCIA DA CLOROFILA A EM PLANTAS DE MINIMELANCIA HIDROPÔNICA SOB ESTRESSE SALINO*

ASPECTOS BIOQUÍMICOS E FLUORESCÊNCIA DA CLOROFILA A EM PLANTAS DE MINIMELANCIA HIDROPÔNICA SOB ESTRESSE SALINO* LAÍS MONIQUE GOMES DO Ó1, ALIDE MITSUE WATANABE COVA2, PETTERSON COSTA CONCEIÇÃO SILVA3, HANS RAJ GHEYI4, ANDRÉ DIAS DE AZEVEDO NETO5, ROGÉRIO FERREIRA RIBAS6 1Doutoranda em Engenharia Agrícola da Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil [email protected]. 2Pós-Doutoranda no Programa de Pós-graduação de Engenharia Agrícola da Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. 3Doutor em Engenharia Agrícola, Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. 4Professor Visitante, Universidade Federal do Recôncavo da Bahia, Cruz das Almas, Bahia, [email protected]. 5Professor Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. 6Professor Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, s/n, Cruz das Almas, Bahia, Brasil, [email protected]. *Este artigo é proveniente da tese de doutorado do primeiro autor. 1 RESUMO A salinidade é um dos principais estresses abióticos que induz distúrbios bioquímicos e fisiológicos em diversas culturas. O objetivo do trabalho foi investigar os efeitos da salinidade da solução nutritiva (CEsol) sobre a produção, acúmulo de solutos orgânicos e inorgânicos e fluorescência da clorofila a em plantas de minimelancia cv. Sugar Baby. O delineamento experimental foi o inteiramente casualizado com quatro repetições. As plantas foram cultivadas em sistema hidropônico com cinco níveis de CEsol: 2,5; 3,5; 4,5; 5,5 e 6,5 dS m-1. Foram avaliados: massa do fruto, biomassa da parte aérea, teores de clorofilas a e b, fluorescência da clorofila a e teores de solutos orgânicos e inorgânicos. A massa do fruto e a biomassa seca da parte aérea foram influenciadas negativamente pela CEsol. Houve redução na concentração de carboidratos solúveis totais, aminoácidos livres, proteínas solúveis e prolina livre com o aumento da CEsol. Os íons sódio, cloreto e razão sódio/potássio aumentaram com a salinidade e os teores de potássio foram reduzidos. O incremento da salinidade aumentou linearmente o teor de clorofila b e reduziu linearmente o rendimento quântico da conversão de energia fotoquímica do FSII promovendo um ligeiro aumento no rendimento quântico da perda de energia regulada do FSII. Palavras-chaves: biomassa, carboidratos, íons tóxicos, estresse abiótico. Ó, L. M. G.; COVA, A. M. W.; SILVA, P. C. C.; GHEYI, H. R.; AZEVEDO NETO, A. D. de; RIBAS, R. F. BIOCHEMICAL ASPECTS AND CHLOROPHYLL A FLUORESCENCE IN HYDROPONIC MINI WATERMELON PLANTS UNDER SALT STRESS 2 ABSTRACT Salinity is one of the main abiotic stresses that induce biochemical and physiological disorders in diverse crops. This study investigated the effects of nutrient solution salinity (ECsol) on production, accumulation of organic and inorganic solutes and chlorophyl a fluorescence in mini watermelon plants cv. Sugar Baby. The experimental design was completely randomized with four replications. The plants were grown in a hydroponic system with five levels of ECsol: 2.5; 3.5; 4.5; 5.5 and 6.5 dS m-1. The variables evaluated were the mass of the fruit, the biomass of the aerial parts, contents of chlorophylls a and b, fluorescence of chlorophyll a, and contents of organic and inorganic solutes. The mass of the fruit and dry biomass of the aerial parts was negatively influenced by ECsol. There was a reduction in the concentration of total soluble carbohydrates, free amino acids, soluble proteins and free proline with the increase in ECsol. The sodium, chloride and sodium/potassium ratio increased with ECsol and potassium levels were reduced. The increase in ECsol linearly increased the chlorophyll b content and reduced the quantum yield of the photochemical energy conversion of the PSII promoting a slight increase in the quantum yield of the regulated energy loss of the PSII. Keywords: abiotic stress, biomass, carbohydrates, toxic ions.

Source Apportionment of Inorganic Solutes in Surface Waters of Lake Baikal Watershed

The aim of this study was to obtain a detailed picture of the origin of the anthropogenic and natural inorganic solutes in the surface waters of the Lake Baikal watershed using limited data on solute sources. To reveal the origin of solutes, the chemical composition of water was considered as a mixture of solutes from different sources such as rocks and anthropogenic wastes. The end-member mixing approach (EMMA), based on the observation that the element ratios in water uncorrelated with one another are those that exhibit differences in values across the different types of rocks and anthropogenic wastes, was used for source apportionment. According to the results of correlation analysis, two tracers of sources of most abundant ions present in riverine waters were selected. The first tracer was the ratio of combined concentration of calcium and magnesium ions to concentration of potassium ion ((Ca2+ + Mg2+)/K+), and the second tracer was the ratio of sulfate and bicarbonate ion concentrations (SO42−/HCO3−). Using these tracers, three sources of main ions in water, such as sulfide-bearing silicate rocks, non-sulfide silicate rocks and carbonate rocks, were apportioned. The results of cluster analysis showed the possibility of using the ratios of strontium, iron, manganese, molybdenum, nickel, and vanadium concentrations (Sr/Fe, Sr/Mn, Ni/V, Mo/V) as tracers of the trace element sources. The use of these tracers and the obtained data on sources of main ions showed the possibility of identifying the natural trace element sources and distinguishing between natural and anthropogenic trace element sources.

Lateral Transport of Organic and Inorganic Solutes

Organic (e.g., sugars and amino acids) and inorganic (e.g., K+, Na+, PO42−, and SO42−) solutes are transported long-distance throughout plants. Lateral movement of these compounds between the xylem and the phloem, and vice versa, has also been reported in several plant species since the 1930s, and is believed to be important in the overall resource allocation. Studies of Arabidopsis thaliana have provided us with a better knowledge of the anatomical framework in which the lateral transport takes place, and have highlighted the role of specialized vascular and perivascular cells as an interface for solute exchanges. Important breakthroughs have also been made, mainly in Arabidopsis, in identifying some of the proteins involved in the cell-to-cell translocation of solutes, most notably a range of plasma membrane transporters that act in different cell types. Finally, in the future, state-of-art imaging techniques should help to better characterize the lateral transport of these compounds on a cellular level. This review brings the lateral transport of sugars and inorganic solutes back into focus and highlights its importance in terms of our overall understanding of plant resource allocation.