Water-retaining Polymer Research Articles

MITIGATING THE EFFECTS OF CLIMATE CONDITIONS ON POTATO CULTIVATION: EXPLORING HYDROABSORBENTS AND PGPRS AS SUSTAINABLE ALTERNATIVES

Potatoes, a widely grown and consumed food around the world, are increasingly facing drought-related challenges. Due to their sensitivity to water availability and shallow roots, prolonged periods of drought have a significant impact on potato growth and yield. To mitigate these effects, the use of water absorbents, also known as water-retaining polymers, is proving to be a promising solution. These substances have the ability to absorb water and release it gradually into the soil, ensuring a constant water supply for the potatoes. At the same time, the presence of beneficial rhizobacteria, especially PGPRs, plays a crucial role in enhancing plant growth, controlling diseases and pathogens affecting potato production, and helping the crop cope with drought stress. A comprehensive study conducted at three different sites in Morocco with different climatic conditions, encompassing a greenhouse and field settings respectively, investigated the effect of two bacterial strains, Pseudomonas koreensis (GAJ222) and Serratia nematodiphila (GAB111), with two doses of hydroabsorbents (3 g and 1.5 g) on the potato variety Agria. The results indicated that the combination of Serratia nematodiphila with 3 g of hydroabsorbents significantly improved growth and yield. Furthermore, treatment with Serratia nematodiphila alone enhanced growth, reaching 51.9 cm, and the application of 3 g of hydroabsorbents promoted robust growth with a chlorophyll concentration of 15 SPAD units. The combined treatment of Serratia nematodiphila and 3 g of water retainers demonstrated a harmonious improvement, with a height of 59.2 cm, and significantly increased tuber yield to 17.1 kg, surpassing yields from the control group. This highlights the potential of these combinations to optimize potato production under drought conditions.

Contribution of soil sustainable management to improve coffee nutrition and mitigate water scarcity

The soil can be managed to improve plant nutrition and resilience under water scarcity. The objective of this study was to evaluate the contribution of soil conditioners, controlled-release fertilizers, and water availability levels to mitigate water scarcity and improve the nutrition of coffee plants. The experiment was conducted in a greenhouse under a randomized block design with four replicates in a factorial scheme (2 irrigation levels × 2 fertilizer types × 5 soil conditioners) of analysis of variance. The factors under study were two irrigation levels (low—40% of water holding capacity, and high—80% of water holding capacity), fertilizer type (conventional and controlled-release), and soil conditioners (coffee husk, gypsum, water-retaining polymer, organic compost, and control without soil conditioner), The characteristics assessed were soil fertility, soil moisture, and nutrient foliar contents. Multivariate analytical methods were used to interpret the results. Soil moisture, chemical attributes, and leaf nutrient contents were analyzed. There was a similarity in the clusters formed by the controlled-release fertilizer treatments, which contribute to plant nutrition. Even under water restriction, the treatments with coffee husk and organic compost were clustered along with soil moisture, favoring the absorption of nutrients. Soil cover with organic compounds improved soil moisture, even under low water availability, which favored plant fertility and nutrition.

Water depletion on substrate and soil conditioner doses in the yellow passion fruit seedling formation

The cultivation of passion fruit requires constantly updated technical information to achieve competitive results. In this context, a commonly discussed aspect is the development of vigorous seedlings. The aim of this study was to assess water depletion levels in a substrate (WDL) and TerraCottem® doses for the formation of yellow passion fruit seedlings. The experimental design used was split plots in a completely randomized design, with four replications. The treatments consisted of 5, 15, 25, 35% of NDA and 0, 2.5, 5.0, 7.5, and 10.0 kg m-3 of TerraCottem® doses. The following variables were measured: plant height (PH), stem diameter (SD), number of leaves (NL), dry biomass of the aerial part (DSB), root system (DRS), total dry biomass (TDM), and the Dickson Quality Index (DQI) was calculated. WDL treatments did not influence the evaluated variables. NL, PH, SD, DSB, DSR, TDM, and DQI showed increases of 12.3, 13.4, 10.0, 30.1, 28.1, 29.5, and 26.8%, respectively, when comparing the highest TerraCottem® dose to the control treatment. Sliced interaction showed double gains for the highest TerraCottem® dose for SD and PH. The plants responded to higher doses of TerraCottem®, indicating synergy of the water-retaining polymer in the plant's water supply, especially in the presence of higher WDL.

Water-Retaining Polymer and Planting Pit Size on Chlorophyll Index, Gas Exchange and Yield of Sour Passion Fruit with Deficit Irrigation.

Water availability is a limiting factor for the cultivation of sour passion fruit. Soil management techniques and the use of water-retaining polymers can increase soil water retention, reducing the frequency of irrigation in the crop. In this context, the objective of the research was to evaluate the gas exchange, the chlorophyll index, and the yield of the sour passion fruit cv. BRS GA1 as a function of irrigation depths, pit volumes, and doses of water-retaining polymer. The experiment was carried out in randomized blocks, in plots subdivided in a 2 × (2 × 5) arrangement, with irrigation depths of 70 and 100% of the crop evapotranspiration (ETc) as the main plot, the subplots with the volumes of pit of 64 and 128 dm3, and doses of the water-retaining polymer of 0, 0.5, 1.0, 1.5, and 2.0 g dm-3. The interaction of irrigation depths × pit volumes × doses of water-retaining polymer influences chlorophyll indexes, gas exchange, and water productivity, with positive impacts on yield of the sour passion fruit. The water depth of 70% of ETc increased the yield of sour passion fruit, in pits of 64 dm3. The application of doses of up to 1.1 g dm-3 of the water-retaining polymer and irrigation with water of 70% of ETc is recommended, and a dose of 2.0 g dm-3 of the water-retaining polymer in a pit volume of 128 dm3, associated with an irrigation depth of 100% ETc causes stress in sour passion fruit plants due to excess water.

Heavy aggregate and different admixtures effect on pavings: pyrite, corundum and water-retaining polymer

Concrete pavings are widely used in the construction industry as flooring for decorative and structural purposes in the gardens, parks, and roads of America, and Europe. In the present study, the effects of pyrite, corundum, and water-retaining polymer additives on the surface wear resistance of concrete pavings were investigated. Concrete pavings were poured in 2 stages and all of the bottom layers of samples were the same, but upper layers of pavings were produced by adding pyrite in the ratio of 0.10, 0.20, 0.30, 0.40 according to the mass of the aggregate, 5 kg /m2 corundum-based surface hardener to the paving surface area, and a high amount of water-absorbing polymer at a ratio of 0.05 and 0.10 to the water content of the mixture. Vertical abrasion, splitting tensile strength, water absorption, freeze-thaw resistance, pendulum footed friction, and surface hardness measurements with Schmidt test hammer experiments were made to TS 2824 EN 1338 standard. Also, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses were carried out to characterize the produced materials. Results of the study indicate that the use of pyrite, corundum, and water-retaining polymers provided improvements in the surface wear resistance of concrete pavings.Concrete pavings are widely used in the construction industry as flooring for decorative and structural purposes in the gardens, parks, and roads of America, and Europe. In the present study, the effects of pyrite, corundum, and water-retaining polymer additives on the surface wear resistance of concrete pavings were investigated. Concrete pavings were poured in 2 stages and all of the bottom layers of samples were the same, but upper layers of pavings were produced by adding pyrite in the ratio of 0.10, 0.20, 0.30, 0.40 according to the mass of the aggregate, 5 kg /m2 corundum-based surface hardener to the paving surface area, and a high amount of water-absorbing polymer at a ratio of 0.05 and 0.10 to the water content of the mixture. Vertical abrasion, splitting tensile strength, water absorption, freeze-thaw resistance, pendulum footed friction, and surface hardness measurements with Schmidt test hammer experiments were made to TS 2824 EN 1338 standard. Also, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses were carried out to characterize the produced materials. Results of the study indicate that the use of pyrite, corundum, and water-retaining polymers provided improvements in the surface wear resistance of concrete pavings.

Behavior of coffee plants under different cropping systems with a focus on mitigating water scarcity

ABSTRACT Sustainable cropping systems can enhance the development of young coffee plants under drought conditions. The objective of this study was to evaluate the behavior of coffee plants grown under different cover crops, soil conditioners, and fertilizers to reduce the effects of water scarcity. The treatments were the association of soil cover management (Urochloa decumbens, polyethylene film, and bare soil), fertilizers (conventional and controlled release), and soil conditioners (coffee husk, agricultural gypsum, water-retaining polymer, organic compost, and control). The assessments carried out were the growth, physiology, and anatomy of coffee plants and soil moisture and resistance to penetration. A multivariate analysis of the results was performed. The coffee plants grown with soil cover (Urochloa decumbens) and organic conditioners (coffee husk and organic compost) had better agronomic performance and higher soil moisture.

Techniques for sustainable coffee crop management: impacts on growth and yield

ABSTRACT The sustainable management of coffee plants can enhance crop growth and yield, improving the plant environment due to the increase in soil’s water storage, leading to a healthier and more productive crop. This study aimed to evaluate the combined effect of soil coverings, soil conditioners, and controlled-release fertilizer on the growth and yield of coffee plants in the first productive biennium. The factors under study were arranged in a 3 × 2 × 5 split plot-factorial experiment, totaling 30 treatments, in a randomized block design with three replications. In the plots, three soil managements were randomized (soil cover in the rows with polyethylene film, soil cover with the ecological management of Urochloa decumbens, and conventional management of spontaneous vegetation). In the subplots, two types of fertilizers used in the fertilization of coffee plants (conventional and controlled-release fertilizer) were tested. In the main plot were tried four soil conditioners (coffee husk, agricultural gypsum, water-retaining polymer, organic compound) and the control without conditioner. Using Urochloa decumbens + coffee husk/organic compound + controlled-release fertilizers resulted in higher growth and yield of the coffee plants. So, sustainable techniques resulted in better plant nutrition and ensured increasing yields, without the effect of bienniality.

Hidrogel como mitigador do estresse salino durante o estabelecimento de mudas de Tagetes patula L.

ABSTRACT Hydrogels favor moisture retention in the substrate and can attenuate the effects of salt stress on the production of potted plants. In this context, this research sought to evaluate the use of hydrogel to mitigate the damage caused by the salinity of irrigation water on the emergence, growth, and thermal index of Tagetes patula L. seedlings. The research was carried out in a greenhouse, in September 2020, in the municipality of Fortaleza, Ceará State, Brazil. The design used was randomized blocks in a split plot. The plots corresponded to seven levels of electrical conductivity of the irrigation water - ECw (0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 dS m-1) and the subplots corresponded to four hydrogel concentrations (0, 1.0, 2.0, and 3.0 g L-1), with five replicates and each subplot consisted of 27 seeds. The application of 3.0 g hydrogel L-1 of substrate favored the production of leaves and reduced the thermal index in plants associated with the increase in the salinity of the substrate up to 6.0 dS m-1. The use of 3.0 g L-1 hydrogel increases seedling height, leaf dry mass, and total dry mass compared to treatments without water-retaining polymer, even at moderate (2.0 to 3.0 dS m-1) and high (4.0 to 6.0 dS m-1) salinity levels, thus indicating a possible effect of mitigation of damage caused by the salinity of the irrigation water. However, the intensity of this mitigating effect decreases at higher levels of salt stress.

The Impact of Polymer on the Productivity and Photosynthesis of Soybean under Different Water Levels

In order to practice sustainable and resource-efficient agriculture, the use of new technologies such as water-retaining polymers is essential. The objective of this study was to evaluate the effect of a polymer incorporated into the soil on gas exchange and yield under different water regimes (WR) in three soybean cultivars. The experiment was conducted at Embrapa Cerrados under field conditions in 2016 and 2017, using three different cultivars (BRS 5980IPRO, NA 5909RG and BRS 7280RR). Soybean cultivars were submitted to four water regimes (representing 30%, 50%, 83% and 100% of evapotranspiration replacement, namely WR1, WR2, WR3 and WR4). No beneficial results were observed in 2016 with Polymer. Most of the reductions in photosynthesis and transpiration by adding the polymer can be attributed to stomatal control, but such reductions did not influence productivity. In 2017, the yield was higher using Polymer in WR4 and WR3 by 40 to 20%, depending on the cultivar. Under severe stress (WR2 and WR1), reduced gas exchange was obtained with Polymer, but the yield was not reduced. These results indicate that Polymer contributed to the prolongation of photosynthetic activity during the reproductive phase of soybean and may represent a potential strategy for increasing yield under moderate drought stress.

Optimization of water use in Coffea arabica L. grown under different agronomic practices

Lower water availability due to climate change has dramatically affected coffee yields and quality. Characteristics related to plants and soil can be explored to obtain more productive and sustainable coffee production under adverse crop conditions. To this end, the objective of this study was to evaluate the potential for using different agronomic practices to optimize water use in coffee plants and to mitigate the effects of lower water availability to the crop. In the plots, three soil management systems (polyethylene film, brachiaria and bare soil) were used. In the subplots, two types of fertilizers were used (conventional and controlled-release fertilizer). Five soil conditioners (coffee husk, gypsum, water-retaining polymer, organic compost, and the control) were distributed throughout the sub-subplots. The plant growth, soil moisture, leaf physiology and anatomy, and soil chemical properties of coffee plants were analysed. The management of the soil cover using polyethylene film or brachiaria stood out as agronomic practices that can be combined with coffee husk applications to enable the better use of water by coffee plants and to favour soil conditioning. Controlled-release fertilizer and gypsum allowed for improvements in the anatomical and physiological characteristics of the plants. The use of organic compost favoured greater water availability; however, it caused losses in terms of coffee growth and physiological parameters due to nutritional imbalance. Therefore, based on results, the use of polyethylene film, brachiaria, controlled-release fertilizer, coffee husks, and gypsum are potential agronomic practices for optimizing water use and mitigating the effects of water deficit in coffee plants

The water-retaining polymer improves the seedlings quality of native forest species in a nursery

The water-retaining polymer improves the seedlings quality of native forest species in a nursery

Polymer materials in concrete technology

Possible directions of rational use of polymer materials in cement concrete technology are proposed. Introduction of crushed plastics into the concrete mixture in an amount of 0.5-2 wt. % helps to increase the strength of concrete during bending and compression. As a water-retaining polymer additive for cement composites, it is proposed to use sodium polyacrylate, and such an additive should be pre-prepared by holding the granules in water until swelling, followed by grinding. The use of styrene, acrylonitrile, and methyl methacrylate monomers as impregnating materials for concrete is considered. Monomers must be applied to the concrete surface together with 2% of the initiating system “benzoyl – dimethylaniline peroxide” (1:0.5). Benzoyl peroxide in this system acts as an initiator, and dimethylaniline is an accelerator for the decay of the initiator into free radicals. The specified maintenance of the initiating system ensures the completeness of the transformation and high strength of the polymer.

HYDROGEL AND WATER REGIMES IN THE CHLOROPHYLL- A FLUORESCENCE AND GROWTH OF Campomanesia xanthocarpa SEEDLINGS

Water availability is one of the most important factors for the growth of tree seedlings in forestry-related regions. We hypothesized that under different water regimes, a water-retaining polymer (hydrogel) can positively contribute to chlorophyll- a fluorescence and growth in Campomanesia xanthocarpa (Mart.) O. Berg. Four water retention capacities (WRC) were evaluated: 25%, 50%, 75%, and 100%, depending on the presence or absence of hydrogel at the substrate. The lowest WRCs, particularly those under 25% without hydrogel, reduced chlorophyll index and negatively affected the photochemical activities of photosystem II. However, under low water availability the hydrogel mitigated the damage inflicted on the reaction centers and chlorophyll synthesis. The greatest growth effects occurred at 100% WRC in the presence of the hydrogel. Physiological indices were higher under 100% WRC without hydrogel and 50% with hydrogel. The increase in biomass and Dickson quality were more pronounced in the seedlings produced under 50% WRC and hydrogel, and the addition of these parameters to the substrate contributed to more viable morphophysiological indicators for the production of C. xanthocarpa seedlings.

Water retainer polymer in coffee plants deployment under different levels of irrigation

The use of water-retaining polymers may be a feasible alternative in regions with low water availability, as they has enhance the performance of coffee plants with more favorable anatomical characteristics to make physiological processes more efficient. However, the advantages of such use have been scarcely reported. Here, we studied the feasibility of using a water-retaining polymer to optimize irrigation water use during the establishment of a coffee plantation. A randomized block design was used in a factorial scheme (4 × 2) with three replications for a total of 24 experimental plots, each consisting of four pots, with one plant per unit. The experiment was installed in a greenhouse at the Coffee Science Department of the Universidade Federal de Lavras, Minas Gerais, Brazil, with four levels of irrigation (25%, 50%, 75%, and 100% of soil water at field capacity), with or without addition of the water-retaining polymer. Growth variables evaluated included: plant height, stem diameter, number of leaves, shoot and root dry weights, root volume and area. Additionally, gas exchange, leaf water potential, and leaf anatomy were analyzed. The use of water-retaining polymer during establishment of the coffee plantation ensured sufficient water supply, thus guaranteeing plant anatomical and physiological functionality and, consequently, a healthy, vigorous growth. Key words: Coffea arabica L.; Seedling establishment; Soil conditioner; Soil water availability; Water deficit.

FLAME RETARDANTS EFFECTS ON THE INITIAL GROWTH OF Schizolobium amazonicum HUBER EX DUCKE

ABSTRACT Flame retardants are efficient in fighting wildfire; however, their environmental implications, especially regarding the vegetation, need to be clarified. This work aimed at assessing the effects of flame retardant on the initial growth of Schizolobium amazonicum. Treatments consisted in applying different flame retardant concentrations via substrate and leaf: Phos-Chek WD-881® (0, 3.00, 6.00, 8.00 and 10.00 mL L-1), Hold Fire® (0, 7.00, 9.00, 12.00 and 15.00 mL L-1) and water-retaining polymer Nutrigel® used as alternative retardant (0, 0.25, 0.50, 0.75 and 1.00 g L-1). Growth analyses were carried out to assess the effects of these substances (10 repetitions per treatment). The aliquot of 10.00 mL L-1 of Phos-Chek WD881 applied on the leaves led to an increase of 70% in leaf area and 15% in seedling height. The same Phos-Chek concentration favored height increase (32%) and total dry mass accumulation (33%) throughout time. The concentration of 15 mL L-1 of Hold Fire® applied on leaves, compromised 45% the accumulation of dry biomass in the seedling. Initially, 1.00 g L-1 of Nutrigel® applied via substrate led to an increase of 70% in leaf area, 29% in plant height, and 89% in leaf dry mass. Therefore, Phos-Chek applied on leaves favored shoot growth in S. amazonicum. Hold Fire® applied on leaves impaired biomass accumulation in seedlings. Nutrigel® applied on substrate does not cause long-lasting damage to the initial growth of S. amazonicum. The aliquot of 0.50 g L-1 administered via polymer leave had positive effect on seedling shoot.

Use of a water-retaining polymer in the cultivation substrate of palmito-juçara (Euterpe edulis Mart.)

Over the years, the natural landscape of Atlantic forest has undergone significant changes. Inventories carried out by the Fundação SOS Mata Atlântica and by the National Institute for Space Research (SOS Mata Atlântica and INPE, 2017), showed that 83.7% of the São Paulo territory initially covered by this biome has already been transformed into pasture, monoculture and other uses. This intensive exploration resulted in extensive degraded areas, resulting from abandonment after the loss of the productive capacity of the soil. For the recovery of physical and chemical characteristics and the reduction of soil loss due to erosive processes, forest species are planted. During planting and in the first weeks of plant growth, the lack or excess of water can limit development. In this case, an alternative used is to add water-retaining polymers to the soil that have the ability to increase water retention. This study evaluated the effect on the growth of Palmito-Juçara (Euterpe edulis Mart) seedlings of different doses of water-retaining polymer incorporated into the growing substrate, with watering on five consecutive days and with alternating watering for a period of three months in a nursery. The experiment started when the seedlings presented 220 days after sowing. The juçara plants were grown in plastic bags filled with 850 g of substrate composed of a mixture of peat, carbonized rice husk, horse manure, chicken manure, tanned bovine manure, mineral fertilizer and dolomitic limestone. To study the effect of the hydro-retaining polymer, the following doses of a polyacrylic potassium copolymer were added to the dry substrate: D0 = without adding the polymer to the substrate (control); D2 = 2g of polymer; D3 = 3 g of polymer; D4 = 4 g of polymer; and, D5 = 5 g of polymer. Each dose was combined with two irrigation regimes, watering for five consecutive days or alternating, in a 5 x 2 factorial arrangement, with 15 repetitions, totaling 150 experimental plots in a randomized block design. The transplanting of the seedlings to the bags took place in April 2019 and every 30 consecutive days, five individuals were collected from each dose and each type of irrigation (50 experimental plots / collection), that is, 3 collections (250 days, 280 days and 310 days after sowing). In each collection, the length of the leaves and the root system, the diameter of the stem, the height of the plant, the dry mass of the aerial part, the dry mass of the root and the total dry mass were measured. After checking the normality of the data and the homoscedasticity of the variances, analyses of variances were performed (ANOVA, p <0.05) and the differences between the means were compared using the Tukey test (p <0.05). The analysis of the results showed significant differences between the irrigations, with greater growth for the variables of leaf length, stem diameter, plant height and dry mass of the aerial part in the initial period of development of juçara plants. In the condition of irrigation in five consecutive days, the highlight was for dose D3 and, in alternate watering, for dose D5.

WATER-RETAINING POLYMER MITIGATES THE WATER DEFICIT IN Schinus terebinthifolia: PHOTOSYNTHETIC METABOLISM AND INITIAL GROWTH

ABSTRACT The use of water-retaining polymer (hydrogel) can mitigate the damage to the photosynthetic apparatus and increase the robustness of young plants under water deficit conditions. Thus, the aim of this study was to evaluate the effect of water-retaining polymer on the morphophysiological aspects of Schinus terebinthifolia Raddi submitted to water deficit. The studied water regimes were characterized by three plant irrigation management: 1) control: irrigated daily, 2) stress: water deficit (irrigation suspension) and 3) stress + hydrogel: water deficit + water-retaining polymer. The plants were submitted to irrigation suspension until photosynthesis approached zero [1st P0], followed by resumption of irrigation (REI) for 15 days. After REI, until recovery of photosynthetic rate of plants, the maintenance of irrigation of all plants for 90 days, characterizing the final recovery (125th day of experiment). The photosynthetic rate reached values close to zero in plants under stress on the 20th day of water restriction, whereas the plants in conditions with hydrogel did not show a decrease in leaf metabolism. Excluding intercellular CO2 concentration, physiological parameters were lower on 1st P0 in plants under water deficit grown without hydrogel than those in plants grown with hydrogel, but all plants showed physiological plasticity. The use hydrogel contributed to the maintenance of the photosynthetic capacity of S. terebinthifolia under water deficit.

Water-retaining polymers on the early growth and quality of bushy cashew (Anacardium humile A. St. Hill) seedlings

Bushy cashew (Anacardium humile A. St. Hill) is an endemic plant species to the Brazilian Cerrado, a region characterized by scarce and poorly distributed rainfall. The use of hydrogel, a water-retaining polymer that features massive water storage and promotes its release into the environment throughout time may be an alternative to reduce the frequency irrigation in the production of bushy cashew seedlings. This study aimed to evaluate the quality and early growth of bushy cashew seedlings as a function of hydrogel doses. The experimental design adopted was in five randomized blocks, with five hydrogel doses (0; 1,0; 2,0; 3,0; and 4,0 g L-1 of soil), and each plot consisting of 10 seedlings, totaling 250 plants. A Yellow Latosol with sandy-loam texture was used for seedling production. The growth evaluation was performed through the variables of emergence speed index, germination percentage, height, diameter, root volume, number of leaves, shoot dry mass, root dry mass, and the Dickson quality index. The results revealed a positive influence of the hydrogel on the growth and quality of bushy cashew seedlings, notably at the dose of 4 g L-1 of soil.

Morphological, physiological and biochemical traits of Cordia trichotoma under phosphorous application and a water-retaining polymer

The application of phosphorus (P) and a water-retaining polymer to the soil can increase the availability of P for Cordia trichotoma, having a positive effect on the plants. The objective of this study was to evaluate the morphological, physiological and biochemical characteristics of C. trichotoma plants were cultivated in a red argisol and treated with 120, 240 and 360 kg P2O5 ha−1 and no phosphorous addition as a control, in the presence (5 g L−1 per seedling) and absence of a water-retaining polymer. Twenty-four months after planting, survival, height, stem diameter, shoot and root dry matter, leaf area, photosynthetic pigment concentration, chlorophyll a fluorescence, acid phosphatase enzyme activity (APase) and P in tissues and soil were determined. The polymer had no effect on survival and the other parameters. The addition of P increased growth, dry matter production, photosynthetic pigment concentrations, the use of light energy and maximum quantum yield of photosystem II. Plants cultivated in soil with 240 kg P2O5 ha−1 application had 4.7 and 5.4 times more shoot and root dry matter, respectively, than control plants. This dosage also showed 52.1% greater photochemical energy use than the control plants. Plants cultivated without the addition of P showed higher activity of the APase enzyme.

EFFECTIVENESS OF WATER-RETAINING POLYMER AS FIRE RETARDANT IN INDIRECT USE

ABSTRACT The use of fire retardants increases efficiency in fighting forest fires, however, it still presents uncertainties regarding environmental contamination, recommendations for preparation, and it lack of regulation in Brazil. In this scenario, alternative products such as water-retaining polymers, that can reduce the rapid evaporation of water, can also have positive effects in terms of reducing fire behavior. Efficiency and ways of using the water-retaining polymer as a short-duration fire retardant (indirect combat) in controlled burns in eucalyptus plantations were evaluated. Five concentrations (dilution in water), three volumes of spray solution, and two post-application times on the combustible material available in the area were evaluated. Controlled burns were conducted downwind, between 10 am and 2 pm, during dry season in the region, with micrometeorological and fire behavior assessments (fire propagation speed and length of flames). Increased spray volume and concentration of water-retaining polymer led to reductions in the spread of fire. In eucalyptus combustible material, the water-retaining polymer can be used as a fire retardant of short duration (effective up to two hours after application), considering a spray volume of 2.0 L m-2 and concentration of 0.0060% (diluted in water).