Irrigation Frequency Research Articles

Amplitude and frequency of wetting and drying cycles drive N2 and N2O emissions from a subtropical pasture

This study investigated the effects of irrigation frequency on N2 and N2O emissions from an intensively managed pasture in the subtropics. Irrigation volumes were estimated to replace evapotranspiration and were applied either once (low frequency) or split into four applications (high frequency). To test for legacy effects, a large rainfall event was simulated at the end of the experiment. Over 15 days, 7.9 ± 2.7 kg N2 + N2O-N ha−1 was emitted on average regardless of irrigation frequency, with N2O accounting for 25% of overall N2 + N2O. Repeated, small amounts of irrigation produced an equal amount of N2 + N2O losses as a single, large irrigation event. The increase in N2O emissions after the large rainfall event was smaller in the high-frequency treatment, shifting the N2O/(N2O + N2) ratio towards N2, indicating a treatment legacy effect. Cumulative losses of N2O and N2 did not differ between treatments, but higher CO2 emissions were observed in the high-frequency treatment. Our results suggest that the increase in microbial activity and related O2 consumption in response to small and repeated wetting events can offset the effects of increased soil gas diffusivity on denitrification, explaining the lack of treatment effect on cumulative N2O and N2 emissions and the abundance of N cycling marker genes. The observed legacy effect may be linked to increased mineralisation and subsequent increased dissolved organic carbon availability, suggesting that increased irrigation frequency can reduce the environmental impact (N2O), but not overall magnitude of N2O and N2 emissions from intensively managed pastures.

Robinia pseudoacacia Seedlings Are More Sensitive to Rainfall Frequency Than to Rainfall Intensity

Climate change causes the global redistribution of precipitation, yet little is known about the effects of the changes in precipitation intensity and frequency on the seedlings of wood trees in warm temperate forests. In this study, we focused on the effects of variability in both the intensity and frequency of water supply on the physiological traits, biomass, and growth of an important plantation wood species, Robinia pseudoacacia. In the greenhouse, we exposed R. pseudoacacia seedlings to three rainfall intensity and three rainfall frequency treatments. The results from the 62-day experiment revealed that lower rainfall intensity and frequency significantly reduced the photosynthetic performance, growth, and biomass of the tree seedlings. In lower rainfall intensity and frequency conditions, the seedlings had improved water absorption and utilization by increasing the water use efficiency and root shoot ratio, and reduced water consumption by defoliating the compound leaves of the lower crown. More importantly, we found that R. pseudoacacia seedlings were more sensitive to rainfall frequency than to rainfall intensity. Therefore, our results suggest that increasing the irrigation water, especially irrigation frequency, could better facilitate the survival and growth of R. pseudoacacia seedlings and eventually promote the process of vegetation restoration in the future global climate change context.

Can we really make catheter-associated urinary tract infections a never event? A level 1 trauma center's experience with prophylactic antibiotic bladder irrigation.

Hospital-acquired catheter-associated urinary tract infections (CAUTIs) are considered "never events" and are reportable to Centers for Medicare and Medicaid Services as a quality indicator. Despite protocols to determine appropriate removal of urinary catheters as soon as possible, severely injured trauma patients often require prolonged catheterization during ongoing resuscitation or develop retention requiring catheter replacement, exposing them to risk for CAUTI. We evaluated whether prophylactic antibiotic bladder irrigation reduces the incidence of CAUTI in critically ill trauma patients. As a quality initiative, gentamicin bladder catheter irrigation (GBCI) was performed on a level 1 trauma center's patients at risk for CAUTI in 2021, defined by indwelling Foley catheterization for a minimum of 3 days. We then conducted a retrospective study using a comparison cohort of 2020 admissions as the control group. Catheter-associated urinary tract infection rates per 1,000 catheterized days were compared between these two groups. Patients with traumatic bladder injuries were excluded. Our cohort included 342 patients with a median hospitalization of 11 (7-17) days, Injury Severity Score of 17 (10-26), and 6 (4-11) days of catheterization. Eighty-six patients, catheterized for 939 at-risk days, received twice-daily GBCI compared with 256, catheterized for 2,114 at-risk days, who did not. Zero patients in the GBCI group versus nine patients in the control group developed CAUTI. The incidence of CAUTI in the GBCI group was significantly less than in the control group (0/1,000 vs. 4.3/1,000 catheterized days, p = 0.018). Prophylactic antibiotic bladder irrigation was associated with a zero incidence of CAUTI among trauma patients at risk for CAUTI. This practice holds promise as effective infection prophylaxis for such patients. The optimal duration and frequency of irrigation remain to be determined. Therapeutic/care management, Level III.

Green roofs sown with an annual plant mix attain high cover and functional diversity regardless of irrigation frequency

Annual plant species have great potential on green roofs as many are highly attractive, fast and cheap to establish via sowing and can provide rapid cover and growth, which is important for ecosystem service provision. While irrigation is essential for survival and growth of annual plants in seasonally hot or dry climates, it is also important to minimize water use as availability is often limited. Therefore, we evaluated how irrigation frequency affects plant cover, species abundance, richness and diversity, plant traits and functional diversity of a 16 species mixture of Australian annual species (4 g m−2 ~ 2100 seeds m−2) sown onto thirty 0.25 m2 green roof modules. The experiment was carried out in Melbourne, Australia, from January (summer) to July (winter) 2020. After a 2-month irrigated establishment phase (to ensure germination and seedling establishment), three irrigation treatments (2, 4 and 6 days between irrigation) were applied to the modules for three months. Plant cover was reduced at lower irrigation frequency (6 days), but ≥ 80% plant cover was achieved in all irrigation treatments. There was no effect of irrigation frequency on species abundance and richness; however, abundance, richness and diversity reduced over time, likely due to competition effects. Plant height and leaf area were also reduced by lower irrigation frequency. At the community level, functional diversity was unaffected by irrigation frequency. Our results indicate that green roofs sown with a mixture of annual plants can achieve good plant coverage, as recommended by green roof guidelines, and maintain high diversity when minimally irrigated in their first growing season.

Exploration of Water-Saving and High-Yield Irrigation Model for Tomato under Microsprinkler Irrigation with Plastic Film in a Greenhouse Based on Spatial Analysis

The purpose of this study was to analyse the suitability of the frequency and amount of microsprinkler irrigation under plastic film technology (MSPF) in a greenhouse. This study was aimed at determining the effects of different irrigation frequency and irrigation amount of the MSPF on the quality, yield (Y), and water use efficiency (WUE) of tomato, and the optimal irrigation period and irrigation amount of tomato with MSPF were determined by spatial analysis method. Irrigation frequency was set 3 levels, 3 d (F1), 5 d (F3), and 7 d (F3), respectively. Irrigation amount was set 3 levels, 0.7 E pan (I1), 1.0 E pan (I2), and 1.2 E pan (I3) ( E pan is the diameter of 20 cm standard pan evaporation, mm), respectively. The results show that increase in the single fruit weight (SFW), transverse diameter (TD), vertical diameter (VD), total soluble solids (TSS), total soluble sugar (TSU), soluble solid content (SSC), sugar-acid ratio (SAR), soluble protein (SP), vitamin C (VC), lycopene (L), Y, and WUE of spring and autumn tomatoes was observed initially with decreasing irrigation frequency; however, decrease in all these variables was observed thereafter. Similarly, SFW, TD, VD, and SAR of spring and autumn tomatoes first added and then reduced with increasing irrigation amount, whereas TSS, SP, TSU, VC, L, and WUE exhibited an overall decreasing trend. On the basis of spatial analysis, the comprehensive score, Y, and WUE of F2I2 tomato were predicted to simultaneously reach more than 95% of the maximum, which is consistent with the earlier studies on comprehensive evaluation of yield and WUE.

Effects of Irrigation Interval, Irrigation Frequency and Growth Medium on Growth and Yield Components of Potato

Effects of Irrigation Interval, Irrigation Frequency and Growth Medium on Growth and Yield Components of Potato

Plant water deficit index-based irrigation under conditions of salinity

In arid and semi-arid regions, water scarcity and soil salinization are major factors impacting sustainable agricultural production. In this study, a macroscopic root-water-uptake model was used to adapt a plant water deficit index (PWDI) for irrigation scheduling under conditions of coexisting soil water and salinity stress-causing factors. The traditional approach, estimating PWDI with average root zone soil water and salt amounts, was improved by weighting the effects of soil water and salinity according to the normalized root length density profile. An experiment growing wheat (Triticum aestivum L.) in soil columns and an experiment growing cotton (Gossypium hirsutum L.) in a salinized field were implemented to explore and quantify the effects of soil water and salinity conditions on plant water status, and thus to validate the improvement and evaluate its application, by monitoring soil water and salinity dynamics and plant growth indexes (e.g., leaf area, dry weight, leaf water potential, transpiration and yield). The results indicate that, even under conditions with equal root zone averages of soil matric and osmotic potentials, plant water status might be significantly different. In general, plants were less stressed when more water and less salinity were allocated in the upper root zone with more roots while less water and more salinity occurred in the lower root zone with less roots. By referring to some information in the soil column experiment, a numerical experiment was conducted to further demonstrate the improvement. The root-weighted approach resulted in improved PWDI estimation and thus was more reliable for irrigation scheduling, leading to higher irrigation frequency and quantity, leaf area index, biomass, yield, and transpiration, without significant decrease in water productivity. However, further improvement could be possible by considering the effects of historical soil water and salinity stresses as well as meteorological conditions on plant water status.

Optimal Irrigation Scheduling for Greenhouse Tomato Crop (Solanum Lycopersicum L.) in Ecuador

Tomato crop is grown worldwide and is considered a mass consumer product. In Ecuador, tomato growers face two major issues: water scarcity and water mismanagement, which cause a reduction in the framers’ gross income and ecosystem services. This paper is aimed at finding an optimal irrigation scheduling in greenhouse tomato crop to achieve a balance among production, fruit quality and water use efficiency. Thus, two experiments were settled. In the first experiment, four water doses (80, 100, 120 and 140% ETc) and two irrigation frequencies (one and two irrigations per day) were compared. The second experiment evaluated the two best water doses of the first one (100 and 120% ETc) and four irrigation frequencies (one and two irrigations per day, one irrigation every two days, one irrigation every three days). Each experiment monitored the variables for tomato production (plant height, stem diameter, fruits per plant, yield) and tomato quality (pH, total soluble solids, titratable acidity). The study concluded that water doses affected more than irrigation frequency to fruit quality and production. The dose of 100% ETc, applied in one irrigation per day, is suggested to obtain a balance between production, fruit quality and water use efficiency.

Optimizing frequency and amount of irrigation needed to establish cool‐season turfgrasses

AbstractLimited information is available on the optimal frequency and amounts of irrigation water needed to establish cool‐season turfgrasses from seed in arid environments. A 2 × 2 factorial study was conducted at New Mexico State University in 2012 and repeated in 2017 to investigate the effect of four irrigation treatments: two reference evapotranspiration (ETo) rates (60 and 120%), and two frequencies (daily and every other day [EOD]) on the establishment of several varieties of Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] (TF). Our hypothesis was that irrigation rates below 100% ETo replacement applied EOD would negatively affect turfgrass establishment. Turfgrasses were seeded in the fall and digital image analysis was used to estimate percent coverage. The Area Under the Curve model was used to estimate days after seeding needed to reach 50 (DAS50) and 90% coverage (DAS90). Statistical analysis indicated a significant interaction (p < .0001) between ETo and species and that irrigation frequency did affect establishment. Perennial ryegrass established the fastest and DAS90 was not affected by irrigation treatment. Kentucky bluegrass and TF established faster when irrigated daily at 120% ETo. Varieties within the same species all performed equally. In general, our study suggests that cool‐season turfgrasses can be established in arid regions using water conserving measures such as irrigating EOD at rates below 100% ETo replacement. Further studies are needed to determine lowest ETo replacement levels or irrigation frequency possible to achieve establishment.

Acclimatization of Mediterranean Native Sages (Salvia spp.) and Interspecific Hybrids in an Urban Green Roof under Regular and Reduced Irrigation

Native-to-Greece sage species, namely, Salvia fruticosa, S. officinalis, S. pomifera ssp. pomifera, S. ringens, S. tomentosa and interspecific hybrids, were evaluated for their acclimatization in an extensive Mediterranean green roof during summer under regular and reduced irrigation (every 2–3 days with substrate moisture 16–22% v/v and 4–5 days with substrate moisture 7–11% v/v, respectively). A substrate (grape-marc compost:perlite:pumice, 3:3:4, v/v) that was 10 cm deep was used. Regardless of the irrigation frequency, S. pomifera ssp. pomifera × S. ringens and S. officinalis × S. pomifera ssp. pomifera showed the highest survival of all hybrids and species, along with satisfactory growth, while S. fruticosa showed the lowest survival. Reduced irrigation resulted in the reduction of aboveground and root biomass, with no damage to the photosynthetic apparatus. S. fruticosa showed the highest (53%) aboveground biomass reduction and S. officinalis, S. officinalis × S. ringens and S. pomifera ssp. pomifera × S. ringens showed the lowest (28, 23 and 3%, respectively), while S. officinalis × S. pomifera ssp. pomifera and S. pomifera ssp. pomifera × S. ringens showed the lowest reduction in root biomass (13 and 16%, respectively). With a reservation for S. fruticosa, Greek Salvia spp. and their interspecific hybrids studied in the present work are recommended for sustainable exploitation in extensive green roofs in arid regions and generally in xeriscaping.

Evaluation of Patch Budding Success in Persian Walnut Affected by Different Treatments after Budding

ABSTRACT Vegetative propagation of Persian walnut (Juglans regia L.) is more difficult than many other fruit trees. Temperature, relative humidity, water status of the scion and rootstock, nutrient uptake, time of grafting, physiological condition of the rootstock, and scion type all can affect grafting success. An experiment was conducted to evaluate the effects of post-budding irrigation frequency (3, 7 and 10-days), budding date (14 June, 5 and 26 July), and rootstock heading methods. All treatments and evaluations of their effects were performed in field conditions, for two consecutive years. Irrigation cycle, budding date and rootstock heading procedure all had significant effects. Bud take was greatest on 26 July (49.3%). Irrigation frequency had no significant effect on bud take but the 3-day cycle resulted in the best scion growth. Bend the branches to create shade at the bud site, rather than cutting the rootstock above the bud site resulted in the best bud take (61.1%). The results obtained in this study show that budding at the right time “provides better climatic conditions,” adjusting the irrigation cycle and choosing the best rootstock heading methods after budding, produces satisfactory results

Biomass and Active Compounds Accumulation of the Medicinal Orchid Pleione bulbocodioides in Response to Light Intensity and Irrigation Frequency.

Pseudobulbs of Pleione species are widely used as traditional medicine in Asian countries, but the mechanism of active compound accumulation remains unclear. In the present study, we investigated the accumulation of biomass and three active compounds (dactylorhin A, militarine and batatasin III) of Pleione bulbocodioides in response to different light intensities and irrigation frequencies. We found that single high light (65 % of full sunlight) or drought stress (14-day irrigation interval) increased active compounds accumulation but the combined effect of these two treatments decreased the total content of these three active compounds. This decrease was due to the plants under combined stress having a significantly lower photosynthetic rate, leaf area and longevity, leading to a dramatic decrease in pseudobulb biomass. Among all treatments, the highest total content of active compounds was observed in plants subjected to the high light level with a high water level (3-day irrigation interval), and plants under medium light intensity (30 % of full sunlight) also had considerable content of active compounds accumulation. To balance the quality and quantity of Pleione pseudobulbs during artificial cultivation, 30∼65 % of full sunlight with the avoidance of drought stress is recommended. Our results suggest the accumulation of the three active compounds is significantly influenced by light intensity and irrigation frequency, which may contribute to the artificial cultivation and quality control of medicinal Pleione.

The Effect of Irrigation Frequency and Amount on the Growth and Yield of Kale (Brassica Oleracea var. Acephala)

The Effect of Irrigation Frequency and Amount on the Growth and Yield of Kale (Brassica Oleracea var. Acephala)

Effects of Salinity on Yield, Yield Components and Water Productivity of Black Carrot (Daucus Carota L.) Under Water Stress Condition

Salinity and drought are some of the main problems affecting global crop yields. In this study, interaction effects of irrigation interval and salinity on yield, soil salinity, other parameters of black carrot were evaluated in a covered rain shelter. The treatments consist of three different irrigation intervals (4 days (I1), 6 days (I2), and 8 days (I3) with 6 different irrigation water salinity levels (0.38 (S1), 1.5 (S2), 3.0 (S3), 5.0 (S4) 7.0 (S5) and 10.0 (S6) dS m-1. The results indicated that the effect of interaction between irrigation interval and salinity was significant on yield, evapotranspiration, chlorophyll content, and soluble solid content (SSC). Yield and evapotranspiration decreased significantly with an increase in salinity and irrigation intervals. The highest yield was observed in I1S1, and the yield response (Ky) in the black carrot was 1.39. The irrigation water salinity up to 1.5 dS m-1 was nonsignificant on yield. However, the increase in soil salinity by 1 dS m-1 caused a decrease of 3.83%, 2.93%, and 3.03% in the yields of I1, I2, and I3, respectively. Moreover, increasing the salinity of irrigation water reduced the chlorophyll content and carrot juice pH value. The result of the study indicated that black carrot is sensitive to salt and water deficit, and the maximum irrigation interval using saline water should not be more than 6 days. Therefore, it can be concluded that in regions where salinity is high, more frequent irrigation minimizes losses that may occur in yield.

Response of Summer Maize Growth and Water Use to Different Irrigation Regimes

Summer maize crop development, yield, and water use characteristics under water deficit conditions at different growth stages were investigated in this study using different irrigation regime treatments at the seedling (S), jointing (J), tasseling (T), and grain filling stages (F) in 2018 and 2019 in China. Ten different irrigation treatments were set, including three-irrigation application intervals (JTFi, STFi, SJFi, SJTi), two-irrigation applications (STi, JTi, JFi), and single-irrigation applications (Ti, Ji). These were compared to the control treatment (CK), which had sufficient irrigation provided at four intervals (SJTFi). The results showed that compared to CK, a water deficit at the seedling and jointing stages had a greater effect on plant height, whereas a water deficit at the tasseling and filling stages had a greater effect on the leaf area index, and a continuous water deficit had an effect on the stem diameter of summer maize. Limitations in terms of the growth and development of summer maize increased with less frequent irrigation. As irrigation decreased, the grain yield decreased, and the water use efficiency increased, and a water deficit at the tasseling stage had the greatest effect on the yield and water use efficiency. The JTFi treatment was the optimal irrigation regime with a yield decline, and its water consumption was reduced by 16.9% (p < 0.05) on average. However, compared to CK, the water use efficiency of the JTFi treatment increased by 17.3% (p < 0.05). Moreover, the JTFi treatment had the smallest maize yield response factor value (Ky) of 0.16, and its comprehensive score was the second highest after CK.

Drip irrigation strategy for tomatoes grown in greenhouse on the basis of fuzzy Borda and K-means analysis method

To design a suitable drip irrigation strategies for tomato production, an experiment was laid out in a randomized complete-block design, six treatments, which completely combined with three drip irrigation frequencies and two drip times were carried out in 2020 and 2021 with the variety “Heshengfeilong” tomatoes in the greenhouse. Four single comprehensive evaluation methods: PCA, TOPSIS, MFA, and GRA were used to comprehensively evaluate the fruit quality. Fuzzy Borda combined evaluation was performed on each comprehensive evaluation result that passed the pre-consistency test (Kendall-W). We found that MFA is the most suitable for evaluating the comprehensive fruit quality because its ranking results have the highest correlation coefficient with fuzzy Borda in 2020 and 2021, namely, 0.989 and 0.994, respectively. Total soluble solids (TSS) can be used as a single indicator representing the comprehensive fruit quality because it has a significant positive correlation with the comprehensive quality score in two years. The results of the TOPSIS evaluation of the TSS and the yield show that the optimal treatment in this experiment is for drip irrigation at 9:00, 11:00, 13:00, 15:00, and 17:00. The K-means clustering algorithm was used to determine the change in moisture content corresponding to different temperature ranges and further determine the irrigation strategy, which is the drip irrigation frequency of 5 times/day, and the drip irrigation volume was obtained according to the change in moisture content. During the day (9:00–19:00), the change in the substrate moisture content is divided into three temperature ranges, namely, 5.90–23.98 °C, 23.98–37.42 °C, and 37.42–53.58 °C, corresponding to 0.44%/2 h (40 ml/2 h), 1.34%/2 h (121 ml/2 h), 2.26%/2 h (203 ml/2 h), respectively. During the night (19:00–9:00 the next day), the change in the substrate moisture content is 0.19%/2 h (17 ml/2 h).

Effect of Irrigation Regime On Yield and Water Productivity of Maize (Zea Mays) in the Lake Tana Basin, North West Ethiopia

Proper scheduling gave water to the crop at the right time in the right quantity to optimize production and minimize adverse environmental impact. Therefore, the objective of this study is to quantify the effects of irrigation regimes on yield and yield components of Maize in the Lake Tana basin during 2016-2018. CROPWAT 8.0 model was used to determine the crop water requirement. Almost all parameters were adopted the default value of CROPWAT 8.0. Field data including; field capacity (FC), permanent wilting point (PWP), initial soil moisture depletion (%), available water holding capacity (mm/meter), infiltration rates (mm/day), and local climate data were determined in the study area. The treatments were arranged in factorial combinations with five irrigation depths (50, 75, 100, 125 and 150% of ETc) and two irrigation intervals (14 and 21 days) laid out in a randomized complete block design with three replications. The result was analyzed using SAS 9 software and significant treatment means separated using least significant difference at 5%. The result showed that the interaction of irrigation depth and irrigation frequency has no significant effect on the average grain yield and water use efficiency of maize. At koga, the highest grain yield (7.3 t ha-1) and water use efficiency (0.9 kg m-3) obtained from 100% ETc. while, at Ribb the highest grain yield (10.97 t ha-1) and water use efficiency (1.9 kg m-3) obtained from 21 days irrigation interval. Therefore, for Koga and similar agro ecologies maize can irrigated with 562 mm net irrigation depth and 21-day irrigation interval and at Rib and similar agro ecologies maize can irrigated with 446.8 mm net irrigation depth and 21- days irrigation interval.

Optimizing drip irrigation with alternate use of fresh and brackish waters by analyzing salt stress: The experimental and simulation approaches

Drip irrigation with alternate use of fresh and brackish waters is an excellent irrigation strategy to overcome salt stress problems induced by brackish water. Understanding salt stresses in the soil profile and their relationship with crop growth is critical when optimizing irrigation strategies with alternate use of fresh and brackish waters. The HYDRUS (2D/3D) model was calibrated and validated using experimental data collected in 2019 and 2020, respectively. The calibrated model was then used to evaluate the effects of different irrigation strategies involving the use of only freshwater (FW) or brackish water (BW), or the alternative use of brackish and fresh waters (1B1F, one irrigation with brackish water and one with fresh water; 2B1F, two irrigations with brackish water and one with fresh water; and 3B1F, three irrigations with brackish water and one with fresh water) on the soil electrical conductivity (ECsw), salt stress, crop growth, and yield. In general, the model performed well, with the average RMSE, M RE , and R2 for ECsw of 0.12 dS m−1, 6.85%, and 0.97, respectively. The average ECsw in the 0–40 cm soil layer (the main root zone) showed large differences between different alternate irrigation strategies, increasing by 55.9% between FW and BW. There was a strong linear relationship between salt stress (ECsw of 3.4–11.8 dS m−1, SS) in the main corn root zone and salts introduced by irrigation water. The SS duration and area increased with the frequency of irrigations with brackish water, while the opposite was observed for the average desalination rate (DR) after irrigation during the entire growth stage. The SS duration was 90, 111, 115, 121, and 121 days for FW, 1B1F, 2B1F, 3B1F, and BW, respectively, while the corresponding values for the duration of high salt stress (ECsw of 7.6–11.8 dS m−1, HSS) were 4, 24, 32, 37, and 46 days, respectively, and the average DRs were 4.3%, 2.4%, 1.9%, 1.7%, and 0.8%, respectively. Average fractions of the SS and HSS areas to the main root zone area for BW increased by 5.3% and 26.6% compared with FW, respectively. When the HSS duration increased by 42 days from the FW to BW scenarios, corn yield, plant height, stem diameter, and leaf area index decreased by 8.8%, 10.4%, 17.7%, and 19.6%, respectively. Additionally, the quantitative relationship between SS and corn yield, i.e., a sensitivity function of the crop yield to soil water and salt stresses, was proposed based on HYDRUS (2D/3D) simulations. The 2B1F scenario can be recommended as the optimal strategy for the studied region, using most brackish water with only a 4% decrease in the corn yield.

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.

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

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).