Deficit Irrigation Research Articles

Quantifying Residual Soil Moisture through Empirical Orthogonal Functions Analysis to Support Legume-Based Cropping Systems

AbstractThis study investigates spatiotemporal variability of residual soil moisture during the OND (October-November-December) season in Ethiopia and its implications for crop productivity. Employing advanced statistical techniques, we analyze spatial and temporal distribution of soil moisture across Ethiopia from 1981 to 2020, focusing on selected crops including legumes: chickpea, field peas, common bean, soybean and alfalfa, to assess the potential of residual moisture to support post-rainy season cropping. Results indicate pronounced east-west moisture gradients, with eastern regions of Ethiopia exhibiting lower moisture levels (< 60 kg.m-2) compared to western regions (> 150 kg.m-2). The central highlands, which are pivotal for agricultural activities, demonstrate significant variability in moisture (standard deviations > 25 kg.m-2), with implications on agricultural sustainability. The northern and southeastern tips of the country are particularly vulnerable to prolonged drought, where climate change and frequent dry spells exacerbate moisture deficits, consequently impacting crop productivity. Despite these challenges, promising opportunities for future crop production emerge in the southeastern region, which is characterized by increasing moisture trend over time ($$\:\tau\:=0.59$$). Findings further indicate that residual moisture adequately meets and supports crop water requirements in the western, central, and southwestern Ethiopia. In these regions, residual moisture supports more than 90% of cropland water requirements of various crops during the initial and late-season growth stages, whereas water requirement coverage drops to less than 20% during the mid-season growth stage. Therefore, by utilizing residual soil moisture alongside supplemental irrigation, Ethiopian farmers can meet crop water needs for double cropping and enhance resilience to climate variability.

Joint guarantee rate index assessment of the contribution of agricultural water-saving measures to river ecological flow in water shortage areas

Reconciling higher ecological water demands and economic purposes with finite freshwater resources remains one of the great management dilemmas. Low water efficiency and large water consumption in agricultural irrigation hinder the protection of river ecological flow in the water shortage areas of Northwest China. By analyzing the surplus and shortage of river ecological protection targets, the intensity guarantee rate index is innovatively proposed to quantitatively evaluate the important contribution of improved water-saving measures for river flow restoration. It compensates for the shortcomings of the duration guarantee rate index in evaluation that may mask ecological problems. Considering ecological baseflow, fish species, and landscape water demand, the ecological flow interval (6.00–12.42 m3/s) was determined. Three scenarios are highlighted for different typical years and irrigation regimes in combination with planting structure adjustment and irrigation water utilization coefficient. In 75 %, 90 %, and 95 % typical years, the maximum total annual water-savings (Scenario 3) are 57.3, 57.1, and 87.2 million m3 (sufficient irrigation); 32.2, 33.9, and 35.5 million m3 (deficit irrigation) respectively. The guarantee degree of river ecological flow under both irrigation regimes increased from the previous 65.6 % to a maximum of 91.7 % and 81.2 %. The increase in the daily guarantee rate and decrease in the intensity guarantee rate under the aforementioned three scenarios indicate a reduction of damage depth and duration of ecological flow. By using a quantitative study, it is pointed out that improving agricultural water-saving is a reasonable and necessary way to protect the river flow.

Improving maize yield and drought tolerance in field conditions through activated biochar application

Amidst depleting water resources, rising crop water needs, changing climates, and soil fertility decline from inorganic modifications of soil, the need for sustainable agricultural solutions has been more pressing. The experimental work aimed to inspect the potential of organically activated biochar in improving soil physicochemical and nutrient status as well as improving biochemical and physiological processes, and optimizing yield-related attributes under optimal and deficit irrigation conditions. Biochar enhances soil structure, water retention, and nutrient availability, while improving plant nutrient uptake and drought resilience. The field experiment with maize crop was conducted in Hardaas Pur (32°38.37’N, 74°9.00’E), Gujrat, Pakistan. The experiment involved the use of DK-9108, DK-6321, and Sarhaab maize hybrid seeds, with five moisture levels of evapotranspiration (100% ETC, 80% ETC, 70% ETC, 60% ETC, and 50% ETC) maintained throughout the crop seasons. Furthermore, activated biochar was applied at three levels: 0 tons/ha (no biochar), 5 tons per hectare, and 10 tons per hectare. The study’s findings revealed significant improvements in soil organic matter, bulk density, nutrient profile and total porosity with biochar supplementation in soil. Maize plants grown under lower levels of ETC in biochar supplemented soil had enhanced membrane stability index (1.6 times higher) increased protein content (1.4 times higher), reduced malondialdehyde levels (0.7 times lower), improved antioxidant enzyme activity (1.3 times more SOD and POD activity, and 1.2 times more CAT activity), improved relative growth (1.05 times more) and enhanced yield parameters (26% more grain and stover yield, 16% more 1000-seed weight, 29% more total seed weight, 33% more apparent water productivity) than control. Additionally, among the two biochar application levels tested, the 5 tons/ha dose demonstrated superior efficiency compared to the 10 tons/ha biochar dose.

Optimizing wheat supplementary irrigation: Integrating soil stress and crop water stress index for smart scheduling

A two-year field experiment was conducted to integrate soil moisture stress with the Crop Water Stress Index (CWSI) for optimizing irrigation in winter wheat (Triticum aestivum L.) under varying irrigation regimes. The study took place at the Water Technology Centre (WTC-02) of ICAR-IARI, New Delhi, where the climate shows a blend of monsoon-influenced humid subtropical and semi-arid conditions. Using a randomized block design (RBD), five irrigation treatments were applied: full irrigation and deficit irrigation (DI) at 15 %, 30 %, 45 %, and 60 % levels. Canopy and ambient air temperature data, along with vapor pressure deficit (VPD), were recorded using a developed integrated sensing device to empirically determine the lower baseline equations and upper threshold for CWSI computation at pre-heading and post-heading stages. The slope (m), intercept (c) of the lower baseline equation, and upper threshold (UL) for pre-heading and post-heading were found: m: −1.94, c: −1.33, UL: 1.92°C and m: −1.30, c: −2.37, UL: 2.0°C, respectively. Results showed that increasing water deficit levels led to significant reductions in grain yield, biomass production, and harvest index. A strong negative correlation (R² = 0.95 and 0.93) between mean seasonal CWSI and yield attributes highlighted the utility of CWSI in yield prediction under varying irrigation regimes. It is recommended to schedule irrigation based on the CWSI approach when CWSI ≥0.35 for optimum wheat yields. Integrating CWSI with soil moisture stress provides valuable real-time insights into crop water status, enabling more precise and smart irrigation scheduling.

Analysis of Farmers’ Perceptions on Sealing Techniques for Runoff Harvesting Ponds: A Case Study from Burkina Faso

Water conservation in arid and semi-arid regions faces significant challenges due to low and irregular rainfall, worsened by climate change, which negatively affects rain-fed crop productivity. Various techniques, including supplemental irrigation using runoff harvesting ponds, aim to address these issues but often suffer from water loss due to infiltration, influenced by the pond liner type. This study uses a factorial analysis to assess the farmers’ perceptions of four pond sealing techniques. Using the Waso-2 method, a survey conducted in 2022 among 41 rainwater harvesting pond owners across three regions of Burkina Faso revealed that farmers prioritized impermeability and ease of maintenance over cost and availability. Concrete, scoring 16/20, was the most preferred, chosen by over 75% of farmers for its durability and resistance to weathering, despite its high cost. Geomembrane, with a score of 12/20, was valued for its waterproofing properties but had durability concerns. Clay, although cheap and available, scored 8/20 due to poor waterproofing on unstable ground. Bitumen, the least favored with a score of 6/20, was hindered by scarcity and lack of familiarity. To enhance supplemental irrigation in Burkina Faso and similar regions, waterproof concrete or durable geomembrane liners are recommended. Further research into improving bitumen and clay liners is also suggested. These findings provide key insights into farmers’ preferences, offering guidance for developing effective water conservation strategies to boost agricultural productivity and address food security challenges in the context of climate change.

Maize (Zea Mays L.) Response to Deficit Irrigation Levels at Different Growth Stages on its Yield and Water Use Efficiency at Koka, Central Rift Valley of Ethiopia

Water scarcity is among the major limitations for crop production. Improving water use efficiency of irrigated crops through water management options is crucial in water scarce areas. Field experiment was carried out at Wondo Genet Agricultural Research Center Koka Research site, to investigate the effect of water stress at different growth stage on yield and water use efficiency of maize. one optimum irrigation and eight growth stage based deficit levels(100% ETC at all growth stages, 75% ETC at all growth stages, 50% ETC at all growth stages, 75% ETC at development growth stage, 50% ETC at development growth stage, 75% ETC at mid growth stage, 50% ETC at mid growth stage, 75% ETC at late growth stage and 50% ETC at late growth stage) were imposed on maize (Zea mays L.) variety Melkassa II as a treatment and laid out in randomized complete block design (RCBD) with three replications. Results indicated that the different levels of growth stage based deficit levels had significant (p<0.01) effect on crop yield, harvest index and water use efficiency. Grain yield reduced with increased stress, whereas water use efficiency was increased with stress level increased. The highest grain yield of 6.4 t/ha and WUE of 1.01 kg/m3 were obtained at 100% ETC and 50% ETC at all growth stages, respectively. Also, 75% ETC at development stage and late stage treatments showed no significant variation with 100% ETC in grain yield. Water use efficiency observed at 75% ETC all growth stages treatment was statistically similar with that of 50% ETC at all growth stages treatment. Grain yield obtained from 50% ETC at mid growth stage was similar with 50% ETC at all growth stages, and water use efficiency was the least and this shows that maize was sensitive to moisture stress at mid growth stage than development and late growth stages. Therefore, maize could be irrigated at 75% ETC at all growth stages and by stressing development or late growth stages up to 50% ETC to increase water use efficiency with a small grain yield reduction for stressed scenario and for non stressed scenario with 100% ETC at all growth stages.

Visualizing Plant Responses: Novel Insights Possible Through Affordable Imaging Techniques in the Greenhouse.

Efficient and affordable plant phenotyping methods are an essential response to global climatic pressures. This study demonstrates the continued potential of consumer-grade photography to capture plant phenotypic traits in turfgrass and derive new calculations. Yet the effects of image corrections on individual calculations are often unreported. Turfgrass lysimeters were photographed over 8 weeks using a custom lightbox and consumer-grade camera. Subsequent imagery was analyzed for area of cover, color metrics, and sensitivity to image corrections. Findings were compared to active spectral reflectance data and previously reported measurements of visual quality, productivity, and water use. Results confirm that Red-Green-Blue imagery effectively measures plant treatment effects. Notable correlations were observed for corrected imagery, including between yellow fractional area with human visual quality ratings (r = -0.89), dark green color index with clipping productivity (r = 0.61), and an index combination term with water use (r = -0.60). The calculation of green fractional area correlated with Normalized Difference Vegetation Index (r = 0.91), and its RED reflectance spectra (r = -0.87). A new chromatic ratio correlated with Normalized Difference Red-Edge index (r = 0.90) and its Red-Edge reflectance spectra (r = -0.74), while a new calculation correlated strongest to Near-Infrared (r = 0.90). Additionally, the combined index term significantly differentiated between the treatment effects of date, mowing height, deficit irrigation, and their interactions (p < 0.001). Sensitivity and statistical analyses of typical image file formats and corrections that included JPEG, TIFF, geometric lens distortion correction, and color correction were conducted. Findings highlight the need for more standardization in image corrections and to determine the biological relevance of the new image data calculations.

Impact of climatic trends on the water demand and irrigation planning for annual crops in the São Francisco River basin, Brazil

This study evaluated the spatial distribution of precipitation (P) and Peman-Monteith reference ET (ETo) in Brazil's São Francisco River basin (1961–2022). The analysis included Mann-Kendall trend tests and future IPCC projections on P and ETo to assess the need for supplemental irrigation (SI) of maize crop over twelve hypothetical growing seasons. The average annual P in the basin was 1300 mm year−1, decreasing from the Upper to the Lower section. Annual ETo averaged 1670 mm year−1, with higher depths in the Middle and Lower-middle sections. Trends for both P and ETo were significant(p < 0.05) in 58% of the basin. The overall trend magnitude in P was positive (average of about 0.5 mm year−2). Trend was decreasing in 56% of the sites (3.2 mm year−2) and increasing in 44% of them (5.3 mm year−2). For ETo, the overall trend was also positive (average of 3.0 mm year−2), with increasing trend in 79% of the sites (4.6 mm year−2) and a decreasing trend of 3.8 mm year−2 in 21% of the area. The need of SI varied both over the year with peaks in the May–August period and over the basin with higher depths in the Middle and Lower-middle sections. Large SI values (>800 mm) were associated with the dry season and areas with persistent trends in decreasing P and increasing ETo. Future IPCC projections indicate increased SI depths in most of the basin by 2081–2100, with the Middle and Lower-middle sections facing potentially unsustainable level for crop production.

Nitrogen leaching and groundwater recharge of alternative lawn conversions in subtropical climates

AbstractClimate change, recurrent droughts, and increasing urban water demands have limited water availability in urban landscapes. Water quantity challenges have led to irrigation restrictions and turfgrass removal programs. An experiment was conducted at the University of Florida, West Florida Research and Education Center, Jay, FL, to evaluate the effect of turfgrass conversion to other landscape types on nutrient leaching and groundwater recharge. In April 2021, all surface vegetation was removed from existing turfgrass plots using a sod harvester. Thereafter, plots were planted or covered with three landscape types: a pollinator landscape with flowering forbs (Mimosa sp., Coreopsis sp., and Phyla sp.) + turfgrass (Eremochloa ophiuroides); a nitrogen (N)‐efficient lawn (Arachis glabrata + Paspalum notatum); and a low‐input landscape with unplanted woodchip mulch. Undisturbed turfgrass (E. ophiuroides) served as a control. For 2 years, leachate samples were collected weekly from previously installed 168‐L drainage lysimeters for NO3‐N and NH4‐N load determination. Temporal changes in landscape composition, groundwater recharge, water use, and soil bulk density were also quantified. While the mulch leached 44.7 kg ha−1 NO3‐N year−1, this landscape still offers positive attributes, including erosion protection and water conservation. Conversely, the pollinator landscape minimized nitrogen leaching (8.3 kg ha−1 NO3‐N year−1) due to their relatively greater water use rates (3.56 mm day−1). The turfgrass and nitrogen‐efficient lawn returned ∼35% of the water inputs as groundwater recharge while maintaining relatively low nitrogen leaching (3.6 and 2.7 kg ha−1 NO3‐N year−1, respectively), making these landscapes efficient for protecting both water quality and quantity.

Deficit Irrigation Regime Improves Phytosanitary Status of Cultivar Arbosana Grown in a Super High-Density Olive Orchard

Super high-density (SHD) planting systems are very efficient in terms of production and water use. In these orchards, water-saving irrigation strategies are used precisely to keep the best sustainability compared to traditional orchards. With agro-climatic and eco-physiological parameter monitoring, the SHD planting system has become even more efficient. SHD orchards, however, could also be more so affected by other pests and diseases than traditional systems, but field responses are still unknown when olive trees are grown in SHD groves. The goal of this two-year field research was to investigate the seasonal changes of the phytosanitary status of ‘Arbosana’ grown in an SHD orchard under both regulated deficit (RDI) and full irrigation regimes (FI). This study investigated the influence of the two different irrigation regimes on the infections of three olive tree key diseases: cercosporiosis (Pseudocercospora cladosporioides), cycloconium (Fusicladium oleagineum), and olive knot (Pseudomonas savastanoi pv. savastanoi). RDI significantly reduced the severity of cercosporiosis in 2020 compared to FI but not in 2021. Cycloconium was observed only as a latent infection during the two studied years and olive knot was not influenced by irrigation but only by weather conditions. These findings suggest that irrigation management can play a key role in controlling cercosporiosis effectively in SHD olive orchards, but also that weather conditions have an even higher impact on the tree key diseases.

Modeling and Optimization of Maize Yield and Water Use Efficiency under Biochar, Inorganic Fertilizer and Irrigation Using Principal Component Analysis

This study was conducted to predict the grain yield of a maize crop from easy-to-measure growth parameters and select the best treatment combinations of biochar, inorganic fertilizer, and irrigation for the maize grain yield and water use efficiency (WUE) using the Principal Component Analysis (PCA) technique. Two rates of biochar (0 and 20 t ha−1) and fertilizer (0 and 300 kg ha−1) were applied to the soil, with maize crop planted, and subjected to deficit irrigation at 60, 80, and 100% of full irrigation amounts (FIA). Maize growth parameters (number of leaves—NL, leaf area—LA, leaf area index—LAI, and plant height—PH) were measured weekly. The results showed that the developed principal component regression (PCR) from the easy-to-measure growth parameters were strong and moderate in predicting the maize yield and WUE, with coefficient of determination; r2 values of 0.92 and 0.56, respectively. Using the PCA technique, the integration of irrigation with the least amount of water (60% FAI) with biochar (20 t ha−1) and fertilizer (300 kg ha−1) produced the highest ranking on grain yield and water use efficiency. This optimization technique showed that with the adoption of the integrative approach, 40% of irrigation water could be saved for other agricultural purposes

Combined effects of deficit irrigation and mulching on fruit quality and bioactive compounds of VNR Bihi guava (Psidium guajava)

The present study was carried out during 2019–20 and 2020–21 at Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand to assess the combined effects of deficit irrigation and mulching on a 5-year- old VNR Bihi guava (Psidium guajava L.) orchard. The experiment consisted of three irrigation regimes, viz. deficit irrigation at 50% ETc (DI50); deficit irrigation at 75% ETc (DI75); and full irrigation at 100% ETc (FI100); and four mulching treatments, viz. silver-black mulch (MSB); black mulch (MB); organic mulch (MOM); and without mulch (MWM) laid out in a factorial randomised block design (F-RBD) with three replications. Results showed that fruit number and yield/tree were recorded highest in trees irrigated with DI75 and mulched with silver-black mulch. Under treatment DI50 fruit had the highest concentration of soluble solids, with Brix levels of 12.35°B and 12.78 °B during the years 2019–20 and 2020–21, respectively. Total sugars content was significantly increased under DI50 by 7.73 and 7.36%, respectively as compared to FI100 during both the years of experimentation. The biochemical properties such as total phenolics, total flavonoids and antioxidant (DPPH) activity also increased as irrigation regimes decreased from FI100 to DI50. The total phenolic and flavonoids content were improved by 19.19 and 33.44%, respectively under DI50 when compared to FI100. Significant differences among different mulch treatments with respect to quality parameters were also observed except DPPH activity. Silver-black mulch followed by black mulch resulted in higher soluble solids content, total sugars, ascorbic acid, total phenolic content, total flavonoids and DPPH activity. These findings demonstrate the positive effect of water deficit practice on bioactive compounds and the appropriateness of deficit irrigation and mulching as irrigation management strategies in the fruit orchards that improve fruit commercial value and conserve water.

Optimization of water and nitrogen management in wheat cultivation affected by biochar application − Insights into resource utilization and economic benefits

In the context of global climate change and natural resource scarcity, agricultural production is facing multiple challenges in improving crop yields and optimizing natural resource use. It is of great practical significance to optimize agricultural practices to achieve sustainable agricultural development. In this study, a two-year winter wheat field experiment was conducted in the Guanzhong Plain, Shaanxi, China, from 2020 to 2022 to assess the effects of biochar, irrigation, and N fertilizer rates on the yield, water-nitrogen use efficiency, and economic benefits of winter wheat. Specifically, biochar was applied to winter wheat at 30 t ha−1 in combination with two irrigation application rates, including regular irrigation (I100; actual evapotranspiration) and deficit irrigation (I80; 0.8 actual evapotranspiration), and three different N fertilizer rates at 210 (NH; conventional applied N rate by local farmers), 160 (NM; moderate N rate), and 110 kg ha−1 (NL; low N rate). The control groups in this study consisted of experimental plots under the NM and N0 (no N) without biochar application. The aboveground dry matter mass (ADM), yield, and net ecosystem economic budget (NEEB) of winter wheat showed increasing trends with increasing N application rates without significant differences between the NH and NM treatments. On the other hand, the water use efficiency (WUE), agronomic N fertilizer use efficiency (aNUE), and N fertilizer recovery efficiency (NRE) showed increasing-decreasing trends with increasing N fertilizer rates, reaching the highest values under the NM treatment scenario. The biochar addition significantly increased the winter wheat yield and WUE (P<0.05). On the other hand, the I80 treatment resulted in higher WUE and irrigation water use efficiency (IWUE) than those under I100 by 5.63 and 13.52 %, respectively. TOPSIS results indicated that the combined I80B1NM treatment was the optimal winter wheat management practice, maintaining high productivity while improving resource use efficiency and economic benefits. The results of the present study provide an important scientific basis and guidance for ensuring efficient and high-quality agricultural products in the Guanzhong Plain and other regions in China with similar climatic characteristics.

The role of the application of nanosilver and humic acid on the physiological and yield traits of corn (Zea Mays L.) under deficit irrigation conditions

Water deficit is the most common abiotic stress and at least 75% of corn fields in Iran are exposed to drought stress during different stages of growth. humic acid (HA) and nanosilver (NS) can help mitigate abiotic stresses in plants; especially drought stress. A field experiment was conducted to study the effect of humic acid and nanosilver on the physiological traits and yield of corn during two crop years. Experimental treatments were including deficit irrigation (100%, 80%, 60% of crop water requirement (CWR)) and nanosilver (0 (NS0), 60 (NS60), 80 (NS80) and 100 (NS100) microliters/liter/ha) and humic acid (control (HA0), 500 (HA500) and 1000 (HA1000) g/ha). The highest amount of chlorophyll a, b and total in 100% CWR+NS60+HA1000 was obtained. The highest amount of proline in 60% CWR + NS60 +HA1000 as well as treatment NS0 +HA1000 were observed. In all irrigation levels, the application of NS100 has reduced chlorophyll a and total. The yield components were affected by HA and nanosilver foliar spraying. The highest grain yield was observed in 100% CWR with the application of NS60 +HA500 at the rate of 10,582 kg/ha. In conditions of 100% CWR, nanosilver concentrations had a positive effect on plant growth and yield, and with increasing stress, high concentrations of nanosilver had a negative effect on growth and yield, but with the combined application of nanosilver and HA, the effect of drought stress decreased, which indicates the positive effect of HA in improving plant growth and yield.

Production and postharvest quality of sour passion fruit under deficit irrigation strategies and foliar application of ascorbic acid

ABSTRACT The objective this study was to evaluate the effects of foliar application of ascorbic acid – AsA on the production and postharvest quality of sour passion fruit under deficit irrigation strategies. The experimental design was randomised blocks, in a split-plot scheme, with plots consisting of six strategies of irrigation with water deficit, based on crop evapotranspiration – ETc (irrigation with 100% ETc during the entire cycle – S1; irrigation with 50% ETc in the different stages: vegetative – S2; flowering – S3; fruiting – S4; and successively in the vegetative/flowering stages – S5; and vegetative/fruiting stages – S6) and three concentrations of AsA (0, 88.06 and 176.12 mg/L), with three replicates and three plants per plot. Water deficit reduces the production of sour passion fruit, regardless of the phenological stage of the plants without AsA application. Irrigation with water deficit in the flowering stage (50% of crop evapotranspiration) reduces the physical and chemical quality of sour passion fruits. Ascorbic acid in applied levels was effective in alleviating the effects of water deficit on production, with emphasis on the concentration of 176.12 mg/L on the quality of sour passion fruits, in the period from 160 to 220 days after transplanting.

Productivity of Wheat Landraces in Rainfed and Irrigated Conditions under Conventional and Organic Input in a Semiarid Mediterranean Environment

Wheat landraces are locally adapted populations that are suitable for low-input agronomic management and constraining pedo-climatic conditions. The productivity of landraces under high-input and optimal conditions is usually lower than modern wheat varieties. The present study compared the response of Sicilian wheat landraces and modern varieties to organic management, including organic fertilization, and conventional management, including mineral fertilization and chemical weed control, under rainfed condition and supplementary irrigation in a field trial conducted on a xerofluvent soil in a semiarid Mediterranean climate. Modern varieties were on average more productive than landraces, although certain landraces achieved comparable yields, in particular under organic management. The increase in grain yield under conventional management in comparison with the organic management was higher for modern varieties than landraces. The loss of productivity in rainfed conditions was lower for landraces compared to modern varieties. The grain quality traits were similar between landraces and modern varieties and in both cases the conventional management led to an improvement of the traits. These findings highlight the resilience and adaptability of traditional wheat landraces to low-input agricultural systems and offer valuable insights into improving the sustainability and productivity of wheat production in Mediterranean environments.

Assessing the Synergistic Effects of Deficit Irrigation and Growth Retardants on Insitu Sprouting and Quality Parameters of Groundnut VRI 8

Background: Groundnut is a crucial oilseed crop cultivated year-round, with seed dormancy controlled by genetic and environmental factors. Preventing pre-harvest sprouting is essential, as it is a common issue. To study the effect of deficit irrigation management and foliar application of growth retardant chemicals on pre-harvest sprouting control efficiency to achieve higher yield of groundnut. Methodology: In a field experiment conducted during early summer 2024 at the Agricultural College and Research Institute, Madurai, the effectiveness of different growth retardant chemicals and deficit irrigation management on reducing in-situ sprouting of groundnut kernels was investigated. The experiment included three irrigation management strategies: conventional irrigation and two deficit irrigation treatments where irrigation was withheld from 90 to 105 DAS (Days After Sowing) and 85 to 100 DAS. Additionally, foliar sprays of growth retardant chemicals were applied at 75 and 90 DAS. The chemicals tested were maleic hydrazide (MH) @ 1250 ppm, cycocel (CCC) @ 1000 ppm, abscisic acid (ABA) @ 750 ppm, and salicylic acid (SA) @ 750 ppm. Proper agronomic practices were followed throughout the crop growth cycle. Results: Among the growth retardant chemicals tested, MH @ 1250 ppm proved effective in inducing dormancy. Withdrawal of irrigation from 90 to 105 DAS also significantly contributed to dormancy induction, extending dormancy by more than 5 days post-harvest as well as reduced the pod loss which significantly increased pod yield. It was because of the reduction in soil moisture content during harvest stage and alteration in the hormonal activities. Specifically, the combined treatment of foliar application of MH @ 1250 ppm and no irrigation from 90 to 105 DAS reduced germination percentage by 12.6%, 36.8% and 60.5% immediately 5, 10 and 15 days after harvest respectively. Conclusion: The reduction in soil moisture content during the harvest stage, coupled with changes in hormonal activities, significantly impacts seed sprouting. These factors can lead to stress conditions that hinder germination, ultimately affecting crop yields. Addressing these issues is crucial for ensuring optimal seed development and enhancing agricultural productivity.

Nitrogen requirements of canola (Brassica napus L.) at sustained deficit irrigation levels in central Free State, South Africa

In South Africa canola (Brassica napus L.) is cultivated in rotation with wheat under winter rainfall in the Western Cape province. Expansion of the crop to the other eight provinces is propagated to reduce a shortage of locally produced plant oils. At the same time, canola may serve as a rotational crop for wheat in these summer rainfall provinces. In central Free State, agronomic information for canola production is lacking. An experiment with a line source sprinkler irrigation system was therefore conducted to establish the influence of water application levels (175, 233, 295, 351 and 420 mm) in combination with nitrogen (N) application rates (0, 70, 140, 210 and 280 kg ha−1) on the branches, pods and seeds per canola plant. The biomass and seed yields of canola were also measured, allowing calculation of harvest indices. All six variables were strongly influenced by the interaction of water and N applications. An optimal seed yield of 2.907 kg ha−1 was estimated with a 351 mm water application and a 280 kg ha−1 N application. This resulted in a water use efficiency of 8.28 kg seed ha−1 mm−1 water and a nitrogen use efficiency of 10.38 kg seed kg−1 N.

Improving yield and irrigation water productivity of green beans under water stress with agricultural solid waste-based material of compacted rice straw as a sustainable organic soil mulch

AbstractThis research aimed at water saving in irrigation by applying deficit irrigation using two strategies, standard drip and partial root drying (PRD), while applying organic and plastic mulch over two growing seasons of green beans. A field experiment was conducted in 2022 and 2023, using four irrigation treatments supplying 100% of the irrigation requirement (IRg), 75% IRg, 50% IRg, and 50% IRg—PRD, and four soil mulching treatments: uncovered soil (UC), plastic mulch (PM), rice straw mulch (RSM), and compacted rice straw mulch (CRSM). The combined effect of deficit irrigation strategies and soil mulching showed that the maximum irrigation water productivity (IWP) of 5.56 kg m−3 was achieved under 50% IRg—PRD &amp; CRSM for both growing seasons, followed by 50% IRg—PRD &amp; RSM and 50% IRg—PRD &amp; PM, with 5.19 and 4.96 kg m−3, respectively. The highest yield of 8936 kg ha−1 was achieved with 50% IRg—PRD &amp; CRSM, followed by 8914 kg ha−1 and 8898 kg ha−1 with 100% IRg &amp; CRSM and 75% IRg &amp; CRSM, respectively. The lowest yield of 6009 kg ha−1 was obtained with 50% IRg &amp; UC. The highest soil moisture content was observed under 100% IRg &amp; CRSM. The application of organic mulches was found to be particularly effective in conserving soil moisture due to enhanced infiltration, improved retention capacity, and suppression of weed growth, ultimately fostering optimal crop development and higher yield. The results of soil temperature variations beneath soil mulches showed that CRSM is effective in alleviating plant water stress, lowering the temperature below the cover and reducing water loss through evaporation from the soil surface. The combination of 50% IRg—PRD &amp; CRSM produced plants with enhanced plant height, fresh and dry weight, leaf area, pod length, and green bean weight, as well as the highest vegetative growth indices. Generally, the organic mulching increased soil temperature, soil moisture, IWP, and green bean production.

Integrating Deficit Irrigation Strategies and Soil-Management Systems in Almond Orchards for Resilient Agriculture

This work was conducted over three-year monitoring seasons of three almond cultivars (Guara, Marta, and Lauranne) subjected to deficit irrigation in combination with cover crops in a Mediterranean semiarid area (SW, Spain). Four water–soil treatments were evaluated based on the conjunction of two irrigation strategies: fully irrigated (FI), covering 100% of the ETC, and regulated deficit irrigation (RDI), with two soil-management systems: bare soil (BS) and cover crop based on a mixture of vetch (Vicia sativa L.) and oat (Avena sativa L.) (CC). Throughout the study period in trees, the yield, the stem water potential (Ψstem), leaf nutrient content (N, P, K, Ca, Mg, Na, Fe, Zn, Mn, and Cu) in soils, organic carbon, microbial biomass, fluoresceine diacetate, and enzymatic activities (dehydrogenase, protease, β-glucosidase, and alkaline phosphatase) were determined. In addition, the dry matter and carbon fixation by plant covers were evaluated. For Guara and Lauranne, yield reductions (22 and 26%, respectively) were found for water-stressed (RDI-CC) plots with respect to non-stressed combination (FI-CC) plots, contrasting with cv. Marta, without a significant impact on productivity in all combinations. That is, the RDI (~3.000 m3 ha−1) strategy enabled acceptable productivity, offering promising possibilities for cultivation performance under water-scarcity scenarios. Important differences in Ψstem could be observed and ascribed to irrigation strategies, especially for Guara and Lauranne, but without significant effects due to the soil-management systems applied. No differences were observed in the tree nutritional status due to the presence or absence of CC; however, its presence increased the fixation of atmospheric carbon, which was not the case under BS conditions. Additionally, CC significantly fostered the microbial processes and enzymatic activities, particularly in upper soil layers (0–10 cm) and with plenty of water supply in FI-CC plots and to a lesser extent in RDI-CC plots, which could encourage prominent aspects for soil quality and health restoration. Thus, the cover crop is congruent with RDI to facilitate soil functionality and water savings in a changing climate, contributing to resilient farming systems in the Mediterranean environment.