Effect Of Regulated Deficit Irrigation Research Articles

Regulated Deficit Irrigation during Vegetative Growth Enhances Crop Water Productivity in Chickpea (Cicer arietinum L.)

To optimize irrigation, agronomists need to modulate crop water productivity (CWP) throughout phenology. We compared regulated deficit irrigation (RDI) and sustained deficit irrigation (SDI) in chickpea (Cicer arietinum L. var. Blanoro), expecting RDI during vegetative growth (VG) to enhance CWP, as opposed to flowering (F) and pod-filling (PF) stages. The effects of RDI and SDI on grain yield, plant height, weight, grain caliber, pods and grains per plant, harvest index, and CWP, were tested through a complete randomized block experiment during the years 2020 and 2021, comparing full irrigation (FI, ETc = 100%), SDI (SDI75, ETc = 75% during all stages), and six RDI treatments varying in ETc% across phenology: VG50, VG75, F50, F75, PF50, and PF75. VG75 had higher CWP while minimizing impacts on productivity. During 2020, the plants were taller (0.44 ± 4.4 m), and increased in harvest index (0.47 ± 0.06), and CWP (0.90 ± 0.2 kg m−3) (p < 0.05), while in 2021, plants were heavier (11.4 ± 2.8 g) and increased in caliber (46.1 ± 3.0 grains); grain yield did not differ between the years (p ˃ 0.05), reaching 861.8 (2020) and 944.7 kg ha−1 (2021). Our results highlight the relevance of maintaining 100% ETc during flowering, and the maintenance of RDI at 75% ETc during vegetative growth.

Yield, water productivity and economic return of deficit-drip-irrigated tomatoes in Kaduna (Nigeria)

Compared to gravity flow systems, pressurized drip irrigation provides more efficient control of the amount of water applied, better irrigation uniformity, and a higher initial capital and operation costs. Hence, an economic analysis is required to determine its profitability over a projected time period. Field experiments were conducted in Afaka (Kaduna, Nigeria), during two dry seasons of 2018 and 2019 to determine the effect of regulated deficit irrigation on the yield, crop water productivity, and projected economic returns of UC 82B tomatoes under pressurized drip irrigation. The economic returns were evaluated using the benefit-cost ratio, net present values, and payback period analyses. The highest fresh fruit yield (19.0 t/ha) was obtained in the full irrigation treatment (T1), while the highest crop water productivity (4.94 kg/m3) was obtained in the deficit treatment with full irrigation at the vegetative and flowering stages followed by 60% of reference evapotranspiration at maturity (T7). The project was found to be profitable over the projected years, with benefit-cost ratios of 1.90 and 1.69; payback periods of 2.7 and 3.2 years for T1 and T7, respectively. The full irrigation of tomatoes was therefore found to be more economical than deficit irrigation in the area, with water not being considered as a limiting factor in terms of costs. Gravity drip irrigation was recommended to reduce the pumping cost of irrigation and thereby increase the profit margin.

The end-use quality of wheat can be enhanced by optimal water management without incurring yield loss.

In China, water-saving irrigation is playing important roles in ensuring food security, and improving wheat quality. A barrel experiment was conducted with three winter wheat (Triticum aestivum L.) genotypes and two irrigation pattens to examine the effects of regulated deficit irrigation (RDI) on wheat grain yield, water-use efficiency (WUE), and grain quality. In order to accurately control the soil water content, wheat was planted in the iron barrels set under a rainproof shelter, and the soil water content in the iron barrel was controlled by gravity method. The mechanisms whereby water management influences the end-use functional properties of wheat grain were also investigated. The results revealed that RDI improved the end-use functional properties of wheat and WUE, without significant yield loss (less than 3%). Moderate water deficit (60% to 65% field capacity) before jointing and during the late grain-filling stage combined with a slight water deficit (65% to 70% field capacity) from jointing to booting increased grain quality and WUE. The observed non-significant reduction in wheat yield associated with RDI may be attributed to higher rate of photosynthesis during the early stage of grain development and higher rate of transfer of carbohydrates from vegetative organs to grains during the later stage. By triggering an earlier rapid transfer of nitrogen deposited in vegetative organs, RDI enhances grain nitrogen content, which in turn could enhance dough elasticity, given the positive correlation between grain nitrogen content and dough midline peak value. Our results also indicate that the effects of RDI on grain quality are genotype dependent. Therefore, the grain end-use quality of some specific wheat genotypes may be enhanced without incurring yield loss by an optimal water management.

Effect of Regulated Deficit Irrigation on Agronomic Parameters of Three Plum Cultivars (Prunus salicina L.) under Semi-Arid Climate Conditions.

Regulated deficit irrigation (RDI) strategies may greatly contribute to save irrigation water, especially in low water availability conditions. The effects of RDI on the growth process, photosynthesis, fruit yield, and some quality traits were assessed for two years on three plum (Prunus salicina Lindl.) cultivars (‘Black Diamond’, ‘Black Gold’ and ‘Black Star’) grown in Midwest Tunisia. The experiment was conducted during two successive seasons (2011–2012). Two water regimes were applied per cultivar during the phase of fruit growth until fruit ripening. Stressed trees receive 50% of the amount of irrigation compared to controls (CI). Several eco-physiological parameters and some pomological criteria were measured, based on the climatic condition (ETo, ETc, and VDP). Results showed that the three cultivars had an aptitude for tolerance for moderate stress with varying degrees of response time to drought stress. Globally, a slight decrease in the gas exchange rate (AN and gs) and the water status (RWC, Ψmin, and Ψos) was registered. Tree yields, size and weight show a slight decrease under water stress. Nevertheless, there was an improvement in the total soluble solid content (SSC) and firmness in same cultivars. Our results proved that the Black Star cultivar was the most tolerant to deficit irrigation, in reason that it maintains a good water status and a high photosynthetic activity.

Evaluation of regulated deficit drip irrigation strategies in apricot

Water is essential for agricultural production and food security. Water scarcity is expected to intensify as a result of climate change and continuing expansion in the world’s population. Therefore, it calls for efficient water management in agriculture ensuring water use to be more efficient, productive, equitable, and environment friendly. Regulated deficit irrigation (RDI) is one of the recent tools used in agriculture water management. The effects of RDI on the performance of 4 years old apricot trees (Prunus armeniaca L. cv. ‘New Castle’) were assessed during two critical crop growth periods (March–July 2016 and 2017) and one non-critical period (August–November 2016) in a randomized block design in the apricot block at Experimental Farm of the Department of Soil Science and Water Management, Dr Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan (HP), India during two consecutive growing seasons (2016 and 2017). In the non-critical period, RDI @60%ETc can be successfully employed to achieve significantly comparative fruit yield and quality with 40% water savings over conventional drip irrigation @100%ETc, while in critical period conventional drip irrigation @100%ETc must be used for higher apricot production. Therefore, the apricot crop should be irrigated through drip irrigation @100% ETc in the critical period (March-July) and @60% ETc in the non-critical period (August-November) with black polyethylene (plastic) mulching in the plant basins to achieve optimum fruit yield and quality characteristics.

Effects of regulated deficit irrigation on soil salinity, physiological processes and fruit quality of gray jujube under desert conditions.

Regulated deficit irrigation (RDI) was applied to gray jujube trees in an oasis region, to determine the effects of this irrigation system on soil salinity, gray jujube physiological processes, fruit yield, and fruit quality. Treatments consisted of severe, moderate and low deficit irrigation (irrigated with 85%, 70% and 55% of CK, respectively) at the flowering stage to fruit set stage. During the other growth stages, all treatments were irrigated with 80% of pan evaporation, which was the same as that in control. The results indicated that soil salinity was enhanced during the periods of water stress, but the high value of soil salinity declined by 3.48%-37.27%, at each depth, after irrigation was resumed. RDI caused a decline in the photosynthetic rate, transpiration rate, and stomatal conductance, but enhanced the water use efficiency of the leaves. However, the leaf photosynthetic rate was effectively enhanced after the recovery of irrigation, especially in the moderate deficit irrigation treatment, which exceeded the control. This led to an improved fruit yield, which was 9.57% higher than that of the control. The deficit treatments caused a significant increase in the soluble solid content, soluble sugar content, single fruit weight and sugar/acid ratio. Enhanced vitamin C content, resulting from deficit treatments, has also been observed in the gray jujube. Therefore, this research shows that RDI provides some benefits in the production of gray jujube trees in desert conditions. Keywords: regulated deficit irrigation, soil salinity, gray jujube, water use efficiency, photosynthetic rate, transpiration rate, stomatal conductance, soluble solid content, sugar/acid ratio DOI: 10.25165/j.ijabe.20191203.4262 Citation: Liu Z P, Zhu C L, Wu S Y, Guo W H, Abudushalamu Y, Jiao X Y, et al. Effects of regulated deficit irrigation on soil salinity, physiological processes and fruit quality of gray jujube under desert conditions. Int J Agric & Biol Eng, 2019; 12(3): 52–59.

Regulated deficit irrigation effects on physiological parameters, yield, fruit quality and antioxidants of Vaccinium corymbosum plants cv. Brigitta

Highbush blueberries require sufficient water throughout the growing season, especially during fruit development. Regulated deficit irrigation (RDI) has been used in many fruit crops to save water and potentially increase fruit quality without reducing yield. Our aim was to determine the effects of RDI on yield, plant–water relations, and fruit quality at harvest. Three irrigation treatments based on actual evapotranspiration (ETa) were applied: 50, 75 and 100% (control) to six-year-old ‘Brigitta’ highbush blueberries in Colbun, Maule Region, Chile, for seasons 2013–2014 and 2014–2015 and to 26-year-old ‘Brigitta’ plants in South Haven, Michigan, USA, during the 2014 season. Severe water deficit treatment (50% ETa) decreased photosynthetic rate, vegetative growth (second season in Colbun and South Haven’s trial), and fruit quality (berry size, titratable acidity, soluble solids, weight), and increased oxidative stress during both seasons in Colbun. The 50% ETa treatment also had the highest yield reduction during Colbun’s second season. In contrast, mild water stress (75% ETa) resulted in similar fruit yields and quality (firmness, fruit size, titratable acidity, soluble solids and berry weight) but with higher water productivity than the 100% ETa treatment, while it achieved intermediate values for antioxidant capacity compared to the 50% ETa treatment.

Regulated deficit irrigation effects on growth, yield, grape quality and individual anthocyanin composition in Vitis vinifera L. cv. ‘Tempranillo’

Regulated Deficit Irrigation (RDI) is an irrigation scheduling technique, originally developed for fruit orchards, that has been successfully adapted for winegrape production. The aim of this work is to evaluate the effect of RDI in vegetative growth, yield and harvest quality in ‘Tempranillo’ vineyards grown under semiarid conditions typical in Mediterranean areas. Two RDI strategies were compared with conventional irrigation practices (CI). CI that consisted in a progressive increase in water deficit as summer progressed, whereas RDI strategies (RDI1 and RDI2) had in common a deficit period just after fruit set and, in RDI2, vines were subjected to an additional stress period shortly after veraison. The experiment was carried out in four consecutive seasons in a commercial vineyard. Water stress at the beginning of berry development resulted in an important reduction of both vegetative growth and berry weight in RDI strategies. No differences in sugar concentration were found between treatments, and RDI berries tended to have lower acidity. The most relevant effect of RDI strategies on grape quality was an increase in anthocyanin and phenolics concentration. In RDI1 berries, this increase was mainly an indirect consequence of smaller berry size. However, in the RDI2 treatment the higher berry anthocyanin concentration reported was not exclusively due to a reduction in berry size. Since harvest quality has been clearly improved by any of the RDI strategies in both years, it can be concluded that RDI constitutes an interesting technique to be applied in ‘Tempranillo’ vineyards grown in semiarid areas aiming to obtain high quality grape.

Effects of regulated deficit irrigation at different growth stages on greenhouse pear-jujube quality.

Effects of regulated deficit irrigation at different growth stages on greenhouse pear-jujube quality.

Effect of Regulated Deficit Irrigation and Crop Load on the Antioxidant Compounds of Peaches

The use of regulated deficit irrigation (RDI) strategies is becoming a common practice in areas with low water availability. Little information is available about the effects of RDI on the antioxidant content of fruits. In this study, the influence of RDI on the content of vitamin C, phenolic compounds and carotenoids was investigated. Two irrigation strategies, fully irrigated (FI) and RDI, were compared at two levels of thinning, commercial and half of the commercial crop load. RDI strategies affected the content of vitamin C, phenolics and carotenoids of Flordastar peaches. RDI caused fruit peel stress lowering the content of vitamin C and carotenoids, while increasing the phenolic content, mainly anthocyanins and procyanidins. Fruit weight was the only quality index influenced by the crop load as it increased in FI fruits at low crop load. In general, fruits from commercial crop load had slightly higher content of antioxidants to fruits from low crop load, although these influences were only observed in the peel. Additionally, the influence of irrigation controlled by two sensors related to plant water level, maximum daily trunk shrinkage (MDS) and sap flow (SF) on the antioxidant constituents of peaches was evaluated. The response of the fruits to SF sensor was similar to that observed for RDI strategy. According to the tested water sensors, SF did not act as a good plant-based water indicator for use in irrigation scheduling, as it caused an increase in the content of phenolics, similar to that observed for fruits subjected to RDI. Therefore, selection of RDI strategies and plant water indicators should be taken into account as they affect the content of antioxidants of peaches.

Regulated deficit irrigation effects on yield, nut quality and water-use efficiency of mature pistachio trees

SummaryRegulated deficit irrigation (RDI) was evaluated on deep rooted, mature pistachio trees grown under high evaporative demand in the low rainfall southern San Joaquin Valley of California. The focus of this work was to assess the impact of deficit irrigation during various parts of the season with the goal of determining which period was most stress tolerant in terms of nut production. Pistachio nuts have a unique fruit growth pattern in which rapid kernel growth does not begin until about six weeks after full shell size has been attained. Our hypothesis was that irrigation could be reduced during this period with limited negative effects on production. The season was divided into three preharvest periods: leafout to full shell expansion (Stage 1), full shell expansion to the onset of rapid kernel growth (Stage 2), and rapid kernel growth to harvest (Stage 3). Water deprivation during Stage 1 applied 7.2% less water than the near-fully irrigated Control without any yield loss, based on mean values for the last “on” and “off” alternate bearing years of this study. Shell splitting (endocarp dehiscence) at harvest (a positive impact) was significantly higher (10.4% relative to the Control) but this was offset by a nut weight reduced by 9.4%. Stage 3 water deprivation (53% less applied water than the Control) significantly reduced nut size, shell splitting, mechanical nut removal by tree shaking, and yield, while increasing kernel blanking and abortion. Postharvest water deprivation (5.0% less applied water than the Control) had no significant negative effects on yield components. Six irrigation regimes that applied water at various rates were used to investigate Stage 2 behaviour. While there were no significant differences in yield components among these regimes, the best production occurred with deficit irrigation during Stage 2 at 50% of near-potential ETc during Stage 2 and 25% of near-potential ETc after harvest. This RDI regime saved about 180 mm of water (23.2% of the Control) and water use efficiency was significantly higher (4.69 versus 3.61 kg marketable fruit per mm water, for this RDI regime and the Control, respectively). We believe RDI during Stage 2 and postharvest is a viable irrigation strategy to save water while maintaining top yields of high quality pistachio nuts. Further work is needed to determine if the improved shell splitting harvest that occurred with Stage 1 stress can be exploited to improve grower profits.

Regulated deficit irrigation effects on yield, fruit quality and vegetative growth of ‘Navelina’ citrus trees

An experiment on regulated deficit irrigation (RDI) was performed during two growing seasons (2007 and 2008) in a drip-irrigated orchard of Navelina/Cleopatra in Senyera (Valencia, Spain). Two RDI treatments, where water application was reduced to 40% and 60% of the «irrigation dose» (ID), were carried out during the initial fruit enlargement phase (Stage II, 17th July to 2nd September). The rest of the year they were irrigated at 110% ID. These treatments were compared with a control, where irrigation was applied without restriction during the whole year at 110% ID. The ID was obtained from the evapotranspiration data, as well as from the characteristic variables of drip irrigation for the specific experimental orchard. The effects of the treatments on yield, fruit quality, and vegetative growth are discussed in relation to tree water status (midday stem water potential, Ψst). Minimal Ψst values reached in the treatment with the highest stress intensity were –1.71 and –1.60 MPa in 2007 and 2008 respectively. These Ψst values reached as a consequence of the water reduction in the RDI summer treatments applied in this study did not affect yield or fruit quality, allowing water savings between 16% and 23%. In conclusion, water restriction during summer, and once «June drop» has finished, favours the better use of water resources by Navelina citrus trees, achieving an increase of water use efficiency (between 14% and 27% in this case), provided that an appropriate irrigation in autumn allows for tree recovery.