Bioactive compounds in different melon (Cucumis melo L.) genotypes and one cultivar grown under deficit irrigation and salt stress

Coupling of regulated deficit irrigation at maturity stage and moderate fertilization to improve soil quality, mango yield and water-fertilizer use efficiency

Introduction: Water shortage is the most important factor affecting crop production in the world. The deficit irrigation is a way to reduce water consumption in farming. The Partial Root- zone Drying (PRD) irrigation is a new improvement in deficit irrigation in which the half of the root zone is irrigated alternatively in scheduled irrigation events. In the fixed partial root zone drying (FPRD) the irrigation is fixed to one side of the root zone in the growing season. Maize is a drought sensitive crop. In maize, secondary traits related to drought resistance are considered in producing tolerate cultivars. Materials and Methods: An experiment was conducted in order to investigate the effects of regulated deficit irrigation, variable partial root zone drying (PRD) and fixed partial root zone drying (FPRD) on the yield, physiological and photosynthetic parameters of forage maize (KSC 704) during the growing seasons of 2014 in Mashhad region. A factorial experiment based on randomized complete block design with four replications was carried out. The treatments included the full irrigation (FI) and the deficit irrigations (regulated deficit irrigation (DI) and the replacements of 80 % (DI80) and 60 % (DI60) of total water requirement, fixed PRD (FPRD) at 100% (FPRD100), 80% (FPRD80) and 60%(FPRD60) of water requirement, and variable PRD at 100% (PRD100), 80% (PRD80) and 60% (PRD60) of water requirement). Drip irrigation tapes were placed between plant rows. In the full irrigation and regulated deficit irrigation treatments, the plants were irrigated from two sides for every irrigation. In the PRD, one of two neighboring tapes was alternatively used for irrigation. In FPRD, a drip tape was used for two plant rows and irrigation was fixed to one side of the root. The irrigation interval was 3 days for all treatments. Dry and fresh forage yield, leaf area index (LAI), stomatal conductance, leaf relative water content (RWC) and chlorophyll content were measured. Results and Discussions: All the measured traits were affected by the deficit irrigation. The highest fresh forage yield (72099 kg/ha) was produced by the full irrigation treatment. The statistical comparison showed that there was no significant difference between regulated deficit irrigation and PRD method for the fresh forage yield. But the FPRD treatment reduced the fresh forage yield. There was no significant difference between the fresh forage yield of FI and PRD80 treatments. The dry forage yield was affected by the different irrigation methods, irrigation levels and the interaction effects of the treatments (p

A global meta-analysis of yield and water use efficiency of crops, vegetables and fruits under full, deficit and alternate partial root-zone irrigation

Supplying organic matter under deficit irrigation conditions could be a practical solution to compensate the negative effect of water stress. For this purpose, studies in pea as a legume and quinoa as a new drought‐tolerant crop were conducted in the south of Morocco between October 2011 and March 2012. Three organic matter levels (0, 5 and 10 t ha−1) were supplied as compost amendment combined with 2 irrigation levels (50 and 100% of full irrigation). The results indicate that stomatal conductance and dry matter have been affected significantly (P < 0.05) only by deficit irrigation, while harvested yield was affected significantly (P < 0.05) by both deficit irrigation and organic manure. The highest seed yields (3.3 t ha−1for quinoa and 5.6 t ha−1for pea) were recorded under full irrigation and 10 t ha−1of compost. Results indicated that organic amendment of 10 t ha−1and 5 t ha−1significantly (P ≤ 0.05) increased seed yield by 18 and 11% under stress conditions and by 13 and 3% under full irrigation for quinoa and by 24 and 11% under full irrigation and by 41 and 25% under water‐deficit irrigation for pea. It can be concluded that organic amendment improved significantly yield and biomass production better under deficit irrigation conditions than under full irrigation. Combining deficit irrigation and organic amendment led to the maximization of crop water productivity.

Irrigation and nitrogen management are crucial for sustainable potato (Solanum tuberosum L.) production. A field experiment was conducted during the 2022 and 2023 growing seasons at Farmington, New Mexico, to evaluate the performance of two chip potato varieties (Lamoka and Waneta) under three irrigation regimes (full irrigation (FI), 20% deficit irrigation (DI) and 40% DI) and seven nitrogen fertilizer rates (0, 60, 115, 170, 220, 280, and 340 kg N/ha). The treatment combinations of irrigation regimes, nitrogen rates, and varieties were arranged in a split–split plot design with three replications as main plot, sub-plot, and sub-sub plot, respectively. The two-year results showed that irrigation regimes had the most significant effect on plant growth, physiology, and tuber yield of the potato varieties. For both Lamoka and Waneta, the plant height and canopy cover were lower under 40% DI than under 20% DI and FI treatments. The SPAD meter values were higher under 40% DI, followed by 20% DI and FI treatments, whereas the stomatal conductance was higher under FI, followed by 20% DI and 40% DI during both growing seasons. Regardless of nitrogen rates and variety, a 20% water-saving irrigation strategy reduced the total tuber yield by 4.5% and 22.1% in the 2022 and 2023 growing seasons, respectively, while the 40% water-saving irrigation strategy reduced total tuber yield by 36.8% and 58.2% in the 2022 and 2023 growing seasons, respectively, as compared to full irrigation. Shifting from full irrigation to 20% DI could save 711.2 to 1036.3 m3/ha of irrigation water. For Lamoka, the highest total tuber yield was obtained with 60 kg N/ha under 20% DI and 220 kg N/ha under FI in 2022 and 2023, respectively. For Waneta, the highest total tuber yield was obtained with 115 kg N/ha under 20% DI and 170 kg N/ha under FI in 2022 and 2023, respectively. Maximum water use efficiency (WUE) was obtained at 60 kg N/ha with 20% DI for both Lamoka and Waneta in 2022, while maximum WUE was obtained at 220 kg N/ha under FI for Lamoka and at 170 kg N/ha for Waneta in the 2023 season. The maximum nitrogen use efficiency (NUE) was achieved with 60 kg N/ha under 20% DI for both varieties during both growing seasons. Thus, for sustainable irrigation and nitrogen management, the application of a 20% deficit irrigation strategy with a lower nitrogen rate (60 to 170 kg N/ha) could be the best option to improve WUE and NUE with minimal tuber yield reduction. Our study suggested that 40% deficit irrigation would not be beneficial as compared to both full irrigation and 20% water-saving irrigation.

Exhaustive crops such as cotton require potassium (K) in copious amounts as compared to other crops. High yielding cultivars in cotton-wheat cropping system, have further increased its demand in cotton growing areas of Pakistan. As cotton is grown in arid and semiarid areas, therefore often prone to water deficiency. The reproductive growth particularly flowering and boll setting are highly sensitive to low soil water potentials, where enough K supply can play a vital role. In this two-year field studies, three cultivars (early, mid and late maturing) were cultivated at two K fertilizer levels 100, 200 kg K ha−1 along with control with no K fertilizer application at two irrigation levels. In first irrigation level, water was applied as per full irrigation schedule, while in water deficit irrigation water was applied at deficit irrigation schedule started after flowering till harvesting. It has been revealed that K application has impact on boll setting as well as seed cotton yield, however early and mid-maturing cultivars are more responsive to K fertilization. Furthermore, irrigation level had significant impact against K fertilization and relatively better response was observed in deficit irrigation as compared to full irrigation. Nevertheless, fiber quality parameters were unaffected by K fertilization. Considering the best benefit cost ratio under water deficiency, it is concluded that 100 kg K2O ha−1 should be applied at the time of seed bed preparation for economical seed-cotton yield of early maturing Bt cotton.

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.

Nitrogen (N) accounts for more than 80% of the total mineral nutrients absorbed by plants and it is the most widely limiting element for crop production, particularly under water deficit conditions. For a comprehensive understanding of sunflower Helianthus annuus N uptake under deficit irrigation conditions, experimental and numerical simulation studies were conducted for full (100% ETC) and deficit (65% ETC) irrigation practices under the semi-arid conditions of the Imperial Valley, California, USA. Plants were established with overhead sprinkler irrigation before transitioning to subsurface drip irrigation (SDI). Based on pre-plant soil N testing, 39 kg ha−1 of N and 78 kg ha−1 of P were applied as a pre-plant dry fertilizer in the form of monoammonium phosphate (MAP) and an additional application of 33 kg ha−1 of N from urea ammonium nitrate (UAN-32) liquid fertilizer was made during the growing season. Soil samples at 15-cm depth increments to 1.2 m (8 layers, 15 cm each) were collected prior to planting and at three additional time points from two locations each in the full and deficit irrigation treatments. We used HYDRUS/2D for the simulation in this study and the model was calibrated for the soil moisture parameters (θs and θr), the rate constant factors of nitrification (the sensitive parameter) in the liquid and solid states (μw,3, and μs,3). The HYDRUS model predicted cumulative root water uptake fluxes of 533 mm and 337 mm for the 100% ETC and 65% ETC, respectively. The simulated cumulative drainage depths were 23.7 mm and 20.4 mm for the 100% ETC and 65% ETC which represented only 4% and 5% of the applied irrigation water, respectively. The soil wetting profile after SDI irrigation was mostly around emitters for the last four SDI irrigation events, while the maximum values of soil moisture in the top 30 cm of the soil profile were 0.262 cm3 cm−3 and 0.129 cm3 cm−3 for 100% ETC and 65% ETC, respectively. The 16.5 kg ha−1 (NH2)2CO (50% of the total N) that was applied during the growing season was completely hydrolyzed to NH4+ within 7 days of application, while 4.36 mg cm−1 cumulative decay was achieved by the end of the 98-day growing season. We found that 86% of NH4+ (74.25 mg cm−1) was nitrified to NO3− while 14% remained in the top 50 cm of the soil profile. The denitrification and free drainage of NO3− were similar for 100% ETC and 65% ETC, and the maximum nitrate was drained during the sprinkler irrigation period. By the end of the growing season, 30.8 mg cm−1 of nitrate was denitrified to N2 and the reduction of nitrate plant uptake was 17.1% for the deficit irrigation section as compared to the fully irrigated side (19.44 mg cm−1 vs. 16.12 mg cm−1). This reduction in N uptake due to deficit irrigation on sunflower could help farmers conserve resources by reducing the amount of fertilizer required if deficit irrigation practices are implemented due to the limited availability of irrigation water.

The study was carried out for 2 months in greenhouse conditions in order to determine the effects of full (IR100) and deficit (IR60) irrigation levels and and proline and glycine betaine applications on some fruit yield and quality chractarictics of Albion strawberry cultivar. In the experiment, as the irrigation level decreased, both the fruit number and the yield per plant decreased significantly. This decrease was determined as approximately 20% in fruit number and 34% in yield. Despite under deficit irrigation stress conditions, 20 mM proline application produced higher fruit number and yield than the control group at full irrigation. The proline preparation applications increased the fruit number and yield by approximately 24% and 56%, respectively. While the rate of non-marketable fruit quality tended to increase with decreasing irrigation levels, this suggests that the plant produces poor-quality fruit under deficit irrigation stress conditions. 10 mM proline application prevented the increase in the ratio of non- marketable fruit quality. In this study, the effects of different irrigation levels and preparation applications on fruit quality traits in the Albion strawberry cultivar varied. The interaction of irrigation levels and preparation applications had a statistically significant effect on fruit weight, chroma and hue values of external color, and total soluble solids content, while the effect on other fruit quality parameters was statistically insignificant. The applications were successful in keeping the fruit quality characteristics high compared to the control group under deficit irrigation stress conditions. However, this success varied according to the preparation type and application dose. As a result, it was determined that foliar proline and glycine betaine applications could increase the resistance of the plant to water stress. On the other hand, it was observed that the high doses used and proline application were more effective than glycine betaine in the positive results obtained.

Combined applications of mixed biomaterial amendments and polyacrylamide (MBAP) to maize in semiarid areas have the potential to improve soil physical properties such that improved crop performance may be obtained under deficient irrigation management. In this study, three MBAP applications were C0 (conventional N fertilization application) and C2 and C4 (MBAP applied at rates of 2 and 4 t ha−1, respectively); three irrigation levels were W3 (nearly full irrigation, 85%–100% of field capacity), W2 (light deficit irrigation, 65%–75% of field capacity), and W1 (medium deficit irrigation, 55%–65% of field capacity). Under the same irrigation level, the MBAP significantly decreased soil bulk densities and increased soil hydraulic conductivities and soil water contents. The effects of irrigation levels on soil bulk densities and soil saturated hydraulic conductivities were not significant. Consequently, MBAP improved soil conditions for maize growth and increased grain and biomass yields, especially at the two deficit irrigation levels. Compared with that of C0, grain yields for C2 and C4 were increased by 52.8% and 39.3% under W2, and by 23.5% and 13.7% under W1, respectively. The MBAP and irrigation had significant interaction effects on evapotranspiration during sowing to jointing and on plant heights at 32 d after sowing. The incorporation of MBAP (2 t ha−1) and chemical fertilizer (111.8 kg N ha−1) resulted in the greatest yields under light deficit irrigation and seemed the best approach to improve soil physical properties and sustain maize productivity using limited water resources in dryland regions.

Modeling yield and biomass responses of maize cultivars to climate change under full and deficit irrigation

HighlightsIrrigated grain sorghum yield and irrigation water use decreased under climate change.Increase in growing season temperature beyond 26°C resulted in a sharp decline in grain sorghum yield.Irrigating during early reproductive stages resulted in the most efficient use of limited water.Irrigating to replenish soil water to 80% of field capacity was found suitable for both current and future climates. Groundwater overdraft from the Ogallala Aquifer for irrigation use and anticipated climate change impacts pose major threats to the sustainability of agriculture in the Texas High Plains (THP) region. In this study, the DSSAT-CSM-CERES-Sorghum model was used to simulate climate change impacts on grain sorghum production under full and deficit irrigation strategies and suggest optimal deficit irrigation strategies. Two irrigation strategies were designed based on (1) crop growth stage and (2) soil water deficit. For the first strategy, seven deficit irrigation scenarios and one full irrigation scenario were simulated: three scenarios with a single 100 mm irrigation scheduled between panicle initiation and boot (T1), between boot and early grain filling (T2), and between early and late grain filling (T3) growth stages; three 200 mm irrigation treatments with combinations of T1 and T2 (T4), T1 and T3 (T5), and T2 and T3 (T6); one 300 mm irrigation scenario (T7) that was a combination of T1, T2, and T3; and a full irrigation scenario (T8) in which irrigation was applied throughout the growing season to maintain at least 50% of plant-available water in the top 30 cm soil profile. For the second strategy, the irrigation schedule obtained from auto-irrigation (T8) was mimicked to create a full irrigation scenario (I100) and six deficit irrigation scenarios. In the deficit irrigation scenarios, water was applied on the same dates as scenario I100; however, the irrigation amounts of scenario I100 were reduced by 10%, 20%, 30%, 40%, 50%, and 60% to create deficit irrigation scenarios I90, I80, I70, I60, I50, and I40, respectively. Projected climate forcings were drawn from nine global climate models (GCMs) and two representative concentration pathways (RCP 4.5 and RCP 8.5). Climate change analysis indicated that grain sorghum yield under full irrigation was expected to be reduced by 5% by mid-century (2036 to 2065) and by 15% by late-century (2066 to 2095) under RCP 8.5 compared to the baseline period (1976 to 2005). Simulated future irrigation water demand of grain sorghum was reduced due to the shorter growing season and improved dry matter- and yield-transpiration productivity, likely due to CO2 fertilization. Based on the simulated grain sorghum yield and irrigation water use efficiency, the most efficient use of limited irrigation was achieved by applying irrigation during the early reproductive stages of grain sorghum (panicle initiation through early grain filling). A 20% deficit irrigation scenario was found to be optimal for current and future conditions because it was more water use efficient than full irrigation with a minor yield reduction of <11%. In summary, these results indicated that strategic planning of when and how much to irrigate could help in getting the most out of limited irrigation. Keywords: CERES-Sorghum, Critical growth stages, Crop yield, Global climate model, Irrigation demand, Soil water depletion.

This work examines the effects of two deficit irrigation strategies, conventional deficit irrigation (DI) and partial root-zone drying (PRD), on mature navel orange trees. The study carried out during two consecutive years (2008 and 2009) in a semi-arid climate on a silty–clay–loam soil in the north of Iran. Both DI and PRD trees were irrigated at two levels, 75 and 50% (DI75, PRD75, DI50 and PRD50) of the full irrigation (FI). In DI, irrigation water was applied to both sides of the tree rows, similar to FI. In PRD, irrigation water was applied alternately to only one side, at each irrigation event. Results showed that DI treatments reduced fruit yield by ∼30% compared with FI, but PRD treatments caused no reduction in fruit yield. No negative impact was detected in fruit quality after applying DI and PRD treatments. Shoot growth decreased in all DI and PRD treatments in both years. In DI, stomatal resistance was higher (50%) than in FI, but it was not significantly affected in PRD. The irrigation water use efficiency of PRD trees increased to nearly twice that of FI. According to these two years' results, we recommend PRD as an acceptable deficit irrigation strategy in the region.

This experiment aimed to evaluate the effects of different levels of irrigation based on potential evapotranspiration (100%, 60%, and 40% PET) and doses of nitrogenous fertilizers (0, 40, and 80 kg ha-1) on the performance of safflower in Qazvin, Iran. Three fractions of potential evapotranspiration: 100%, 60%, and 40% PET are considered as full irrigation (FI), mild deficit irrigation (MDI) and severe deficit irrigation (SDI), respectively. The mutual effects of nitrogen and deficit irrigation levels were significant on some growth characteristics such as longitudinal growth, number of secondary branches, canopy width, leaf chlorophyll content, number of capitula, and thousand seed weight. Results revealed that the effectiveness of nitrogen fertilizers was discernable under FI and MDI conditions, however, under SDI, the application of nitrogen fertilizers did not have any improvement effects on evaluated traits. The highest seed yield was recorded in FI+N80 and the seed yield of MDI+N80 was in the second place with a difference of 80 kg ha-1. However, the best seed quality in terms of protein percentage was related to plants grown under SDI+N80, which was 43% higher than FI+N0. The plants grown under FI+N80 and SDI+80 conditions showed the highest seed oil content with 28% and 27.1%, respectively. 

Introduction: Lack of water and deterioration in the quality of soil and water resources are considered to be the prime cause of reduced crop yield in arid and semi-arid regions ‘More crop per drop’ by trickle irrigation, deficit irrigation, and uncommon water are the best strategies for mitigating water crises. Different irrigation management strategies are needed to increase production in different areas. In areas where sufficient water is available, a full irrigation strategy could be a suitable option, while in areas where water is limited, deficit irrigation would be an appropriate method, and finally in areas where water resources are saline, management strategies for achieving sustainable production as well as economic yields would be suitable. Maize is the third most important grain crop in the world following wheat and rice and it is the main source of nutrition for humans and animals. Because of the importance of maize in the world, increasing maize production under environmental stresses is a big challenge for agricultural scientists. Different methods of irrigation and the use of saline water that had satisfactory results for increasing agricultural production have been studied by several investigators . The main objective of this study was to establish an efficient use of limited water resources as well as to explore the possibility of replacing saline water with fresh water using different management techniques. Materials and Methods: A field experiment was conducted over two maize cropping seasons (2012–2013) in northern Iran (Gorgan Agricultural Research Station) to compare different alternate irrigation scenarios using saline water on corn yield, salinity and soil moisture distribution in a randomized complete block design with three replications. Treatments were: T1 and T2 = 100 and 50 % of crop water requirement with non-saline water, respectively; T3 and T4 = variable and fixed full irrigation with saline and non-saline water in every other row, respectively; T5 and T6= fixed and variable deficit irrigation with non-saline water in every other rows, respectively and T7= full irrigation with saline water. To create the desired water salinity (8 dS/m), non-saline well water (1.5 dS/m) and drainage water (20–35 dS/m) were blended in different proportions. A T-tape drip irrigation system (20 m in length) was used in the field experiment. Results and Discussion: In general, corn yield in 2013 was about 1270 kg ha-1 higher than in 2012. From the weather records it can be seen that the second year was drier than the first year. Yield analysis showed that deficit irrigation treatments (T2, T5 & T6) and also alternate salinity treatments (T3 & T4) did not significantly difference. In other words, the deficit irrigation management had no effect on yield. Corn yield in T3 and T4 with 50% of saved fresh water was just reduced to 7 and 1 % of T1, respectively. As a result, comparing treatments T3 and T4 with full irrigation have shown that treatments T3 and T4 are the best option. Comparison of moisture distribution in deficit irrigation treatments showed the highest water content in surface and deep layers was related to the treatments T6 and T2, respectively. The distribution of salinity in the soil profile for treatments T3 and T4 showed that after two years of irrigation with saline water, there is the possibility of use saline water for corn production, but drainage and leaching of soil will need to maintain sustainability. Conclusion: Naturally, in water scarce areas that use some strategic management such as deficit irrigation or saline water use, there is available arable farmland to further develop the irrigated area, and thereby increase total production. According to the results of the two-years where there was a shortage of water to meet crop water requirement and saline water was not available, the use of deficit irrigation managements as described in this study can save fresh water resources and increase total production and farmer's income. If the region is facing a shortage of water resources and saline water is available nearby agricultural land, it is suggested to use alternate furrow irrigation with saline and non-saline water; with the crop water requirement being met by the saline water, the total output will be higher than using deficit irrigation management with non-saline water. Comparision of the distribution of moisture in deficit irrigation treatments showed that surface soil moisture was lower in the treatment of T5 because it was more lateral distribution. In the deeper layers, soil moisture of the treatment T2 was more than others, because it was the predominant infiltration. The two treatments T3 and T4 because of the combined matric and osmotic potential and the movement of water along the sides and deep percolation, resulting widely distributed in soil moisture and thus remaining lower moisture in the soil compare to full irrigation treatments. Consequently, this finding indicates that after two years of corn irrigation using saline (8 dS/m) and non-saline water in every other row (treatments T3 and T4) production can be increased, and in case of proper leaching and drainage management, agricultural sustainability will also preserve.