Normal Irrigation Research Articles

A smart surface irrigation design based on the topographical and geometrical shape characteristics of the land

Designing an efficient irrigation system on the farmland is a challenging issue which is dependent on many characteristics of the farmland. In this paper, the topographical and geometrical characteristics of the land are analyzed for designing an efficient furrow surface irrigation system. The topographical characteristics of the farmland can be changed in the cultivation process, so designing an efficient irrigation system requires modeling the last state of the topographical and geometrical characteristics of the land. The proposed method uses the digital elevation model, aspect of the slope and slope model of the land as topographical information and geometrical shape of the land as geometrical information. It designs the irrigation system at the field level for delivering water from the inlet of the land to the plants and uses a two steps designing strategy. First, the algorithm segments the land based on the topographical characteristics and geometrical shape into some plots. Then the ditches network is designed based on the topographical data and the geometrical shape of the land for providing water to the head ditch of each plot. The proposed method designs an efficient furrow irrigation system based on many well-known metrics. It was evaluated in an experimental field and compared with the traditional farmer designed irrigation system and two other normal irrigation systems. The evaluation shows that the proposed method can improve efficiency by decreasing the used water and irrigation time by about 50%.

The Alleviation Effects of Biostimulants Application on Lettuce Plants Grown under Deficit Irrigation

Τhe aim of this study was to examine the potential of using biostimulants for the amelioration of deficit irrigation effects on field-grown lettuce plants growth parameters (cv. Doris (Romaine type) and cv. Manchester (Batavia type)). Therefore, five biostimulatory products that differed in their composition were evaluated, including seaweed extracts, amino acids, humic and fulvic acids, macronutrients, Si, and vegetable proteins, while a control treatment with no biostimulants applied on plants was also considered. Plants were subjected to three irrigation regimes, e.g., rain-fed plants (RF), deficit irrigation (I1; 50% of field capacity) and normal irrigation (I2; 100 of field capacity). The results indicate that the application of seaweed extracts, macronutrients, and amino acids (SW treatment) alleviated the negative effects of deficit irrigation on plant growth and chlorophyll content of Romaine-type plants. On the other hand, Batavia-type plants were more susceptible to water stress, since the highest crop yield plant was observed under the full irrigation treatment and the application of vegetal proteins and amino acids (VP treatment). In general, the application of biostimulants on the Romaine type improved plant growth under water shortage conditions compared with fully irrigated plants in almost all measurements, whereas the Batavia-type plants appeared to be more sensitive to deficit irrigation. Therefore, the ecofriendly practices of deficit irrigation and biostimulant application could be useful in leafy vegetable production on a genotype-depended manner.

Plant-based nano-fertilizer prepared from Paulownia Tomentosa: fabrication, characterization, and application on Ocimum basilicum

BackgroundThe use of hazardous and toxic chemical material has become limited by the green synthesis of nano-particles (NPs) from plants and other living organisms. In the current study, a new nano-fertilizer was green synthesized from Paulownia tomentosa leaves and then its effectiveness in alleviation of drought stress in Ocimum basilicum was investigated. Five concentrations of nano-fertilizer (0, 50, 70, 90 and 110 ppm) at three irrigation regimes including 100% of field capacity (IRF100), 75% of field capacity (IRF75), and 50% of field capacity (IRF50) were evaluated. Nano-fertilizers were prepared using the green hydrothermal method.ResultsBased on TEM analyses nanoparticles sizes were 5–8 nm. The results of FTIR appearance indicated the main distinctive peaks of the Paulownia-based nano-fertilizer (NFPs) in the spectrum. In addition, the nitrogen peaks in the XPS spectra indicate that the prepared carbon dots NFPs are nitrogen-doped. Moreover, there are functional groups, such as COOH or OH groups on the surface of Paulownia-based nano-fertilizer (NFPs). The results illustrated that drought stress increased proline (73%), alcohol-soluble carbohydrates (78%), and malondialdehyde (41%) in comparison with normal irrigation; in contrast, soluble proteins (73%), Chlorophyll a (46%), Chlorophyll b (39%), Chlorophyll total (42%), and carotenoid (77%) were reduced in the same condition. The O. basilicum biological yield was reduced in moderate (12.40%) and severe (24.42%) drought stress in comparison with full irrigation conditions (IRF100). Paulownia-based nano-fertilizer (NFPs) caused an increase in soluble proteins and photosynthetic pigments. Application of NFP-90 reduced the production of proline and malondialdehyde, respectively, 51.8% and 30.8% compared to non-application under severe stress conditions, which indicates alleviated the adverse effect of drought stress. The highest biological yield of basil was obtained at a 110 ppm concentration of NFPs.ConclusionOverall, results showed that using NPs biosynthesized from Paulownia leaves could be an economically and environmentally friendly method as a nano-fertilizer.Graphical

Assessment of Zinc, Boron, and Iron Foliar Application on Wheat Yield and Yield Components Under Drought Stress

ABSTRACT While eliminating their deficiency, leaf consumption of micronutrients enhances the quantitative and qualitative yield of the plant. To examine the impact of irrigation regimes and foliar application of zinc, boron, and iron on wheat yield and yield components, an experiment was conducted in the form of split plots in Varamin (Iran) over two crop years 2016–17 and 2017–18. The main factor of irrigation regimes included three levels (Tr: regular irrigation, Ts: irrigation interruption at the onset of stem growth and Tss: irrigation interruption at the onset of stem growth and seed filling) and the secondary factor included foliar application of micronutrients at eight levels (MC: control), MB: foliar application of boron (B), MZ: zinc (Zn), MI: iron (Fe), MZB: Zn + B, MBI: Fe + B, MZI: Zn + Fe and MZBI: Zn + B + Fe). Irrigation interruption at the onset of stem growth and seed filling (Tss) led to a significant reduction in seed yield and its components. With an average of 6788 kg ha−1, the highest seed yield belonged to normal irrigation treatment. With an average of 6549 kg ha−1, Fe + Zn + B treatment had the highest seed yield, indicating a 17% increase compared to the control treatment. Given the positive effect of iron, zinc, and boron micronutrients on wheat agronomic characteristics, these treatments under normal irrigation and drought stress conditions are suggested to be applied for the development of wheat cultivation in cold temperate areas with semi-arid climate.

Yield and yield components of common bean as influenced by wheat residue and nitrogen rates under water deficit conditions

Incorporation of crop residues into agricultural system has become a worldwide efficient practice for enhancing crop production. The main objectives of this experiment was to investigate the major role of incorporating wheat ( Triticum aestivum L.) residues and nitrogen (N) fertilizers rates under different water requirements (WR) on growth, seed yield and yield components of common bean ( Phaseolus vulgaris L.). The results showed that seed yield under 80% WR in retained crop residue plots was ∼ 11% higher than WR treatment with no residue incorporation. Seed yield was not significantly different between residue retention and removal treatments in 2016, whereas it was higher (12% and 17%) under residue retained plots compared to removed ones in subsequent years. Seed yields responded to N up to 170 and 225 kg ha −1 in removed and retained residue treatments, respectively in 2017 and 2018. Annual increment of seed yield in residue retained plots (36%) was 2.11 times higher than the residue removed ones (17%). There was higher soil N content in 50% residue retention with 225 kg N ha −1 under both water deficit treatments in all years. The highest soil organic carbon (SOC) was achieved with normal irrigation in retained residue plots with 225 kg N ha −1 in all years. Overall, wheat residue incorporation into the soil and N-supply substantially contributed to counteracting yield declines of common bean under water deficit conditions. • Wheat residue incorporation into soil improved soil characteristics. • Wheat residues incorporation stored higher SOC and N than removed ones. • Application of wheat residue in combination with N fertilization enhancing bean growth. • Wheat residues application with sufficient N rates ameliorating water stress condition.

Evaluation of Genetic Variability of Bread Wheat Genotypes under Normal Irrigation and Water Stress Conditions Using Multivariate Analysis

Evaluation of Genetic Variability of Bread Wheat Genotypes under Normal Irrigation and Water Stress Conditions Using Multivariate Analysis

Effect of Sowing Date and Plant Spacing on Yield and Yield Components of Dry Field Bean (Phaseolus vulgaris L.) Under Normal Irrigation at Dry lands. South Omdurman Region, Sudan

A field experiment was conducted for two consecutive winter seasons (2015/2016 and 2016/2017) at the Demonstration Farm of the Faculty of Agriculture – Omdurman Islamic University (Fetahab), to study effect of sowing date and plant spacing on yield and yield components of Dry Field Bean (Phaseolus vulgaris L.) at South Omdurman Region. Three sowing dates were investigated (3rd wk of October, 1st and 14th November). Also three plant spacing were used (10, 15 and 20cm) between plants. The treatments of two factors arranged in a randomized complete block design with four replicates. Yield and yield components studied were days to start and to 50% flowering, number of pods/ plant, number of seeds per pod, 100-seed weight, seed yield per plant and seed yield per unit area. Results showed that, days to start and to 50% flowering were significantly reduced for November sowing date (beginning and mid-November) compared with October sowing date for both seasons. Also these sowing dates reported a significantly higher mean of number of pods per plant, number of seeds per pod and seed yield per plant in the first season. On the other hand, plant spacing did not significantly affect for any yield components attribute; however, the wide space (20 and 15cm) achieved the higher values for these parameters than the narrow one. Also, it was observed that, the interaction between sowing date and plant spacing did not significantly affect neither growth attribute nor yield and yield components for both seasons. However, number of branches per plant during 12th wk of the 2nd season was affected by this interaction.

Single Trait Selection and Independent Culling Levels in Improving Egyptian Cotton Yield (G. barbadense L.) under Normal Irrigation and Water Deficit

Single Trait Selection and Independent Culling Levels in Improving Egyptian Cotton Yield (G. barbadense L.) under Normal Irrigation and Water Deficit

Combining ability of some sunflower parental lines in both normal and drought stress conditions

Abstract General and specific combining abilities of three cytoplasmic male sterile and four restorer lines of sunflower were studied in a randomized complete block design with three replications under normal irrigation and drought stress conditions in Eslamabad-e-Gharb, Iran during two growing season (2019 and 2020). Drought stress reduced seed yield, oil yield, thousand seeds weight and head diameter by 21.9%, 18.1%, 14.3% and 11.5%, respectively. Line × tester analysis indicated that the effect of lines was significant for the number of days to flowering, plant height, grain yield and seed oil percentage under both normal and drought stress conditions. The effect of lines was significant for number of days to maturity and number of seeds per head under normal condition and for thousand seeds weight under drought stress condition. Contribution of lines × testers were higher than the variances of lines or testers for of most of all the studied traits indicating the major role of non-additive effects on expression of theses traits. R131 was differentiated with the highest positive general combining ability for grain and oil yield in both normal and drought stress conditions. Among the testers, AGK32 and AF81-222 had the highest general combining ability for grain yield under normal and stressed conditions, respectively. R131×AGK38, with grain yields of 4414 and 3457 kg ha-1 under normal and drought stress conditions respectively, had the highest specific combining ability for grain and oil yield under both conditions. The results of this study showed that the genetic materials and environmental conditions can affect the nature of gene effect and combining ability of sunflower parent lines and crosses.

The influence of different bacteria consortium and irrigation levels on yield and physiological attributes of durum wheat (Triticum durum Desf.) grown under organic farming conditions

BackgroundInorganic fertilizers help to prevent yield and quality losses in agricultural production; however, adversely affect soil quality and human health. The rising public awareness is switching the production focus from conventional to organic farming. Therefore, obtaining higher yields under organic farming conditions is inevitable. Different bacterial consortia have been found helpful in improving crop yields under stressful and benign environments. Therefore, current study tested the impact of two bacterial consortia on yield and physiological attributes of durum wheat (Triticum durum Desf.) grown under organic farming conditions with two different irrigation levels. MethodsTwo bacteria consortiums [(consortium 1 = Bacillus megaterium RCK-869 + Pantoea agglomerans RK-120 + Paenibacillus polymyxa RCK-540 + Bacillus subtilis RCK-561), (consortium 2 = Azospirillum, Rhizobium, Azotobacter and Acetobacter) and two irrigation levels, i.e., 50 and 100% of the required moisture were included in the study. Data on chlorophyll index, flag leaf area, soluble sugar content, plant height, protein ratio, and grain yield were drecorded. ResultsThe GY in bacteria-free treatment was 3512.0 kg ha−1, which increased to 4868.3 kg ha−1 with the application of bacteria consortium 1. The application of 50% irrigation significantly reduced the yield and related traits, whereas the application of bacteria consortium 1 significantly improved these traits under normal and 50% irrigation. Overall, higher values of the studied traits were recorded during 1st year than 2nd year. The decrease in total precipitation and relative humidity, and the increase in temperature in the second year caused a decrease in grain yield, agronomic and physiological parameters. ConclusionBacteria consortium consisting of Bacillus bacteria significantly improved the yield and related traits of durum wheat under deficit and normal irrigation. Therefore, bacterial consortium consisting of B. megaterium + P. agglomerans + P. polymyxa + B. subtilis could be used to improve durum wheat production under organic farming conditions and deficit irrigation.

Assessment of Wheat Genotypes under Low Irrigation Conditions Using Agro-physiological Traits and Grain Quality in North Delta of Egypt

Water scarcity in Egypt and globally makes producing new varieties having high grain yield using less water requirements is an important goal for wheat breeders. The present research was conducted to assess the response of sixteen bread wheat genotypes under normal irrigation (five irrigations) and low irrigation (one irrigation, 25 days, after sowing irrigation.) during 2018/19 and 2020/21 seasons at the Experimental Farm of Sakha Agricultural Research Station, Egypt. A randomized complete block design with three replicates was used for each irrigation treatment separately. Results showed that the normal irrigation treatment had considerably higher mean values for all studied traits except, proline, malondialdehyde, activity of peroxidase and catalase enzymes,1000-kernel weight, protein content, wet and dry gluten which had significantly higher mean values under low irrigation treatment. Under low irrigation conditions, the four genotypes Sakha 95, Line 4, Line 8 and Misr 3 superior other genotypes in grain yield with insignificant difference among them. Sakha 95 and Line 8 had the highest chlorophyll a and b, proline content, chlorophyll florescence, activity of both catalase and peroxidase enzymes. While, Line 4 had the highest activity of catalase and peroxidase, heaviest 1000-kernel weight and high content of crude protein. In addition to Misr 3 recorded the best values of both wet and dry gluten. It could be recommended with cultivation Sakha 95 or Misr 3 to achieve high grain yield with less irrigation water. While Line 8 and Line 4 need more evaluation to use it in the regions which suffering from water shortage also it will be benefit for breeder to use these genotypes in wheat breeding program.

Breeding Long Shelf-Life (LSL) Tomato Landraces to Non-Trellised Culture and Water Deficit Irrigation: The Effect on Yield and Postharvest Storage

Non-trellised culture of tomato is gaining interest among farmers cultivating long shelf-life (LSL) landraces because of the reduction in production costs. This cropping system can benefit from the selection of determinate growth genotypes, mirroring the advancements achieved in processing tomatoes. With this aim, and profiting from the natural variation found within the Penjar landrace, we selected traditional determinate genotypes and breed novel lines carrying both the self-pruning (sp) and the compound inflorescence (s) mutations. Traditional genotypes and breeding lines were compared to commercial controls in a three multi-locality trial and under two irrigation regimes (normal watered, 100% ETc; and water deficit, 50% ETc). Water use efficiency, harvest index, yield and fruit quality traits were studied at harvest. During postharvest, the effects of genotype and management practices on shelf life were assessed under different storage conditions (controlled conditions/cold storage/farmer facilities). All genotypes used water more efficiently under water deficit irrigation than under normal irrigation. Harvest index was improved in the determinate genotypes and was neither affected by locality nor by irrigation factors. Breeding lines showed yields similar to the controls and the traditional ones; however, they displayed a plant architecture that facilitated their management. They also presented higher postharvest shelf life than controls and traditional lines. Shelf life was significantly affected by genotype (G), locality (L, at early stages), and irrigation regime (I, at later stages), with the contribution of the genotype to the phenotypic variance increasing along the postharvest. Low watering increased shelf life in some genotypes while cold storage and high humidity conditions impeded the long shelf-life trait. Overall, sunscald incidence and percentage of unripe fruits when using a single harvest strategy are the major limitations for non-trellised culture of Penjar tomato. In conclusion, this study sheds light on the main aspects of management and on breeding targets to promote a non-trellised culture of Penjar tomato in combination with optimal water use efficiency.

The Evaluation of Common Bean (Phaseolus vulgaris L.) Genotypes under Water Stress Based on Physiological and Agronomic Parameters.

Drought affects common bean productivity, and the severity of its impact is expected to increase due to climate change. The use of versatile genotypes could contribute to securing future bean production. This study investigates the adaptability of 10 common bean genotypes of indeterminate growth type under water scarcity conditions by measuring agronomic and physiological parameters. The evaluation occurs under irrigation treatments applied at two different phenological stages (anthesis (WDA) and seed filling initiation (WDSF)). The recorded adaptabilities of the genotypes (G) showed that G10 produced the highest overall seed yield in the normal irrigation (NI) (197.22 g plant−1) and WDA (192.78 g plant−1), while the G6 had the highest yield at WDSF (196.71 g plant−1). For the genotype’s average mean, chlorophyll content decreased by 10.5% under drought at WDSF. Net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (E) were reduced at WDA by 53%, 80.8%, and 61.4% and at WDSF by 43.75%, 57.7%, and 36%, respectively, while relative water content (RWC) reduced by 16.48%, on average, for both stages. G10 and G6 showed adaptability when water scarcity occurred at an early (WDA) or later stage (WDSF), respectively, providing insights into using germplasm resources to cope with the drought effect.

The Physiological Responses of Maize Seedlings with Different Amylose Content to Drought Stress

In this study, we investigated the physiological responses of maize with different amylose content at seedlings to drought stress. For waxy maize (WMS) and normal maize (NMS), the decline of photosynthesis under drought stress (DS) was due to the stomatal limitation. DS increased the non-photochemical quenching coefficient (NPQ), whereas decreased the activities of peroxidase (POD) and the plant height (PH), compared with the plants under normal irrigation. The content of starch increased and decreased significantly upon moderate and severe drought stress, respectively. For high amylose maize (HAMSs), they showed stomatal limitation upon moderate stress, while non-stomatal limitation upon severe stress. The NPQ and POD showed contrary trend compared with WMS and NMS. DS significantly decreased the starch content and PH of them. The principal component analysis (PCA) showed HAMSs were more sensitive to drought than WMS and NMS. The GBSSIIa level of HAMSs was also lower than that of WMS and NMS. Therefore, we conclude that HAMSs respond to DS through redox regulation to avoid oxidative damage, whereas WMS and NMS by increasing starch biosynthesis, and the higher GBSSIIa level may produce more amylose, which could promote the growth of maize under drought effectively.

Estimation of Genetic Variance Components of Sunflower Fatty Acids Under Normal irrigation and Drought Stress Conditions Using Line × Tester Method

Estimation of Genetic Variance Components of Sunflower Fatty Acids Under Normal irrigation and Drought Stress Conditions Using Line × Tester Method

Variation of yield and physiological characteristics of Lathyrus sativus L. populations under terminal drought

Grass pea is one of the oldest native crops grown in vast geographical regions of Iran, however ‎little is known about its tolerance to water shortage during post flowering period. We conducted ‎field experiments in 2018 and 2019 to study the effects of terminal drought on growth, yield, and ‎some physiological characteristics of grass pea (Lathyrus sativus L.) ecotypes. Nine local grass pea ‎ecotypes (Baft_1, Baft_2, Bardsir, Dehbakri, Kuhbanan, Rabor, Sirjan, Shiraz, and Torbat ‎Heydarieh), collected from different climatic regions in the east, southeast, and south of Iran, were ‎exposed to either normal irrigation or terminal drought (water withholding after flowering). Normal ‎irrigation was applied after 60 mm water evaporation from class A evaporation pan for the whole ‎growing season. Terminal drought decreased seed and biological yields, relative to normal ‎irrigation, with Baft_2 and Rabor the superior ecotypes in both treatments. Among yield traits, pod number per plant had very high correlation with seed and biological yields in either irrigation regime and was the highest in high yielding ecotypes. Leaf surface area, relative water content (RWC) and starch content decreased while soluble sugars and proline content increased by terminal drought. The highest yielding ecotypes, Baft_2 and Rabor had not the highest leaf area and RWC though they had the highest starch content under normal and sugars content under terminal drought. Also they had the greatest water use efficiency in both years and watering regimes. Proline content, RWC and sugar contents did not significantly correlate with seed or biological yield under terminal drought. Our results suggest that drought tolerance in ‎grass pea is closely associated with better utilization of water and plant photosynthetic capacity, as reflected in high starch ‎accumulation and conversion to sugars, perhaps as an osmotic adjustment factor. Also, high yielding ecotypes allocated higher dry matter to reproductive tissues.

Grain yield, chlorophyll and protein contents of elite wheat genotypes under drought stress

BackgroundDrought stress at different growth stages significantly alters growth, yield, and quality traits of wheat. However, great variability exists among genotypes regarding their response to drought stress. Therefore, determining the impacts of drought stress on yield and quality traits would help to select the superior genotypes. MethodsThis study investigated the effects of drought stress on wheat grain yield, chlorophyll, and protein contents. Fourteen (14) recently developed elite bread wheat (Triticum aestivum L.) genotypes were used in this study for evaluation under irrigated (full irrigation) and drought conditions (half of normal irrigation). The data relating to growth, yield and protein contents were recorded. ResultsSignificant differences (P ≤ 0.01) were noted among genotypes for all recorded traits. Drought stress significantly reduced the days to 50 % heading, days to 50 % maturity, grain filling, plant height (cm), number of spikes per m2, chlorophyll index (SPAD), peduncle length (cm), number of grains spike-1, thousand grain weight (g) and grain yield (kg ha−1). However, protein contents were increased under drought stress. Correlation analysis showed significant positive association of grain yield with thousand grain weight, number of spikes per m2, spike length, chlorophyll index, grain filling period and number of grains spike-1 under both irrigated and drought stress conditions. The protein contents expressed positive and negative relationship with yield under drought stress and irrigated conditions, respectively. Bioplot analysis revealed that genotype ‘V-19618′ and ‘V-19600′ proved superior under drought conditions regarding grain yield and related traits, while genotype ‘V-19574′ proved better under both irrigated and drought conditions. ConclusionsThese identified genotypes, i.e., ‘V-19618′ and ‘V-19600′ can be utilized in future wheat breeding programs to induce desirable characters for producing drought tolerant wheat genotypes.

Selenium-induced modulations in growth, productivity and physiochemical responses to water deficiency in Quinoa (Chenopodium quinoa) grown in sandy soil

Water stress is one of the major global problems that limits the growth and production of various crops. The current investigation aims to study the possibilities of mitigating the effect of drought stress on Quinoa plant grown under sandy soil by foliar treatment with selenium through assessment growth, productivity, and many physiological and biochemical measurements. Selenium (SE) was exogenously-applied as a foliar treatment with concentrations SE25 mg/L and SE50 mg/L to Quinoa plants grown under (full irrigation I100 = 100%) and (deficit irrigation I60 = 60%) in open field in growing seasons (2019/2020 and 2020/2021). Exposure of Quinoa plants to water stress led to significant decreases in shoot growth, yield, chlorophyll a, chlorophyll b, carotenoids and indole acetic (IAA) comparing with full irrigation (I100). While, increased root length, fresh and dry weight, total phenolics, total soluble sugars TSS, proline and free amino acids (FAA). Furthermore, water deficit decreased yield and its components as well as carbohydrates, protein, nitrogen, phosphorus and potassium contents of the yielded Quinoa grains compared with those plants grown under normal irrigation (I100). However, foliar spraying with selenium particularly at 50 mg/L to stress plants significantly improved growth and productivity of Quinoa plants. Moreover, treatment Quinoa plant with different levels of selenium reduced the effect of water stress by enhancing growth and productivity of Quinoa plants through improving photosynthetic pigments, IAA, total phenolics, TSS, proline and FAA contents. As a result, this findings suggest using 25 or 50 mg/L selenium as a foliar application strategy for Quinoa plants grown under drought stress to maintain higher growth and the studied biochemical aspects and yield as well as yield components and mitigate the inhibitory action of water stress on plant growth and productivity.

Exogenously Applied Salicylic Acid Boosts Morpho-Physiological Traits, Yield, and Water Productivity of Lowland Rice under Normal and Deficit Irrigation

The main constraint on rice cultivation in the Mediterranean area is the limited irrigation and its large water consumption. In addition, rice is very sensitive to drought conditions because of drought stress on morpho-physiological traits and yield reduction. The application of salicylic acid (SA) has been noticed to be very effective in alleviating the adverse effects of drought stress on rice. The current investigation was conducted as a split-split arrangement under a randomized complete block design with two lowland rice cultivars (Giza177 and Giza179) and SA as a foliar application at four concentrations (0, 400, 700, and 1000 µM) under normal and drought conditions. The results showed that plant growth, leaf photosynthetic pigments, yields, and the most studied traits were significantly affected by irrigation (I), cultivar (C), and SA concentration (p ≤ 0.05 or 0.01). The interaction effect of I × C × SA was only significant on the carotenoids content (p ≤ 0.05). The reduction in grain yield and most studied traits was more pronounced under drought conditions. The Giza179 proved to be a drought-tolerant cultivar under all SA concentrations under drought conditions, while Giza177 was a drought-sensitive cultivar. The application of 700 µM SA gave the best grain yield in both rice cultivars under drought conditions compared to other SA concentrations. Grain yield for normal irrigation (Yp) and drought stress (Ys) conditions were highly positively correlated with indices of the mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), yield index (YI), yield stability index (YSI), drought resistance index (DI), harmonic mean (HM), and golden mean (GOL). While they are highly negatively correlated with the indices of the stress susceptibility index (SSI), tolerance index (TOL), yield reduction ratio (YR), stress susceptibility percentage index (SSPI), and abiotic tolerance index (ATI). It could be concluded that SA, as a growth regulator, could be used to alleviate the harmful effect of inadequate water availability in soil on rice cultivars as well as to improve the growth, water productivity, and grain yield.

Effectiveness of cyclic irrigation on yield, yield components and water productivity

The efficiency of cyclic irrigation (CI) (using river water (RW) and drainage water (DW)) was investigated and compared with normal irrigation (NI) (using only RW). A 24 × 30 m research area was selected and divided into three plots – A (maize), B (soybean) and C (sunflower). Plot A was designed to produce DW for the irrigation of plots B and C. In plot B, a split-plot design was applied with randomised complete blocks with two treatments: irrigation type and rate of urea fertiliser application. The experimental design of plot C was similar to that of plot B except for the rate of fertiliser application. Analysis of variance (Anova) results for soybean revealed that the interaction between irrigation type and urea level had significant effects on growth yield and biological water productivity (WP) (P < 0.01) and fresh leaf weight (P < 0.05). The Anova results for sunflower showed that the interaction between irrigation type and urea level had significant effects on 100-seed weight, seed yield and seed WP (P < 0.05). The highest increase in WP for sunflower was for forage WP (0.768 kg/m3 for NI and 2.603 kg/m3 for CI). The WP of RW for total forage, total seed and total biological yields for CI compared with NI increased by 76.67%, 72.95% and 75.45%, respectively. The lowest increase in WP was for sunflower seed yield (0.276 kg/m3 for NI and 0.821 kg/m3 for CI). Overall, the data showed that, compared with NI, CI led to water savings of 45.59% and increased WP.