Irrigation Water Regimes Research Articles

Characterization and Use of a Crop-Residue-Based Mat Mulch in the Production of Pepper (Capsicum annuum) during Dry Season

Agricultural mulches from plant waste constitute an ecological alternative due to their capacity to biodegrade and incorporate into the soil. This work aimed at evaluating, during a drought, the effects of a mat mulch, based on banana rachis and rice straw, on bell pepper (Capsicum annuum) production, and to characterize the material, both mechanically (traction resistance) and physical-chemically (water retention capacity, organic and inorganic components). Two contrasting irrigation regimes were used to determine the effect of the mat mulch on edaphic and productive parameters such as plant height, basal stem diameter, number of fruits and flowers, harvest, plant biomass, macro- and micronutrients in leaves, weeds/m2, and soil temperature. Treatments with the mat mulch resulted in increased height, number of fruits and flowers, biomass, and P, Zn and Cu concentrations. The mat mulch contributes to soil water retention, improves pepper agronomic variables response in plant’s height, basal stem diameter, and the number of flowers and fruits, especially with a low water irrigation regime. Furthermore, a 95% reduction in weed/m2, and soil temperature (18 °C) compared to air temperature (26.8 °C) was found. The characteristics of the waste-based mat mulch in soils offer new possibilities for environmentally friendly, efficient, and sustainable agricultural practices.

Calibration and Evaluation of the FAO AquaCrop Model for Canola (Brassica napus) under Varied Moistube Irrigation Regimes

The AquaCrop model was calibrated and validated for canola (Brassica napus) under Moistube irrigation (MTI) and various water regimes [(i) 100%, (ii) 75%, and (iii) 55% of crop water requirement (ETc)] over two seasons, 2019 and 2020. The normalised root mean square (nRMSE), Model Efficiency (EF), R2, and the Willmot’s index of agreement (d) statistics were used to evaluate the model’s efficiency in simulating biomass (B), canopy cover (CC), yield (Y), and harvest index (HI). The calibration results indicated the model simulated with accuracy the CC (under 100% ETcR2 = 0.99, EF = 0.92, nRMSE = 6.4%, d = 0.98) and 75% ETc (R2 = 0.99, EF = 0.92, nRMSE = 10.3%, d = 0.98). The model simulated CC well for validation for 100% ETc (R2 = 0.97, EF = 0.93, nRMSE = 22.5%, d = 0.98) and 75% ETc (R2 = 0.84, EF = 0.45, nRMSE = 59.2%, d = 0.86) irrigation regimes. Final biomass simulations were reasonably good under 100% ETc, 75% ETc, and 55% ETc irrigation regimes (R2 > 0.90, d > 0.65). The study showed the usefulness of AquaCrop for assessing yield response of canola to full and deficit irrigation scenarios under MTI.

Electrical signaling related to water stress acclimation

Nowadays, the debate involving climate change concerns safeguarding the water resources of the planet, an extremely important topic also in agriculture. In particular, the problem of scarce water availability becomes more and more pressing every year and at the agronomic level it is necessary to make intelligent use of water without affecting the quality and quantity of production. The aim of this work is to understand when the plant is under water stress conditions at the electrical signal level, in order to achieve the information of true needs of water in plants. The proposed methodology considered the plant black kale cultivated in hydroponic condition: the plants were based in an electrically isolated environment, with electrodes inserted in their stems to acquire and study the electrical activity associated with determined irrigation cycles. By using different stop/flow water irrigation regimes, an acclimated and a not-acclimated group of plants have been selected to experience different periods of prolonged water flow stress. Results indicated that the evaluation of a measure of statistical dispersion, the daily variance of the electrical resistance, can be closely related to the induced water stop/flow stress. Moreover, experiencing an acclimation stage has shown to allow a better recovery response for the plant.

Management of Water-Nitrogen units under Different Deficit Irrigation Strategies for Zea maize Crop

Drip irrigation method can be more efficient than other types of irrigation methods, such as surface flood irrigation or sprinkler irrigation. Field experiments were carried out at the experimental farm, Faculty of Agri., Tanta Univ., Egypt, during summer seasons of 2018 and 2019 due to the limited water, as it is an important factor for agriculture expansion with the aim of providing water and fertilizer and improving the water distribution uniformity. Maize crop (Triple Hybrid 321). The factors of study were three laterals’ positions; these positions were lateral line directly beside crop row (FI); lateral line was placed at 15 cm from crop row (PRD1) and alternate partial root zone drying at 15cm from crop row (APRD2). Three irrigation water regimes noted: (100, 75 and 50% of the ETc). Three rates of nitrogen fertilization were used (100% ”600kg”, 50%”300kg” and 0%” control” of kg N ha-1). The results indicated that the maximum yield of maize crop was obtained from the maximum nitrogen level (100%) and when the lateral placement was directly next to the crop row. The minimum maize crop yield was achieved using nitrogen fertilization (0%) and lateral positioning 15 cm away from the plant line. The chlorophyll content is affected by the nitrogen fertilization level and lateral positions. PRD2 and PRD1 these lateral positions increase the chlorophyll content compared to FI as, the highest values were 41.7 and 40.7 were recorded at PRD2+100%N and PRD1+50%N respectively. The distribution uniformity value was high at 200kPa and the distribution uniformity values were low at 50 and100kPa respectively.

Improving Alfalfa Forage Yield and Water Use Efficiency under Irrigation Water Stress and Humic Acid Applications in Calcareous Soil

This Investigation was carried out at Nubaria Agricultural Research Station (30° 54´ N, 29° 57´ E, and 15m above sea level), Agricultural Research Centre (ARC), Ministry of Agriculture and Land Reclamation (MALR), El-Behiera Governorate, Egypt, during 2016-2018 period to study the effects of application liquid humic acid on alfalfa forage yield and quality under irrigation water regime. Three irrigation water regime treatments were100%, 80% and 60% of ETp and three humic acid rates 0, 3 and 6 L/ha humic acid were tested in a strip-plot design. As water requirements decreased forage yield significantly decreased, in the 4 seasons for each year. No significant differences were found between the fresh or dry forage yields or leaf/stem ratio under 100% water requirement without humic acid and 80% water requirement with 6 L/ha humic acid. No significant differences were found between protein content under the interaction between irrigation water requirements and humic acid rate. Irrigation water use efficiency increased under water stress as an application of humic acid rate increased. The previous results indicate that, under experimental conditions, it is possible to save 20% of the amount of added water when adding 6 L/ha humic acid with an insignificant increases in yield amount to 11.421 t /ha.

Interactive effect of soil mulching and irrigation regime on yield, irrigation water use efficiency and ‎weeds of trickle–irrigated onion

ABSTRACT Reducing the water loss sources, i.e. soil evaporation and weeds presence, is an essential act for keeping well soil moisture to crop growth, especially under drought conditions. Therefore, two–year field trials were conducted for seeking the best compatible practice between irrigation regime and weed control method in onion onion. Three irrigation water regimes (60%, 80% and 100% of the crop water requirements, CWR) and seven weed control practices (rice, wheat and peanut straws as soil mulches as well as oxadiargyl, oxyfluorfen, weeding, and unweeded) were applied. Findings revealed that the application of 60% of CWR either with peanut straw mulch or weeding recorded the maximum reduction in weed biomass. In plots mulched by peanut straw irrigation with 80% of CWR produced acceptable marketable bulb yield, NPK contents, flavonoids content and economic returns closing irrigation by 100% of CWR. In conclusion, the rate of water loss from soil surface through evaporation was much lower in case of mulch treatment than non–mulched one. Thus, mulch not only keeps weeds out but also maintains soil moisture. This allows the opportunity to reduce irrigation water by 20% (80% of CWR) with gaining acceptable yield, saving water and raising benefit/cost ratio.

Effect of Moisture Regimes on Water use Efficiency of Rabi / Summer Groundnut Genotypes in Northern Transition Zone of Karnataka

Background: During rabi / summer irrigation water is a scarce resource, but crop needs more water due to non-rainy season and warmer climate. Hence, a field experiment was conducted during rabi / summer season of 2016-17 to study the effect of irrigation water regimes on water use efficiency (WUE) of groundnut genotypes in Northern Transition Zone of Karnataka. Methods: This field study comprised of four main plots as water regimes viz. I1: (control) seven irrigations at 15 days interval from sowing to 105 DAS, I2: Stress at pegging stage; withdrawal of one irrigation between 45 - 60 DAS, I3: Stress at pegging and pod filling stage; withdrawal of two irrigations between 45-75 DAS, I4: Stress at pegging, pod filling and kernel development stage; withdrawal of four irrigations from 45-105 DAS and four genotypes as sub plots viz. G1: Dh-86, G2: Dh-101, G3: K-9 and G4: G2-52. Treatments were replicated thrice and laid out in split plot design. Result: Among the water regime, I2 recorded significantly higher WUE (6.2 kg ha-1 mm-1) followed by I1 (control; 5.5 kg ha-1 mm-1). Water regime I2 also recorded significantly higher pod yield and haulm yield (2,857 kg ha-1 4,648 kg ha-1, respectively) along with other yield attributes, but was found at par with control (I1). This study showed that WUE as well as yield of rabi / summer groundnut can be enhanced if crop was exposed only to mild stress by skipping an irrigation at pegging stage out of total seven irrigations. Among the genotypes, Dh-86 with 2,375 kg ha-1 of pod yield performed significantly better over others like Dh-101 (2,215 kg ha-1), K-9 (2,048 kg ha-1) and G2-52 (1,880kg ha-1) suggesting differential response to moisture stress, thus choice of moisture stress tolerant genotypes is equally important to enhance WUE. Interaction between irrigation regime and genotypes showed that Dh-86 (G1) with I2 irrigation regime recorded significantly higher WUE (6.9 kg ha-1 mm-1), pod yield (3,168 kg ha-1) and net return (Rs. 95,655 ha-1) and was found at par with full irrigation regime (I1).

Nitrification and Denitrification Processes in Rice (Oryza Sativa), with an Emphasis on Reduced Water Irrigation Regimes in USA

The nitrogen cycle is the basis for understanding nitrogen dynamics in soil fertility and ecosystem health. Nitrification and denitrification are key nitrogen cycle components that influence nitrogen uptake in food crops, thus critical to food security. Rice (Oryza sativa) is comparatively unique in that the nitrification-denitrification sequence is a perceived loss of available nitrogen for plant uptake and the production of nitrous oxide (N2O) has severe implications in climate change. This review focuses on recent research involving nitrification and denitrification, with an emphasis on rice. The review also focuses on the emerging irrigation strategies associated with furrow irrigation and alternating wetting-drying irrigation. With growing global interest in reducing irrigation water application, new research paradigms are emerging to perfect these reduced water applications systems to guarantee food security and farm profitability.

Exogenous glutathione-mediated tolerance to deficit irrigation in salt-affected Capsicum frutescence (L.) plants is connected with higher antioxidant content and ionic homeostasis

As an important medicinal plant used in traditional and modern medicine, chili peppers are sensitive or moderately sensitive to drought or salt stress, respectively. Therefore, potential changes due to foliar-applied glutathione (GSH; 0, 0.4 and 0.8 mM) response on growth, yield, and physio-biochemical attributes, as well as water use efficiency (WUE) and fruit alkaloid capsaicin of chili pepper plants were investigated when grown under deficit irrigation in salt-affected soil (EC = 6.74 dS m–1). Two deficit irrigation water (DiW) regimes (80% and 60% of soil field capacity; FC) were used versus 100% of FC as a control. Both DiW treatments negatively affected growth and yield parameters, SPAD chlorophyll index, nutrient status, K+/Na+ ratio, and plant anatomical features. In contrast, osmoprotectants, ascorbate, glutathione, capsaicin, and phenolic contents, as well as WUE were increased in association with higher Na+ and Cl– contents. However, exogenously-applied GSH caused significant increases in the above-mentioned parameters along with an additional increase in osmoprotectants, antioxidants, and capsaicin contents, and a decrease in Na+ and Cl– levels compared to corresponding controls. The highest WUE, growth, and fruit yield responses were recorded at 0.8 mM GSH applied to plants under DiW at 80% FC + salinity (6.74 dS m–1). Therefore, this study suggested the use of leafy-applied GSH at 0.8 mM for satisfactory growth and yield with the highest WUE of chili pepper plants grown under salt-affected conditions with deficit irrigation.

Efficiency of seed bio-priming technique for healthy mungbean productivity under terminal drought stress

Recently, drought-induced damaging impact in reducing the crop growth and development is drastically ranked at the top under various abiotic stresses. And especially water stress at the reproductive growth stages termed as terminal drought has become a severe threat for mungbean productivity. To mitigate the drought stress condition, “bio-priming” has emerged as a newly agronomic and sustainable technique in improving the mungbean production. A 2-year field study during Kharif season 2017–2018 was conducted to investigate the efficacy of rhizobacteria seed priming in mungbean (AZRI mung-06), at Agronomic Research Area, Department of Agronomy, Bahauddin Zakariya University, Multan, Pakistan. The experiment comprised two factors containing FA (seed treatments, control (dry seeds), hydro-priming, silicon (Si)-priming, and bio-priming (mixture strains of Pseudomonas fluorescens+Rhizobium phaseoli)) and FB (irrigation water-regimes at various growth stages including leaf formation (L), stem elongation (S)+flowering (F)+pod formation (P) containing treatments are normal irrigation (IL+S+F+P) and terminal drought stress (IF+P)). All the treatments were arranged in randomized complete block design under factorial design and were replicated thrice. Results indicated that the exposure of drought stress at flowering and pod formation stages hampered the morpho-physiological growth and yield of mungbean. Nevertheless, seed priming treatments particularly bio-priming were effective in alleviating the detrimental effects of drought stress. Bio-priming significantly increased the yield and yield components (seeds/plant, 1 000-grain weight and harvest index) of mungbean and regulated the activities/levels of antioxidants (superoxide dismutase, catalase, peroxidase, ascorbic acid, and total phenolics) under drought stress. Compared with the control, bio-priming increased the seed yield of mungbean by 8–12% under normal as well as drought stress conditions during both years of study. Bio-priming also improved the nutrient uptake behavior followed by Si- and hydro-priming treatments under terminal drought stress. The study emphasized the effectiveness of bio-priming as dual seed treatment method may be helpful for vigorous germination of mungbean production along with plant tolerance against terminal drought stress. Among the various treatments, plants treated with bio-priming technique compensated the grain yield due to having strong antioxidant defense system and better nutrient uptake behaviour under terminal drought stress. Economic analysis also concluded that bio-priming is the easiest, cost-effective, friendly, and sustainable approach for the maximization of the mungbean production.

Differential physio-biochemical and yield responses of Camelina sativa L. under varying irrigation water regimes in semi-arid climatic conditions.

Camelina sativa L. is an oilseed crop with wide nutritional and industrial applications. Because of favorable agronomic characteristics of C. sativa in a water-limiting environment interest in its production has increased worldwide. In this study the effect of different irrigation regimes (I0 = three irrigations, I1 = two irrigations, I2 = one irrigation and I3 = one irrigation) on physio-biochemical responses and seed yield attributes of two C. sativa genotypes was explored under semi-arid conditions. Results indicated that maximum physio-biochemical activity, seed yield and oil contents appeared in genotype 7126 with three irrigations (I0). In contrast water deficit stress created by withholding irrigation (I1, I2 and I3) at different growth stages significantly reduced the physio-biochemical activity as well as yield responses in both C. sativa genotypes. Nonetheless the highest reduction in physio-biochemical and yield attributes were observed in genotype 8046 when irrigation was skipped at vegetative and flowering stages of crop (I3). In genotypic comparison, C. sativa genotype 7126 performed better than 8046 under all I1, I2 and I3 irrigation treatments. Because 7126 exhibited better maintenance of tissue water content, leaf gas exchange traits and chlorophyll pigment production, resulting in better seed yield and oil production. Findings of this study suggest that to achieve maximum yield potential in camelina three irrigations are needed under semi-arid conditions, however application of two irrigations one at flowering and second at silique development stage can ensure an economic seed yield and oil contents. Furthermore, genotype 7126 should be adopted for cultivation under water limited arid and semi-arid regions due to its better adaptability.

Irrigation water regime and manure extract for wheat production grown under drip irrigation

Irrigation water regime and manure extract for wheat production grown under drip irrigation

Modelo de aseguramiento agrícola privado para pequeños productores agrícolas en México

El Gobierno Federal ha incentivado la práctica de seguros agrícolas con subsidios a los productores usuarios de estos servicios, pero la forma en que han sido canalizados los gastos para fortalecer la práctica de los seguros no ha sido suficiente para lograr, sobre todo entre productores pequeños, generalizar esta práctica. El objetivo de esta investigación fue proponer un modelo de seguro agrícola, quien lo adquiere recibe beneficios adicionales a los que normalmente existen y se obtienen en los seguros tradicionales, en el año 2018. La metodología parte del principio teórico de los ciclos económico de Burns y Mitchell el cual es uno de los primeros estudios de ciclos económicos basado en series de tiempo de Avella-Gómez y Ferguson. Con la técnica estadística de regresión aplicada a datos de producción y rendimientos del cultivo básico, para este caso el maíz blanco, modelado con el programa Statistical Analysis System (SAS). Algunos resultados y conclusiones, observados fueron que a diferencia de los seguros tradicionales, se propone que los montos a pagar por concepto de primas de aseguramiento, se determinen antes de cada ciclo agrícola, con información de campo obtenida por especialistas y técnicos gubernamentales que están más cerca de los productores. Se considera que se deben determinar montos diferentes de prima de seguro por región agrícola de los Distrito de Desarrollo Rural, por cultivo y por régimen hídrico de riego o temporal.

Effect of Irrigation Levels and Some Soil Applied Herbicides on Weeds, Water Use efficiency and Productivity of garlic (Allium sativum L.)

Two field experiments were conducted during 2016/2017 and 2017/2018 winter seasons in clay soil at El-Kanater El-Khiria, Horticulture research station to study the effect of two irrigation water regimes i.e. 75 & 100 % of potential evapotranspiration (ETc) under six weed control treatments by Pendimethalin (Stomp extra 45.5% CS at the rate of 1.7 l/fedden), oxyfluorfen (Roal 24% EC at the rate of 750 cm3/fed. and/ or supplemented with additional hand hoeing once and hand hoeing twice addition to unweeded check on weeds , garlic yield and their water relationship i.e. consumptive use (Cu) and water use efficiency (WUE).Experimental design was split plot where the two treatments of water regime were allocated in the main plots and weed control treatments in subplots in four replicates. The main findings show that the experimental field was infested by annual weeds for the unweeded check by 1.35 and 1.47 ton/feddan dry weight of weeds, exhibited yield loss of 16.1 and 15.1% of garlic yield per feddan than hand hoeing twice in both 2016 /2017 and 2017/2018 seasons, respectively.Also all various weed categories as well as various yield components and yield of garlic tended to increase significantly in both seasons with adding irrigation water by 100 % from potential evapotranspition (ETc) treatment, meanwhile, water use efficiency for irrigation treatments tended to increase by 75 % from potential evapotranspition (ETc) 19.9 and 25.2% of ETc in 2016 /2017 and 2017/2018 seasons, respectively, and economically feasible. The reduction in garlic yield under irrigation level by 75 % equal 7&4 % in 1st and 2nd seasons and can consider non mean full difference with saving irrigation water476 &579 cubic meter which equal two irrigation. While, water use efficiency for Stomp at 1.7 L/fed, Stomp + h. hoeing once, Roal at 075 L/fed, Roal+ h. hoeing once and h. hoeing twice tended to increase by 34.0 & 53.8 & 28.8 & 43.4 and 29.7%, respectively more than unweeded check in the first season and by 29.2 & 38.4 & 27.0 & 31.9 and 26.5%, respectively, more than unweeded check which attributed the reduction of weed competition for water consumption. All weed control treatments gave significant effect on controlling weeds and increased growth characteristics and bulb garlic yields. Stomp at 1.7 L/fed h plus hand hoeing once gave the highest increase in net income (LE) by 118.3 and 94.4% respectively, more than unweeded check. Regarding, the interaction between irrigation water levels and weed control treatments, there was a little significant effect with soil moisture 100 % and herbicide residue of Stomp and Roal herbicides which in weed control elements used in garlic bulb less than allowable level.

Nutritional yield and nutritional water productivity of cowpea (Vigna unguiculata L. Walp) under varying irrigation water regimes

There is a need to mainstream traditional crops in sub-Saharan Africa, in order to tackle food and nutritional insecurity through incorporating nutritional quality into crop water productivity, in the wider context of the water–food–nutrition–health nexus. The objective of the study was to determine the effect of irrigation water regimes on the nutritional yield (NY) and nutritional water productivity (NWP) of cowpea under Moistube irrigation (MTI) and subsurface drip irrigation (SDI). We hypothesized that NY and NWP of cowpea were not different under MTI and SDI and that deficit irrigation improved NWP. The experiment was laid as a split-plot design arranged in randomized complete blocks, replicated 3 times, with 3 irrigation water regimes: 100% of crop evapotranspiration (ETc), 70% of ETc, and 40% of ETc. Irrigation type and water regime did not significantly (p > 0.05) affect the nutritional quality of cowpea. Similarly, NWP of crude fat (28.20–39.20 g∙m-3), ash (47.20–50.70 g∙m-3) and crude fibre (30.70–48.10 g∙m-3) did not vary significantly. However, protein and carbohydrate NWP showed significant (p < 0.05) differences across irrigation water regimes and irrigation type. The highest protein NWP (276.20 g∙m-3) was attained under MTI at 100% ETc, which was significantly (p < 0.05) higher than SDI (237.1 g∙m-3) and MTI (189.8 g∙m-3) at 40% ETc. Cowpea is suited for production in water-scarce environments; however, there are trade-offs with carbohydrate NWP. This should not be of concern as often diets are already energy-dense but lacking in other micronutrients.

Exogenously applied proline enhances growth and productivity of drought stressed onion by improving photosynthetic efficiency, water use efficiency and up-regulating osmoprotectants

Drought and salinity are the main limiting factors negatively affect plant growth and productivity. Proline is recently reported to play a positive role in plants exposed to various abiotic stresses. A two year field experiment was implemented consecutively to assess the potential effect of exogenously applied proline (1 and 2 mM) under different irrigation water regimes (IWR) (120 %, 100 %, 80 % and 60 % of ETc.) on growth, plant defense system, physio-biochemical attributes, bulb yield and water use efficiency of onion cultivated in saline calcareous soil. Results showed that, exogenously-applied proline significantly enhanced growth as well as, plant water status, photosynthetic efficiency, and osmoprotectants of drought-stressed onion which consequently reflected in increased bulb yield. Treatments of 80 % and 60 % of ETc had increased water use efficiency (WUE) by 32.0 % and 26.5 % respectively, compared to full irrigation (100 % of ETc). The effect of proline was negligible on unstressed plants, but when applied under deficit irrigation (DI) treatments (80 and 60 % of ETc), WUE reached 50 % higher than control. These plants also had a higher content of total soluble sugars but a lower content of proline and amino acids. Exogenous proline application markedly enhanced onion growth traits compared to non-treated plants due to increased cell membrane integrity (MSI) and leaf water content (RWC), also improved photosynthetic efficiency and up-regulated osmoprotectants contents. Results revealed that proline foliar application on onion plants might attenuate drought stress by increasing their sugar content and via improving plant self-defense system. Consequently, combination of DI at 80 % and 1−2 mM proline is highly recommended to attain optimal yield with the opportunity of saving 20−40 % of irrigation water during onion growing season.

Effect of Irrigation Systems and Water Regime on Growth, Yield Components, Water Use Efficiency and Water Productivity of Guava (PSIDIUM GUAVAJA L.) Grown in Clay Soil

Effect of Irrigation Systems and Water Regime on Growth, Yield Components, Water Use Efficiency and Water Productivity of Guava (PSIDIUM GUAVAJA L.) Grown in Clay Soil

Stem electrical properties associated with water stress conditions in olive tree

The analysis of the electrophysiological activity of plants permits a real-time information of the plant status (e.g. light availability and water stress). However, even though it is clear that the role of the electrical signals in plant is crucial, especially in processes involving the propagation of rapid signals, a systematic approach for the interpretation of the electrical patterns is still missing. In this work a multi-electrodes approach has been applied to study the electrical signals in olive trees plants subjected to three different level of water stress. In particular, by using specific water irrigation regimes, a control group, a mid/mild stressed group and a high stressed group have been monitored and subsequently subjected to a long period of prolonged drought stress. Physiological parameters and electrical activity have been continuously monitored for the whole experiment to highlight any correlation between the electric signal and the water stress. Our results showed that it has been possible to differentiate the electric signals related to drought conditions of different intensity (i.e. control, mild and high). In particular we have found that the average daily relative electrical resistance change, the opposite of the electrical conductance, is directly related to the drought stress whilst the signal variance increases during the period of main water stress. Additionally, a proposed signal classification system has been successfully able to detect the absence/presence of stress and to effectively recognize daily class samples (93 % control, 76 % mild and 80 % high). The set-up could provide a useful tool for monitoring water conditions in plants and has several potential applications for sensor and automatic system in greenhouse or field able to monitor directly the plant water status.

RESPONSE OF WHEAT PRODUCTIVITY TO IRRIGATION REGIMES AND NITROGEN FERTILIZATION LEVELS

Wheat is the main cereal crop in Egypt. The gap between production and consumption is about 60%. Research efforts are needed to reduce this gap, therefore; the objective of this work was to study the effect of three water regimes as irrigation at 45%, 60% and 70% depletion of the available soil moisture, and three nitrogen fertilization levels on two wheat varieties (Giza 168 and Giza 171).The field experiments were carried out at Bahry El-Methaq region, Alexandria Governorate, Egypt during the two successive winter seasons of 2015/2016 and 2016/2017. The experimental design of the study followed split split plot design (SSPD) with three replicates, keeping two bread wheat cultivars {Giza 168 and Giza 171 } as the main plots, irrigation regimes (irrigation at 45%, 60% and 70% depletion of the available soil moisture) as subplot, and the three fertilization levels as 100%, 80% and 60% from recommended fertilizer rates of nitrogen fertilization common applied as sub-subplot. The results showed that seasonal ET0 was 665.9 mm for the first season and 624.8 for the second season. Wheat crop transpiration was 600.28 mm at 2015-2016 growing season and 572.95 mm for the next season. The seasonal applied irrigation water in total was 2702.2 m3, 2792.6 m3 and 2879.1 m3 at 45%, 60% and 70% depletion treatments for 2015-2016 growing season, respectively. The corresponding values for the next growing season were changed to 2802.5 m3, 2687.4 m3 and 2716.4 m3. Based on the irrigation regimes and water balance by the budget technique, the irrigation events of wheat at 45%, 60% and 70% depletion treatments were 29, 23 and 21, which required irrigating for 23.17, 23.94 and 24.69 hours in the first season, respectively. The second season results changed to 28, 23 and 20 irrigations, which required irrigating for 24.4, 22.96 and 23.29 hours. The results indicated that the maximum grain yield and water use efficiency of wheat regardless of the variety under investigation could be obtained with irrigation at 60% depletion of the available soil moisture and 100% of the recommended nitrogen fertilization. The yield and water use efficiency of Giza 168 under these conditions were 2.78 ton/fed and 1.02 kg/m3. While for Giza 171, 3.4 ton/fed and 1.24 kg/ m3 were obtained with 22.3% and 21.6% increase in yield and water use efficiency, respectively.The results indicated a significant effect of crop cultivars and nitrogen fertilization levels on biological yield, straw yield, grain yield, WUE of grain yield and WUE of straw yield. Meanwhile, irrigation regimes showed insignificant effect on the previous parameters. The interaction of wheat cultivars, nitrogen fertilization levels and irrigation water regime levels showed insignificant effect on biological yield, straw yield, grain yield, WUE of grain yield and WUE of straw yield.

Synergistic responses of drip-irrigated wheat crop to chitosan and/or silicon under different irrigation regimes

Water scarcity is considered as a key restriction for food production worldwide. Chitosan (Chi) and silicon (Si) play a crucial role in plants metabolic processes under normal or stress conditions. Field experiments were done at the Res. Station, Nat. Res. Cen., El-Nubaria Province, Egypt, in 2014/15 and 2015/16 seasons in a split-plot based on randomized complete block design with three replications, for assessing the defensive role of Chi and/or Si on wheat growth, yield, some physio-anatomical attributes and water use efficiency under different irrigation regimes. The experimental treatments included three irrigation water regimes (100, 70, and 40% of drip irrigation water requirement "IWR") as the main factor, as well as Chi and/or Si (water, 125 mg L−1 Si, 250 mg L−1 Chi, and 125 mg L−1 Si+250 mg L−1 Chi) as the sub-factor.Water deficit significantly decreases plant growth, yield, photosynthetic pigment, and relative water content; whereas significantly induced noticeable changes in leaf and stem anatomy as well as organelle's ultrastructure. Application of Chi + Si gave the highest plant growth and yield attributes, maintaining plant water status, along with improved physiological trials under irrigation regimes. Additionally, the application of Chi + Si under severe drought showed an ameliorative effect on cell ultrastructure compared with drought-affected plants only including well-developed chloroplasts, increased plastoglobules and maintained nucleus and mitochondria structure.Overall, this investigation proposes that the application of 125 mg L−1 Si plus 250 mg L−1 Chi twice at 50 and 70 days from sowing had potential to mitigate the water deficit effects, improving water use efficiency as well as increasing the wheat yield and its quality.