Low Irrigation Levels Research Articles

Responses of Soil Water, Temperature, and Yield of Apple Orchard to Straw Mulching and Supplemental Irrigation on China’s Loess Plateau

The combination effect of straw mulching and supplemental irrigation on the soil water and heat, and the growth and productivity of mature apple trees on the Loess Plateau of China remains unclear. Field experiments were conducted in 2022 and 2023 to evaluate the combined effect of straw mulching and supplemental irrigation (two irrigation types, ring and double-row drip irrigation, and three irrigation levels: high, medium, and low irrigation level) on the soil water and temperature, growth, yield, and water productivity (WP) of a mature apple orchard. Local rainfed cultivation was used as the control (CK). The results showed that straw mulching increased soil moisture by 2.4–6.5% compared to the CK treatment. Supplemental irrigation significantly increased soil moisture in the 0–60 cm layer by 3.0–8.1%, and its effect increased with an increasing irrigation level. Straw mulching significantly reduced soil temperature by 7.8% compared to the CK treatment. Supplemental irrigation significantly increased the new shoot length and stem thickness of apple trees. Under straw mulching, a medium supplemental irrigation level significantly increased both apple yield and WP compared to the CK treatment. In this study area, it is recommended to choose a combination of straw mulching and a medium supplemental irrigation level.

Enhancement in Tomato Yield and Quality Using Biochar Amendments in Greenhouse under Salinity and Drought Stress.

Enhancing saline water productivity in arid regions is essential for sustainable agriculture. Adding biochar can improve the quantity and quality of tomato yield under higher levels of salinity and lower levels of irrigation. The experiment aimed to evaluate the effects of biochar on enhancing tomato fruit quality and yield under salinity and drought stress. The experiment combines two treatments for irrigation water quality (0.9 and 2.3 dS m-1), four irrigation levels (40, 60, 80, and 100%) of crop evapotranspiration (ETc), and the addition of 5% of biochar to treated soil (BC5%) and untreated soil (BC0%). The results showed that the decrease in the water quality and irrigation levels negatively impacted the yield and properties of tomato fruit, while 5% of biochar application positively improved the yield. Adding biochar decreased the tomato yield by 29.33% and 42.51% under lower-saline-irrigation water than the control, negatively affecting the fruit's physical parameters and mineral content. In contrast, adding biochar and irrigating with saline water at 60% of ETc improved the firmness and quality characteristics of the fruit by 56.60%, 67.19, 99.75, and 73.57% for vitamin C (VC), total titratable acidity (TA), total soluble solids (TSS), and total sugars (TS), respectively, compared to the control, and also reduced the sodium content of the fruits under all irrigation levels compared to untreated plants by biochar. Generally, biochar with saline water under deficit irrigation with 80 and 60% of ETc could be an excellent strategy to enhance the qualitative characteristics of tomato fruits and save approximately 20-40% of the applied water.

Study on Water and Salt Transport Characteristics of Sunflowers under Different Irrigation Amounts in the Yellow River Irrigation Area

The control of irrigation volume is of significant importance in arid regions of northwest China. Particularly, it has a crucial impact on the salinization of shallow groundwater areas. In 2022 and 2023, field experiments were conducted to test three distinct under-membrane irrigation treatments. These treatments were assigned water quotas of HW (27 mm), MW (22.5 mm), and LW (18 mm). The HYDRUS-2D model was integrated with a field experiment to accurately simulate the dynamic fluctuations of soil water and salt in the sunflower root zone. The model’s performance was assessed and verified using real-field data from 2022 and 2023, and the simulation results closely matched the measured values. This research also used stable hydroxide isotopes to assess the water supply from various soil layers at different time intervals in sunflower plants. The results indicated that the three different levels of irrigation applied under the membrane had a significant impact on soil water content. Specifically, there was a significant difference in soil water content at a depth of 0–40 cm (p < 0.05), while there was little effect on the water content at a depth of 40–60 cm (p > 0.05). After irrigation, the average salt content in the top 0–20 cm of soil decreased by 7.0% compared to the medium and low irrigation levels, and by 10.8% compared to the medium irrigation level. Additionally, the medium irrigation level resulted in a 10.8% decrease in salt content compared to the low irrigation level, and a 4.1% decrease compared to the medium irrigation level. During the same period, the soil salinity levels at depths of 0–20 cm, 20–40 cm, 40–60 cm, and 60–100 cm in the area outside the membrane were measured to be 2.7~4.8 g·kg−1, 2.8~4.0 g·kg−1, 2.7~3.4 g·kg−1, and 1.7~2.6 g·kg−1, respectively. These levels decreased by 13.1~55.5%, 0.7~42.8%, −0.4~16.2%, and −72.7~7.5%, respectively. Following irrigation, the HW treatment mostly absorbed water in the 0–40 cm soil layer, while the MW and LW treatments absorbed water in both the 0–40 cm and 60–80 cm soil levels. The results indicated that the most optimal drip irrigation method beneath the membrane in this location was achieved when the amount of water applied was between 25–30 mm. This method demonstrated a combination of water conservation, high crop yield, and effective salt suppression.

Effect of Cut-Off Irrigation levels on Production of Teosinte Forage Crop in Clay Soil

The present study was carried out at Sakha Agricultural Research Station (clay soils) middle north of Nile Delta area during summer seasons 2021 and 2022 in randomized complete block design with three replications. The objective of this research was to find out the response of yield, water saving and some water functions for teosinte forage crop to cut-off surface irrigation owing to produce " more per less”. Three irrigation levels were executed; 100% i.e., full irrigation, 90% cut-off irrigation and 80% cut-off irrigation. The mean performances of plant height, fresh and dry forage yields in the two seasons and combined are significantly affected by irrigation levels applied, whereas normal or control treatment with100% irrigation i.e., no cut-off (Trt. A) has the tallest of plant height. On the other hand, the low irrigation level with 80% cut-off (Trt. C) has the shortest plants at the three cuts. Also, traits reduced with the decrease of irrigation water level at the three cuts. Both fresh and dry forage yields are severely decreased when plants irrigated by 80% cut-off. Decreasing the irrigation water level than the commonly controlled of 100% without cut-off (Trt.A) markedly reduced all studied growth characters at the three cuts. The inhibiting effect of the water deficit stress on the studied parameters notably appeared more pronounced under the 80% cut-off than that of 90% .The obtained results may refer to that decreasing the irrigation water lowered the soil moisture content which restricted the mobility of nutrients to plant that would reduce the efficiency of physiological and metabolic processes needed for plant growth. Regarding water relations, irrigation with 90% cut-off resulted in several advantages; almost same yield as obtained under full irrigation, 10% water saving as well as the highest values of crop-water functions of water productivity (WP) and productivity of irrigation water (PIW). The mean values of fresh forage yield of 100% irrigation levels recorded 610 and 685 Kg/strip with compared to 585 and 655kg/strip for 90 %irrigation treatment at first and second cuts, respectively in the first season.

Reducing Irrigation and Increasing Plant Density Enhance Both Light Interception and Light Use Efficiency in Cotton under Film Drip Irrigation

High-density planting is an effective technique to optimize yields of mulched cotton. On the other hand, deficit irrigation is an emerging water-saving strategy in cotton cultivation, especially suitable for arid and water-scarce areas. However, the relationships between deficit irrigation, high-density planting, and regulation mechanisms of canopy light radiation and light use efficiency (LUE) in cotton is not yet clear. To clarify the mechanism of light interception (LI) and the LUE of cotton canopies, three irrigation treatments [315 (50% Fc), 405 (75% Fc, farmers’ irrigation practice), and 495 mm (100% Fc), where Fc was the field capacity] with three plant densities [13.5, 18.0 (farmers’ planting practice), and 22.5 plants m2] were applied. The findings of this research revealed that, under deficit irrigation, the above-ground dry matter (ADM) was reduced by 5.05% compared to the farmers’ irrigation practice. Over both years and across all plant densities, LI and LUE under deficit irrigation decreased by 8.36% and 4.79%, respectively, relative to the farmers’ irrigation practices. In contrast, LI and LUE for the highest irrigation level increased by 10.59% and 5.23%, respectively. In the case of the interaction (plant density and irrigation level), the ADM under deficit irrigation and high-density combination increased by 7.69% compared to the control (farmers’ irrigation × sowing practices interaction effects). The LI and LUE also exhibited an increase in 1.63% and 6.34%, respectively. Notably, the LI effect of the middle and upper cotton canopy under film drip irrigation reached 70%. A lower irrigation level resulted in a higher percentage of LI in the lower canopy region. The leaf area index, light interception rate, and extinction coefficient escalated with the increase in plant density. Under deficit irrigation treatment, the LI of the 0–30 cm canopy in high plant density settings increased by 8.6% compared to the control (farmers’ irrigation × sowing practices interaction effects). In conclusion, deficit irrigation and increased plant density improved the interception of LI and LUE of cotton canopy. These findings may help the farmers to optimize their agricultural management strategies in water-deficient areas.

Exogenous silicon application improves fruit yield and quality of drip-irrigated greenhouse tomato by regulating physiological characteristics and growth under combined drought and salt stress

Improving crop productivity in drought-stressed and salt-affected regions is the key to promoting sustainable agriculture. Silicon is considered to improve the stress tolerance of crops, but how exogenous silicon application affects the fruit yield and quality of tomato under combined drought and salt stress remains unclear. A greenhouse experiment was conducted over two consecutive growing seasons (autumn 2021 and spring 2022) to investigate the effects of exogenous silicon application on leaf greenness, photosynthesis and chlorophyll fluorescence parameters, fruit yield and quality of drip-fertigated greenhouse tomato under various drought and salt stresses. There were three irrigation levels: I1 (90–100% θf, where θf is the field capacity), I2 (70%–80% θf) and I3 (50%–60% θf), two soil salinity levels: S0 (0.1%) and S1 (0.4%), and two silicon application rates: T0 (0 mmol L−1) and T1 (2.4 mmol L−1), resulting in a total of 12 treatments with three replicates. The results showed that the combined drought and salt stress significantly reduced leaf silicon content, plant height, leaf area index, aboveground biomass, net photosynthetic rate, transpiration rate and stomatal conductance of tomato plants, while the exogenous silicon application promoted these parameters. Irrigation level, salinity level, silicon rate and the interaction of irrigation level and salinity level had significant effects on fruit yield. Compared to S0, S1 decreased fruit yield by 18.42%, 17.91% and 20.64% under I1, I2 and I3, respectively. Exogenous silicon application significantly improved fruit yield by 6.52% (I3S0) - 17.73% (I2S1). Irrigation level, salinity level and silicon rate had inconsistent effects on fruit quality. Exogenous silicon application significantly increased total soluble solids, Vitamin C, soluble sugars and lycopene content, without significant effect on titratable acid. The lower irrigation level and higher salinity level resulted in better fruit quality. The path analysis showed that leaf silicon content, net photosynthetic rate, lycopene, average fruit weight had significant direct positive effects on fruit yield. The results are informative for improving drip-fertigated greenhouse tomato productivity and quality under drought-stressed and salt-affected conditions.

Soil Potassium Effects on Cotton Lint Yield and Fiber Quality on the Texas High Plains

When comparing soil potassium (K) levels common in West Texas to the current Mehlich III-K critical levels for cotton (Gossypium hirsutum L.), fertilizer K applications are seldom recommended. However, when soil K is applied, positive responses in cotton yield have been reported. Studies were conducted in Lamesa and New Deal, TX to: 1) determine K effects on leaf K concentrations; 2) evaluate whether K application increases crop growth, yield, and fiber quality in sufficient K soils; and 3) evaluate whether K application under water deficit conditions also increases growth, yield, and fiber quality. In Lamesa, muriate of potash (KCl) was applied using two methods, knife-injected (0-0-15) and broadcast (0-0-60); and at New Deal, KCl was applied using knife injection. Potassium application rates included 0, 45, 90, 135, and 180 kg ha-1 with both high (90% ET) and low (30% ET) irrigation levels. At Lamesa in 2016 at 90% ET irrigation, lint yield was greater when 90 kg K ha-1 was broadcast (2,153 kg ha-1 lint) compared to the 180 kg K ha-1 treatment, and all K treatments with 30% ET irrigation. There were no lint yield differences in 2017 at Lamesa. At New Deal, lint yield was similar amongst all K application rates in both years. Although K application increased yield with the 90% ET irrigation level with broadcast application, no differences were observed in water-deficit cotton suggesting further research is needed to better understand the dynamics of K on lint yield in semiarid cotton production systems.

Irrigation modulates the effect of increasing temperatures under climate change on cotton production of drip irrigation under plastic film mulching in southern Xinjiang.

Warming and drought brought about by climate change seriously harm sustainable agricultural production in southern Xinjiang. It is still unclear how irrigation can improve the ability of crops to cope with climate change. Therefore, in this study, we calibrated and validated the AquaCrop model using data collected in cotton production from 2017 to 2018. The model effectively simulated the growth, biomass, and yield of cotton plants at the experimental site under different warming and irrigation conditions. The meteorological data collected from 1987 to 2016 were used in a simulation to predict cotton production under 3 temperature scenarios (temperature increased by 0°C, 1°C, and 2°C) and 6 levels of irrigation (198, 264, 330, 396, 495, and 594mm) to explain the modulating effect of plastic film mulching-coupled drip irrigation on cotton production in terms of increasing temperatures under climate change in southern Xinjiang. Model prediction showed that an increase in temperature reduced cotton yield under a low irrigation level, while an increase in irrigation mitigated the impact of climate change on cotton yield. An increase of 1°C did not significantly reduce cotton yield at 198-330 mm of irrigation. Under a 2°C increase, 396-594 mm of irrigation was required to ensure plant growth and yield formation. Both aboveground biomass and yield increased with the rise in the irrigation level at the same temperature. High water use efficiency was achieved at 495mm of irrigation without significant yield loss. Therefore, in the low-temperature scenario, it can be preferentially considered to achieve sustainable water use through water management, while in the high-temperature scenario innovative agricultural measures are required to avoid yield loss. Optimizing irrigation strategies can reduce warming-induced damage to crops under climate change.

Potential pathways to reduce environmental impact in a greenhouse tomato production: Life cycle assessment for different irrigation and fertilization treatments

Greenhouse vegetable cultivation with high productivity but also with high resource consumption has rapidly developed in Northern China. A comprehensive assessment of environmental impacts from the greenhouse production is vital to identify the important contribution processes and propose potential solutions to alleviate the environmental burden. A life cycle assessment (LCA) was used to examine the environmental impacts of greenhouse tomato production with the system boundary from greenhouse construction to tomato harvest. The impact of two fertilizers (organic and inorganic) under two irrigation levels was also compared. Nine impact categories including resource demand of energy consumption (EC) and water depletion (WD), pollution impact of global warming potential (GWP), acidification potential (ACP), eutrophication potential (EUP), and photochemical oxidation (PHO), and toxicity impact of territory toxicity potential (TTP), freshwater toxicity potential (FTP), and human toxicity potential (HTP) were selected to calculate the total environmental index. The results showed that the greenhouse construction stage contributed to 85.1% of EC, 91.0% of GWP, 68.1% of ACP, 93.2% of EUP and 89.4% of PHO while the tomato production stage resulted in more than 97% of WD and toxicity impact. After normalizing and weighting, FTP was the most environmental risk with an environmental index of 0.106, followed by EUP and ACP. For different treatments, organic fertilizer (N1) with low irrigation level contributed to the largest ironmental index of 0.295 while inorganic fertilizer (N2) with regular irrigation level had the least. Organic fertilizer generally had lower environmental burden in all impact categories with an exception of the toxicity impact. Due to the stronger release of heavy metals, N1 had higher TTP, FTP and HTP than N2. Reducing heavy metals content in organic fertilizers, optimizing organic fertilizer application regime, extending the greenhouse life span, and recycling or reusing the construction materials are recommended to mitigate the environmental risks of solar greenhouse vegetable production.

Modeling and determining the best combination of nitrogen and irrigation levels for achieving high yield in sweet corn

In order to model the combination of nitrogen application and irrigation level on corn yield, a three-years experiment (2018, 2019, and 2020) was perfumed based on a split-plot design. Four levels of Nitrogen fertilizer (0, 75, 125, 175, and 225 kg ha−1) and three levels of irrigation (100%, 80%, and 60% FC) were applied in all three years. Different methods and models were tested to simulate the relationship between yield and nitrogen along with irrigation and the final results indicated that interaction term between irrigation regimes and nitrogen fertilizer levels is the most influential source on kernel yield of sweet corn. This is the first time considering a model that includes this interaction term in modeling the kernel yield of sweet corn. In addition, our results showed that a complete polynomial model would complex the explanation of the model and it can be replaced with an adjusted model in which irrigation, the square of nitrogen levels, and their interaction are the only sources with no significant loss of goodness of fit. The negative coefficient of squared nitrogen treatment indicated that under a lower irrigation level (around 60% FC) higher nitrogen fertilizer level than about 180 might lead to slightly decrease in the kernel yield. Overall, providing water of about 90% to 100% FC and a nitrogen level of about 180 kg ha−1 is recommended to reach a high kernel yield and higher economic efficiency.

Response of maize hybrids under limited irrigation capacities: Yield and yield components

AbstractGrain yield of maize (Zea mays L.) in the semiarid Texas High Plains (THP) is greatly reduced when irrigation cannot meet peak water requirements. Drought‐tolerant hybrids may mitigate yield losses resulting from water deficits. We examined the effect of irrigation capacity (8.47 and 4.23 mm d–1) and planting rates (74,000 and 95,000 seeds ha–1) during three growing seasons (2016–2018) on grain yield and yield components of three maize hybrids, two of which were considered drought tolerant. Crop water deficits at the low irrigation level usually extended temporally from seventh leaf collar to dough stage. Mean grain yields varied from 5.2 Mg ha–1 under the low irrigation level to 19.9 Mg ha–1 at the high irrigation level. Hybrid did not influence grain yield and aboveground biomass in all 3 yr. Although kernel number and kernel mass were significantly influenced by hybrid across all years, this did not result in grain yield differences because greater kernel mass compensated for reduced kernel number. Harvest index did not significantly differ between conventional and drought‐tolerant hybrids. In 2016, grain yield was significantly influenced by plant density only at the low irrigation level, with 44% greater yields at the low plant density. For the patterns and level of water stress observed during these three growing seasons, the three hybrids performed similarly. Besides using hybrids well adapted to the region, mitigation of yield reductions under limited irrigation capacities in the THP can be achieved by concentrating irrigation on less land area and optimizing planting rates.

Water availability and seasonality affect phytomass production and photosynthetic pigments of Aloysia citrodora Paláu

Vegetative growth can be affected by different environmental factors. The objective of this work was to evaluate phytomass production and photosynthetic pigments of Aloysia citrodora plants submitted to different irrigation levels and seasons. The experiment was carried out in a protected environment from August 2015 to March 2017, in an experimental randomized blocks design, 4x4 factorial scheme, with four blocks with four plants each. The irrigation levels tested were 25%, 50%, 75% and 100% of the field capacity, in the four seasons of the year (autumn, winter, spring and summer). Plant height, fresh and dry mass of branches, fresh and dry mass of leaves, leaf area and photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids) were evaluated. It was observed that water availability and seasons influence phytomass production as well as the photosynthetic pigment analyzes. Low irrigation levels and cultivation during autumn and winter adversely affect vegetative growth. Furthermore, our results indicate that for higher phytomass production, it is recommended to cultivate Aloysia citrodora during spring and summer under irrigation levels of 75% and 100% of field capacity. Spring season promotes higher content of photosynthetic pigments. This study will open new avenues and perspectives to elucidate possible changes in secondary metabolites of Aloysia citrodora, a medicinal plant, in the presence of changes in the growing seasons and different stress conditions, including water stress.

Effect of irrigation levels and weed management practices on weeds, water productivity and yield of cauliflower

Water shortage and weed infestation are major constraints in vegetable production. Micro-irrigation integrated with weed management practices is one way to maximize the yield and water productivity in crops. A field trial was conducted during Rabi seasons of 2018-19, 2019-20 and 2020-21 at the Water Management Farm of CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur to study the effect of irrigation levels and weed management practices on weeds, crop and water productivity in cauliflower. The experiment was laid out in split plot design with three irrigation levels (0.9 PE, 0.7 PE and 0.5 PE) in main plots and four weed management practices (black polythene mulch, pre-plant incorporation (PPI) of pendimethalin 1.5 kg/ha followed by (fb) hand weeding, pendimethalin 1.5 kg/ha PPI fb straw mulching and weedy check) in sub plots. The treatments were replicated thrice. The irrigation given to crop at 0.9 PE level proved to be better in terms of yield and net returns in cauliflower. Black polythene mulch resulted in efficient weed control and improving crop developmental parameters and yield attributes. There was progressive increase in weed density and biomass with increase in irrigation level, with least in lower irrigation level of 0.5PE. It is concluded that higher crop productivity and returns in cauliflower can be obtained by using black polythene mulch and irrigation applied at 0.9PE level. However, under limited water availability, the best alternative will be applying irrigation at 0.7 PE level and using black polythene mulch.

Enhancing Growth and Yield Parameters in Mulberry through Different Levels of Drip Irrigation and Mulching

The experiment was conducted to find out the impact of levels of drip irrigation and mulching on growth, yield and quality parameters of mulberry. Among different levels of irrigation 0.8 CPE recorded higher values for growth and leaf yield (47613 kg ha-1 year-1) parameters. Compared to lower levels of irrigation 0.5, 0.6 and 0.7 CPE. Also, mulberry plants mulched with black plastic polythene cover recorded higher values for growth and leaf yield (45143 kg ha-1 year-1) compared to plants without mulching. The interaction effect 0.8 CPE along with mulching (T8) recorded higher values for all the growth and yield parameters compared to other combination of treatments and lower values for the same were recorded in 0.5 CPE along in without mulching plot. The study revealed that adoption of drip irrigation in mulberry at 0.8 CPE along with mulching is appropriate to enhance the growth parameters (plant height, number of shoots, number of leaves, leaf area and total dry matter content) and leaf yield.

Improved water productivity in summer squash under water deficit with PGPR and synthetic methyl amine applications

Insufficient freshwater resources require the improvement of deficit irrigation with approaches that induced high yields by increasing the adaptation of plants to physiological and photosynthetic responses to water scarcity in the soil. The aim of this study is to evaluate water productivity applying combinations of three different plant growth promoting rhizobacteria-PGPR (Bacillus megaterium TV91C, Bacillus megaterium TV6D, Bacillus subtilis RK1900) with a synthetic methylamine molecule for summer squash (Cucurbita pepo L.) at four irrigation levels (full irrigation, and 15, 30 and 45% deficit irrigation), comparing with control (without PGPR and MA). For that, the results of the small plot field experiment carried out in squash growing season of 2017 and 2018 in a semi-arid region were evaluated. PGPR + MA applications decreased the harmful effects on photosynthetic traits (Pn, gs, Ci and Tr), chlorophyll content, electrolyte leakage and leaf relative water content by water deficit and significantly improved also. Although the negative correlations between yield and physiological and photosynthetic traits, PGPR + MA applications provided higher marketable yield as much as the plants full irrigated even at low irrigation levels with a potential root growth from physiological and photosynthetic improving. Higher yield in PGPR + MA applications resulted in higher water productivity for water consumption and decreased irrigation quantities also increased water productivity for irrigation quantity applied. The most striking result was that all PGPR + MA applications resulted in significantly higher water consumption and water productivity for irrigation quantity applied values at all irrigation levels compared to the fully irrigated control treatment. Therefore, it would be possible to optimize water productivity, with water saving and squash yield increases from PGPR + MA applications in terms irrigation water management.

Evaluation of Some Transpiration Regulators in Sunflower for Saving Irrigation Water in Relation to Productivity

An experimental field trial was conducted in seasons of 2015 and 2016 at Giza Experimental Station of Agricultural Research Centre (ARC), Egypt to evaluate the foliar spray effect with transpiration regulators (Potassium, Kaolin and Ascorbic acid) and three levels of irrigations (100%, 80% and 60% of Et0) on yield, its attributes, and water productivity of two sunflower cultivars (Giza 102 and Solala 120). The factorial treatments were arranged in split- split plot design with three replications. The irrigation levels (100%, 80% and 60% of Et0) were devoted for main plots, while subplots contained the three spraying treatments of transpiration regulators. (Potassium at 1%, Kaolin at 3% and Ascorbic acid at 100 ppm), in addition to control treatment (water spray). Sub-sub plots were occupied by the two sunflower cultivars (Giza 102 and Solala 120). Obtained results proved that, increasing irrigation levels up to (80- 100%) caused significant increase in all growth characteristics, photosynthetic pigments (total chlorophyll), relative water content (RWC %) and seed oil %. Also, yield parameters being head diameter, 1000-seed weight and seed yield) show significant reduction under water deficit. Foliar spray with (Potassium at 1%, Kaolin at 3% and Ascorbic acid at 100 ppm), positively affected all the growth and physiological criteria of the tested plants compared with control. Generally, under low irrigation levels, application of transpiration regulators effectively reduced the detrimental impact of drought stress on growth, yield and its components of the two used cultivars in the two seasons. While, foliar spraying of potassium under 100% of Et0 gave the best treatment in this respect. Concerning cultivars, WUE (water use efficiency) for Solala 120 was significantly higher than for Giza 102 in the two seasons. All interactions among factors under study due to WUE were not significant in 2015 and 2016 seasons.

Jujube is at a competitiveness disadvantage to cotton in intercropped system

AbstractIntercropping is a key methodology used by farmers to improve economic benefits. However, in certain areas such as Xinjiang, China, limitations in available irrigation water make intercropping difficult to implement. Farmers are therefore challenged to improve economic benefits in water‐limited conditions. We evaluated the effectiveness of intercropped common jujube (Zizyphus jujuba Mill.) and cotton (Gossypium hirsutum L.) under different irrigation regimes. Using a factorial design, crops were planted individually and together (i.e., intercropping) under five different irrigation systems. We measured growth parameters and evaluated the temporal distribution of root system growth and fruit yield. Intercropped cotton displayed higher fitness metrics and outperformed the single‐cropped cotton in crop yield. Intercropping, however, had the opposite effect on jujube plants: the overall fitness and yield of jujube were significantly curtailed under the interspecific competition induced by this planting technique. Under low irrigation levels, cotton plants tended to invade the jujube niches that reduced jujube growth and development. Our findings suggest that in a jujube/cotton intercropping system, cotton is the dominant competitor, whose ability to inhibit the development of the less competitive jujube is exacerbated under water deficit situations. Although intercropping system affected jujube development, overall cotton yield, and therefore benefit to farmers was considerably higher using this system. However, the competitive ability of jujube gradually increases as the plant aged which could reduce the economic advantages of the intercropping system.

Eco-physiological Responses of Amaranthus cruentus L. to Deficit Irrigation under Different NPK 20:10:10 Fertilization Rates

The aim of this research was to investigate the responses of Amaranthus cruentus L. to deficit irrigation under fertilization, in a 2 by 3 factorial experiment with two levels of irrigation (1.5 litre/week and 0.75 litre/week) corresponding to 2600 and 1300 mm/year respectively and three levels of NPK 20:10:10 (0, 138, 275 kg ha-1). This experiment was conducted in a screen house in Cameroon, and lasted for 12 weeks after the nursery phase. Growth parameters and chlorophyll fluorescence were measured weekly for 8 weeks. Destructive sampling was done at 12 WAT to determine biomass partitioning, water use efficiency and the root/shoot ratio. Data were analyzed for variance and relationships in the MINITAB Version 17 statistical package. Within each irrigation level, plant mass decreased as fertilizer rates decreased, while root: Shoot ratio increased instead. Plant mass expressed higher values at the higher irrigation levels while root: Shoot ratio was lower compared to that at lower irrigation levels. This shows a strategy for resource re-allocation to roots under both water and nutrient deficit. Harvest index was statistically similar across irrigation and fertilizer levels. Within the higher irrigation levels, WUE of plants decreased with a decrease in fertilizer rates but not for plants subjected to deficit irrigation. While chlorophyll fluorescence values differed significantly across treatments, all values were below 0.8, indicative of stress. Factor analysis showed that growth of A. cruentus was highly fertilizer-dependent, while chlorophyll fluorescence was irrigation-dependent. This suggest that fertilizer application is essential in ameliorating the effects of deficit irrigation, and will be essential in the production of this crop under deficit irrigation.

Mitigating the Harmful Effects of Water Deficiency Stress on White Lupine (Lupinus albus L.) Plants by Using Algae Extract and Hydrogen Peroxide. تخفیف الآثار الضارة الناتجة عن اجهاد نقص المیاه على نباتات الترمس الأبیض باستخدام مستخلص الطحالب وفوق اکسید الهیدروجین.

Water deficit is a major growth limitation factor affecting plant growth and productivity. To counteract the harmful effects of drought stress, lupine plants were sprayed with two concentrations of algae extract (1 g L-1 and 2 g L-1) and hydrogen peroxide solution (0.5% and 1%) under low irrigation level. Morphological, physiological and anatomical studies were performed. It was found that all treatments enhanced plant height, root length, number of leaves, average leaf area, shoot and root fresh and dry weights. A significant increment in chlorophyll a and b, carotenoids and total pigments contents, as well as a significant decrease in electrolyte leakage was noted in treated plants compared with untreated under water deficit. Increment in levels of osmoprotectants such as proline, total free amino acids, glycine betaine and total soluble sugars contents was highly significant in case of 2 g L-1 algae extract treatment compared with untreated plants group. Anatomical studies of root, stem and leaf of treated and untreated plants revealed that 2 g L-1 algae extract treatment followed with 0.5% H2O2 induced significant increments in the thickness of the studied plant organs compared with the untreated plants under water deficit conditions. In general, the concentrations of 2 g L-1 algae extract and 0.5% H2O2 were the most effective doses regarding all the studied characteristics.

Drought-Conditioning of Quaking Aspen (Populus tremuloides Michx.) Seedlings During Nursery Production Modifies Seedling Anatomy and Physiology.

In the western US, quaking aspen (Populus tremuloides Michx.) regenerates primarily by root suckers after disturbances such as low to moderate severity fires. Planting aspen seedlings grown from seed may provide a mechanism to improve restoration success and genetic diversity on severely disturbed sites. However, few studies have examined the use of container-grown aspen seedlings for restoration purposes from both the outplanting and nursery production perspective. Thus, the purpose of this novel study was to examine how alterations in irrigation levels during nursery production across three seed sources would impact seedling performance attributes on harsh, dry outplanting sites. Irrigation treatments were based on three irrigation levels, determined gravimetrically: High = 90%, Medium = 80%, and Low = 70% of container capacity. The three seed sources represented a latitudinal gradient across the aspen range (New Mexico, Utah, and Alberta). Carbon isotope analysis indicated irrigation treatments were effective in creating higher levels of water stress for both the Low and Medium irrigation levels compared to seedlings under the High irrigation level. Seedlings subject to the Low irrigation level were found to induce greater height, higher photosynthetic rates, larger percentages of hydraulically active xylem, and faster xylem flow velocities compared to the High irrigation level. The lack of an interaction between irrigation treatments and seed source for nearly all response variables suggests that nursery conditioning via irrigation limitations may be effective for a range of aspen seed sources.