FI Treatments Research Articles

Improving mango production using partial root drying technique and organic fertilisation: Field and modeling study

ABSTRACT The decreasing in water availability due to climate change can affect agricultural production. The water shortage problem led to the development of several water saving techniques. One of the waters saving techniques in irrigation is the partial root-zone drying (PRD) method. Tow field experiments accompanied by a modeling study were carried out during seasons 2020/2021 and 2021/2022, respectively, using four deficit irrigation strategies [FI (100% of full irrigation), DI1 (0.75FI), DI2 (0.5FI) where water was supplied to both sides of the mango trees and DI3 (Partial Root-zone Drying, PRD = 0.5FI) where water was supplied to a single side of each tree in an alternating manner)]. The four irrigation methods were designated as the study’s major plots. Then, for the purpose of adding compost, each main plot was divided into four smaller plots [NC (No-Compost), C12 (12 ton ha−1), C18 (18 ton ha−1) and C24 (24 ton ha−1)] to investigate the effects of such treatments on increasing water productivity, yield, and the quality of mango fruits. The results indicated that adding compost with PRD irrigation method decreased water stress throughout the root zone and increased the yield, water productivity and fruit quality. Compost addition C24 (24 ton ha−1) with PRD irrigation increased the amount of soil organic matter and microorganism activity when compared to other treatments. Additionally, C24 treatment improved mango quality under both FI and PRD treatments, the PRD technique enhanced fruit yields by 3.8% and 7.3% and water productivity by 51.6% and 53.8% for 2021 and 2022 seasons, respectively, compared to FI, while reducing the applied irrigation water by 50% for each season. In comparison to other irrigation strategies, the PRD strategy had shown superior outcomes in enhancing the yield, water productivity, and quality of mango yield. With the use of compost “C24” as organic matter fertilizer, PRD proved to be an effective dual technique to save water and increase productivity. Under both current and future water scarcity caused by climate change, it could be a successful adaptation technique. The SALTMED model produced accurate simulations of the soil moisture content, mango production, and water productivity during the two seasons.

Evaluation of AquaCrop for potato yield and biomass simulation under different water amounts in drip and furrow irrigation methods

AbstractPotato is one of the most important crops for meeting food needs worldwide. The water requirement of this crop is high, and its yield is sensitive to the amount of irrigation water. Studying different amounts of irrigation water in irrigation methods is not only expensive but also time‐consuming, so it is necessary to use water‐driven crop models such as AquaCrop. This research aims to evaluate the accuracy of AquaCrop for simulating potato yield and biomass in Iran at three irrigation levels (full irrigation [FI] stands for 100%, I80 for 80% and I65 for 65% of the crop water requirement) via two irrigation methods (furrow irrigation and drip irrigation). For furrow irrigation, the normalized root mean square error values in the FI, I80 and I65 treatments varied between 17% and 28% for yield and 12% and 17% for biomass. These results for drip irrigation were 17%–22% (yield) and 9%–18% (biomass). For furrow irrigation, the average root mean square error values for potato biomass and yield were 0.89 and 0.68 t ha−1, respectively. The corresponding results for drip irrigation were 0.79 and 0.64 t ha−1, respectively. Based on all the results, the accuracy of AquaCrop was good for both irrigation methods, even though its accuracy under severe water stress conditions (I65) for the drip irrigation method was better than that for furrow irrigation.

Interactive effects of irrigation system and level on grain yield, crop water use, and greenhouse gas emissions of summer maize in North China Plain

Irrigation management is one of most critical factors influencing soil N2O and CO2 emissions in dryland agriculture. To explore the effects of irrigation systems and levels on the mitigation of N2O and CO2 emissions from maize fields and to determine the balance among greenhouse gases (GHG) emission, water-saving and grain yield, a two–year field experiment was conducted in the North China Plain (NCP) during the growing seasons of 2018 and 2019. Two irrigation systems (i.e., flood irrigation, FI, and drip irrigation, DI) were adopted with four irrigation levels in each system, including 65 mm/event (sufficient irrigation, CK), 50 mm/event (decreased by 23 %), 35 mm/event (by 46 %) and 20 mm/event (by 69 %), respectively. The results showed that both irrigation systems and levels had significant effects on soil N2O and CO2 emissions (P < 0.05). Nitrous oxide (N2O) and CO2 emissions peaked following irrigation or irrigation + fertilization events during sowing to early filling stage (R1), with the peak values increasing with irrigation levels. Meanwhile, peak values from FI were higher than those from DI at 50 mm and 65 mm irrigation levels. The average cumulative N2O and CO2 emissions of DI treatments were 14.9 % and 6.23 % lower than those of FI treatments (P < 0.05), respectively. Soil moisture was identified as one of the most crucial factors influencing N2O and CO2 fluxes. Deficit irrigation efficiently deceased cumulative N2O and CO2 emissions, but moderate to severe deficit irrigation brought significant reduction in grain yield. Drip irrigation with a slight deficit irrigation level (decreased by 23 %) obtained the best economic and environmental benefits, which achieved the dual goal of lower GHG emissions but higher WUE without sacrificing grain yield.

Sustainable high grain yield, nitrogen use efficiency and water productivity can be achieved in wheat-maize rotation system by changing irrigation and fertilization strategy

The winter wheat-summer maize rotation system is one of the most successful intensification agricultural systems in China, but low and unstable grain yield (GY) and high soil nitrate-N leaching caused by erratic precipitation and inefficient management of irrigation and fertilization have attracted wide attention. A two-year (2018–2020) field experiment was carried out to evaluate the effects of four water and nitrogen management strategies (a conventional irrigation and fertilization (CK) and three drip fertigation treatments (rain-fed: RF, deficit irrigation: DI and full irrigation: FI)) on soil water, soil nitrate-N residual, GY, water productivity (WP), nitrogen use efficiency (NUE) and net income in a winter wheat-summer maize rotation system. The results indicated that water and nitrogen management strategies had significant effects on soil water content in the 0–320 cm soil profile. More than 90 mm soil water in the 0–320 cm soil layer was consumed by winter wheat, and the soil water consumption followed the order of RF > DI > CK > FI. The soil water consumption can be replenished by irrigation and precipitation during the summer maize season, but the soil water in 180–260 cm under RF was significantly lower than that in the other treatments, which could not be fully replenished. There was no significant difference in the nitrate-N residual in the 0–180 cm soil layer among the treatments at harvest, but the nitrate-N residual rate of CK (less than 40% and 30% at winter wheat and summer maize harvest) was significantly lower than that of drip fertigation (more than 50% and 40% at winter wheat and summer maize harvest) in the 0–60 cm soil profile, but significantly higher than that in the 60–180 cm soil profile. These results indicate that drip fertigation had a lower risk of nitrate leaching compared with CK treatment. GY and NUE of DI and FI treatments were significantly higher than those of CK and RF treatments, but DI used 25% less irrigation water than FI, resulting in higher WP. The WP of DI was increased by 6.8–7.4% and 4.2–16.0% for winter wheat and summer maize compared with FI, respectively. From the perspective of winter wheat-summer maize rotation system, the two-year average net income of DI was increased by 2.8%, 37.9% and 59.9% compared with FI, RF and CK, respectively. Therefore, deficit irrigation with nitrogen fertigation was recommended as a sustainable fertigation strategy for achieving higher grain yield, nitrogen use efficiency, water productivity and net income and reducing the risk of soil nitrate-N leaching in the winter wheat-summer maize rotation system.

Water budgeting in conservation agriculture-based sub-surface drip irrigation in tropical maize using HYDRUS-2D in South Asia

In water scarce regions of South Asia, diversification of rice with maize is being advocated towards sustainability of cereal-based cropping systems. Adoption of innovative agronomic management practices, i.e., conservation agriculture (CA) and sub-surface drip irrigation (SSDI) are considered as key strategies for much needed interventions to address the challenges of water scarcity under projected climate change. Benefits from CA and SSDI concerning water economy are well-established, however, information about their complementarity and water budgeting in cereal-based systems are lacking. A field study was conducted with process-based model (HYDRUS-2D) to understand water transport, root water uptake and components of soil water balance in maize grown in rotation with wheat after five years of continuous adoption of conservation agriculture. In this study, altogether eight treatments comprising of 6 CA+ treatments (CA coupled with SSDI); permanent beds using sub-surface drip (PB-SSD) with (WR) and without (WOR) crop residue at different N rates, 0, 120 and 150 kg N ha−1 were compared with CA (PB using furrow irrigation-FI with crop residue-120 kg N ha−1) and conventional tillage practices (CT) (CT using FI without crop residue-120 kg N ha−1). Results showed that the model could simulate the daily changes in profile soil water content with reasonable accuracy in all the treatments. Simulated soil water balance indicated higher cumulative root water uptake (CRWU), lower cumulative evaporation (CE) and higher soil water retention in CA+ (PB-SSD+ crop residue at 150 and 120 kg N ha−1) than CA and CT plots. Hydrus-2D model efficiency > 0, RMSE between 0.009–0.026 and R2 value between 0.80–0.92 at P < 0.01 indicates that the model is performing efficiently. The mean evaporation from CA+ treatments was 10 and 36% less than CA and CT treatments, respectively. On average, CRWU under CA+ treatments were 14–48% higher than FI treatments. The mean cumulative deep drainage in CA+ plots was 80–100 mm less than CA and CT plots. In CA+ based plots significantly higher biomass production and radiation use efficiency were observed with reduced water use than CA and CT. Therefore, the study justifies the water-saving nature of CA+, while maintaining higher productivity and meeting the transpiration demand of crops and halting unnecessary evaporation and deep drainage losses.

Response of tomato cultivars to irrigation management strategies employed by emerging farmers in the Greater Giyani Municipality

Intensification of low-tech agricultural production is required in the Greater Giyani Municipality (Limpopo province, South Africa) to respond to changing climatic conditions, water scarcity and increased food demand of the local market. Two years of field experiments were conducted on two typical small-scale farms under real-world conditions. The objective was to test the response of locally available tomato (Lycopersicon esculentum Mill.) cultivars (Rodade, STAR 9006, Commander, HTX 14 and MFH) to two different irrigation strategies (full irrigation FI and deficit irrigation DI). While results showed high tomato yield variability (ranging between 9.2 t ha−1 and 59.7 t ha−1) depending on the farms, environmental conditions (heatwaves, diseases) and irrigation management, STAR 9006 appeared to be the best performing cultivar and HTX 14 the worst. Seasonal evapotranspiration under FI was between 400 and 620 mm depending on the length of the season and harvesting time. Crop water productivity was generally higher for DI than FI treatments. Deficit irrigation appeared to be feasible to reduce water use for some cultivars (eg cv. STAR 9006), however, an economic analysis should be conducted at specific sites/farms to determine the impacts of DI on farmers’ income as some yield losses can be expected during drought years.

Effects of Irrigation and Planting Geometry on Soybean (Glycine max L.) Seed Nutrition in Humid Climates

This study investigates the effect of irrigation (FI, all rows-irrigation; HI, alternate row irrigation; RF, rainfed) and planting geometry (PG) (SR, single-row; TR, twin-row) on soybean seed constituents. Results showed that most of these seed components were significantly affected by crop season due to contrasting precipitation and solar radiation patterns, particularly during July-August, coinciding with early reproductive and seed development stages. Both seed protein and oil levels responded positively to irrigation, while most of the amino acids were nonresponsive. The protein content ranged between 36.3 and 37.6% in 2018, while it was between 36.4 and 38.3% in 2019. Total seed oil content varied between 24.2 and 26.1% in 2018 and between 25.3 and 26.5% in 2019. Among amino acids, glycine, alanine, valine, and methionine levels were significantly higher in both FI and HI treatments. Among sugars, only sucrose was higher in response to the RF treatment, and irrigation did not affect both stachyose and raffinose. Oleic acid was higher in RF, while no significant differences were observed for linolenic and linoleic acids. Similarly, seasonal variation was significant for stearic acid content, but the 2019 season had relatively higher accumulation (stearic acid: between 4.1 and 4.5% in 2018 and from 4.6 to 4.9% in 2019). These results indicate that both irrigation and climate during seed development can alter some seed composition constituents and play critical roles in determining seed nutritional qualities.

Screening for water stress tolerance in eleven plum (Prunussalicina L.) Cultivars using agronomic and physiological traits

The purpose of this study was to evaluate eleven plum cultivars (Prunus domestica L.) for drought tolerance based on agronomic performance and various physiological traits. The experiment was carried out under field conditions in Sais Plain (NW Morocco) on eight-year-old plum trees under drip irrigation. Two water treatments were applied during the fruit set (late March) to harvest (June): a control treatment fully irrigated at 100 % of seasonal ETc (FI), and a continuous deficit treatment irrigated at 50 % of ETc (CDI). The plasticity to drought was assessed through the following traits: yield, fruit weight, number of leaves per 10 cm of shoot, wood density, leaf area, stomatal density, stomatal area, stomatal area index, chlorophyll pigments content (Cha and Chb), stomatal conductance and leaf content of cuticular waxes and proline. Results showed significant differences among cultivars in response to water stress regarding all the above mentioned traits. The cluster analysis based on mean ratios of CDI and FI treatments for all traits highlighted three distinct clusters within the studied cultivars, with regard to drought tolerance level. The PCA analysis using the above-named ratios revealed that water stress effects on fruit weight, leaf area, stomatal density, stomatal area and leaf proline content had the highest impact on discrimination among the cultivars for drought tolerance. Therefore, retained cultivars for their remarkable tolerance to drought were, in order of importance, "INRA-PR34″, "INRA-PR35″, "INRA-PR41″ and "Santa Rosa", while the cultivar "Timhdit" was the most sensitive, with a strong yield decrease of 95 %. The results herein reported identified cultivars, with high degree of plasticity in response to water deficit, suggesting their use in breeding programs aiming at improving the species drought tolerance.

Assessment of water stress tolerance in eleven pomegranate cultivars based on agronomic traits

The aim of this study was to assess eleven Mediterranean pomegranate cultivars for drought tolerance based on their responses to severe water stress. The experiment was performed under field conditions in Sais Plain (NW Morocco) on twelve-year-old pomegranate trees (Punica granatum L.), under drip irrigation. For each cultivar, two treatments were applied from fruit set to harvest: a control treatment irrigated at 100 % of seasonal ETc (FI), and a continuous deficit treatment irrigated at 50 % of ETc (CDI). The measurements concerned fruit yield, fruit weight, aril content, aril weight, seed weight, juice content, shoot length, leaf area, foliage density, wood density and concentration of chlorophyll-a and chlorophyll-b. Results showed clear differences among pomegranate cultivars in response to water stress. The most frequent effects of water stress were recorded on yield, fruit weight and chlorophyll pigment contents. Fruit yield was not affected in Zheri Automne cultivar, while it was significantly decreased under CDI in all other cultivars by 14 % in Bzou to 51% in Ounk Hmam. A significant decrease of fruit weight was observed in six cultivars, with a rate of 13 % in Gordo de Jativa cultivar to 24 % in average for Grenade Jaune, Grenade Rouge and Ounk Hmam. These last cultivars were the only ones affected in juice content by 9–11%. Regarding CDI effect on vegetative growth, it was recorded a high decrease of shoot length in the cultivars Gjeibi (78 %), Sefri (64 %) and Mollar Osin Hueso (38 %). The cultivars ranking for drought tolerance based on mean ratios of all traits between CDI and FI treatments was drawn according to cluster analysis, combined to a scoring method. It was thus retained that the most drought tolerant cultivar was Zheri Automne, followed by Djebali and Bzou, while Grenade Rouge cultivar was the most sensitive.

Canopy cover evolution, diurnal patterns and leaf area index relationships in a Mchare and Cavendish banana cultivar under different soil moisture regimes

The biggest abiotic threat to banana (Musa spp.) production is water deficit, but physiological indicators in plantations are lacking. Canopy Cover (CC) seems to be a relevant parameter, but so far not used in banana fields. Field experiments were conducted to determine the effect of optimal irrigation (FI) versus rainfed (RF) on CC and Leaf Area Indices (LAI) in two experiments with different cultivars (Mchare ‘Huti Green’ [HG, AA] and Cavendish ‘Grand Naine’[GN, AAA]) (n = 3 for HG, n = 4 for GN) until harvest of cycle 1 (C1), studying C1 and C2 plants. Soil moisture was followed using Time Domain reflectometry. CC and LAI were reduced 8–9 weeks after the start of soil moisture divergence between RF and FI treatments in both experiments (p < 0.05), leading to a reduction in CC growth rate (r) and maximum CC (CCmax) in RF plots (p < 0.05). On a daily timescale, CC varied diurnally (i.e. was reduced) under high evaporative demands, whereby soil moisture depletion increased the CC reduction. Cultivar specific CC-LAI curves were created following the Lambert-Beer equation, whereby HG had a lower extinction coefficient than GN (0.52 vs. 0.67). CC growth over time seems a promising indicator for water deficit in the field. Diurnally, CC is more affected by evaporative demand than soil moisture depletion, although soil moisture depletion increases CC diurnal drops under high ET0.

Irrigation and Planting Geometry Effects on Cotton (Gossypium hirsutum L.) Yield and Water Use

Addressing the challenges of dwindling groundwater resources and ever-increasing demands for water necessitate enhancing water use efficiency (WUE) in irrigated agriculture. In a 2-year study, we examined the effects of different levels of irrigation and PG on lint yield and WUE of furrow irrigated cotton in a Dundee silt loam in the Mississippi Delta. The main plots were three irrigation regimes: irrigating every furrow (FI), alternate furrow (HI), and no irrigation (RF) and subplots were two planting geometries (PG): single-row (SR) and twin-row (TR). Across FI and HI no significant differences were observed in plant height and biomass yield at flowering, but chlorophyll content index and leaf area index (LAI) were positively affected. Canopy closure in TR planting occurred earlier than SR leading to higher leaf areas available for harvesting more light during photosynthesis. Averaged across the irrigation regimes, the TR planting enhanced lint yield by 10.6% in 2018 and 17.6% in 2019 compared to SR. The average lint yield in SR and TR were: 1779 and 2028 kg ha-1 under FI, 1803 and 2082 kg ha-1 under HI, and 1573 and 1788 kg ha-1 under RF treatments, respectively. In FI and HI treatments, TR had higher lint yield than RF treatment by 13.8% and 16.5%, respectively. Lint yield in HI with TR had the highest irrigation WUE (3.4 kg ha-1 mm-1) followed by HI with SR (2.7 kg ha-1 mm-1). These results demonstrated that cotton grown in TR with HI could reduce irrigation water demand in silt loams.

Deficit irrigation: a viable option for sustainable confection sunflower (Helianthus annuus L.) production in the semi-arid US

With water resources becoming more limited in arid and semi-arid regions, water-saving strategies are needed to reduce agricultural water use. A furrow-irrigated field experiment was conducted during 3 years (2010–2012) in the western US to evaluate the response of confection sunflower to deficit irrigation. Treatments were full irrigation (FI, irrigation as scheduled by farmers), two deficit irrigation strategies (R1, started irrigation when miniature floral heads appeared; and R4, started irrigation when floral heads began to open), and rainfed (CK) as control. Results showed that growth and yield of confection sunflower were significantly affected by treatments. The FI and deficit irrigation treatments (R1 and R4) led to significantly higher leaf area index (LAI), aboveground biomass, head diameter, and yield compared with the CK treatment. Relative to FI, deficit irrigation decreased sunflower LAI, head diameter, and aboveground biomass. Average yield was 6% and 15% less in R1 and R4 treatments, respectively, compared with the FI treatment. There was no significant difference in yield between FI and R1, except during extremely dry years, suggesting that the R1 strategy may maintain yield while reducing one irrigation event. Based on the growth and yield of sunflower, an irrigation for crop establishment and then resuming of irrigation at the R1 stage could be considered as a water-saving strategy for surface-irrigated confection sunflower grown in water-scarce regions.

Fruit growth, yield and oil quality changes induced by deficit irrigation at different stages of olive fruit development

Experiments were performed in a high-density olive orchard to compare the effect of regulated deficit irrigation (RDI) at two different phenological stages with fully-irrigated trees (FI) over two years. Stress was imposed either prior to pit hardening (RDI 1) or after endocarp sclerification during the initial phase of oil accumulation (RDI 2). Fully irrigated trees received 2277 and 1648 m3 ha−1 in 2012 and 2013, respectively, RDI 1 ones 76 and 53% of those volumes in 2012 and 2013, respectively (RDI 2 trees 48 and 67%). There were no differences in fruit set or return bloom due to the irrigation regime. At harvest differences in fruit size between FI and RDI treatments were significant only in the first year. The fruit yields of RDI 1 and RDI 2 trees were 70 and 81% of FI ones, respectively (means of two years), but the yield efficiency was similar across all treatments. The phenolic concentration in RDI 1 fruits was higher than that in fruits from trees subjected to the other water regimes. Verbascoside, 3–4 DHPEA-EDA, and oleuropein of RDI 1 fruits were higher in 2012 (only verbascoside in 2013). Oleuropein and 3–4 DHPEA-EDA of RDI treatments were higher than those of FI in 2013. Higher concentrations of biophenols were measured in oils from RDI 1 trees in both years, whereas FI and RDI 2 showed similar values. An early water stress was more effective to increase the phenolic concentration of olive oil compared with a late deficit or full irrigation.

Root water uptake of pepper plants (Capsicum annuum L.) under deficit irrigation system

ABSTRACTRoot water uptake is a component of water balance that has not been clearly understood. This study was carried out in a completely randomized design with three replications under the greenhouse condition at Shahrekord University, Shahrekord, Iran. In this study, the root water uptake (RWU) by pepper plant under various irrigation water levels was investigated. Irrigation treatments included control (full irrigation level, FI) and three deficit irrigation levels, 80%, 60% and 40% of the plant's water requirement called DI80, DI60 and DI40, respectively. A no-plant cover treatment with three replications was also used to measure evaporation from the soil surface. Daily measurements of volumetric soil moisture (VSM) were made at 10 cm intervals of the soil column. The differences between the measured VSM and the VSM in the next day, and evaporation rate at the soil surface at the same layer of the no-plant cover treatment were calculated and, eventually, the RWU in each layer per day was estimated. The results showed that the maximum and minimum RWUs were found in the FI and DI40 treatments, respectively. The averages of root water uptakes in the DI80, DI60, and DI40 treatments were reduced by 17.08%, 48.72% and 68.25%, respectively. Furthermore, in the DI80 treatment, the reduced rate of water uptake was less than the reduced rate of water applied to the plants.

Soil moisture dynamics in a hedgerow olive orchard under well-watered and deficit irrigation regimes: Assessment, prediction and scenario analysis

A study was conducted in a hedgerow olive orchard (SW Spain) to assess the capability of the HYDRUS 2D/3D model in predicting seasonal soil water dynamics in a well-watered (full irrigation, FI) and two regulated deficit irrigated plots (60RDI and 30RDI) differing in the timing and level of water stress imposed. The simulated soil water balance components were used to assess the suitability of the irrigation management accomplished in the experimental orchard and that of the irrigation treatments for different soil types and management scenarios. Soil water content (θ) was measured in all four plots per irrigation treatment with two access tubes per plot installed at 0.1m and 0.4m away from the dripper. Comparison of simulated against observed θ showed mean absolute errors ranging from 0.03 to 0.045cm3cm−3, root mean square errors from 0.035cm3cm−3 to 0.056cm3cm−3 and Nash–Sutcliffe efficiency coefficients from 0.438 to 0.834 across all treatments and probe locations. The modelled soil water balance components showed that drainage water losses represented 9–12% only of the applied irrigation water across all irrigation treatments. Scenario analysis revealed that daytime irrigation led to higher drainage water losses in FI than nighttime irrigation. For the same irrigation volumes, rootzone soil pressure head decreased (i.e. became more negative) when the irrigation frequency of the RDI treatments increased, thus supporting the lower irrigation frequencies scheduled in RDI as compared to FI in the experimental orchard. Scenario analysis also revealed the importance of adjusting irrigation schedules to soil type, irrespective of whether FI or RDI treatments were to be implemented.

Physiological and growth responses of pomegranate tree (Punica granatum (L.) cv. Rabab) under partial root zone drying and deficit irrigation regimes

This study evaluated the effects of full irrigation (FI, 100% ETC), partial root zone drying and deficit irrigation with mild (75%ETC) and severe (50% ETC) water stress on the physiological and growth behavior of pomegranate trees in southern Iran in 2011 and 2012. The experiment was set up as a split plot design in completely randomized blocks design with three replications. Results showed that the stem water potential (ψstem) was directly related to the soil water deficit (SWD), and it varied from −2.07 to −3.27MPa in 2011 and −1.67 to −3.23MPa in 2012. In all times of measurements, higher values of stomatal conductance (gs), net photosynthesis (An) and leaf scale transpiration (Tr) were obtained in FI and mild water stress treatments (An: 3.15–12.64μmolm−2s−1, gs: 0.032–0.129molm2s−1 and Tr: 2.72–9.48mmolm2s−1) in comparion with those obtained in the severe water stress treatments (An: 2.11–11.81μmolm−2s−1, gs: 0.021–0.11molm2s−1 and Tr: 1.89–7.58mmolm2s−1). Results generally showed low values of gs in the Rabab cultivar in the studied arid area. Furthermore, the hydraulic signaling (ψstem) in response to the water stress and weather conditions controlled the seasonal variation of gs. Transpiration efficiency (TE) increased with increasing the degree of water stress and PRD showed higher TE (1.17–1.18μmolmmol−1) than that in DI strategies (1.06–1.07μmolmmol−1). Furthermore, the value of intrinsic water use efficiency (IWUE) in FI (85μmolmol−1) was statistically lower than that obtained in mild (PRD75, DI75) and severe (PRD50, DI50) water stress treatments (87.8–89.9μmolmol−1). Different irrigation strategies did not significantly affect the fruit growth rate, and its maximum values occurred at about 170 DAB (0.27–0.35mmd−1) in all irrigation strategies. The LAI values in FI and mild water stress strategies were significantly different compared with those in the severe water stress treatments. For all irrigation strategies, the maximum LAI values occurred at flowering stage (68 DAB), and was 6.09 and 6.15 (FI), 5.97 and 6.04 (DI75), 6.33 and 6.64 (PRD75), 4.60 and 4.82 (DI50) and 4.91 and 5.03m2m−2 (PRD50) in 2011 and 2012, respectively. In conclusion, PRD75 is the recommended, applicable water-saving strategy and good alternative with respect to FI among other irrigation managements when water resources are limited in order to increase TE and IWUE while other physiological and growth parameters are maintained at an acceptable level.

Yield and economic return response of silage maize to different levels of irrigation water in a sub-humid zone

Field studies were conducted during the summers of 2007 and 2008 to determine the response of silage maize (Zea mays L.) to different levels of irrigation water to guide programs for the development of improved irrigation management practices for sub-humid zones. The experiments were carried out in Bursa, Marmara region, Turkey. Silage maize plants (cv. ‘Ada-523’) were subjected to different levels of irrigation using a drip system in the field on a clay-loam soil. Fully irrigated (FI = 100%) plants were irrigated at 100% pan evaporation (Epan) replenishment with 7-day intervals. In other treatments, irrigation was applied as excessive (EI = 125% Epan) and deficit (DI-75 = 75% Epan, DI-50 = 50% Epan, DI-25 = 25% Epan, NI – no irrigation). Plant height, first ear height, stem diameter, number of ears per plant and net income decreased with decreases in the amount of irrigation, but the effect of soil water deficit on the number of leaves per plant and ear ratio in forage was minor. The highest forage yields were obtained with EI (125% Epan), FI (100% Epan) and DI-75 (75% Epan) treatments. FI treatment produced the highest net income based forage yield. Severe soil water deficit substantially reduced forage yields and net income in both years. The results showed that full irrigation during the whole growing season is preferable for higher forage yield and net income. However, in regions of water scarcity, farmers should adopt the deficit irrigation (DI75 = 75%, DI-50 = 50% and DI-25 = 25% Epan) approach to achieve economically sustainable crop production. As an alternative to full irrigation during the entire growing season, the irrigation at a rate of DI-75% Epan can be recommended as optimal level because it achieved irrigation water savings of 25%, an increase of 16% in forage yield irrigation water use efficiency, satisfactory crop morphological characters and an acceptable net income with a yield loss of only approximately 7% compared with full irrigation.

Assessment of drip and flood irrigation on biomass production, nutrient content and water use efficiency of maize (Zea mays L.)

An experiment was conducted in wooden boxes to assess flood, surface and sub-surface drip irrigation on biomass production, nutrient content and water use efficiency of maize (Zea mays L.). Four levels of irrigation treatments were applied: (i) SD1 = Drip irrigation pipe was set up on the surface of the soil ; (ii) SSD2 = Drip irrigation pipe was buried up to 5 cm depth; (iii) SSD3 = Drip irrigation pipe was buried up to 7.5 cm depth and (iv) FI = Flood irrigation was practiced without any drip irrigation pipe. Leaf area, leaf area index and biomass production of maize were significantly (p &lt; 0.05) higher in SSD3 than SSD2 and FI treatments. Biomass production was 37.2, 41.1, 54.2 and 35.2 g in SD1, SSD2, SSD3 and FI treatments, respectively. Water use efficiency (WUE) was also significantly (p &lt; 0.05) higher in surface and sub-surface drip irrigation than flood irrigation. Values for WUEs were 0.248, 0.298, 0.430 and 0.156 kg/m3 in SD1, SSD2, SSD3 and FI treatments, respectively. As a result, all three drip irrigation treatments enhanced water use efficiencies than flood irrigation. Comparing the three drip irrigation treatments, significantly (p &lt; 0.05) higher nitrogen was found both in leaf and stem (3.3 and 3.8%) in sub-surface drip irrigation at 7.5 cm depth than flood irrigation (2.2 and 1.4%). Although, potassium contents in leaf and stem were not significantly different between the treatments, but had a tendency to be higher in drip irrigation treatments. Above all, drip irrigation performed better with higher water use efficiency.&#x0D; Dhaka Univ. J. Biol. Sci. 22(1): 47-54, 2013 (January)

Potential antianxiety activity of Fumaria indica: A preclinical study

Background:In the view of diverse CNS modulating properties of Fumaria indica, present study was planned to evaluate its putative anxiolytic activity in behavioural models of rats, followed by elucidation of mechanism of observed activity through biochemical estimations.Materials and Methods:Effects of seven daily 100, 200 and 400 mg/kg oral doses of a Fumaria indica extract (FI) was compared with those of an acute oral dose (5 mg/kg) of lorazepam in a battery of rat models consisting of open-field, elevated plus and zero maze, social interaction, and novelty induced feeding tests.Results:Dose dependant antianxiety effects of FI observed in all tests were qualitatively similar to those of the reference anxiolytic drug. Although FI treatments did not alter the concentrations of noradrenaline and serotonin in hippocampus and hypothalamus, concentrations of both these monoamines were dose dependently elevated in prefrontal cortex of FI treated animals. Flunitrazepam binding in brain frontal cortex was also elevated by the extract. Moreover, higher levels of brain expressions of the cytokines TNF-α, IL-1β, and IL-10 observed in animals with prior experience on elevated plus maze were almost completely reversed by the lowest dose of FI tested in the behavioral models.Conclusion:Taken together, these observations strongly suggest that FI is a functionally novel type of antianxiety agent, and that inhibition of cytokine expressions in the brain could be involved in its mode of action.

Above- and below-ground interspecific interaction in intercropped maize and potato: A field study using the ‘target’ technique

The association of maize (Zea mays L.) and potatoes (Solanum tuberosum L.) is an overyielding multi-cropping system. However, knowledge on specific interactions in field conditions, especially below-ground interactions, is deficient. To evaluate the nature and strength of interspecific interactions between maize and potatoes, field and pot experiments were conducted using the ‘target’ technique, with three interaction models: no interaction (NI), below-ground interaction (BI) and full (both above- and below-ground) interaction (FI). Plants were sampled at flowering and harvest periods to measure biomass and calculate the log response ratio (lnRR), root:shoot ratio and land equivalent ratio (LER).In the field experiment, the lnRR value of both BI and FI treatments for potatoes was>0, whereas for maize it was<0. This result accorded with differences in biomass, yield, Harvest Index and root:shoot ratio between the two treatments for both crops. Results showed that maize was subjected to competition (negative interaction), while potatoes obtained facilitation (positive interaction) when they were intercropped. In addition, after flowering there were no significant differences between BI and FI treatments in terms of biomass, lnRR, yield and LER for the two crops. Thus, compared with above-ground interaction, below-ground interaction (i.e. root competition for maize and root facilitation for potatoes) plays a more important role for crop growth and intercropping advantages.In the pot experiment, however, the lnRR values of both BI and FI treatments were<0 for both crops, so potatoes did not obtain a net profit from maize. However, the competitive capability of potatoes were significantly greater than maize when they were intercropped, which is consistent with results from the field experiment. Similarly, there were no significant differences between BI and FI treatments in terms of biomass, lnRR, root:shoot ratio and LER for the two crops.In summary, our study suggests that the root facilitation produced by maize for potatoes is a mechanism for overyielding in the maize–potato intercropping system. The potential of this system merits further research.