Irrigation Depth Research Articles

Evaluating agricultural yield and economic implications of varied irrigation depths on maize yield in semi-arid environments, at Birfarm, Upper Blue Nile, Ethiopia

Evaluating agricultural yield and economic implications of varied irrigation depths on maize yield in semi-arid environments, at Birfarm, Upper Blue Nile, Ethiopia

Evaluation of Canopy Temperature Based Crop Water Stress Index for Deficit Irrigation Management of Sugar Beet in Semi-Arid Climate

Highlights Sugar beet irrigation scheduling was based on daily average crop water stress index between 13:00 and 16:00 hours. Three crop water stress index thresholds, 0.2, 0.35, and 0.55, were evaluated for irrigation scheduling. Season evapotranspiration decreased and soil water extraction increased as crop water stress threshold increased. There was no significant difference in root or sucrose yield between full irrigation and 0.2 crop water stress index, while seasonal irrigation depths were reduced from133 to 185 mm. Abstract. Sugar beet is an economically important crop in the semi-arid Intermountain Western U.S., with seasonal water use ranging from 500 to 900 mm. Sugar beet is a deep-rooted crop (1.5-2 m) in unrestricted soil profiles that can utilize stored soil water to reduce seasonal irrigation requirements. Effective use of stored soil water below 0.6 m requires precise irrigation scheduling and knowledge of soil water availability below 0.6 m, which is usually unknown due to the labor and expense of soil water monitoring at deeper depths and uncertainty in effective rooting depth and soil water holding capacity. Deficit irrigation (DI) management of sugar beet using a thermal-based crop water stress index (CWSI) has the potential to overcome soil water monitoring limitations and facilitate the utilization of stored soil water to reduce seasonal irrigation requirements. The objective of the research summarized in this paper was to implement and evaluate the effect of automated DI scheduling of sugar beet using three daily average CWSI thresholds (0.2, 0.35, and 0.55) on seasonal irrigation requirement, crop evapotranspiration, seasonal soil water depletion, root yield, estimated recoverable sugar (ERS) yield, and water use efficiency compared to full irrigation. There were no significant differences in root and ERS yield between full irrigation and 0.2 CWSI DI treatment, while seasonal ET was significantly decreased, seasonal soil water extraction was significantly increased, and seasonal irrigation depths were reduced from 133 to 185 mm. Root and ERS yield water production functions were curvilinear with a downward concave. Root and ERS yield water use efficiencies were constant or increased slightly for crop evapotranspiration reductions up to 85% of full irrigation evapotranspiration. The results indicate that irrigating when the average daily CWSI sugar beet exceeds 0.2 is an effective means for mild deficit irrigation scheduling to reduce seasonal irrigation requirements with no significant effect on root and ERS yield. Keywords: Crop water stress index, Evapotranspiration, Irrigation, Irrigation scheduling, Root yield, Sucrose yield, Sugar beet.

Agronomic characteristics of carrot cultivars under water stress

The objective of the study was to evaluate the agronomic performance of carrot cultivars subjected to different levels of water supply. The experiment was conducted in a randomized block design, in a split-plot scheme with four replicates. Five irrigation depths were used in the plot, one to replace 100% of the crop’s evapotranspiration (ETc), two in deficit (50% and 75% of ETc) and two in excess (125% and 150% of ETc). Four carrot cultivars were used in the subplots: Brasília, Alvorada, Esplanada, and Nantes. Two carrot cultivation cycles were carried out, the first lasting 121 d and the second lasting 103 d after sowing. The following variables were evaluated: total fresh mass of the plant, fresh carrot mass, carrot length, length of the aerial part, average carrot diameter, carrot volume, green shoulder, crop productivity, water productivity, and water potential of the plants. The Brasília carrot cultivar had better development and the Esplanada cultivar was less adapted to the studied environment. All carrot cultivars were affected by stress caused by excess and lack of water. Carrot irrigation must be carried out with a depth equal to 100% of the crop’s evapotranspiration for the region and conditions similar to those of the present study.

Determination of Irrigation water requirement and Scheduling of onion at Low land area of Wag-himra, Northern Ethiopia

Irrigation that saves water is important for satisfying the economic and environmental sustainability of commercial agriculture and improving the living standard of the people. Precision irrigation scheduling is critical to improving irrigation efficiency. A field experiment was conducted in two consecutive years at Abergelle irrigation schemes. The aim of the study was to determine crop water requirement and irrigation schedule of onion (when and how much to irrigate) for most market-oriented crops. The treatments were arranged with a factorial arrangement randomized complete block design with three replications. Three Levels of CROPWAT, fixed application depth (125%, 100%, and 75%ETc) and, three irrigation intervals (3, 4, and 5 days) and 1-farmer practice were used as control. The study result showed that 75% CROPWAT fixed depth at 3-day intervals achieved high water productivity, and saved 2873m3ha-1 of irrigation water compared with farmers’ method of irrigation. It provides additional irrigated land of 0.84 ha with a yield gain of 10.44 t ha-1. Therefore, a 3-day irrigation interval with 75% CROPWAT irrigation depth was recommended for the optimum yield and water productivity of the crop.

Gas exchange and yield of yellow passion fruit under different irrigated depths, planting hole volumes, and hydroretentive polymer application

Passion fruit cultivation relies on irrigation to increase yields in the semiarid of northeastern Brazil. Water scarcity is one of the factors that most affect crop physiology, leading to lower yields. Therefore, this study aimed to assess the influence of planting hole volume and application of a hydroretentive polymer on physiological and productive aspects of irrigated yellow passion fruit cv. BRS GA1 in the Northeast semi-arid region of Brazil. The experiment was conducted in randomized blocks, in a split-plot design 2 × (2 × 2). Treatments consisted of irrigation depths (100% and 70% of the crop's evapotranspiration requirement - ETc), planting hole volumes (64 dm3 and 128 dm3), and soil with and without application of hydroretentive Polymer (1.5 g dm3), with four replicates and three plants per plot. The analyzed variables included chlorophyll a and b indices, gas exchange, and yellow passion fruit yield. The findings showed that hydroretentive polymer application to the soil increases chlorophyll content and gas exchange in yellow passion fruit. Moreover, photosynthetic rates were not limited by a 30% reduction in irrigation depth and increased in plants grown in 128-dm3 planting holes with hydroretentive polymer. Based on yield results, irrigation depths can be reduced to 70% of the ETc by applying hydroretentive polymer in 64-dm3 planting holes.

Multipurpose optimization of yield production in agriculture using fuzzy self-reproducing automata theory

Abstract In determining the irrigation depth of barley, it is inevitable to find the best periods to increase the efficiency of water consumption and also to achieve the highest yield of the product. A multi-objective optimization model has been presented to improve irrigation planning and the allowable amount of irrigation during the growth period using genetic algorithm based on nondominated sorting (NSGAII) and cellular automata. Under this concept, the structure of the optimal water supply allocation model is included in the form of two main objective functions. Therefore, the first objective function is to minimize water allocation and the second objective function is to maximize the total income from the cultivation pattern compared to its costs. The latest data related to the cultivation pattern and economic information such as product sales price and production costs in the planting and harvesting stages were collected for 1 year of study. The daily data of river flow, rainfall and climatic data of Hulunbuir district in Inner Mongolia province were converted into 10-day periods. It shows the optimal irrigation planning results of winter barley in three different scenarios. In ten periods of growth, the rainfall is enough to provide most of the plants’ water needs.

Deficit Irrigation on Fruit Yield and Quality of Sweet Pepper

Background: Deficit irrigation is an approach to use less water in crop growth in places where water resources are the limiting factor for agricultural production, to maximize the production per unit of volume of water available. Objective: The study aimed to evaluate the effect of four levels of irrigation applied to replenish soil moisture depletion on the growth and yield of two sweet pepper cultivars. Methods: The experiment was performed on field conditions from January to June 2020 in a randomized block experimental design with three repetitions arranged in divided plots, the main plot was the four irrigation depths, and the sub-plots were the two cultivars (Tres Filos and Pepón) for a total of eight treatments. The irrigation depths applied corresponded to 60%, 80%, 100%, and 120% of the crop evapotranspiration. Results: The ANOVA (analysis of variance) of the main factors indicates that for the irrigation treatment factor, the number of fruits per plant for the two varieties is statistically equal when irrigation is applied at 120, 100 and 80% of the crop evapotranspiration (ETc) and greater than the one obtained with irrigation at 60% of ETc. For the cultivars factor, the number of fruits per plant and the fruit yield (g plant-1) in the different irrigation treatments was higher in the cv Tres Filo, but the weight of the fruit was higher in the cv Pepón. Conclusion: The application of irrigation at 60% of the ETc represents a saving of 40% of the volume of water compared to the application at 100% of ETc. The reduction in the number of fruits per plant, fruit weight, and average yield (g plant-1) of both cultivars was only 4.21%, 7.47%, and 11.95%, respectively. Therefore, if the limiting factor for agricultural production is water availability, it is advisable to irrigate at 60% of the ETc and increase the surface for irrigation to increase total production.

Effect of Interval and Depth Irrigation on Water Use Efficiency, Cucumber Productivity under Green House Conditions and Drip Irrigation

A field experiment was conducted to study the effect of intervals and depths irrigation on water use efficiency and productivity of Cucumber under drip irrigation system. It was carried out during fall season 2021 in Al-Saqlawia, far about 45km southeast of Al-Ramadi, located at longitude 33° 24’ 57’' E and latitude 33° 24’ 57’' N. The experiment included two factors; the first is irrigation interval (I) which included two-days interval (I2) and four-days interval (I4). While the second one is irrigation depth which included 100% water depth and 50% water depth. The drip irrigation system was evaluated at operational pressure 50 kPa (0.5 bar) in order to determine the closest actual discharge to the design discharge, and calculating the uniformity coefficient and discharge variance. The results showed that 50kPa operational pressure gave an actual discharge of 3.94 Lh−1, which was the closest to the design discharge 4Lh−1, highest uniformity coefficient of 96.61% and lowest variance of 9.58%. While the highest yield achieved was 108 and 80-ton ha−1 at water depth (d50) for two irrigation interval 2 and 4 days compared to the lowest yield of 50 and 70-ton ha−1 at water depth (d100) for the same irrigation interval, respectively. While the highest water use efficiencies achieved was 20.9 and 15.48 kg m−3 at depth (d50) for 2-day and 4-day intervals, respectively. Finally, the best value for crop water consumptive use was obtained under drip irrigation system of 51.6 cm season−1.

Real-Time Sprinkler Irrigation (RTSI) Scheduling for Improving Wheat Crop Water Productivity in Vertisols

An experiment was conducted at ICAR- Central Institute of Agricultural Engineering (CIAE) Bhopal, Madhya Pradesh, India, during the rabi seasons of 2017-18 and 2018-19 with the objectives of to study improved irrigation scheduling for enhancing water productivity of wheat crops in Vertisols. The experiment involved permanent raised bed cultivation in Vertisols and was laid out in Randomized Block Design (RBD) with two planting systems (elevated bed and flatbed) replicated three times. The elevated bed levels were set as 5, 10, 15 and 20 cm. Soil moisture was continuously monitored using a real-time sensor network sprinkler irrigation, during crop growth period. Field data on soil moisture, crop performance, and yield were regularly recorded at different crop growth stages. The results indicated that both conventional sprinkler irrigation and real-time moisture sensor-based sprinkler irrigation led to substantial water savings of 27 and 35%, respectively with corresponding yield increase of 9 and 15% when compared to gravity (flood) irrigation, showing their effectiveness. Soil moisture variability study revealed that average soil moisture levels significantly varied when bed elevation was 10 cm or more, as compared to control (bed with normal field level) in different crop physiological stages. This variation occurred under sprinkler irrigation in Vertisols for recommended irrigation water depth. Under recommended irrigation water application through sprinkler, the wheat crop yield increased for elevation variations up to 10 cm bed elevation and the yield reduced significantly for more than 15 cm bed elevation. For sprinkler irrigation, the developed irrigation water application prescriptions (water depth/irrigation) include 400 mm irrigation depth (ID) for bed of 0 cm elevation, 476 mm ID for bed of 20 cm elevation and 552 mm ID for 30 cm bed elevation to sustain the wheat crop yield under soil moisture variability in Vertisols.

Sustainable Water Management for Small Farmers with Center-Pivot Irrigation: A Hydraulic and Structural Design Perspective

In Pakistan, surface water supply for irrigation is decreasing, while water demand is increasing for agriculture production. Also, due to the fast rate of population growth, land holding capacity is decreasing. So, there is a need to develop appropriate technologies and design approaches for small-scale farmers to improve modern irrigation practices. In this study, a hydraulic and structural layout of CPIS was designed for small-scale farmers with some modifications. The hydraulic parameters and structural design of the CPIS were designed using IrriExpress and SAP2000 software, respectively. An economic analysis of the modified CPIS was carried out. The results revealed that in one complete revolution of the whole system, its span slope varied from 2.98 to 0.1%, and the wheel slope varied from 2.35 to −2.4%. The timing setting was 60% for one revolution, and the irrigation depth was 10 mm. When the time setting was reduced from 100% to 10%, the irrigation hours per cycle and irrigation depth both increased. Variendeel type-II trusses were designed for structural purposes using SAP2000 software. This design led to a 17% reduction in weight by lowering it from 1.916 to 1.5905 tons and a 44% reduction in joint count, decreasing it from 32 to 18. Our economic analysis revealed that the structural part of the system is more expensive than the hydraulic, electric and power parts for small-scale design. So, it was suggested that CPIS is suitable for land holdings from 100 to 250 acres, because when the area increases to more than 250 acres, there is no significant change in the cost. A towable system is more economical for small-scale farmers due to its lower cost per acre. This study will be helpful for the optimization of CPISs to improve water use efficiency and crop yield.

Irrigation depth and nitrogen rate effects on seed cotton yield, fiber quality and water-nitrogen utilization efficiency in southern Xinjiang, China

Seed cotton yield and fiber quality are two primary factors that influence the international competitiveness of cotton. To enhance the water-nitrogen utilization efficiency and promote the sustainable cotton production, field experiments were performed in 2020 and 2021 to explore the effects of irrigation depth and nitrogen (N) fertilization rate on N uptake and distribution, seed cotton yield, fiber quality traits and water-nitrogen utilization efficiency in the Korla region of southern Xinjiang, China. Three irrigation depths (W1: 60% ETc, W2: 80% ETc, W3: 100% ETc; ETc was crop water consumption) and four N rates (N0: 0 kg ha−1, N200: 200 kg ha−1, N300: 300 kg ha−1, N400: 400 kg ha−1) were applied. The results showed irrigation depth and N rate significantly influenced N uptake and distribution in plant organs, seed cotton yield, crop water productivity (WP), partial factor productivity of nitrogen (PFPN) and some fiber quality traits. Increasing irrigation depth improved plant height, leaf area index, aboveground dry matter and seed cotton yield, while increasing N rate increased and then declined these indicators. At the squaring and flowering stages, the N accumulation in all parts of cotton increased as irrigation depth and N rate increased, whereas it increased and then declined with increasing N rate at the boll-setting and harvesting stages. At the squaring and flowering stages, N was mainly accumulated in the leaves. As the growth period progressed, N was transported to bolls and the proportion of N content in leaves decreased. The proportion of N accumulation in cotton bolls was largest at the boll-setting and harvesting stages, and the N accumulation in plant organs followed the order of boll > leaf > stem > root. As irrigation depth increased, PFPN increased but WP decreased. As N rate increased, PFPN decreased but WP increased and then declined. The increases in N rate improved fiber quality. The maximum seed cotton yield (7578 kg ha−1 in 2020 and 7173 kg ha−1 in 2021) and greater WP, PFPN and fiber quality occurred in W3N300, which was recommended as a sustainable cotton production strategy in the Korla region of southern Xinjiang and elsewhere with similar environments to improve water-nitrogen utilization efficiency, seed cotton yield and alleviate soil nitrate pollution risk.

Intermittence in irrigation management and nitrogen optimize yield and water use efficiency in baby lettuce

Aim of the study: To evaluate the influence of irrigation management strategies and nitrogen (N) on baby lettuce growth, yield, and water use efficiency in a protected environment. Area of study: Botucatu, SP, Brazil. Material and methods: The experiments were conducted in two consecutive cycles, and the treatments corresponded to the combination of irrigation management strategies with N doses. Irrigation strategies comprised 3 possibilities: continuous irrigation (Cont); intermittent irrigation with three irrigation pulses at one-hour intervals (Int1); and intermittent irrigation with irrigation depth split and applied at 7:00, 11:00, and 15:00 h (Int2). Two N doses were evaluated, 100 and 130 kg/ha of N, applied in daily fertigation according to the irrigation management strategies. Main results: Intermittent irrigation strategies (Int1 and Int2) promoted the highest vegetative growth, increased leaf water content, and increased total yield (49.55 and 55.30; 46.83 and 49.50 t/ha) and marketable yield (46.77 and 52.44; 45.11 and 47.17 t/ha) in the first and second cycles, respectively, in addition to optimizing water use efficiency. The N dose of 130 kg/ha increased the total yield (51.61 t/ha), marketable yield (48.98 t/ha), and water use efficiencies of total yield (53.60 kg/m³) and marketable yield (50.88 kg/m³) only in the first crop cycle. Research highlights: The use of intermittence in irrigation management proved to be more efficient in obtaining high yields and maximized the efficiency of use of water as a factor of production.

Produtividade da cultura do amendoim sob irrigação plena e deficitária na fase reprodutiva

ABSTRACT Peanut cultivation has national and global significance in agriculture and industry. Under water-limited conditions, its yield decreases to the extent that it compromises the success of the exploitation. This study focused on evaluating peanut crop yield and production components under full and deficit irrigation applied in the reproductive phase, to determine the impact of water supply on the yield of peanuts grown in the off-season in the State of São Paulo, Brazil. The experiment was conducted for two years and followed a randomized blocks design with five irrigation levels distributed in strips, with four repetitions. The treatments consisted of crop evapotranspiration replenishments from 100 to 10%. In the first year, under suitable temperatures, the maximum yield reached 3,922 kg ha-1 with the application of 277 mm of irrigation depth and decreased up to 35% with the lowest irrigation depth (48 mm). In the second year, suboptimal temperatures caused a delay in the growing cycle and caused a 33% reduction in crop yields. Despite the potential benefits of deficit irrigation in increasing water productivity, low temperatures pose a risk to peanut yield, especially during the off-season crop in the region.

Optimizing evapotranspiration and crop irrigation requirements of tropical forages cropping systems in Southern Brazil.

Crop irrigation requirements are usually estimated based on crop evapotranspiration (ETc) as determined by the reference evapotranspiration (ETo) and crop coefficient (Kc). There is a lack of knowledge on the irrigation requirements of tropical forage crops in Brazil, contrasting with the increasing use of irrigation in pastures. The effort of this study was to investigate what would be the water needs of tropical forages in Southern Brazil, based on a robust experimental database. The study was carried out in São Paulo State-Brazil using different forages species and their combinations [Guinea grass (GG); Guinea grass + black oat + ryegrass (GOR); Bermuda grass (BG), and Bermuda + black oat + ryegrass (BOR)]. The experimental fields were fully irrigated, and the Kc values were derived from ETc measurements on lysimeters; ETo was estimated using daily data from a nearby weather station and the standard FAO56 parameterization. Mean daily ETc values for GG, GOR, BG and BOR were 4.1, 2.9, 3.6, and 3.4mm, respectively, and respective mean Kc values were 0.99, 0.90, 1.0, and 0.94. Average Kc values for all plots decreased as ETo increased, producing a negative Kc-ETo relationship, mainly when ETo reached values greater than 5mm d-1. This was most likely due to internal plant stomatal resistance to vapor release from the leaves diffusing to the atmosphere at high ETo. So, the time-based Kc curves described by FAO 56 manual should be adjusted for the analyzed crops considering different ranges of ETo to improve the required irrigation depth.

Sustainable ecosystem management based on optimal water allocation and equity measures

Abstract Allocation of water resources is an interesting research topic and one of the main challenges of arid regions. From the point of view of agriculture, this issue is closely related to ecological balance, economic development and social stability. Therefore, fair, efficient and sustainable allocation of water resources for users and decision-making is essential. This paper presents a dynamic stochastic programming model that predicts soil moisture content in a growing season based on data collected from an experimental farm. The model included three types of loam soil, silt loam and clay loam with three treatments of irrigation intervals of 3, 7, 10 and 14 days and three amounts of water allocation with three replications. The proposed framework was evaluated with two criteria of spatial and temporal equity, and the optimal water allocation was analyzed based on this criterion. The results showed that the criterion of temporal equity for loam soil with 7-day irrigation intervals is more than twice that of 14-day irrigation intervals. In addition, the depth of irrigation has had the greatest impact on the fluctuations of the criterion of equity in water allocation in the growing season.

Assessing resource utilization, food production and ecosystem service value from spring wheat farmland under reduced irrigation and N fertilization management using a process simulation-based framework

Excessive irrigation and nitrogen (N) fertilization have caused severe reductions in farmland water and N productivity, and functional degradation of agroecosystems in arid to semi-arid regions. Thus, a process simulation-based framework for resource, food, and ecology (RFE) trade-offs was used to optimize the irrigation and N fertilization strategy (IRNF). A scenario study was conducted based on the framework that was developed in our previous companion study in the arid to semi-arid regions of Northwest China. Based on the local IRNF (i.e., 450 mm irrigation and 340 kg ha−1 N fertilization), reduced irrigation and N fertilization management scenarios were proposed considering eleven irrigation depth reduction cases and ten N fertilization reduction cases in three hydrological years (wet, normal, and dry). The integrated responses of spring wheat yield, water and N productivity, and ecosystem service value (ESV) to various IRNFs were quantified and assessed. The results showed that the local IRNF obtained higher yields and positive ESVs, but was also produced higher greenhouse gas (GHG) emissions, N losses, and water consumption, thus resulting in lower water and N productivity and higher negative ESVs. Among the negative ESVs, GHG emission value accounted for the largest proportion of the total negative ESV (75–80 %), followed by water consumption and fertilizer loss values. Compared with the local IRNF, the scenarios with 210 mm irrigation and 240 kg ha–1 N fertilization in wet years, 240 mm irrigation and 200 kg ha–1 N fertilization in normal years, and 300 mm irrigation and 200 kg ha–1 N fertilization in dry years could not only reduce negative ESVs, improve water and N productivity, and save water and fertilizer resources, but also maintain acceptable yields and positive ESVs. These recommendations reduced the total negative ESV by 4.8–7.7 %, increased water and N productivity by 4.0–8.9 % and 44–69 %, and saved irrigation water and N fertilizer resources by 33.3–53.3 % and 29.4–41.2 % in three hydrological years in relation to the local IRNF, respectively. This study indicates that the framework is a reliable tool for achieving farmland RFE trade-offs and generating appropriate IRNFs for different hydrological years in arid to semi-arid regions. Therefore, sustainable development goals in RFE systems may be achieved by optimizing irrigation and fertilization management.

Effect of Partial Drip Irrigation Methods on Soil Moisture and Water Potential Distribution, Growth Characteristics and Yield of Maize

A field experiment was conducted during the autumn of 2021 at the Agricultural Research Department station / Abu Ghraib to evaluate the soil moisture, water potential distribution, and growth factors of maize crops under alternating and constant partial drip irrigation methods. In the experiment, two irrigation systems were used, surface drip irrigation (DI) and subsurface irrigation (SD); under each irrigation system, five irrigation methods were: conventional irrigation (CI), and 75 and 50% of the amount of water of CI of each of the alternating partial irrigation APRI75 and APRI50 and the constant partial irrigation FPRI75 and FPRI50 respectively. The results showed that the water depth for conventional irrigation (C1) was 658.3 and 579.4 mm for the DI and SD irrigation systems, respectively, and the irrigation depth was reduced to 18% when applied APRI75 and FPRI75 and 37% when applied APRI50 and FPRI50 respectively. The moisture distribution differed according to the irrigation method, and the SD provided a higher moisture content and lower water potential due to the lower evaporation rate from the soil surface. Also, the growth traits of maize varied according to the irrigation system and its methods. The SD system was significantly superior in the grain yield of maize with an increase of 5.4% compared with DI, and the alternating partial irrigation treatments were significantly superior to the constant partial irrigation. Keywords: Matric suction, Zea mays L., irrigation system, irrigation depth.

Root endophyte Piriformospora indica significantly affects mechanisms involved in mitigating drought stress in rice (Oryza sativa)

An experiment was conducted during the summer season of 2020 at College of Agriculture, Kerala Agricultural University, Vellayani to study the potential of a beneficial root endophyte Piriformospora indica Sav. Verma, Aj. Varma, Rexer G. Kost & P. Franken in mitigating drought stress in rice (Oryza sativa L.). The field experiment was undertaken in the lowland paddy fields with sandy clay loam texture in randomized block design. Treatments were Piriformospora indica colonized and non-colonized rice seedlings under 3 irrigation intervals of 30 mm, 35 mm and 40 mm cumulative pan evaporation and 2 irrigation depths of 1.5 cm and 3 cm. Plants colonized with P. indica significantly enhanced the yield attributes and root parameters. This symbiotic association alleviated the negative effects of drought stress by maintaining higher proline content (71.8 μmole/g) and relative leaf water content (74%) irrespective of interval and depth of irrigation. Colonization boosted the uptake of phosphorus and maintained higher chlorophyll stability index (79.20%). Yield attributes of P. indica colonized plants subjected to severe stress, were observed to be equivalent to those of non-colonized plants under moderate stress and association with the endophyte resulted in saving of 30 mm water and could help rice to combat drought stress. Higher phosphorus uptake enhanced the root volume (29.1cm3 ) under severe water stress facilitated improved nutrient uptake (10.6 kg/ ha) from deeper layers of soil for colonized plants compared to the control plants and acted as a mitigating mechanism against drought stress.

Productivity potential and profitability of castor (Ricinus communis L.) with sprinkler irrigation

In Andhra Pradesh, Amrabad Mandal in Mahabubnagar district was inhabited predominantly by Chenchus. They depend on forest produce for their livelihood. The area under castor gradually came down in these villages due to erratic rains and inadequate irrigation. Farmers felt the need for an efficient water management system for castor. Castor crop was re-introduced in to these villages with sprinkler irrigation with Tribal Sub Plan. The productivity potential and profitability of castor increased with sprinkler system as compared to flood irrigation. The factors for ready adoption of sprinklers were delineated such as limited availability of water, controlling of irrigation depth increased crop yield and converting rainfed area to irrigated area. Adoption of sprinkler irrigation have changed the economic dependence on money lenders, improved the input use in castor and increased the gross monetary returns to the Chenchu farmers.

Fuzzy modeling of coffee productivity under different irrigation depths, water deficit and temperature

The coffee culture has great economic importance on the world stage, especially for Brazil. Considered one of the most traded commodities on the world's trading exchanges. Thus, the main objective of this study was to develop a system based on fuzzy rules to evaluate coffee productivity, using irrigation, soil water deficit and ambient temperature as the main production factors. The research was developed from searches of scientific data on the main variables for coffee production. The work was divided into two stages: the first in the scientific search for data collection and the second in the development of the fuzzy model. With this, it was parameterized that the input variables would be the temperature, the irrigation depth, and the water deficit of the soil and for the output variable the coffee productivity. Based on the model prediction, the fuzzy system showed which variable values are necessary for the best coffee productivity, by a set of rules involving the variation of water deficit (60%), temperature (30°C) and irrigation (300 mm), for a productivity of 24 sc ha-1. The performance of the fuzzy system was tested by comparing it with articles on the subject that relate coffee production with irrigation, water deficit and temperature of the environment and in almost all cases the model was efficient, reinforcing the assessment of the strength of the scheme, the analysis was extended to several scenarios relating the same three input variables.