Arid Agriculture Research Articles

An Experimental Study on Concrete and Geomembrane Lining Effects on Canal Seepage in Arid Agricultural Areas

Canal lining is commonly used to reduce seepage loss and increase water use efficiency. However, few studies have quantitatively estimated the seepage control effects of different lining materials under different service times. Ponding tests were conducted on the same canal section with four different lining statuses to investigate the canal lining effect on seepage control and its impact factors in arid areas. The cracks and holes in different lining materials were surveyed, and the canal seepage rates under the four test treatments were calculated by monitoring the water level change in the canal. The results show that the cracks in the joints of the two precast concrete slabs and holes in the geomembrane, which are located 0.25 m above the canal bottom on two sides of the canal, are responsible for the increased seepage loss. The new concrete and geomembrane lining combination reduces seepage by 86% compared with no lining, while seepage can be reduced by 68% using the concrete and geomembrane lining combination after three service years, and the amount decreases to 11% by using geomembrane lining with a three year service time. Based on the experiment and literature, a statistical relationship between the seepage reduction and lining service time was established, which provided a possible and easy way to estimate seepage losses from lined canals and improve the estimation accuracy using an empirical formula. Without considering the service time lining effect, the seepage loss is underestimated by 58%, and the canal water use efficiency is overestimated.

Identifying Optimal Sites for a Rainwater-Harvesting Agricultural Scheme in Iran Using the Best-Worst Method and Fuzzy Logic in a GIS-Based Decision Support System

Rainwater-harvesting (RWH) agriculture has been accepted as an effective approach to easing the overexploitation of groundwater and the associated socioeconomic impacts in arid and semiarid areas. However, the stability and reliability of the traditional methods for selecting optimal sites for RWH agriculture need to be further enhanced. Based on a case study in Tehran Province, Iran, this study proposed a new decision support system (DSS) that incorporates the Best-Worst Method (BWM) and Fuzzy logic into a geographic information system (GIS) environment. The probabilistic analysis of the rainfall pattern using Monte Carlo simulation was conducted and adopted in the DSS. The results have been demonstrated using suitability maps based on three types of RWH systems, i.e., pans and ponds, percolation tanks, and check dams. Compared with traditional methods, the sensitivity analysis has verified that the proposed DSS is more stable and reliable than the traditional methods. Based on the results, a phase-wise strategy that shifts the current unsustainable agriculture to a new paradigm based on RWH agriculture has been discussed. Therefore, this DSS has enhanced the information value and thus can be accepted as a useful tool to ease the dilemma resulting from unsustainable agriculture in arid and semiarid areas.

Influence of Organizational Politics on University Teachers' Performance

The purpose of the study was to explore the relationship of organizational politics on the performance of teaching faculty of the universities of Pakistan. The nature of the study was descriptive. The public sector universities of Punjab were the population of the study. The researchers randomly selected the four universities, i.e. the University of the Punjab Lahore, Bahaud din Zakria University Multan, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi and The Islamia University of Bahawalpur. Two questionnaires, namely Organizational Politics by Vigoda (2007) and Teachers Performance Evaluation Scale (TPES) by Shehzad and Farooqi (2016), were adapted for the study. The statistical techniques t-test and Structural Equation Modelling (SEM) were applied to analyse the data. It was inferred that organizational politics had significant impact and relationship with the performance of university teachers. It is recommended that a qualitative approach may be adopted to get a further in-depth understanding of the phenomenon.

Photobiological and lipidic responses reveal the drought tolerance of Aster tripolium cultivated under severe and moderate drought: Perspectives for arid agriculture in the mediterranean

In the past Aster tripolium has already proved to be a good candidate for saline agriculture in soils with low water availability. Thus, the aim of the present work was to disentangle the photobiological and biochemical mechanisms underlying the response of A. tripolium to PEG-induced drought stress, by exposing plants to PEG-induced moderate and severe drought conditions. Plant primary productivity was maintained under moderate drought conditions, due to the presence of alternative electron donors fueling the PSII. Additionally, the high anthocyanin production under drought conditions, act as photoprotective shields against photoinhibition. Moreover, the increased quinone turnover rate simultaneously with a net rate of RC closure and density increase, acted as a counteractive measure, allowing high energy fluxes into the photosystems under drought conditions. PSI showed an activity reduction, indicating that under drought conditions the ETC activity acts as an energetic escape route. Furthermore, membrane remodeling could also be observed under drought. The total fatty acid and omega-3 linolenic acid (18:3) contents were maintained, under osmotic stress. Membrane restructuring with lower amounts of polyunsaturated fatty acids (18:3) is considered an adaptation to osmotically stressful environments. Increased 18:1 and 16:1t fatty acids production improve the LHCs and chloroplast membrane stabilization, allowing the LHC to maintain its efficient functioning. The results here presented are very similar to the ones observed in the past regarding A. tripolium feedback to salinity stress, indicating that the mechanisms to overcome osmotic stress, either due to increased salinity or reduced water availability, are the same.

DEVELOPING TEACHERS’ CAPABILITIES THROUGH FORMAL MODE OF TRAINING IN PUNJAB

Teachers are nation builders and they can perform their duties up to the marks with the help of professional’s skills. Thus, teacher training through formal mode at M.Ed. level in Punjab has been focus of study for many educational researchers. It helps to know the aspects which may be intervened to increase the teacher’s professional capabilities towards teaching. Objectives of the study were to investigate the contribution of existing teacher training programs through formal education system in Punjab. Two questionnaires were developed for this purpose. Data was collected, organized, tabulated and interpreted. The population of the study included the students and teachers of M.Ed program of Sargodha University and Pir Mehar Ali Shah Arid Agriculture University Rawalpindi. Total population of teacher student ratio was 18 and 99. By applying formula of Gay, R.L. (2000) the sample was taken as 16 and 80. Results showed that both the groups of respondents agreed that instructional material was easy to understand and curriculum fulfils the needs of concerning teaching of M. Ed. program. Teachers were regular, necessary guidance and counseling was provided to students. All the students were agreed that examination was conducted on time and examination centre’s were accessible to students. Teachers agreed that course contents were comprehensive and according to the national level. They also agreed that they used modern technology in teaching learning process. Teachers/ agreed that final examination fulfils the purpose and need of summative assessment.

Identification of Pesticide Residues and Prediction of Their Fate in Agricultural Soil

Fourteen pesticides were screened and determined through quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction process combined with GC-MS/MS in arid agriculture soil. The aims of the current investigation were to account the occurrence of organochlorine (OCP) and organophosphates (OPP) pesticide residues as well as other groups of pyrethroids (PYRs), carbamates, and biopesticides using a combined of QuEChERS and GC-MS/MS techniques in agriculture soils at Al-Kharj region, Saudi Arabia, and to investigate correlation between pesticide losses in soils and some physicochemical characteristics of pesticides including an octanol-water coefficient partition (Kow) and the vapor pressure (Vp). Prediction of pesticide fate by considering both pesticide and soil physio-chemical properties will facilitate the management of pesticide application and minimize the hazards of environmental pollution. The fate of pesticide residue in soils is generally controlled by soil/air exchange, water interaction, and biodegradation. The results indicated that 14 pesticide residues were measured in collected samples of various soils, spinosad, chlorpyrifos methyl, dimethoate, chlorpyrifos, lindane (γ-HCH), permethrin, and methomyl which were the most abundant sources of contamination in the studied region. p,p-DDT, o,p-DDT, bifenthion, β-cyfluthrin, and methidathion were less commonly detected. Single parameter least squares regression equations (sp-LSRE) for Vp and Kow against the loss of each pesticide residue showed a significant change in concentration levels (p < 0.05) between the two seasons. The results showed that vapor pressure and octanol-water partition coefficient data are not enough to model pesticide residue losses in arid low organic carbon soil. More soil-related data is needed to describe the dissipation mechanisms of these pesticide residues in the region.

Sensitive Factors Identification and Scenario Simulation of Water Demand in the Arid Agricultural Area Based on the Socio-Economic-Environment Nexus

Water scarcity has seriously threatened the sustainable development of Zhangjiakou City, an arid agricultural area in North China, and the ecological security of its neighboring areas. In this study, a system dynamics model is established based on variable sensitivity analysis and is employed to simulate water demand (2015–2035) in four designed alternative development scenarios in Zhangjiakou City. The results show that: (1) the variables related to irrigation farmland are the main driving factors of water demand, especially the area and water use quota. (2) The total water demand will rise continually in the current development scenario and economic priority scenario, and the proportion of agricultural water demand will drop to 67% and 63%, respectively. It will decline continually in the water-saving priority scenario and balanced development scenario, and the proportion of agricultural water demand will drop to 56% and 57%, respectively. (3) Water consumption per ten thousand yuan of GDP will fall to around 20 m3 in 2035 in each scenario, indicating that the reduction of water demand only by slowing down economic growth cannot improve the efficiency of water use. The research results will be beneficial to extract feasible strategies and policies for balancing economic development and water conservation.

Effect of water soluble humic acid applied to potato foliage on plant growth, photosynthesis characteristics and fresh tuber yield under different water deficits

Water scarcity is the main limiting factor in agricultural crop production in arid and semi-arid areas in northern China. Humic acid could improve the plant resistance to mitigate the abiotic drought damages, which is a potential strategy to improve the crop production in these regions. An experiment to investigate the effect of water soluble humic acid on plant growth, photosynthesis characteristics and fresh tuber yield of potato under different water deficits was carried out under greenhouse conditions in 2014 and 2015. Treatments included foliar application of fresh water (FW), humic acid diluted with water 500 times (HA) and control (CK), and the water deficits included 45%, 60% and 75% of the field water holding capacity. The HA treatment showed highly significant (P ≤ 0.01) effect on dry biomass, root/shoot ratio and photosynthesis parameters, improved the dry biomass above ground (DM-AG) by 14.12–36.63%, 11.62–36.26% and 7.85–20.85% over the whole growing season at water deficits of 45%, 60% and 75% of the field water holding capacity respectively in 2014 and 2015; decreased the root/shoot (R/S) ratio in the early growing season and increased the R/S ratio in the later growing season; showed an improved effect on leaf soil plant analysis development (SPAD), photosynthesis rate (Pn) and stomatal conductance (Gs) and decreased transpiration rate (Tr) and intercellular CO2 concentration (Ci) compared with the control. HA usually showed a better effect on photosynthesis parameters in 60% of the field water holding capacity than 45% and 75% except on Pn. Compared with control, HA increased fresh tuber yield by 34.47–63.48%, 35.95–37.28% and 23.37–27.15% at 45%, 60% and 75% of the field water holding capacity respectively. HA enhanced the potato plant growth, and improved photosynthesis parameters and fresh tuber yield under different water deficits under green house conditions, and represents an opportunity to improve crop production and sustainability of agriculture in arid and semiarid regions.

Endophytic passenger bacteria associated with Genista cinerea nodules growing in North African drylands

This study aimed to characterize endophytic bacteria associated with root-nodules of a wild legume (Genista cinerea: Fabaceae) growing in arid soils of Algeria. A total of ten non-symbiotic endophytic bacterial strains were isolated and identified using a combination of conventional and molecular approaches based on 16S rRNA gene sequencing. Moreover, growth variations of the isolates under different environmental conditions were examined using advanced statistical modeling techniques (Markov Chain Monte Carlo sampler for multivariate generalized linear mixed models-MCMCglmm). The results revealed the existence of a large physiological diversity among the endophyte isolates, which formed two distinct groups. Group 1, included fast-growing and salt-tolerant isolates and Group 2 covered acid-sensitive isolates. The bacterial isolates showed capabilities to assimilate different carbonaceous and nitrogenous substances, with consistent and large tolerances to pH [4–10], temperature [4–55 °C], and salinity [NaCl = 2–10%]. In addition, The MCMCglmm indicated that scored growth rate increased with pH and decreases at high level of salinity. The endophytic strains were classified as fast-growing bacteria belonged to the β and γ-Proteobacteria including Achromobacter, Klebsiella, Luteibacter, Pantoea and Pseudomonas. The present findings may support the idea that these isolates are passenger bacteria able to colonize nodules of Genista cinerea. Furthermore, the salt and temperature tolerant patterns found among the isolates reflect the environmental stresses pressure and the importance of using efficient indigenous endophytic strains for successful plant inoculation in arid agriculture.

Effect of different priming treatments on seed germination of sago palm (Cycas revoluta L.)

King sago palm or sago cycas are the other name of Kangi palm ( Cycas revoluta ) sago palm has been used as an indoor and outdoor landscape plant for centuries. The present study was conducted to estimate the effect of different priming treatments on seed germination of sago palm ( Cycas revoluta L.) in the research area of Department of Horticulture PMAS, University of Arid Agriculture Rawalpindi, Pakistan. The Experiment consisted of ten treatments; the seeds without pulp were soaked in solution of 500, 750 and 1000 ppm GA 3 and 2%, 3% and 4% solution of KNO 3 for 24 hr at room temperature. In case of hot water treatment, seeds were primed at 80 o C, 90 o C and 100 o C for 30, 20 and 10 minutes respectively. The effect of different concentrations of gibberellic acid (GA 3 ), potassium nitrate (KNO 3 ) and hot water on various parameters like germination rate, germination percentage, germination value, decayed seed percentage, time of germination, number of leaves and seedling height were studied. Significant results of germination rate (55.56 days), germination value (192.19) were achieved from 500 ppm GA 3 . Maximum germination percentage (73.33%) and number of leaves (2) were observed in KNO 3 at 2% followed by 500 ppm GA 3 . Similarly lowest decayed seed percentage (26.66%) and time of germination (59.41 days) were noted in 2% KNO 3 . The seedling height was optimum (19.33 cm) in 3% KNO 3 followed by 2% KNO 3 . Best germination results were obtained due to permeability of hard seed coat made by low concentrations of priming treatments (KNO 3 @ 3%).

Potentially Toxic Element Content in Arid Agricultural Soils in South Iran

Potentially toxic elements (PTE) are considered to be dangerous threats, both for human health and the environment. Here, the contamination level, sources, and ecological risks posed by PTE were investigated in 19 topsoils from agricultural lands in the Bandar Abbas County on the southern coast of Iran. The soil fraction &lt;63 μm was used for the analysis of the pseudototal contents of PTE (arsenic, cadmium, cobalt, chromium, copper, lead, manganese, molybdenum, nickel, vanadium, and zinc). The results were analyzed using principal component analysis (PCA) and Pearson’s correlations, different pollution indices [enrichment factor (EF), contamination factor (Cf), and modified degree of contamination (mCd), and the potential ecological risk index (PERI). The results of the pollution indices showed that the contamination levels of the studied agricultural soils are low to moderate, while the average PERI values indicate that the ecological risks of PTE range from low to high in the soils of the studied area. Correlations and PCA analyses suggest that studied elements have three possible origins: geogenic (chromium, cobalt, copper, manganese, vanadium, and zinc), anthropogenic (cadmium, nickel, phosphorus and lead) and atmospheric (arsenic) sources. These findings are helpful for the long-term assessment of PTE in the Bandar Abbas County.

Unsustainability Syndrome—From Meteorological to Agricultural Drought in Arid and Semi-Arid Regions

Water is the most important resource for sustainable agriculture in arid and semi-arid regions, where agriculture is the mainstay for rural societies. By relating the water usage to renewable water resources, we define three stages from sustainable to unsustainable water resources: (1) sustainable, where water use is matched by renewable water capacity, ensuring sustainable water resources; (2) transitional, where water use occasionally exceeds renewable water capacity; and (3) unsustainable, with lack of water resources for agriculture, society, and the environment. Using available drought indicators (standardized precipitation index (SPI) and streamflow drought index (SDI)) and two new indices for agricultural drought (overall agricultural drought index (OADI) and agricultural drought index (ADI)), we evaluated these stages using the example of Fars province in southern Iran in the period 1977–2016. A hyper-arid climate prevailed for an average of 32% of the province’s spatio-temporal coverage during the study period. The area increased significantly from 30.6% in the first decade (1977–1986) to 44.4% in the last (2006–2015). The spatiotemporal distribution of meteorological drought showed no significant negative trends in annual precipitation during 1977–2016, but the occurrence of hydrological droughts increased significantly in the period 1997–2016. The expansion of irrigated area, with more than 60% of rainfed agriculture replaced by irrigated agriculture (especially between 1997 and 2006), exerted substantial pressure on surface water and groundwater resources. Together, climate change, reduced river flow, and significant declines in groundwater level in major aquifers led to unsustainable use of water resources, a considerable reduction in irrigated area, and unsustainability in agricultural production in the period 2006–2015. Analysis of causes and effects of meteorological, hydrological, and agricultural drought in the area identified three clear stages: before 1997 being sustainable, 1997–2006 being transitional, and after 2006 being unsustainable.

The influence of compost humic acid quality and its ability to alleviate soil salinity stress

Purpose Soil salinization is one of the most severe abiotic stresses which threaten sustainable agriculture in arid and semi-arid regions including Morocco. The application of organic amendments like composts to saline soils has been confirmed to alleviate soil salinity stress. The present work aims to study the effect of humic acids (HA), as one of the products resulting from organic matter decomposition, on soil salinity reduction. Methods In this perspective, four composts made from mixtures corresponding to initial C/N ratios of 25, 30, 35 and 40 were tested. The four composts were made from mixtures of different proportions of greenhouse wastes, olive mill waste and sheep manure in Souss-Massa region. Representative samples underwent physicochemical analysis, extraction, purification and analysis of HA. The maturity of compost was assessed through some maturation index, prior to the main trial of the interaction between extracted HA and sodium carbonates salt (Na2CO3), largely encountered in saline soils. Results The results showed that the compost with initial C/N ratio of 35 is the most recommended for application as an amendment to alleviate soil salinity. Conclusion The salt stress alleviating effect of compost may be advocated to compost humic acids and their ability to chelate sodium on their carboxylic sites.

Evaluation of Common Bean (Phaseolus vulgaris L.) Germplasm for Resistance to Angular Leaf Spot Disease [Phaeoisariopsis griseola (Sacc.) Ferraris] under Cold Arid Conditions of Ladakh

An experiment was conducted to identify promising accessions suited for cultivation under cold arid conditions of Leh, Ladakh. Twenty two accessions of French bean were screened for resistance to angular leaf spot disease during the spring seasons of 2016 and 2017 in the Experimental field of High Mountain Arid Agriculture Research Institute (HMAARI) Leh, Ladakh, Sheri Kashmir University of Agricultural Sciences and Technology of Kashmir. The study revealed that under natural epiphytotic conditions none of the accessions was resistant in reaction. Eight accessions viz., Acc-WB22, Acc-1643, Acc-1690, Acc-811, Acc-4564, WB-1247, WB-185 and Acc-252 were moderately susceptible. All other fourteen accessions viz., Acc-966, Acc-335, Acc-1129, Acc-21529, Acc-WB216, Acc-719, WB-956, Acc-622, Acc-1492, Acc-195, Anupama, WB-6, WB-257 and Local exhibited susceptible reaction

Functional relationships between aboveground and belowground spinach (Spinacia oleracea L., cv. Racoon) microbiomes impacted by salinity and drought

Salinity is a major problem facing agriculture in arid and semiarid regions of the world. This problem may vary among seasons affecting both above- and belowground plant microbiomes. However, very few studies have been conducted to examine the influence of salinity and drought on microbiomes and on their functional relationships. The objective for the study was to examine the effects of salinity and drought on above- and belowground spinach microbiomes and evaluate seasonal changes in their bacterial community composition and diversity. Furthermore, potential consequences for community functioning were assessed based on 16S V4 rRNA gene profiles by indirectly inferring the abundance of functional genes based on results obtained with Piphillin. The experiment was repeated three times from early fall to late spring in sand tanks planted with spinach (Spinacia oleracea L., cv. Racoon) grown with saline water of different concentrations and provided at different amounts. Proteobacteria, Cyanobacteria, and Bacteroidetes accounted for 77.1% of taxa detected in the rhizosphere; Proteobacteria, Bacteroidetes, and Actinobacteria accounted for 55.1% of taxa detected in soil, while Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria accounted for 55.35% of taxa detected in the phyllosphere. Salinity significantly affected root microbiome beta-diversity according to weighted abundances (p = 0.032) but had no significant effect on the relative abundances of microbial taxa (p = 0.568). Pathways and functional genes analysis of soil, rhizosphere, and phyllosphere showed that the most abundant functional genes were mapped to membrane transport, DNA repair and recombination, signal transduction, purine metabolism, translation-related protein processing, oxidative phosphorylation, bacterial motility protein secretion, and membrane receptor proteins. Monoterpenoid biosynthesis was the most significantly enriched pathway in rhizosphere samples when compared to the soil samples. Overall, the predictive abundances indicate that, functionally, the rhizosphere bacteria had the highest gene abundances and that salinity and drought affected the above- and belowground microbiomes differently.

Farmers' perception towards shelterbelts in hot arid regions of Rajasthan: An analysis by garrett's ranking technique

Shelterbelt plantations are one of the biggest ecofriendly technologies to address wind erosion, control sand movement and related problems in the arid areas, which cover 12 per cent of India and more than half of Rajasthan. However, the role of shelterbelts in arid agriculture is changing. A survey was undertaken to investigate the farmers' perception toward field shelterbelts/windbreaks and its impact in farmers' fields in the arid district of Bikaner, Rajasthan. Questionnaire, group discussion and observations were used for data collection. The respondents of the study were the farmers having already established shelterbelts in their farms. The study revealed that farmers were using windbreaks on agricultural lands mainly to protect crops from strong winds, provide shade to livestock, reduce crop damage from frost and cold winds, reduce soil erosion etc.; while the biggest challenge was the competition by trees to the crops growing below them. The farmers' preference for tree species was also noted to have changed over the years. Though old shelterbelts were mainly of Acacia tortilis, farmers now prefer Dalbergia sissoo (45 per cent prevalence), since it does not affect crop growth and for its economic timber value. Other species like Zizyphus sp., Eucalyptus sp., Cordia myxa etc. when used as shelterbelts provide fruits and fuelwood which provide additional income to farmers.

Economic efficiency of innovation in the restoration of soil resources in organic agricultural production

The intensification of the use of the main means of agricultural production dictates the need to restore and increase soil fertility. The purpose of the study is to develop a methodological basis for calculating the economic efficiency of innovation in the restoration of soil resources in organic agricultural production with an assessment of its practical implementation in the conditions of arid agriculture in the south of Russia. To prevent the loss of a significant part of soil resources, their restoration, an innovative approach to organotransformation in the restoration of soil resources has been developed. The proposed approach allows integrating organic farming and animal husbandry with the processes of restoration of soil resources for the implementation of organotransformation of soil formers in degraded soil resources. In the methodology for determining the economic efficiency of the innovative approach of organotransformation, five modifications are proposed. The implementation of the recommended modification provides for the lowest costs for the restoration of soil resources, a sufficient level of fertility for obtaining high yields, the net income is about 27 thousand rubles/ha or 454 rubles/c. The application of the developed approach confirms the economic feasibility of innovation in the agricultural sector of the economy in organic agriculture.

Study of depression in university students in Pakistan.

To assess the prevalence of depression among university students in Pakistan. The descriptive cross-sectional study was conducted from October 1, 2017, to February25, 2018, at Agriculture University, Faisalabad, Gomal University, Dera Ismail Khan, PirMehr Ali Shah Arid Agriculture University, Rawalpindi, University of Peshawar and Qurtuba University, Dera Ismail Khan, Pakistan. Data was collected using a pre-tested, structured questionnaire, and was analysed using SPSS 19. Of the 1159 subjects, 367(31.6%) were males and 792(68.3%) were females. The overall age range was 19-45 years. Of all the subjects, 986(85%) had some degree of depression, while 173(15%) were normal. Depression in females was significantly higher than males (p<0.05). Depression also had a significant association with academic grades (p<0.001). Depression was found to be common among university students in Pakistani.

Arsenic Contamination in Rice Grown Under Anaerobic Condition in Arid Agriculture: Assessment and Remediation.

Arsenic (As) concentrations in fine (2) and coarse (3) rice varieties belonging to Hafizabad, Gujranwala and Sheikhupura districts was assessed initially by means of field survey, followed by pot experiments. Bulk soil samples collected from same rice districts (Hafizabad and Gujtanwala) were spiked with As (0, 10, 20mgkg-1) and each was amended with iron sulphate (0, 25, 50gkg-1) to investigate their effect on plant growth and uptake under anaerobic conditions. Survey results revealed that mainly fine long grain (Super Basmati and KSK 515) and coarse long grain (Basmati 386 and Kainat) rice varieties were grown in the area. Overall, 16% rice grain samples were above the recommended permissible limit (RPL) of 300mgkg-1. Among varieties, 24% grain samples of coarse and 12% of fine varieties had As concentration above the RPL. Results of pot experiments showed a significant decrease in straw and grain yield and increase in As concentration with increasing rates of As spiking. Paddy yield increased significantly when As spiked soils were amended with iron sulfate; and opposite was true for As concentration.

Effects of Irrigation Water Salinity on Maize (Zea may L.) Emergence, Growth, Yield, Quality, and Soil Salt

Freshwater shortage is becoming one of the major limiting factors for the sustainable development of agriculture in arid and semi-arid areas of north China. A two-year field experiment about mulched drip irrigation on maize was conducted in Hetao Irrigation District with five irrigation water salinity levels (total dissolved solids; 1, 2, 3, 4, and 5 g·L−1). The effects of irrigation water salinity on maize emergence, growth, yield, grain quality, and soil salt were determined. The results indicated that with the soil matric potential of −20 kPa and irrigation quota for each application of 22.5 mm, the irrigation water salinity showed negative influence on maize emergence and maize morphological characteristics (plant height, leaf area index, stem diameter, and dry matter), as irrigation water salt concentrations exceeded 3 g·L−1. The water use efficiency decreased linearly with the irrigation water salinity raised from 1 g·L−1 to 5 g·L−1, while maize grain protein increased and starch content decreased with the increase of irrigation water salt contents. Additionally, both the vertical radius and horizontal radius of salt isoline by mulched drip irrigation reduced with the irrigation water salt concentrations, when the irrigation water salinity was above 3 g·L−1. Summarily, irrigation water salinity of 3 g·L−1 was recommended for maize mulched drip irrigation in this study.