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This work aimed to study the intrinsic tolerance of Greek lentil accessions to imazamoxherbicide by combining bioassays, pot and field experiments. Initially, 31 genotypes wereevaluated in Petri dish bioassays for their tolerance to six concentrations of imazamox. Theaverage root length of 10 lentil seedlings/dish at seven days after herbicide application was usedfor non-linear regression analysis and the GR50 values (the amount of the herbicide required for50% root length reduction of the seedlings) were estimated to calculate the resistance ratio (R/S)of each cultivar. The results of the in vitro test clued the selection of nine accessions for furtherstudy in pot experiment, to assess their tolerance to four rates [0 (control), 20, 30, 40 g ai ha-1]of imazamox post-emergently applied at the seven true-leaf stage (V7 stage). Five weeks aftertreatment, the number of survived plants was recorded and the above-ground dry weight wasdetermined in each pot. There was no direct correlation in the results of in vitro test and the potexperiment, suggesting no matching between the two methods. The evaluation of fiveaccessions (cultivars with high commercial interest and accessions sporting tolerance in potexperiment) in field experiment demonstrated different but increased susceptibility toimazamox. Specifically, compared to the untreated control, the imazamox treatments reducedplant growth, delayed flowering and maturity and reduced yield, dry weight, 1000-seed weightand harvest index. Yet the protein concentration was increased in herbicide treatments. Thefindings of the study showed clearly that the evaluated lentil accessions lack genes withresistance to imazamox and different methods have to be used for assessing any potentialtolerance.
The dynamic and static deficit (DDI, SDI), partial root drying (DPRD, SPRD) and full (FI)irrigation strategies were applied in Agria and Ramos potato cultivars in a semi-arid area. FIreceived 100% of the potential evapotranspiration (ET); SDI and SPRD received 75% of ETduring the growth period; DDI and DPRD received 90% of ET in the first third, 75% of ET inthe second third and 50% of ET in the last third of growth period. Results showed that freshtuber yield and tuber nitrogen (N) content were negatively correlated meaning that by increasingthe tuber N content, tuber yield decreased. PRD irrigation strategy had significantly the highesttuber N content than FI and DI. Dry matter water productivity (WPDM) was significantlydifferent between the irrigation strategies. The DI strategies had significantly higher WPDM thanFI and PRD ones. DDI and DPRD increased WPDM by 26 and 19% compared to SDI and SPRD,respectively. WPDM in Ramos (1.08 kg m-3) was higher than Agria (0.82 kg m-3). The newlyintroduced Dry Matter-Water Content Index (DMWCI) was higher in PRD and Agria than DIand Ramos, respectively. Conclusively, the DI treatments are the recommended water savingirrigation strategies under these experimental conditions in terms of highest WPDM and greaterdry matter allocation to tubers, though the PRD irrigation strategy had higher tuber N content.Ramos is the favored potato cultivar for processing industry based on its higher WPDM and tuberdry matter content than Agria.
Nitrogen (N) in plants is generally diagnosed by a soil test and plant tissue analysis.However, such analyses are costly in terms of time and money and are not easily accessible byresearchers and extension workers, let alone farmers. Alternative cost-effective methods arerequired for rapid analysis of the N status of crops and to guide N management in wheat. Theobjective of this study was to assess whether the SPAD values using a leaf chlorophyll metercould be used to apply N at the maximum tillering (MT) stage of irrigated spring wheat grownunder light soils of South Asia. Experiments were conducted over two years under light soils atthe Wheat Research Centre (WRC), Dinajpur, Bangladesh. Treatments were 80, 100 and 120kg N ha−1, applied two-thirds as basal and one-third at the crown root initiation (CRI) stagealong with additional 10, 20 and 30 kg N ha−1 (first year) and 0, 10, 20 and 30 kg N ha-1 (secondyear) at MT. Rates at MT were determined on the basis of SPAD values, which fell below thecritical value of 37.5, recorded at 45 days after sowing (DAS). SPAD values recorded at 55 and65 DAS were positively correlated with grain yield (GY), indicating that the application of extraN at MT influences wheat GY. Our results have two major implications: (i) SPAD values basedon a leaf chlorophyll meter can be used for N application and (ii) extra 30 kg N ha-1 at MT isrecommended for achieving maximum GY of irrigated spring wheat under the light soils ofSouth Asia.
The present study investigated the impact of environmental pollution, represented in soil,irrigation water and air heavy metals, on the growth and production of Egyptian clovercultivated at south Greater Cairo, Egypt. Plants were sampled through five quadrats (0.5×0.5m), distributed equally in four cultivated farms in unpolluted and polluted sites, at theharvesting time. In addition, soil, air and irrigation water were collected from each farm.Significant differences in air, soil and irrigation water between the polluted and unpolluted siteswere recognized. Plant density, shoot and root lengths; as well as biomass and yield wereremarkably lower in the polluted site. In contrast with chlorophyll b; chlorophyll a andcarotenoids contents were lower in clover cultivated in the polluted site. However, chlorophylla/b ratio was significantly higher in plants from the polluted site. It was found that, As, Cr, Ni,Zn, Ag and V were significantly higher in clover shoots than roots, while Pb, Cd, Cu, Fe, Mnand Co concentrations were higher in the roots. The bioaccumulation and translocation factorsof most heavy metals were greater than unity indicating high potential of the study species forphytoremediation in polluted areas. Egyptian clover accumulated toxic concentrations of Fe, Pb,Ni, Zn, Cd, Cr and Co, which have adverse effects directly on livestock and indirectly on humanhealth through its flow in the food chain. In order to use Egyptian clover as a forage crop, itscultivation should be avoided in polluted areas.
Wheat-corn cropping system is one of the most important grain production systems in theworld. However, the integrative impacts of soil tillage on crop yield, N use efficiency (NUE)and greenhouse gases (GHGS) emissions are not well documented in this system. Thus, a twoyear field experiment was carried out in a typical wheat-corn cropping system with four tillageregimes during the wheat season, including no-tillage (NT), rotary tillage (RT), sub-soilingtillage (ST) and sub-soiling with rotary tillage (SRT) in a randomized block design with threereplicates. No-tillage was conducted for all treatments during corn season. Over the two years,the highest yields of wheat, corn and annual were found in the SRT treatment, while the lowestannual yield was found in the NT treatment averagely. Two-year average annual yield in theSRT was 19643.9 kg ha-1, which was 4.8, 5.9 and 7.7% higher than that in the ST, RT and NTtreatments, respectively (P<0.05). SRT also stimulated plant N uptake with a higher N harvestindex and higher partial factor productivity (PFP) than those under the other tillage practices(P<0.05). Although SRT stimulated N2O emission in wheat season, it significantly reduced theemission in corn season compared with the NT (P<0.05). Thus, no significant differences intotal GHGS emissions, area-scaled and yield-scaled global warming potential (GWP) werefound among the tillage practices. Our results indicate that sub-soiling with rotary tillage mightbenefit crop production for high yield and N use efficiency with less GHGS emissions forwheat-corn cropping system in North China Plain.
The introduction of ecological sanitation (ECOSAN) toilets in villages near Bangalore hascreated opportunities for safer sanitation and recycling of human excreta, as fertilizers, in ruraland peri-urban areas. Field experiments were conducted at the University farm on French beansand Maize as the test crops in succession for 2 consecutive years in the same field. Differenttreatment combinations tried include human urine, with and without gypsum, Farm yard manure(FYM), chemical fertilizers and control. The fertilizer value of human urine were assessed andsupplied to the crops based on the nutrient content. The results revealed that yield of two cropswere significantly highest in treatment receiving human urine + FYM followed by human urinealone. Generally the results showed that human urine performed well than the commerciallyavailable chemical fertilizers (urea) applied as a source of N for crops and does not pose anysignificant hygienic threats and leave any significant flavor in food products.
Adoption of drip irrigation in Kerala State of India is very low and potential exists toincrease its adoption in the State. A field survey was conducted in two districts to determine themajor factors influencing farmers’ adoption of drip irrigation and to draw conclusions that willhelp in developing policy and institutional interventions to encourage the adoption. The resultsindicated that adoption index of farmers is higher in Kozhikode, when compared with theThrissur district. However, with respect to different crops, adoption index is not statisticallysignificant. Socioeconomic characteristics such as age, education, experience, land holding size,etc. have a positive influence on drip irrigation adoption index by farmers. Farmers haverealized yield improvement in the range of about 13% to 47% through drip irrigation, whencompared to surface method of irrigation for arecanut, coconut and nutmeg. High productivityand income from cultivation of crops like coconut, arecanut and nutmeg have acted as anincentive to adopt the costly system of drip irrigation in the case of both Kozhikode andThrissur farmers. The number of drip irrigation components and type of emitters indicated asignificant and linear response for drip irrigation adoption. The reported constraints experiencedby farmers include rainfall, clogging of drippers, high initial cost, inadequate subsidy, difficultyin getting subsidy, etc. This information will help to prioritize the factors that affect adoptiondecisions and provide insights for improving the crop and water productivity.
Salinization of soil is primarily caused by capillary rise from saline shallow groundwater orapplication of saline irrigation water. In this investigation, the transient state analytical modelwas modified to predict water uptake from saline shallow groundwater, actual cropevapotranspiration, soil water content, dry matter, seed yield and soil salinity under differentsaline groundwater depths, irrigation water salinities and deficit irrigation for quinoa.Considering the effect of salinity on soil saturated hydraulic conductivity and maximum rootdepth in presence of shallow saline groundwater, the model resulted in good agreement betweenthe measured and predicted saline groundwater uptake, soil salinity increase at differentgroundwater depths (300-800 mm) and water salinity (10-40 dS m-1). Therefore, the modifiedmodel is applicable for quinoa yield and soil salinity prediction and it could be a valuable toolfor soil salinity management in presence of shallow saline groundwater. Furthermore, predictionof quinoa yield by the modified model can be used for better irrigation water salinitymanagement under different saline groundwater depths, irrigation water salinities and deficitirrigation.
This study was aimed at evaluating the effect of crop rotation and various tillage systems onthe chemical and biological properties of soil in the years 2013-2015. The first order factorincluded cropping systems: a) crop rotation (pea – winter wheat – spring wheat) and b)monoculture of winter wheat, whereas the second order factor were tillage systems:1) conventional (CT), 2) reduced (RT) and 3) No-tillage (NT). In the autumn season, in the CTsystem, shallow ploughing (at the depth of 10–12 cm) and pre-winter ploughing (25–30 cm)were applied for pea and spring wheat crops, whereas shallow ploughing and pre-sow ploughing(20–22 cm) were applied for winter wheat crop; in the RT system, only a cultivator was appliedfor spring wheat and pea crops as well as a cultivator and a tillage set for winter wheat; in theNT system glyphosate was applied on all plots as well as a cultivator and a tillage set were usedbefore winter wheat sowing. The study demonstrated that the soil sampled from plots with croprotation contained more organic C and available forms of P, K and Mg and that it wascharacterized by a higher activity of dehydrogenase, phosphatase and urease than the soilsampled from monoculture. In addition, it was characterized by a higher number of earthwormsthan the soil from monoculture. The RT and NT systems affected an increase in the contents oforganic C and total N and in the enzymatic activity of soil, compared to the CT system.
Energy and water availability were identified as the first order controls of evapotranspiration(ET) in ecohyrodrology. With a ~1,000 km precipitation gradient and distinct wet-dry climate,the North Australian Tropical Transect (NATT) was well suited for evaluating how energy andwater availabilities constrain water use by vegetation, but has not been done yet. In this study,we addressed this question using Budyko framework that quantifies the evapotranspiration as afunction of energy-limited rate and precipitation. Path analysis was adopted to evaluate thedependencies of water and carbon fluxes on ecohydrological variables. Results showed that themajor drivers of water and carbon fluxes varied between wet and dry savannas: down-wellingsolar radiation was the primary driver of the wet season ET in mesic savanna ecosystems, whilesoil water availability was the primary driver in inland dryland ecosystems. Vegetation cansignificantly regulate water and carbon fluxes of savanna ecosystems, as supported by thestrong link of LAI with ET and GPP from path analysis. Vegetation structure (i.e. the tree:grassratio) at each site can regulate the impact of climatic constraint on ET and GPP. Sites with a lowtree:grass ratio had ET and GPP that exceeded sites with high a tree:grass ratio when the grassyunderstory was active. Identifying the relative importance of these climate drivers andvegetation structure on seasonal patterns of water use by these ecosystems will help us decideour priorities when improving the estimates of ET and GPP.