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1.
There is growing concern that air pollution may have adverse impacts on crops in developing countries, yet this has been little studied. This paper addresses this issue, for a major leguminous crop of the Indian sub continent, examining the effect of air pollution in and around an Indian city. A field study was conducted using a gradient approach to elucidate the impact of air pollutants on selected production characteristics of Vigna radiata L. cv. Malviya Jyoti (mung bean) plants grown from germination to maturity at locations with differing concentrations of air pollutants around peri-urban and rural areas of Varanasi. The 6 -h daily mean SO2, NO2 and O3 concentrations varied from 8.05 to 32.2 ppb, 11.7 to 80.1 ppb and 9.7 to 58.5 ppb, respectively, between the sites. Microclimatic conditions did not vary significantly between the sites. Changes in plant performance at different sites were evaluated with reference to ambient air quality status. Reductions in biomass accumulation and seed yields were highest at the site experiencing highest concentrations of all three gaseous pollutants. The magnitude of response indicated that at peri-urban sites SO2, NO2 and O3 were all contributing to these effects, whereas at rural sites NO2 and O3 combinations appeared to have more influence. The quality of seed was also found to be negatively influenced by the ambient levels of pollutants. It is concluded that the air pollution regime of Varanasi City causes a major threat to mung bean plants, both in terms of yield and crop quality, with serious implications for the nutrition of the urban poor.  相似文献   

2.
Three bush bean cultivars (Lit, Groffy and Stella) were grown under four levels of ozone exposure (ambient air+50 ppb O3 ambient air+25 ppb O3, ambient air and charcoal filtered air) in open- top chambers. Number and leaf injury statistics showed significant reduction in the number of healthy leaves as the level of O3 increased. The area based leaf injury percentages of the cvs. Lit, Groffy and Stella were 69.8, 57.9 and 71.1% at the highest O3 level, 24.1, 19.6 and 30.3% at the 2nd highest O3 level, and 4.5, 0.7 and 5.6% at the ambient air, respectively. The plants grown in the filtered air revealed no injury symptoms. The stomatal conductances were found to decrease gradually in each cultivar as the O3 level increased. At the highest O3 level, Chlorophyll fluorescence measurements on the 2nd leaf from the top on 24th day of exposure resulted in significantly the highest Fv/Fm values, the lowest f0 and the highest Fm values whereas the 4th leaf showed the smallest Fm and correspondingly the smallest Fv/Fm values. This is an indication of photosystem II damage after accumulation of a high ozone dose in the 4th leaf. The photosynthetic rate of the 2nd leaf measured on 30th day of exposure was comparatively higher at the highest exposure but the data taken from the same leaf on 40th day of exposure showed significantly lower photosynthetic rate than the plants in ambient air. Both chlorophyll fluorescence and photosynthetic measurements indicated that ozone stressed leaves experience a stimulation of photosynthesis (possibly due to increased assimilate demand) prior to irreversible damage. Bush bean leaves need to accumulate a critical ozone dose(an AOT40 of presumably > 18 ppm-h) for reduction of the photosynthetic capacitys.  相似文献   

3.
A fully automated rain exclusion canopy system has been designed and constructed to study the impact of simulated acid rain on the growth and yield of agricultural crops. The system consists of three, mobile greenhouse shelters which exclude ambient rainfall and apply simulated acid rain (SAR) treatments to crops established in field plots. All aspects of the field system are controlled by a microcomputer and data acquisition system. In addition, elevated ambient levels of gaseous pollutants (e.g. O3, SO2, NOx) are reduced in field plots via an air exclusion system consisting of large blowers, potassium permanganate-treated alumina filters and perforated polyethylene tubes. Gaseous pollutants can be injected into the treatment plots via the blowers.  相似文献   

4.
Open-top chambers ventilated with ambient or chiarcoal-filtered air were used to assess the impact of air pollution on the yield of local cultivars of wheat and rice, at a site on the outskirts of Lahore. At this location, 6-h mean O3 concentrations reach 60 ppb in certain months, and annual mean NO2 concentrations are 20–25 ppb. The experiments showed significant yield reduction in two successive seasons which ranged from 33% to 46% in wheat and from 37% to 51% in rice. The major yield parameter affected was the number of ears or panicles per plant, although there was also evidence of small effects on 1000 grain weight and on the number of grains per ear/panicle. These results have significance in terms of the maintenance of agricultural yields as pollution emissions rise in south and south-east Asia.  相似文献   

5.
The effects of ambient O3 at two different levels of nitrogen, phosphorus, and potassium, (recommended and 1.5 times the recommended NPK) on three tropical varieties of mustard (Brassica campestris L. var. Kranti, Aashirwad and Vardan) were explored to unravel the mechanism of protection under higher NPK level at a rural experimental site using open top chambers. Ambient O3 concentrations ranged from 27.7 to 59.04 ppb. Lipid peroxidation, antioxidative enzymes, and metabolites were higher, whereas photosynthetic pigments and protein were lower in all the varieties of mustard grown in non-filtered chambers than in filtered chambers. The magnitude of response varied with varieties, NPK levels and ages. Vardan showed a maximum stimulation in the antioxidative defense system, thus efficient scavenging of ROS produced by O3 and consequently conferred greater tolerance in terms of least reductions in pigments and protein as compared to Kranti and Aashirwad. The antioxidant defense system was not stimulated in response to 1.5 times the recommended NPK, but higher levels of pigments and protein were maintained compared to the recommended NPK under ambient O3 levels.  相似文献   

6.
Grain sorghum (Sorghum vulgare Pers.) is an important animal feed crop, and it is sometimes planted as a substitute for field corn. Although sorghum is grown in areas of the central and southern U.S. where potentially damaging concentrations of O3 exist, no data are available regarding the sensitivity of grain sorghum to O3. Plants of grain sorghum (DeKalb A28+ ) were field-grown in open-top chambers and exposed to O3(7-hr day?1 seasonal mean concentrations of 0.016, 0.040, 0.059, 0.078, 0.102, and 0.129 ppm) for 85 days to determine the impact of O3 on grain yield. A randomized complete block design incorporated three replicates of all treatments. Foliar injury was noted at the two highest 03 treatments. Analysis of variance of the data indicated highly significant O3 effects on overall grain yield. There was a general decrease in yield as O3 increased, and the overall grain yield reductions were caused primarily by reductions in individual seed weight. Quadratic, Weibull, and plateau-linear models all adequately described the response of grain sorghum to O3. Yields were not markedly affected at O3 concentrations below the 0.10 ppm treatment, and the predicted yield loss of 15% at a seasonal 7-hr mean O3 concentration of 0.13 ppm indicates that grain sorghum exhibits considerable tolerance to O3.  相似文献   

7.
臭氧(O3)浓度升高危害小麦生长,现有研究尚不清楚推广新的小麦品种能否减缓O3对籽粒产量、农田蒸散和水分利用效率的负面效应,且研究O3浓度升高对麦田水分利用效率的影响对农业用水管理具有重要意义。本研究利用完全开放式O3浓度升高平台（O3-FACE）,通过连续观测农田小气候特征,结合能量平衡法分析O3浓度升高对麦田水热通量、小麦籽粒产量和田间水分利用效率的影响。结果表明：O3浓度升高显著降低了开花后第32天小麦旗叶的叶绿素含量,降低了乳熟–成熟期的麦田潜热通量平均值和正午峰值,但影响幅度较小。O3浓度升高对麦田平均水热通量及其分配无显著影响,也未影响籽粒产量、产量组成和田间水分利用效率。不同于10年前江淮地区主推的扬辐麦2号、烟农19和嘉兴002等品种,当前推广的农麦88表现出极强的O3抗性。在O3浓度不断升高背景下,种植农麦88有助于减缓O3浓度升高对田间蒸散和水分利用效率的影响。  相似文献   

8.
Potential for carbon dioxide (CO2) biosequestration was determined during the reclamation of highly saline–sodic soils (Aridisols) after rice (2003) and wheat (2003–2004) crops at two sites in District Faisalabad, Pakistan. Two treatments were assessed: T1, tube-well brackish water only; and T2, soil-applied gypsum at 25% soil gypsum requirement?+?tube-well brackish water. The irrigation water used at both sites had different levels of salinity (EC 3.9–4.5 dS m?1), sodicity (SAR 21.7–28.8), and residual sodium carbonate (14.9 mmolc L?1). Composite soil samples were collected from soil depths of 0–15 and 15–30 cm at presowing and postharvest stages and analyzed for pH, ECe, and sodium adsorption ratio (SAR). After rice harvest, there was no significant effect of gypsum application on ECe, pH, and SAR at both sites, except pH at 0–15 cm depth decreased significantly with gypsum at site 1. After wheat harvest, ECe, pH, and SAR decreased significantly with gypsum at site 1, whereas the effect of gypsum on these parameters was not significant at site 2. Compared to initial soil, ECe and SAR in soil decreased considerably after rice or wheat cultivation, particularly at site 1, whereas pH increased slightly due to cultivation of these crops. For rice, the total CO2 sequestration was significantly increased with gypsum application at both sites and ranged from 1499 to 2801 kg ha?1. The total sequestration of CO2 was also significantly increased with gypsum application in wheat at both sites and ranged from 2230 to 3646 kg ha?1. The amounts of CO2 sequestered by crops due to gypsum application were related to seed and straw yield responses of rice and wheat to gypsum, which were greater at site 1 than site 2. Also, the yield response to applied gypsum was greater for rice than wheat at site 1, whereas the opposite was true at site 2. Overall, the combined application of gypsum with brackish water reduced soil ECe and SAR compared to brackish water alone, particularly at site 1. Our findings also suggest that the reclamation strategies should be site specific, depending on soil type and quality of brackish water used for irrigation of crops. In conclusion, the use of gypsum is recommended on brackish water–irrigated salt-prone soils to improve their quality, and for enhancing C biosequestration and crop production for efficient resource management.  相似文献   

9.
This study presents the first experimental evidence of the sensitivity of rice plants to ambient air pollution from the Southeast Asian tropical region. Two widely adopted local cultivars of rice (Oryza sativa L.), MR84 and MR185, were grown in open top chambers ventilated with charcoal-filtered air and non filtered air, and in adjacent open plots on the campus of University Putra Malaysia. This is located on the south side of the Klang Valley, a rapidly developing area embracing Kuala Lumpur and other satellite cities, but where agriculture remains important The experimental period was from October 2000 to January 2001, corresponding to the main rice growing season in peninsular Malaysia. Adverse impacts on rice growth and yield were observed and were attributed to phytotoxic levels of ambient ozone. There was a clear difference in the sensitivity of the two selected cultivars. A yield reduction of 6.3% was observed for cultivar MR185 (p < 0.01) which was largely due to an increase in grain sterility, whilst the yield reduction for cultivar MR84 was not statistically significant. The reasons for these differing responses are discussed, and a comparison of the present findings with crop responses to ozone found under European conditions suggests a higher sensitivity in our study crops. With increasing industrialisation and urbanisation, this study highlights the need for further examination of the sensitivity of a wider range of crops and cultivars to ambient air pollution in this region, and also points to the potential for appropriate cultivar selection to ameliorate impacts.  相似文献   

10.
Rice, dry bean, corn, and soybean are important food crops. Phosphorus (P) deficiency is one of the most yield-limiting factors for these crops grown on highly weathered Brazilian Oxisols. Four greenhouse experiments were conducted to determine P requirements of these four crops. The P levels used were 0, 50, 100, 200, and 400 mg kg?1. Growth, yield, and yield components evaluated of four crop species were significantly increased with the application of P fertilization. Most of the responses were quadratic in fashion when the P was applied in the range of 0 to 400 mg kg?1. Maximum grain yield of upland rice was obtained with the application of 238 mg P kg?1 of soil, maximum dry bean grain yield was obtained with the application of 227 mg P kg?1 of soil, and maximum grain yield of soybean was obtained with the application of 224 mg P kg?1 of soil. Maximum shoot growth of corn was obtained with the addition of 323 mg P kg?1 of soil. Most of the growth and yield components had significant positive association with grain yield or shoot dry weight. Phosphorus concentration and uptake were greater in the grain compared to straw in upland rice and dry bean plants. Overall, P-use efficiencies decreased with increasing P rates.  相似文献   

11.
ABSTRACT

The degree of complementarity vis-à-vis competition amongst the component crops, which is influenced by their relative planting dates, may affect the productivity of intercrop systems. This study assessed the effect of the relative planting dates of legumes on yield and yield components of three legume species. Field experiments were conducted in two consecutive years at two sites with contrasting soil types. Grain yield and yield components were determined at harvest maturity. A 4-weeks delay in incorporating legumes caused total yield loss of cowpea at both sites, decreased chickpea yield by 82% at the clay soil site, and led to negligible yield of Bambara groundnut in loamy sand soil. In contrast, sowing legumes 2 weeks after cassava decreased grain yield of cowpea (both sites), chickpea (clay soil) and Bambara groundnut (loamy sand soil). Intercropping decreased grain yield of chickpea (year 1) and Bambara (year 2) at the clay and loamy sand soil sites, respectively, but had no effect on cowpea yield. Although planting the legumes same time with cassava gave the highest grain yield, we suggest more studies, including sowing the legumes prior to planting cassava, before making categorical recommendations.  相似文献   

12.
Two cultivars of soybean (Pusa 9814 and Pusa 9712) were investigated to evaluate the impact of ambient and elevated concentrations of ozone (O3) in a suburban site of India with and without application of 400 ppm ethylenediurea (EDU) in open top chambers having filtered air (FCs), non-filtered air (NFCs), and non-filtered plus 20 ppb O3 (NFCs?+?20 ppb). Significant reductions were observed in various growth parameters, biomass accumulation, and yield attributes of soybean cultivars due to ambient O3 in NFCs and elevated concentration of O3 in NFCs?+?20 ppb. Reductions in all parameters were of lower magnitude in plants treated with EDU as compared to non-EDU treated plants. Yield (weight of seeds plant?1) increased by 29.8% and 33% in Pusa 9712 and by 28.2% and 29.0% in Pusa 9814 due to EDU treatment in plants grown at ambient and elevated levels of O3, respectively. The results clearly showed that (a) EDU can be effectively used to assess phytotoxicity of O3 by providing protection against its deleterious effects, (b) EDU can be used for biomonitoring of O3 in areas experiencing its higher concentrations, and (3) EDU is more effective against higher concentrations of O3.  相似文献   

13.
Abstract

Corn (Zea mays L.) is next to rice as an important food crop grown in South Sulawesi, Indonesia. However, yields obtained by farmers are rather low, around 0.6 to 1.0 ton/ha. Efforts to increase yield have been tried through the application of NPK fertilizers. A study was conducted to determine the effects of N, P and K application on corn yield and what soil constrains, in terms of nutrient elements in the corn plants, exist in the latsols found at Desa Tokka, Sinjai, and South Sulawesi. It was found that application of K significantly increased the growth and corn grain yields on the latosols at Sinjai. Without K, grain yield and the K content in the ear leaf were low. The correlation between grain yield and rate of K shows that an application of 72 kg K2O/ha together with 90 kg N and 80 kg P2O5 per ha produce the best yield of 3.6 tons/ha. The K content in the ear leaf of 1.8% was related to this maximum yield.  相似文献   

14.
A field experiment was conducted under two natural field conditions at the Research Farm (normal soil) and Proka Farm (salt-affected soil) of The Institute of Soil and Environmental Sciences (ISES), University of Agriculture, Faisalabad, Pakistan, to evaluate the performance of 11 rice genotypes in normal and salt-affected conditions. The experiment was laid out in randomized complete block design (RCBD) with three replications. The gas exchange attributes were measured at vegetative stage whereas the grain and straw yields and the yield components were recorded at maturity. After harvesting, the ionic parameters including sodium (Na+) and potassium (K+) were determined. Afterward, grain quality in terms of length, width, milling recovery, broken fraction, and chalkiness was also determined for the selected genotypes. Salt-affected conditions adversely affected the physiology, yield, and quality of the tested genotypes. The genotypes KS-282 followed by Shaheen Basmati showed significantly higher photosynthetic rate, transpiration rate, and stomatal conductance under both normal and salt-affected conditions, whereas the genotypes 99404 followed by 99417 showed minimum values of gas exchange attributes. The grain and straw yields were the highest in the case of KS-282 at both sites, whereas the lowest grain and straw yields were observed in the case of 99440 followed by 99417 under both normal and salt-affected conditions. Regarding the quality attributes, Super Basmati produced longer grains but with higher broken fraction and lower milling recovery, whereas the reverse was observed in the case of KS-282.  相似文献   

15.
Barley (Hordeum vulgare L.) is a cereal grown for animal feed, human consumption, and malting. Nutrient concentrations are important as they provide information regarding the dietary values of barley consumed by animals or human beings. In addition, grain nutrient removal may be useful for refining fertilizer recommendations. A study was conducted in 2015 and 2016 investigating the cultivar effects on grain yield, quality, and grain nutrient concentrations and removal under irrigated conditions for two-row barley cultivars. Adjunct and feed cultivars produced the highest yields compared with the all-malt and food cultivars. Specific quality and nutrient values were greater than or equal to in the food cultivar compared to the malt or feed cultivars. Variations in nutrient concentrations were measured among the adjunct and all-malt cultivars, which could potentially affect the malting and brewing qualities. Grain yield, quality, nutrient concentrations and nutrient removal varied among cultivars grown under identical environmental conditions, which may influence end-use.  相似文献   

16.
A linear gradient field exposure system was modified from one originally described by Shinn et al. (1977) and used to expose field grown soybeans (Glycine max cv Hark) to a concentration gradient of a mixture of two gaseous pollutants: SO2 and 03. Since this technique does not use enclosures, study plants experienced near ambient fluctuations in environmental conditions, including wind, and hence were exposed to widely fluctuating pollutant concentrations. Plants in the gradient system were exposed to both pollutants for 57 h on 12 days during the pod-filling period (31 August–17 September). Mean concentrations during the 57 h of exposure at the ‘high’ end of the gradient were 0.16 and 0.06 µl l?1 (PPM) SO2 and O3, respectively, with 10 h at greater than 0.25 and 0.10 µl?1 SO2 and O3, respectively. Total doses for these plants were estimated to be 9.0 and 3.5 µl?1 · h SO2 and O3, respectively. Comparison with plants exposed to ambient air indicated that exposure to SO2 and O3 reduced total yield per plant and dry mass per bean by as much as 36 and 15 %, respectively. Since concurrent exposure to a much higher dosage of SO2 alone (20.2 µl l?1 · h) was observed in a separate experiment to have no significant effect on yield, 03, although present at moderately low levels, was probably responsible (alone or synergistically with SO2) for the greatest reduction in seed size and yield.  相似文献   

17.
三大粮食作物产量潜力与产量差研究进展   总被引：17，自引：4，他引：17  
产量潜力和产量差的研究对揭示未来粮食增产潜力,有针对性地制定提高作物产量的措施具有重要意义。通过总结近年发表的64篇经典文献,本文总结了世界三大粮食作物小麦、水稻和玉米的产量潜力和产量差的研究进展,并对定量产量潜力和产量差的4种常用方法进行了比较分析。研究表明:1)当前全世界小麦、水稻、玉米的平均产量潜力分别为6.7 t-hm-2、8.1 t-hm-2、11.2 t-hm-2,农户产量分别实现了产量潜力的60%、60%、53%。2)模型模拟是目前定量评估产量潜力最为有效的方法之一,综合使用模型模拟和高产纪录两种方法进行比较分析产量潜力结果会更加可靠;试验产量和高产农户产量一般会低于模型模拟产量潜力,对探索农户短期内增产潜力具有重要意义。3)优化栽培管理措施比如应用土壤-作物综合管理系统等方法是缩小产量差的有效途径。因此,当前三大粮食作物具有较大增产潜力,如何有效缩小产量差、提高作物产量、保证粮食安全是未来需要关注的重点。  相似文献   

18.
Root biomass, length, and branching frequency, and number and type of mycorrhizal short roots were determined for loblolly pine seedlings grown at two levels of soil Mg and exposed to chronic levels of O3 and simulated acidic rainfall. Seedlings were planted in a sandy loam soil having approximately 15 or 35 mg kg?1 Mg and were exposed to subambient; ambient, or twice ambient concentrations of O3 in open top chambers from May through October. Seedlings also received ambient amounts of simulated rainfall at pH 3.8 or 5.2. Root biomass, length, and branching frequency were not significantly affected by O3, rainfall acidity, or soil Mg treatments. Seedlings grown in the subambient O3 treatment had a greater number of short roots infected with mycorrhizae than seedlings grown in ambient or twice ambient O3 treatments, but trends were not statistically significant. Increasing rainfall acidity and soil Mg concentration resulted in a significantly (P = 0.07) greater number of mycorrhizal short roots, due primarily to an increased occurrence of one corraloid mycorrhizal type. Results suggest that mycorrhizal fungi differ in their response to O3, rainfall acidity, and soil Mg status, and suggest that mycorrhizal infection is more sensitive than seedling root growth to O3, acidic rainfall, and soil Mg status.  相似文献   

19.
Ponderosa pines (Pinus ponderosa Dougl. ex. Laws) 21 to 60 yr old were used to assess the relative importance of environmental stressors (O3, drought) versus an enhancer (N deposition) on foliar retention, components of aboveground growth, and whole tree biomass allocation. Sites were chosen across a well-described gradient in ozone exposure (40 to 80 ppb per h, 24 h basis, 6 month growing season) and nitrogen deposition (5 to 40 kg ha-1 yr-1) in the San Bernardino Mountains east of Los Angeles, California. A high level of chlorotic mottle indicated high O3 injury at sites closest to the pollution source, despite potential for the mitigating effects of N deposition. At the least polluted site, foliar biomass was evenly distributed across three of the five needle-age classes retained. At the most polluted site, 95% of the foliar biomass was found in the current year's growth. High N deposition and O3 exposure combined to shift biomass allocation in pine to that of a deciduous tree with one overwintering needle age class. Based on whole tree harvests, root biomass was lowest at sites with the highest pollution exposure, confirming previous chamber exposure and field studies. Aboveground growth responses in the high-pollution sites were opposite to those expected for O3 injury. Needle and lateral branch elongation growth, and measures of wood production increased with increasing proximity to the pollution source. An enhancement of these growth attributes suggested that N deposition dominated the ponderosa pine response despite high O3 exposure.  相似文献   

20.
不同施硫量对冬小麦光合特性和产量的影响   总被引：16，自引：3，他引：16  
以8901-11和4185两个冬小麦品种为材料,于2001～2002年度在河北农业大学教学基地进行了试验,研究了不同施硫水平对小麦光合特性和产量的影响。试验设4个施硫量处理,分别为S0、30、60、90kg/hm2,采用裂区设计,3次重复。试验结果表明,在一定的供硫范围内(0～60kg/hm2),顶部功能叶在各生育时期,倒3叶和旗叶在展开到衰亡过程中的叶绿素含量增加,光合速率提高,可溶性蛋白质含量增加。在该施硫量范围内,两品种的产量均随着施硫量的增加而增加,且以60kg/hm2的施硫量水平产量最高,单位面积穗数、每穗粒数和千粒重随施硫量的变化趋势也同产量的变化趋势基本一致。  相似文献   

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