Effect of Cadmium and Iron on Rice (Oryza Sativa L.) Plant in Chelator-Buffered Nutrient Solution

ABSTRACT

To better understand the mechanisms responsible for differences in uptake and distribution of cadmium (Cd), nutrient-solution experiments were conducted with different varieties of rice (Oryza sativa), ‘Khitish’ and ‘CNRH3’. The plants were grown in a complete nutrient solution with different levels of pCd (-log free Cd⁺² activity) and pFe [-log free iron (Fe⁺²) activity]. The required concentrations of chelating agent and metals were determined using a computerized chemical equilibrium model such as Geochem-PC. Experimental treatments included a combination of four pCd activity levels (0, 7.9, 8.2, and 8.5) applied as Cd (NO₃)₂ 4H₂O, and two pFe activity levels (17.0 and 17.8) applied as FeCl₃. The application of both Cd and Fe in solution culture significantly affected plant growth, yield, and Cd accumulation in plant tissue. In general, yield of rice was decreased by an increase in amount of solution Cd; however, yield response varied among the cultivars. At the 7.9 pCd level, yields of rice cultivars ‘Khitish’ and ‘CNRH3’ were reduced to 69% and 65%, respectively, compared with control plants. Root Cd concentrations ranged from 2.6 mg kg^?1 (control plants) to 505.7 mg kg^?1 and were directly related to solution Cd concentrations. In rice plants, Cd toxicity symptoms resembled Fe chlorosis. Differential tolerance of varieties to phytotoxicity was not readily visible, but a significant interaction of substrate Cd and variety was obtained from dry-matter yields. Significant interactions indicated that response of tissue Cd concentration, plant Cd uptake, and translocation of Cd to the aerial parts were dependent on variety as well as substrate Cd. Uptake of Cd by roots was significantly higher than by shoots. Higher Cd uptake by rice plants decreased the uptake of other beneficial metals.

The effect of Cd and Fe on the rate of phytometallophore release was also studied in the nutrient solution. Among the rice genotypes, ‘Khitish’ was the most sensitive to Cd toxicity. In both genotypes, with the onset of visual Cd-toxicity symptoms, the release of phytometallophore (PM) was enhanced. Among the rice varieties, ‘Khitish’ had the highest rate of PM release. Treatments with the metal ions studied produced a decrease in chlorophyll and enzyme activity. A decrease in concentrations of chlorophyll pigments in the third leaf was observed due to the highest activity level of Cd (pCd 7.9). Activities of enzymes such as peroxidase (POD) and superoxide dismutase (SOD) are altered by toxic amounts of Cd. Changes in enzyme activities occurred at the lowest activity of Cd (pCd 8.5) in solution. Peroxidase activity increased in the third leaf. Results showed that in contrast with growth parameters, the measurements of enzyme activities may be included as early biomarkers in a plant bioassay to assess the phytotoxicity of Cd-contaminated solution on rice plants. Evidence that Cd uptake and translocation are genetically controlled warrants the selection of varieties that assimilate the least Cd and that translocate the least metal to the plant part to be used for human and animal consumption.     

Direct and Residual Effects of Fly Ash-Based Integrated Fertilization on Rice (Oryza sativa L.) and Rapeseed (Brassica camprestris L.)

Integrated effects of fly ash (FA), farmyard manure (FYM), and chemical fertilizers recommended dose of fertilizer (RDF) on the performance of rice (Oryza sativa L.) and their residual effect on rapeseed (Brassica camprestris L. vartoria) were studied for two years in loamy acidic inceptisol of Assam, India.

The FA was generated from a bituminous and lignite coal-based captive thermal power plant of Hindustan Paper Corporation Ltd (HPCL), Assam. Rice yields were higher when FA, FYM, and RDF were used collectively vis-à-vis sole application of RDF reflected also in rapeseed under residual effect . FA effect on mean rice equivalent yield of the rice–rapeseed system was the highest (24.4%) under integrated application. Nickel (Ni) and cadmium (Cd) contents in rice decreased with increasing FA, while arsenic (As) was just the opposite. Integration of FA, FYM, and RDF was effective in lowering Ni, Cd, and As in rice compared to 100% RDF alone or together with FA. The residual effect on rapeseed was similar for Ni and As while the Cd content increased. Blending of FA, FYM, and RDF also positively altered the residual soil pH, organic carbon (C), and nitrogen, phosphorus, and potassium (NPK). Thus, FA can be an integral component of integrated plant nutrition system (IPNS) in augmenting crop yield and residual benefits in loamy acid inceptisol.     

三种类型阻控剂对不同品种水稻富集镉的影响

如何降低水稻中镉(Cd)的含量已经成为一个研究热点。在湖南省衡阳县某地受轻度镉污染的农田上种植两季水稻(早稻、晚稻),随机采购市场上销售的阻控剂(石灰、硅肥和叶面锌肥),研究这3种类型阻控剂对水稻富集镉及稻谷中镉含量的影响,这3种类型的阻控剂的施用方式是石灰和硅肥作为基肥施于土壤,叶面锌肥通过叶面喷施。结果表明:与没有施加阻控剂相比,除石灰和晚稻锌处理之外,其他处理增产效果显著。在3种类型的阻控剂中,叶面锌肥对籽实富集镉的阻控效果最佳,分别使早稻Y俩优792和晚稻农香130降低了51.28%和50.92%,基施硅肥阻镉效果次之。田间试验结果进一步表明施硅肥和喷施叶面锌肥可作为当地的水稻镉污染阻控剂,但叶面锌肥与稻谷中镉的交互作用需要更深入的探讨。     

Effect of Nitrogen on the Alleviation of Boron Toxicity in Rice (Oryza Sativa L.)

Pot experiments were conducted in the greenhouse on a calcareous soil to study effect of nitrogen (N) on the alleviation of boron (B) toxicity in rice. The treatments consisted of factorial combination of six levels of B (0, 2.5, 5, 10, 20, and 40 mg kg^?1 as boric acid), and four levels of N (0, 75, 150, and 300 mg kg^?1 as urea) in a completely randomized design with three replicates. Boron addition (higher than 2.5 mg kg^?1) significantly reduced the seeds yield. Nitrogen addition alleviated the growth suppression effects caused by B supplements. Yield was increased by application of 2.5 mg B kg^?1 at all N levels, but at higher levels, B significantly decreased the yield of rice. Boron concentration declined with increasing N levels. Boron application increased the concentrations of B, potassium, phosphorous (P), and zinc. Nitrogen application decreased the concentration of Zn and increased the concentration of N and P.     

Genotypic Divergence in Expression of Zinc-Deficiency Symptoms of Rice (Oryza sativa L.) in Sand Culture

Zinc (Zn) deficiency is a ubiquitous disorder constraining rice production worldwide. A sand culture experiment was conducted in factorial randomized block design with three replications to study the relative performance of 18 rice (Oryza sativa L.) genotypes experiencing Zn stress. Modified Hoagland’s solution was employed as the nutrient medium and the experiment was maintained for 60 days from sowing. The genotypes were categorized as efficient (Norungan, ASD 16, Pokkali, Pusa Vikas, TRY 1, and Triveni), moderately efficient (White Ponni, CO 47, ADT 36, IR 8, ASD 20, and TRY 2), and inefficient (ADT 38, PMK 3, CO 43, CSR 10, ADTRH 1, and MDU 5) to Zn stress based on the preliminary solution culture experiment (Sudhalakshmi 2007). Growth performance, dry-matter production, biochemical constituents, and enzymatic activity of rice were measured employing graded levels of Zn (at 0, 0.025, 0.05, 0.1, and 0.2 mg L^?1) and were statistically analyzed using the method of Panse and Sukhatme (1978). The efficient rice genotypes showed minimum reduction in dry-matter production in Zn stress conditions while the inefficient rice genotypes suffered severe reduction. Zinc-efficient rice genotypes were not responsive to fertilizer. Dry-matter production, chlorophyll a, chlorophyll b, total chlorophyll, soluble protein, and indole-3-acetic acid (IAA) oxidase activity can be employed as diagnostic tools to differentiate Zn-efficient and Zn-inefficient rice genotypes in sand culture.     

Application of Biochar and Compost for Enhancement of Rice (Oryza Sativa L.) Grain Yield in Calcareous Sandy Soil

The application of compost to calcareous soils by farmers is a well-established practice and has been shown to improve yields. However, incorporation of biochar and mixture of biochar and compost into calcareous soils is a relatively novel concept for improving soil quality and yield since calcareous soils comprise a large scale of soils worldwide. The objective of this study was to determine the effects of the co-application of biochar and compost on the soil properties, nutrient status and grain yield of rice in calcareous sandy soil. The experiment was conducted in a factorial arrangement based on randomized complete block design with three replications. The compost application rates were 1% and 3% (w/w; compost/soil) and the applied rates of biochars (rice straw biochar, RSB; sugarcane bagasse biochar, SBB) were 0.3% and 0.9% (w/w; biochar/soil). The results showed that soil pH decreased with increasing application rates of either compost or biochars. However, soil EC was enhanced through increasing the application rates of compost and biochars. The co-application of biochar and compost improved soil total N and available P concentrations. The soil available K increased with increasing the rate of incorporated biochars and compost. An increase of soil available K was more predominate with the application of RSB than SBB. The RSB, also, added a considerable amount of silicon (Si) to the soil. The co-incorporation of biochars and compost enhanced soil available concentrations of Fe, Zn, Cu, and Mn as well. The RSB was more effective than the SBB in grain yield enhancement almost certainly due to a higher Si content in RSB. Furthermore, the concurrent application of biochars and compost increased grain yield more than applying them individually. A higher application rate of biochar and compost induced a higher grain yield. The co-application of highest rates of RSB (0.9%) and compost (3%) induced the highest grain yield (26.1 g/pot) among the treatments. The increase in yield compare to the control were 321% and 260% for 0.9% RSB + 3% compost and 0.9% SBB + 3% compost, respectively. The increase in the grain yield was due to an improvement in the soil chemical properties and nutrients enhancement. Finally, the co-application of the highest rate of RSB (0.9%) and compost (3%) is recommended to obtain the appropriate rate of rice grain yield in calcareous sandy soil.     

Biochar and crop residue application to soil: effect on soil biochemical properties,nutrient availability and yield of rice (Oryza sativa L.) and wheat (Triticum aestivum L.)

In the recent past, biochar and crop residues have attracted lots of attention as a viable strategy for maintaining soil health. This paper evaluates the comparative effect of two different doses (equivalent to 2 and 5 t C ha^?1) of each of pine needle and Lantana biochar (PBC and LBC), wheat residue and lentil residue (WR and LR) on soil biological properties, nutrient availability and yield of rice and wheat in pot culture. Energy-dispersive X-ray spectroscopy (EDS) revealed higher C content of biochar than crop residues. Evaluation of biochemical quality reflected high recalcitrance indices of C and N for both PBC and LBC. Application of LBC and PBC increased the wheat grain yield significantly by 6.2%–24.2% over control. Both PBC and LBC significantly increased N and P uptakes in grain over the control and crop residues. Both biochars recorded a significant decrease of 33.9 and 71,7% in β-glucosidase activity in comparison to control at termination of study. PBC and LBC also resulted in more soil available N, P and K in soil at different intervals. The geometric mean of enzyme activities (GMea) reflected improved soil quality by PBC and LR and reduction by LBC application.     

Impacts of Calcium Silicate Slag on the Availability of Silicon and Trace Contaminants in Rice (Oryza Sativa L.)

Calcium silicate slag from the phosphorus fertilizer industry has the potential to be used as a liming agent or for silicon (Si) fertilization in rice production, but it contains trace elements that may contaminate rice grain and straw. A greenhouse study was performed to evaluate the bioavailability of Si and trace elements from slag (0, 1000, 2000, and 4000 mg kg^?1) surface-applied or incorporated to a mineral soil and an organic soil. Slag application increased Si availability and rice grain yield relative to the control. Trace element and radioactivity in soil and rice grain were not significantly affected by slag supplementation. The applied slag showed minimal influence on plant available cadmium (Cd), chromium (Cr), or lead (Pb); however, copper (Cu) and zinc (Zn) in the organic soil increased, whereas Ni in the mineral soil decreased. Results indicate that the evaluated slag may be used as a Si fertilizer or liming amendment for rice with minimal environmental risks.     

Selenium Speciation and Distribution Characteristics in the Rhizosphere Soil of Rice (Oryza sativa L.) Seedlings

A five-step sequential extraction procedure was used for the fractionation of selenium (Se) in rhizosphere and nonrhizosphere soils with rice (Oryza sativa L.) seedlings. Results showed that in rhizosphere soils without the addition of Se, the soluble Se (Sol-Se), exchangeable Se and Se bound to carbonates (Exc-Se), Se bound to organic-sulfide matter and elemental Se (OM-Se), and total Se contents were significantly greater than those in nonrhizosphere soils, whereas the residual Se (Res-Se) was less than that in the nonrhizosphere soils. After the addition of Se, the Sol-Se and OM-Se contents in the rhizosphere soils were still evidently greater than those in nonrhizosphere soils, but the Exc-Se was significantly less in rhizosphere soils than in nonrhizosphere soils. Our overall results suggest that the Se bioavailability in rice rhizosphere soils is greater than that in nonrhizosphere soils. Selenium bioavailability in the rhizosphere soil is not correlated with Se accumulation in rice seedlings.     

化肥减量配合紫云英还田对双季稻产量及氮肥利用率的影响

旨在明确化肥减量条件下不同紫云英还田量对亚热带双季稻区早、晚稻产量及氮肥利用率的影响。以双季稻种植模式为研究对象,设置2个不同的减肥量处理配施不同的紫云英还田量,观察紫云英连续还田下不同处理对双季稻产量和养分利用率的影响。结果表明:与常规施肥处理(100%F)相比,20%减肥量各处理的早稻产量均得到显著提高,增产幅度为5.0%～13.2%;40%减肥量条件下,配施15 000～22 500 kg/hm~2紫云英早稻产量不减产,而配施30 000～37 500 kg/hm~2紫云英后早稻产量有显著提高,增产幅度为5.4%～8.5%。各减肥配施紫云英处理的晚稻产量均随紫云英还田量的增加而升高(P0.05)。各减肥配施紫云英处理早稻化学氮肥的农学利用率、偏生产力及回收率均较常规施肥处理显著提高,但晚稻的氮肥利用率无显著差异。将紫云英还田输入的氮纳入总氮素投入后,早稻总氮素的农学利用率和回收率均随紫云英还田量的增加而降低;与100%F相比,各减肥配施紫云英处理的农学利用率未显著降低,但紫云英还田量达到37 500 kg/hm~2及以上时会导致早稻的氮素回收率显著降低。各紫云英还田处理土壤全氮含量均高于100%F(P0.05),且土壤速效氮含量均显著高于100%F处理(P0.05)。亚热带双季稻种植模式下,长期紫云英还田配合减量施肥对早、晚稻产量和氮肥利用率均产生正面效应,且能提高土壤有机质含量和全氮含量,土壤速效氮含量显著高于常规施肥处理。因此,适量紫云英还田配施化肥除可减少化肥用量外,也是亚热带双季稻区兼顾提升稻米产量和培肥土壤的有效技术。本试验条件下,化肥减量40%配合22 500～30 000 kg/hm~2紫云英的配比综合效果较好。     

缓释硼肥种肥用量对红壤油菜生长发育和产量的影响

为明确种肥同播条件下红壤耕地的适宜硼肥用量,在红壤旱地和水田通过开展种肥同播不同硼肥用量试验,本研究设置施硼肥量为0(T1,对照)、4.5(T2)、9.0(T3)、13.5 kg·hm^-2(T4)4个处理,研究其对油菜出苗、生长发育、硼肥吸收利用效果、籽粒产量、品质等的影响。结果表明,红壤耕地增施硼肥,油菜花期可缩短9~20 d,全生育期缩短2~11 d。红壤中有效硼含量严重缺乏,增施硼肥可显著提高油菜生物量和菜籽产量。适宜的硼肥用量可通过增加成株率、单株角果数和每角粒数提高产量。施硼量为9.0 kg·hm^-2时,菜籽产量达最佳水平,为2 131.6 kg·hm^-2,较对照增产336.1%。收获期硼吸收量和各器官中硼含量随施硼量增加而增加,施硼量为13.5 kg·hm^-2时硼吸收量和各器官中硼含量均达到最大值。硼肥利用率随施硼量增加呈降低趋势,土壤基础有效硼含量越低,硼肥贡献率越大,施硼增产效果越好。施硼量为9.0 kg·hm^-2时,菜籽含油量和产油量达最佳水平,与对照相比含油量增加6.7个百分点,产油量达996.4 kg·hm^-2,较对照增加401.5%。综合菜籽产量、含油量、硼肥利用率和产油量等因素,推荐红壤旱地硼肥施用量为9.0 kg·hm^-2,水田可适当增加施用量,但不宜超过13.5 kg·hm^-2。本研究为我省红壤耕地油菜生产硼肥施用和油菜全程机械化生产提供了技术参考和理论依据。     

Conservation tillage and mulching effects on the adaptive capacity of direct-seeded upland rice (Oryza sativa L.) to alleviate weed and moisture stresses in the North Eastern Himalayan Region of India

A field experiment was conducted to study the effects of tillage and mulch on weed growth, soil moisture storage, productivity and profitability of upland rice during 2012–2013 at Lembucherra, India. Tillage treatments included CT-RI: conventional tillage with 100% residue incorporation and NT-RR: no-till with 100% residue retention. Mulches included rice straw (SM), Gliricidia (GM), brown manuring (BM) and none (NM). CT-RI registered the highest total weed density (89–168 weeds m^?2) and biomass (9.6–183 g dry weight m^?2) than those for the NT-RR (75–161 weed m^?2 and 8–155 g dry weight m^?2). In addition, NT-RR stored (122–172 mm) more soil moisture (0–40 cm soil depth) in comparison with that for the CT-RI treatment (110–161 mm) during crop growing season. Tillage treatments did not have the significant effect on yields. NT-RR reduced the cost of cultivation by 31.5% compared with that for the CT-RI. Thus, the net returns under NT-RR were more than those for the CT-RI. The BM recorded the lowest weed biomass and density as compared to that under other mulches. Therefore, cultivation of upland rice using NT along with BM mulching enhanced productivity and profitability of rice cultivation in India.     

不同减量氮肥配施紫云英对田面水氮磷流失及水稻生长的影响

为指导水稻田合理施肥,防治稻田面源污染,试验开展了不同氮肥减施比例对紫云英—水稻轮作体系下稻田田面水氮磷流失的影响研究。2020年在浙江建德开展田间小区试验,设置冬闲(CK)和冬种紫云英(CT)2个处理,并在冬种紫云英基础上设置4个减氮比例,分别为0(CT0),10%(CT1),20%(CT2),30%(CT3),共5个处理,每个处理重复3次。在水稻移栽施肥后开始稻田田面水样品采集(包括施肥2周内的连续采样以及2周后相隔7,14,28天的间隔采样),测定田面水氮磷浓度;于水稻成熟后采集土壤和植物样品,测定土壤理化性状以及水稻生长性状和产量。各处理田面水总氮、可溶性氮、铵态氮以及总磷、可溶性磷均在施肥后第1天达到峰值,总氮在基肥后4天内降幅明显,为最大值的4.2%~9.1%,可溶性磷在施基肥5天内降至最大值的4.7%~13.7%。采样期内,CK处理田面水总氮、可溶性氮、总磷和可溶性磷的平均浓度分别为48.87,36.82,0.82,0.64 mg/L,CT0、CT1、CT2、CT3的总氮平均浓度分别为CK的93.9%,78.1%,79.7%,69.7%;可溶性氮平均浓度分别为CK的95.1%,84.1%,85.7%,73.2%;总磷平均浓度分别为CK的90.9%,76.9%,96.2%,81.3%;可溶性磷平均浓度分别为CK的79.4%,73.8%,87.3%,68.7%。与CK相比,CT2、CT3显著提高土壤有效磷含量,增加幅度分别为61.7%和37.0%。比较冬闲处理,翻压紫云英使水稻株高增高0.7%~3.5%,有效穗数增加7.0%~15.2%,水稻增产0.4%~4.9%。与冬闲处理相比,冬种紫云英配合不同比例氮肥减施均能降低稻田田面水氮磷流失风险,其中以30%氮肥减量效果最好;紫云英配合减氮施肥措施能够提升土壤有效磷、全氮含量和水稻产量,其中均以紫云英配合20%减氮施肥效果最好。综合稻田田面水氮磷流失风险、土壤肥力以及水稻产量,紫云英配合20%减氮施肥是较为适合该地区的种植方式。     

Effects of Ammonium Nitrate and Monosodium Glutamate in Waste Water on the Growth,Antioxidant Activity,and Nitrogen Assimilation of Lettuce (Lactuca sativa L.)

It has been hypothesized that the uptake of organic as opposed to inorganic nitrogen compounds found in wastewater can be properly substituted for plant nutrients. The objective of this study was to compare effects of applying monosodium glutamate wastewater (MGW) and ammonium nitrate (NH₄NO₃) (AN) on nitrogen metabolism and growth of lettuce. The results showed that while NH₄NO₃ (AN), NO₃^-, nitrite content and NR activity increased the protein content of lettuce. Applying MGW with a high concentration of 17 amino acids and macro- and microelements improved the fresh weights of shoot and root as well as the protein content of lettuce. Antioxidant activities were not affected by AN and MGW, and their interaction effects only increased POD after 8 weeks. In conclusion, substituting a portion of the chemical fertilizers with MGW improved lettuce growth, but did not increase NO₃^- accumulation in leaves.     

转Bt-cry1Ab玉米花粉对意大利蜜蜂生长发育及体内酶活性的影响

自10年前首次种植转基因植物以来,转基因作物已在全球得到大面积推广。这些转基因作物中绝大多数品种具有抗虫基因能够增强作物对靶标昆虫的抗性。同时转抗虫基因植物可能带来的生态安全和环境问题也引起了国际社会广泛的关注。鉴于此,本实验开展了转Bt-cry1Ab基因抗虫玉米花粉