Effect of Nitrogen Fertilizer Forms on Growth,Photosynthesis, and Yield of Rice Under Cadmium Stress

ABSTRACT

A pot experiment was conducted to study the influence of four nitrogen (N) fertilizer forms [Urea; calcium nitrate, Ca(NO₃)₂; ammonium sulfate, (NH₄)₂SO₄; and organic N] on growth, photosynthesis, and yield of rice under two cadmium (Cd) levels (0 and 100 mg Cd kg^?1 soil). Cadmium addition significantly reduced photosynthetic rate, and the reduction varied with N fertilizer form, with ammonium (NH₄ ⁺)-N and urea treated plants having more reduction. Nitrogen form had a distinct effect on SPAD value, and the effect was also dependent on Cd level and growth stage. Cadmium-stress significantly reduced flag leaf area, but for the second leaf, only the plants supplied with organic N showed the reduction. There was a significant difference in plant height among four N forms, with NH₄ ⁺- and nitrate (NO₃ ^?)-treated plants having the highest and lowest height, respectively. Cadmium stress caused significant reduction in grains per panicle and total plant weight, and the reduction varied with N form, with organic N treatment showing more reduction. There were significant differences among N forms in N and Cd concentrations of the plants subjected to Cd stress, with NH₄ ⁺-N treated plants having highest N and lowest Cd concentrations and NO₃ ^?-treated plants having lowest N and highest Cd uptake. The results showed that the inhibition of Cd stress on growth and yield formation of rice is closely related to N fertilizer form.     

Effect of calcium sprays,time of harvest,cold storage,and ripeness on fruit quality of ‘anjou’ pears 1

Calcium chloride (CaCl₂), increased Ca concentrations in fruit cortex and peel of ‘Anjou’ pears (Pyrus communis L.). Calcium sprays reduced the fruit disorders: brown core, cork spot and superficial scald. Fruit size (weight) increased while fruit Ca concentrations decreased with fruit at the later harvest dates. The earliest harvest date was associated with a lower incidence of fruit disorders. Superficial scald increased in fruit held longer in cold storage and in ripened fruit. Shelf‐life and fruit quality of Ca‐sprayed fruit was improved due to higher Ca concentrations in fruit peel and cortex resulting in overall enhancement of fruit appearance, and in improvement in the control of the incidences of cork spot, scald, brown core, and external and internal rots, and in amelioration of fruit juiciness and fruit color.     

Agronomical Performance of Upland Rice Cultivars Inoculated with Azospirillum brasilense Depends on the Plant Genotype

Plant growth–promoting bacteria may play an important role on rice development; however, its interaction with different genotypes is still uncertain. This work aimed to assess the effect of inoculation of Azospirillum brasilense AbV5 strain on the agronomical performance of different rice cultivars under field conditions during two consecutive years and to determine the response of rice cultivars to indole-acetic acid (IAA) rates under in vitro conditions using for both conditions a randomized block design. Field experiments evaluated the productivity components and grain yield of inoculated and noninoculated cultivars and in vitro assays monitored the plantlet growth under different IAA rates. Field experiments showed that the general average grain yield of rice cultivars inoculated with A. brasilense AbV5 strain was significantly greater. Fifty percent of the evaluated cultivars had statistically significant increase in yield varying from 40 to 108 percent upon inoculation with A. brasilense AbV5 strain, while 35 percent showed no significant change in yield (?6 to ?28 percent). In vitro assays showed rate- and cultivar-dependent responses of upland rice to exogenous IAA. These results show a cultivar-dependent response of rice to inoculation with A. brasilense AbV5 strain, which can be related with IAA production by AbV5 strain.     

Growth,Nutritional, and Yield Parameters of Wetland Rice as Influenced by Microbial Consortia Under Controlled Conditions

A pot culture experiment was undertaken under controlled conditions in the National Phytotron Facility to investigate the interactive effect of microbial inoculants—blue-green algae (BGA), Azospirillum, phosphate-solubilizing bacterium (PSB) Pseudomonas striata, vesicular-arbuscular mycorrhizal fungus (VAMF), and Azolla, individually and in combination with chemical fertilizers and/rock phosphate on the wetland rice (Oryza sativa L.) cultivar ‘PNR 381’. The microbial inoculants—BGA, PSB, VAMF, and Azospirillum—positively interacted with one another, resulting in significant improvement in yield and nutritional parameters. Application of biofertilizers also substantially improved soil (peat) fertility status by increasing the nitrogen (N), phosphorous (P), and organic carbon content. The biofertilizer combination BGA + PSB + VAMF + Azospirillum was best for improved growth and yield traits, nutritional status of rice, and sustained soil (peat) fertility. Azolla, which is a highly competitive organism, suppressed the growth of the other four inoculants. The inclusion of VAMF and PSB was observed to significantly improve the zinc nutrition of the paddy and the P utilization of the applied rock phosphate. A basal dose of nitrogenous fertilizer was essential for deriving maximum benefits from applied inoculants, thereby underlying the supplementary/complementary role of biofertilizers in efficient nutrient management in agriculture.     

水稻栽后植株氮素积累特征及其与根系生长的关系

以冈优22、Ⅱ优162和K优047为材料,通过大田试验研究了不同种植方式下水稻秧苗栽后根系和地上部氮素积累的动态特征及其与根重的关系。结果表明,栽后40.d内,地上部及根系氮素积累量呈指数模型增加。茎鞘、发根节和叶片氮含量与根重呈极显著正相关;根系氮含量与根重呈显著负相关;各器官氮积累动态与根重均呈极显著的正相关关系。全生育期植株氮积累量拟合Logistic曲线较好,决定系数在0.988以上,氮素积累量与根重呈显著的正相关关系,生育期越靠前,相关系数值越大。3种种植方式中,自移栽至孕穗期氮积累量以常耕插秧最高,常耕抛秧其次,免耕高留茬抛秧较低;孕穗后免耕高留茬抛秧各器官氮含量最高,氮积累量也逐渐超过常耕抛秧。3个杂交稻组合中,前期以冈优22的氮积累量最高,后期Ⅱ优162增加速率较快,K优047在整个生育期中均最低。     

Dry Matter and Yield of Lowland Rice Genotypes as Influence by Nitrogen Fertilization

ABSTRACT

Rice is a staple food for more than 50% of the world's population and nitrogen (N) is one of the most yield limiting nutrients in lowland rice ecosystems. A field experiment was conducted for two consecutive years to evaluate dry matter production and grain yield of 12 lowland rice genotypes (BRS Jaçanã, CNAi 8860, BRS Fronteira, CNAi 8879, CNAi 8880, CNAi 8886, CNAi 8885, CNAi 8569, BRSGO Guará, BRS Alvorada, BRS Jaburu, and BRS Biguá) at five N rates (0, 50, 100, 150, and 200 kg ha^{? 1}). Genotypes showed significant variation in grain yield and shoot dry weight. Genotype BRSGO Guará was highest yielding, whereas genotype BRS Jaburu was lowest yielding and the remaining genotypes were intermediate in grain yielding potential. Grain yield and shoot dry weight were having significant quadratic increase with increasing N rates in the range of 0 to 200 kg ha^{? 1}. However, 90% of the maximum yield is often considered as an economical rate, which was 120 kg for shoot dry weight and 136 kg N ha^{? 1} for grain yield. Shoot dry matter was having significant positive quadratic association with grain yield across 12 genotypes.     

Sulfur Alleviates Growth Inhibition and Oxidative Stress Caused by Cadmium Toxicity in Rice

A hydroponic experiment was conducted to investigate the effect of sulfur (S) on growth inhibition and oxidative stress caused by Cd²⁺ toxicity, using two rice cultivars with different grain Cd²⁺ content. Treatments consisted of factorial arrangement of three S levels (0.2, 0.4, and 0.8 mmol), two cadmium (Cd) levels (0 and 1 μ mol), and two rice cultivars (‘Bing 97252,’ a cultivar with low grain Cd²⁺ content, and ‘Xiushui 63,’ a cultivar with high grain Cd²⁺ content). The results showed that Cd²⁺ addition in the medium generally increased Cd²⁺ and malondialdehyde (MDA) content in both roots and shoots; the increases were more pronounced in ‘Xuishui 63’ than in ‘Bing 97252.’ Dramatic reductions in growth parameters, including plant height, root and shoot weight, tillers per plant, chlorophyll content, and net photosynthetic rate were found in the plants exposed to Cd stress relative to the plants without Cd²⁺ treatment. ‘Xiushui 63’ showed more sensitivity than ‘Bing 97252’ under Cd²⁺ exposure. In comparison with the lower S level (0.2 mmol), the higher S levels (0.4 and 0.6 mmol) helped alleviate Cd toxicity, characterized by a significant increase in growth parameters, and a decrease in Cd²⁺ and MDA content in both roots and shoots. In addition, superoxide dismutase (SOD) activity in the plants varied among tissues, cultivars, and Cd treatments. High Cd²⁺ and MDA content was consistently accompanied by higher SOD activity, and higher S levels caused a marked increase in glutathione content and a reduction in SOD activity, indicating a positive effect of S in alleviating oxidative stress.     

Manganese foliar supplementation impacts rice yield in tropical lowlands

Abstract

The aim of this work was to evaluate manganese (Mn) sources and levels effects in irrigated rice production in central Brasil (tropical lowlands of Tocantins state). The experiment was conducted in a 5x5?+?1 factorial scheme, five Mn sources and five levels (0.5; 1.0; 1.5; 2.0; and 2.5?kg ha^?1), applied in induction of tillering of rice plants, plus a control without treatment, and Mn content in leaves (mg kg^?1), number of panicles per area (m²), hundred grains weight (g), intact grains (%), and grain yield (kg ha^?1) were analyzed. Treatments with Mn-carbonate source got the best results and this source at the level of 1.5?kg ha^?1 provided the highest yield: 7,375?kg ha^?1. Higher values were obtained with the application of 1.0 to 1.5?kg ha^?1 of Mn, except for the intact grains where the best means were obtained at 2.5?kg ha^?1.     

UPLAND RICE GENOTYPES EVALUATION FOR PHOSPHORUS USE EFFICIENCY

Phosphorus (P) deficiency is one of the most yield limiting factors in crop production in Brazilian Oxisols. A greenhouse experiment was conducted to evaluate 20 upland rice genotypes at low (25 mg P kg^?1) and high (200 mg P kg^?1) P levels applied to a Brazilian Oxisol. Grain yield and yield components were significantly influenced by P level and genotype treatments. There was a significant interaction between P level and genotype treatments in relation to grain yield, indicating genotypes responded differently under two P levels. Based on grain yield efficiency index (GYEI), genotypes were classified into efficient, moderately efficient and inefficient groups. The efficient genotypes in utilizing P were ‘BRA052053’, ‘BRS Primavera’, ‘BRA052015’, ‘BRA052023’, ‘BRA01506’, ‘BRA052045’, ‘BRA032033’, ‘BRA01596’ and ‘BRA052034’. Remaining genotypes were classified as moderately efficient in P use efficiency. None of the genotypes were fall into inefficient group. Grain yield was significantly and positively related with shoot dry weight, panicle number, grain harvest index, 1000-grain weight and had a negative and significant correlation with spikelet sterility. Grain weight was having maximum contribution in total rice plant weight comparing to root and shoot, indicating improvement in harvest index of modern Brazilian upland rice cultivars by breeding.     

Distinctive expression of a zinc-binding protein in rice callus grown in medium with high zinc concentration

We investigated the growth, contents of water-soluble protein and free amino acids of the callus of japonica rice (Oryza sativa L. cv. Nipponbare) cultured in liquid N6 medium containing a high concentration of zinc. Furthermore, we determined the N-terminal amino acid sequence of a Zn-binding protein expressed in large quantities in the callus. The addition of Zn stimulated the growth of the callus and increased the Zn concentration. The callus subjected to the high-Zn treatment (hereafter referred to as CHZn) contained a larger amount of soluble proteins and a smaller amount of free amino acids than the control callus. Zinc-binding proteins were separated by affinity chromatography. The SDS-PAGE pattern of these proteins showed a distinctive protein band of about 29 kDa. Especially, CHZn contained larger quantities of 29 kDa protein than the control callus. Twenty-seven N-terminal amino acids of the protein were sequenced as DYAPMTLTIVNNCPYPVWPGIQANSGH. Results of homology search to the amino acid sequences from the nr-aa database and the dbEST database suggested that this 29 kDa protein may be a novel zinc-binding protein and that the protein may regulate the concentration of free zinc in the cytoplasm of callus cells through its binding to zinc ions.     

锌铬复合污染对水稻不同生育期土壤酶活性的影响

通过盆栽试验,研究了锌铬复合污染对水稻(Oryza sativaL.)不同生育期土壤酶活性的影响。结果表明,锌铬复合污染对水稻生长有抑制作用,随土壤中锌铬浓度的增加,不同生育期水稻生物量均呈下降的趋势,而根冠比呈一定的升高趋势,差异极显著(P<0.01)。在锌铬污染下,土壤过氧化氢酶活性随土壤中锌铬浓度增大而降低。与对照相比,在水稻分蘖期、孕穗期及灌浆结实期土壤过氧化氢酶活性的最小值分别降低了34.17%、23.02%和4.89%;除在灌浆结实期锌与铬浓度互作间的差异不显著外,其他生育期的锌浓度间、铬浓度间及锌与铬浓度互作间的差异均极显著(P<0.01)。在水稻分蘖期,土壤脲酶活性、转化酶活性随土壤锌铬浓度的增加而降低,但在孕穗期及灌浆结实期则升高,其差异均极显著(P<0.01)。线性回归及偏相关分析表明,在水稻不同生育期,土壤过氧化氢酶活性与土壤中锌、铬浓度均有极显著的线性回归关系,并呈显著或极显著负相关关系,这说明锌铬复合污染对土壤过氧化氢酶活性可能产生协同或加和的抑制效应。土壤脲酶活性在水稻灌浆结实期与土壤中锌浓度有极显著的线性回归关系,偏相关系数为0.7253**;土壤转化酶活性在水稻分蘖期、灌浆结实期与土壤中铬浓度均有极显著的线性回归关系,偏相关系数分别为-0.7426**、0.8056**,这说明锌铬复合污染对土壤脲酶活性及转化酶活性未产生复合效应。     

Field Application Strategies for the Inoculant Biofertilizer Biogro Supplementing Fertilizer Nitrogen Application in Rice Production

Biofertilizer research for rice in Vietnam has focused on the isolation and selection of strains that can fix nitrogen, solubilize inorganic phosphates, stimulate plant growth, and breakdown soil organic matter. This paper assesses the consistent positive effect of BioGro on grain yield and agronomic parameters, including the rates and times for its application, the need for continued inoculation of crops grown in the same site, varietal differences, and nitrogen (N), phosphorus (P), and potassium (K) combinations on the effectiveness of BioGro. The commercial biofertilizer, BioGro, consists of four strains, one formerly considered as nitrogen fixing, Pseudomonas fluorescens, a soil yeast strain, Candida tropicalis is P-solubilizing, and two other bacilli, Bacillus amyloliquefaciens and Bacillus subtilis, potentially breaking down cellulose, protein, and starch. All four strains contribute to plant growth promoting rhizobacteria (PGPR) effect as shown by enhanced root growth. BioGro can be produced in local factories providing there is technical backup in the supply of starter culture and quality control of the final product.     

水稻雄蕊导管发育研究

本文以水稻粤泰保持系为材料，采用ATPase定位方法研究了单核至三核花粉期雄蕊导管的发育。单核边位花粉期，分化的导管胞质变浓厚、细胞核染色质浓缩、核转变为新月形并出现凋亡小体；此外，导管内物质也可以大分子形式直接撤离。单核边位晚期，雄蕊导管发育成熟。在二核和三核花粉期，导管内重新出现具有ATPase活性的物质，同样的现象也存在于农垦58s可育花药成熟导管中。以上结果暗示水稻雄蕊导管分化存在程序性死亡及非程序性死亡多种途径，水稻成熟导管内具有ATPase活性物质可能是一种普遍现象。