Phosphorus Use Efficiency in Upland Rice Genotypes Under Field Conditions

Phosphorus (P) deficiency is one of the most yield limiting factors for crop production in South American soils. Upland rice (Oryza sativa L.) is an important crop in South American cropping systems, including Brazil. A field experiment was conducted with the objective to evaluate 20 upland rice genotypes for phosphorus (P) use efficiency. The P rate used was low (0 kg P ha^?1) and high [87 kg P ha^?1 or 200 kg phosphorus pentoxide (P₂O₅) ha^?1]. Plant height, shoot dry weight, grain yield, panicle number, 1000 grain weight, spikelet sterility, and grain harvest index were significantly influenced by P and genotype treatments. The P X genotype interaction was significant for grain yield, indicating that genotypes responded differently under two P rates. Overall, grain yield increased by 12% with the addition of P fertilization. Based on grain yield efficiency index, genotypes were classified into efficient, moderately efficient, and inefficient group. The genotypes that were classified as efficient in P use were BRA032048, BRA042094, BRA02601, BRA032051, BRA032033, BRA052015, BRA042156, BRA01600, BRA01506, BRA052023 and BRA042160. The inefficient genotypes in P us efficiency were BRS Primavera, BRA052045, BRA01596, and BRS Sertaneja. Grain harvest index had a significant positive association with grain yield and spikelet sterility had a significant negative association with grain yield, as expected. Average, P-use efficiency of five genotypes was about 17 kg kg^?1 (kg grain yield per kg P applied).     

Nitrogen-Use Efficiency in Lowland Rice Genotypes under Field Conditions

Rice is staple food for more than 50% of the world's population. Nitrogen (N) is one of the most yield-limiting nutrients for lowland rice production around the world. Two field experiments were conducted at two locations for two consecutive years to evaluate N-use efficiency of 12 lowland rice genotypes. Growth, grain yield, and yield components were significantly influenced by N as well as genotype treatments. Location?×?year?×?genotype and location?×?year?×?N interactions were significant for most of the growth, yield, and yield components, indicating influence of these factors on yield and yield components. Overall, the most N-efficient genotypes measured in terms of grain yield were BRA 031032, BRA 031044, and BRA 02654 and the most inefficient genotypes were BRS Jaçana, BRS Fronteira, and BRA 02674. Genotypes had linear and quadratic responses to added N in the range of 0 to 200 kg ha^?1. Nitrogen significantly influenced plant height, shoot dry weight, panicle number, and 1000-grain weights. Nitrogen-use efficiency (kg grain per kg N applied) varied from 33 to 49 kg grain per kg N applied, with an average value of 40 kg grain per kg N applied. The genotype BRA 031044 produced the greatest N-use efficiency, and the lowest N-use efficient genotype was BRS Fronteira. There was a significant linear association between N-use efficiency and grain yield.     

Lowland Rice Genotypes Evaluation for Potassium-Use Efficiency

Lowland rice significantly contributes to world as well as Brazilian rice production and information on genotypes potassium-use efficiency is limited. A greenhouse experiment was conducted with the objective to evaluate lowland rice genotypes for potassium (K)–use efficiency. Ten genotypes were evaluated at 0 mg K kg^?1 (low) and 200 mg K kg^?1 (high) of soil. Grain yield and shoot dry weight were significantly affected by K as well as genotype treatments. Genotypes CNAi 8860, CNAi 8859, BRS Fronteira, and BRS Alvorada were the best in relation to K-use efficiency because they produced best grain yield at low as well as at higher K levels. Shoot dry weight, number of panicles per pot, and 1000-grain weight had highly significant (P < 0.01) association with grain yield. Spikelet sterility, however, had significant negative association with grain yield. These plant parameters were mainly influenced by genotypes, indicating importance of selecting appropriate genetic material for improving grain yield. Soil K depletion was significant at harvest, suggesting large amount of K uptake by lowland rice genotypes.     

Potassium-Use Efficiency in Upland Rice Genotypes

Potassium (K) uptake is greatest among essential nutrients for rice. Data related to yield, yield components, and K-use efficiency by upland rice genotypes are limited. A greenhouse experiment was conducted to evaluate influence of K on growth, yield and yield components, and K-use efficiency by upland rice genotypes. Potassium levels applied to an Oxisol were zero (natural K level) and 200 mg K kg¹ of soil and 20 upland rice genotypes were evaluated. Plant height, shoot dry weight, grain yield, 1000-grain weight, and spikelet sterility were significantly affected by K and genotype treatments. Genotypes Primavera and BRA 1600 were the most efficient and genotype BRAMG Curinga was most inefficient in producing grain yield. Plant growth (plant height and shoot dry weight) and yield components (panicle number, grain harvest index, 1000-grain weight, and panicle length) were significantly and positively associated with grain yield. However, spikelet sterility was significantly and negatively correlated with grain yield.     

Nitrogen Uptake and Its Association with Grain Yield in Lowland Rice Genotypes

ABSTRACT

Nitrogen is one of the most yield–limiting nutrients in lowland rice in Brazil. A field experiment was conducted for two consecutive years to evaluate nitrogen (N) uptake by five lowland rice genotypes and its association with grain yield. The nitrogen rate used was 0, 50, 100, 150, and 200 kg ha^?1. The genotypes evaluated were CNAi 8886, CNAi 8569, BRSGO Guará, BRS Jaburu, and BRS Biguá. Grain yield and dry matter yield of shoot were significantly influenced by N rate. However, response varied from genotypes to genotypes. Genotype BRSGO Guará, BRS Bigua, and BRS Jaburu were having linear response, whereas genotypes CNAi 8886 and CNAi 8569 were having quadratic response with the N application rate in the range of 0 to 200 kg ha^?1. Overall, genotypes BRSGO Guará and CNAi 8886 were the best because they produced higher yield at low as well as at higher N rates. Nitrogen uptake in shoot was having quadratic relationship with grain yield, whereas nitrogen uptake in the grain was linearly associated with grain yield.     

Yield and Yield Components and Phosphorus Use Efficiency of Lowland Rice Genotypes

Phosphorus deficiency is main constraints for lowland rice production in various rice producing regions of the world. A greenhouse experiment was conducted using lowland (Inceptisol) soil with the objective to determine response of seven lowland rice (Oryza sativa L.) genotypes to phosphorus fertilization and to evaluate their phosphorus (P) use efficiency. Phosphorus treatments included control (0 mg P kg^?1) and 200 mg P kg^?1 of soil. Plant height and shoot dry weight were significantly (P < 0.001) influenced by P treatments. Phosphorus X genotypes interaction was significant for shoot dry weight, indicating different response of genotypes under two P levels. At low P level, none of the genotypes produced grain yield, indicating original P level in the soil was too low for lowland rice yield. However, genotypes differed significantly in grain yield at high P level. Panicle number, panicle length, and thousand grains weight had a significant quadratic association with grain yield. However, spikelet sterility had a significant linear negative association with grain yield. The P use efficiency expressed as agronomic efficiency (AE), physiological efficiency (PE), agro-physiological efficiency (AP), apparent recovery efficiency (ARE), and utilization (UE) were significantly different among genotypes. These efficiencies were having significantly positive association with grain yield, with exception to ARE, indicating improving grain yield with improved P use efficiencies in rice.     

Potassium Soil Test Calibration for Lowland Rice on an Inceptisol

Potassium (K) plays an important role in many physiological and biochemical processes in plants and its adequate use is an important issue for sustainable economic crop production. Soil test–based K fertilizer recommendations are very limited for lowland rice (Oryza sativa L.) grown on Inceptisols. The objective of this study was to calibrate K soil testing for the response of lowland rice (cv. Ipagri 109) to added K. A field experiment was conducted in the farmers' field in the municipality of Lagoa da Confusão, State of Tocantins, central Brazil. The K rates used were 0, 125, 250, 375, 500, and 625 kg K ha^?1 applied as broadcast and incorporated during sowing of the first rice crop. Rice responded significantly to K fertilization during 2 years of experimentation. Maximum grain yield of about 6,000 kg ha^?1 was obtained with 57 mg K kg^?1 soil in the first year and with 30 mg K kg^?1 in the second year. This indicated that at low levels of K in the soil, nonexchangeable K was available for plant growth. Potassium use efficiency designated as agronomic efficiency (kg grain produced/kg K applied) decreased significantly in a quadratic fashion with increasing K level in the soil. Agronomic efficiency had a significantly linear association with grain yield. Hence, improving agronomic efficiency with management practices can improve rice yield.     

Comparative Efficiency of Nitrogen Sources for Lowland Rice Production

Rice (Oryza sativa L.) is the staple food for more than 50% world population and nitrogen (N) is one of the most yield-limiting nutrients for rice production worldwide. A greenhouse experiment was conducted to evaluate the efficiency of three N sources for lowland rice production. The N sources used were ammonium sulfate, common urea, and polymer-coated urea. There were three N rates, i.e. 100, 200, and 400 mg N kg^?1 applied with three sources plus one control treatment (0 mg N kg^?1). Growth, yield, and yield components were significantly increased either in a linear or quadratic fashion with the addition of N fertilizers in the range of 0–400 mg kg^?1 soil. Maximum grain yield was obtained with the addition of ammonium sulfate at 100, 200, and 400 mg kg^?1 of soil. Common urea and polymer-coated urea were more or less similar in grain production at 100 and 200 mg N kg^?1. However, at 400 mg N kg^?1 treatments, polymer-coated urea produced the lowest grain yield. Most of the growth and yield components were positively related to grain yield, except spikelet sterility which was negatively related to grain yield. Nitrogen use efficiency decreased with increasing N rate in all the three N sources. Maximum N use efficiency was obtained with the addition of ammonium sulfate at lower as well as at higher N rates compared with other two N sources.     

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.     

Nitrogen Uptake and Use Efficiency in Upland Rice under Two Nitrogen Sources

Upland rice is an important crop in South America, including Brazil. Nitrogen (N) is one of the most yield-limiting nutrients in upland rice production in Brazil. A greenhouse experiment was conducted to evaluate N uptake and use efficiency as influenced by N sources. The soil used in the experiment was an Oxisol. The N sources were ammonium sulfate and urea, and N rates were 0, 50, 100, 150, 300, and 400 mg kg^?1 of soil. Nitrogen concentrations in the root, shoot, and grain were significantly influenced by N sources. The N rate and N source significantly influenced the N uptake in root, shoot, and grain. Similarly, nitrogen rate by N source interaction was also significant for N uptake in the root, shoot, and grain, indicating N source has a significant influence on uptake of N. Overall, concentration (content per unit dry weight) of N was greater in the grain, followed by root and shoot. Agronomical efficiency, apparent recovery efficiency, and utilization efficiency of N were significantly influenced by N rate and varied with N sources. However, physiological and agrophysiological efficiencies were only influenced significantly by N sources. Overall, N recovery efficiency was 33% for ammonium sulfate and 37% for urea. Hence, the large amount of N lost from soil–plant system may be by denitrification or voltilization.     

Response of Upland Rice Genotypes to Nitrogen Fertilization

Nitrogen (N) is one of the most yield-limiting nutrients for upland rice production in Brazilian Oxisol soils. A field experiment was conducted for two consecutive years at the National Rice and Bean Research Centers Experimental Station Capivara with the objective to evaluate 10 promising genotypes of upland rice for N-use efficiency. The N rates used were 0 kg ha^?1 (low) and 100 kg ha^?1 (high). Plant height, shoot dry weight, grain yield, panicle number, and 1000-grain weight were significantly influenced by N and genotype treatments. Nitrogen × genotype interactions were not significant for most of the growth, yield, and yield components, indicating that differences among genotypes were consistent across N rates. Based on grain yield efficiency index (GYEI), genotypes were classified as N efficient or inefficient. Among 10 genotypes, four genotypes were efficient and six were moderately efficient in N use in the first year. In the second year, three genotypes were efficient and seven were moderately efficient in N use. Genotype BRA 052015 was classified as efficient in N use in both the years. Grain harvest index and GYEI had significant linear relationships with grain yield.     

Comparison of Conventional and Polymer Coated Urea as Nitrogen Sources for Lowland Rice Production

Nitrogen (N) is one of the most yield limiting nutrients in lowland rice production. Improving N use efficiency is essential to reduce cost of crop production and environmental pollution. A greenhouse experiment was conducted with the objective to compare conventional and polymer coated urea for lowland rice production. Grain yield, straw yield, panicle density, maximum root length, and root dry weight were significantly increased in a quadratic fashion with the increase of N rate from 0 to 400 mg kg^?1 soil. Nitrogen source X N rate interactions for most of these traits were not significant, indicating that lowland rice responded similarly to change in N rates of two N sources. Based on regression equations, maximum grain yield was obtained with the application of 258 mg N kg^?1 soil and maximum straw yield was obtained with the addition of 309 mg N kg^?1 soil. Nitrogen use efficiency (grain yield per unit of N applied) was maximum for polymer coated urea compared to conventional urea. Root length and root dry weight improved at an adequate N rate, indicating importance of N fertilization in the absorption of water and nutrients and consequently yield. Polymer coated urea had higher soil exchangeable calcium (Ca) and magnesium (Mg), Ca saturation, Mg saturation, base saturation, and effective cation exchange capacity compared to conventional urea. There was a highly significant decrease in soil exchangeable potassium (K) with increasing N rates at harvest of rice plants.     

Nitrogen,Phosphorus and Potassium Interactions in Upland Rice

Upland rice is an important crop in South America, including Brazil. Nutrient interactions are important in determining crop yields. A greenhouse experiment was conducted to evaluate interaction among nitrogen (N), phosphorus (P), and potassium (K) in upland rice production. The treatments applied to upland rice grown on an Oxisol were three levels of N (N₀, N₁₅₀ and N₃₀₀ mg kg^?1), three levels of P (P₀, P₁₀₀ and P₂₀₀ mg kg^?1) and three levels of K (K₀, K₁₀₀ and K₂₀₀ mg kg^?1). These treatments were tested in a 3 × 3 × 3 factorial arrangement. Grain yield, shoot dry weight, plant height, root dry weight, maximum root length, panicle number, 1000-grain weight, and grain harvest index were significantly influenced by N, P, and K treatments. The treatment that did not receive P fertilization did not produce panicle or grain. Hence, P was most yield-limiting nutrient compared to two other nutrients. At the N₀P₀K₀ treatment, rice did not produce grains, indicating severe deficiency of these nutrients in Brazilian Oxisols. Maximum grain yield was obtained with the N₃₀₀P₂₀₀K₂₀₀ treatment. Grain yield had significant positive association with plant height, shoot dry weight, root dry weight, maximum root length, 1000-grain weight, panicle number, and grain harvest index. Among these growth and yield components, shoot dry weight had the highest positive association with grain yield and root length minimum positive association with grain yield. Hence, adopting adequate soil and crop management practices can improve growth and yield components and increase grain yield of upland rice.     

Zinc Nutrition of Lowland Rice

Zinc (Zn) deficiency in rice has been widely reported in many rice-growing regions of the world. A greenhouse experiment was conducted with the objective of determining Zn requirements of lowland rice. Zinc rates used were 0, 5, 10 20, 40, 80, and 120 mg Zn kg^?1 of soil applied to an Inceptisol. Zinc application significantly affected shoot dry weight and grain yield as well as concentrations and uptakes of Zn in soil and plant. Maximum yield of shoot dry weight and grain yield were achieved at 5 and 20 mg Zn kg^?1 of soil, respectively. Zinc concentration and uptake in shoot as well as Zn uptake in grain had significant quadratic increases as Zn concentration increased in the soil solution. Zinc concentration as well as uptake was greater in the shoot as compared with concentration and uptake in the grain. Zinc-use efficiencies significantly decreased with increasing Zn rates in the soil except agrophysiological efficiency, which had significant quadratic increases with increasing Zn rates. On average, about 6% of the applied Zn was recovered by the lowland rice plants. Mehlich 1 extracting solution extracted much more Zn than diethylenetriaminepentaacetic acid (DTPA). However, Mehlich 1 as well as DTPA-extractable Zn had significant positive correlations with each other as well as with Zn uptake in grain and shoot.     

Phosphorus Nutrition of Lowland Rice in Tropical Lowland Soil

Rice is a main food crop for about half of the world's population, and phosphorus (P) is the main limiting nutrient in rice production in tropical lowlands. A greenhouse experiment was conducted to evaluate P requirements of lowland rice grown on a lowland soil (Inceptisol). Dry matter, grain yield, and yield-attributing characteristics were significantly (P < 0.01) influenced by P fertilization. Based on quadratic response, maximum shoot dry weight and grain yield were obtained with the application of 190 mg P kg^?1 of soil. Maximum panicle, tiller number, and plant height were obtained with the application of 177 192, and 175 mg P kg^?1 of soil, respectively. Mehlich 1–extractable P for maximum grain yield was 15.6 mg kg^?1 of soil. Variability in grain yield with plant growth and yield parameters was in the order of tiller > shoot dry weight > panicle number > spikelet sterility > plant height > grain harvest index > panicle length > weight of 1000 grains. Phosphorus uptake in shoot and concentration and uptake in grain significantly (P < 0.01) increased grain yield. However, variability in grain yield was greater with concentration and uptake of P in the grain. Similarly, P harvest index was also significantly associated with grain yield. Agronomic P-use efficiency, apparent P-recovery efficiency, and P-utilization efficiency decreased quadratically with increasing P rates, whereas physiological P-use efficiency increased quadratically and agrophysiological P-use efficiency decreased linearly with increasing P rates. Agrophysiological and utilization P-use efficiencies had significant positive correlation with grain yield.     

不同氮肥施用对双季稻产量及氮肥利用率的影响

通过田间小区试验,研究了不同氮肥处理对双季稻产量及氮肥利用率影响。结果表明:增施氮肥处理比不施氮肥处理双季稻的有效穗数、每穗粒数均显著提高,早稻产量增产77.0%~127.1%,晚稻增加62.9%~108.0%;早稻中等量控释氮肥处理较普通尿素处理水稻单位有效穗数、每穗粒数、农学利用率均增加,同时增产5.0%,氮肥利用率提高18.0个百分点;减量控释氮肥处理与普通尿素处理比有效穗数、每穗粒数、产量、氮肥农学利用率有所下降但氮肥利用率提高18.6~20.2个百分点,晚稻中各控释氮肥处理较普通尿素处理每穗粒数增加、产量增产,增产率为9.7%~27.7%,氮肥利用率提高28~31.1个百分点,且农学利用率显著提高;不同用量控释氮肥处理间早稻有效穗数、产量随氮肥用量增加而增加,晚稻中当施氮水平≤162 kg/hm2(按纯氮算)时,水稻单位有效穗、每穗粒数、结实率、产量随氮肥增加而增加;当施氮水平162 kg/hm2(按纯氮算)时,随施氮量增加而减少。     

缓释氮肥对水稻的增产效果及其氮素利用率

在潜育性粘壤质水稻土上研究了缓释性氮肥对水稻产量和氮肥利用率的影响。结果表明:4种供试缓释氮肥对水稻增产效果和吸氮量的顺序均为:IBDU>OM>U>GUS>CDU>CK;施肥后9d土壤中铵态氮含量最大,依次为:U>OM>IBDU>GUS>CDU>CK;在最大分蘖期前土壤硝态氮含量较多且相对稳定,至孕穗期急剧降低,抽穗至成熟期再度回升;相对于尿素,IBDU和OM能明显提高氮素利用率,分别比尿素的利用率增加了14.62%和8.57%。     

Application of Controlled-Release Urea in Rice: Reducing Environmental Risk While Increasing Grain Yield and Improving Nitrogen Use Efficiency

The low use efficiency of nitrogen (N) in rice production attributes to N losses and environmental pollution. One of the ways to improve N use efficiency is by using controlled-release urea (CRU). Field experiments in consecutive three years were conducted to compare the effects of six different types of CRU fertilizers on yield and N accumulation in straw and grain of rice. The special purpose was to provide information for application of CRU in rice. For three seasons, CRU-treated plants had significantly greater grain yields than conventional urea-treated (total N as basal fertilizers, N_t) plants. The greatest grain yields were obtained from CRU-3, CRU-4, and CRU-3 treatment in 2012, 2013, and 2014, respectively. The N accumulation in rice straws and rice grains of the CRU-treated plots was significantly greater than that of the N_t treatment. Compared with that of the N_t treatment, CRU treatments increased the N use efficiency significantly, although there were differences among the six types of CRU fertilizers. It can be inferred that CRU performed significantly better than conventional urea. Generally, CRU-3 and CRU-6 were the best CRU fertilizers used in rice production in Jianghan Plain, China.     

Agronomic Evaluation of Dry Bean Genotypes for Potassium Use Efficiency

Dry bean is an important legume worldwide, and potassium (K) deficiency is one of the important constraints for bean production in most of the bean growing regions. A greenhouse experiment was conducted with the objective to evaluate fifteen dry bean genotypes grown on a Brazilian lowland (Inceptisol) United States Soil Taxonomy classification and Gley humic Brazilian Soil Classification system), locally known as “Varzea” soil. The K rate used was 0 mg kg^?1 (low, natural soil level) and 200 mg kg^?1 (high, applied as fertilizer). Straw yield, seed yield, pods per plant, seeds per pod, 100 seed weight, and seed harvest index were significantly increased with the addition of K fertilizer. These traits were also significantly influenced by genotypic treatment. Similarly, root length and root dry weight were also influenced significantly by K and genotype treatments. The K X genotype interactions for most of these traits were also significant, indicating variation in these traits with the variation in K level. Based on seed yield efficiency index (SYEI), genotypes were classified as efficient, moderately efficient, and inefficient in K use efficiency. Maximum grain yield was obtained with 74 mg K kg^?1 extracted by Mehlich 1 extracting solution. Similarly, K saturation required for maximum grain yield was 1.1%.     

合理氮肥运筹提高双季机插稻产量及氮肥利用率

为明确双季机插稻合理氮肥运筹,2013—2014年在长江中游双季稻地区(江西上高)研究了氮肥施用量、施用比例及施用时期对双季机插稻产量与氮素吸收利用效率的影响。结果表明,适量施氮可同步增加有效穗数和每穗粒数,从而扩大群体库容量,机插早、晚稻分别在施氮量为180,195kg/hm2时即可达到较高产量,同时保持较高的氮素吸收利用率。在适宜施氮量下,施氮比例及追氮时期对双季机插稻产量及氮素吸收利用具有显著影响,基蘖肥与穗肥比例早稻8∶2至7∶3、晚稻7∶3,移栽后7天+倒2叶抽出期追施氮肥有利于分蘖成穗,中后期维持较高的叶面积指数(LAI)和干物质积累量,粒叶比协调,穗数充足,穗型较大,总颖花量高,并同步提高产量及氮素吸收利用率。