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1.
Phosphorus (P) deficiency is one of the most yield-limiting factors in lowland rice production on Brazilian Inceptisol. The objective of this study was to evaluate eight P sources for lowland rice production. The P sources were simple superphosphate (SSP), polymer-coated simple superphosphate (PSSP), ammoniated simple superphosphate (ASSP), polymer-coated ammoniated simple superphosphate (PASSP), triple superphosphate (TSP), polymer-coated triple superphosphate (PTSP), monoammonium phosphate (MAP), and polymer-coated monoammonium phosphate (PMAP). These P sources were applied in four rates (i.e., 50, 100 200, and 400 mg P kg?1) + one control treatment (0 mg P kg?1). Plant height, straw yield, grain yield, panicle number, and root dry weight were significantly increased in a quadratic fashion with increasing P levels from 0 to 400 mg kg?1 of all the P sources evaluated. However, overall maximum root length and P-use efficiency were significantly less at greater P levels. Based on regression equation, maximum plant height was obtained with 262 mg P kg, maximum straw yield was obtained with 263 mg P kg?1, maximum grain yield was obtained with 273 mg P kg?1, and maximum panicle density was obtained with 273 mg P kg?1. Plant growth and yield components had significant positive association with grain yield, except maximum root length. Based on grain yield and average P rate of maximum grain yield, which is 273 mg kg?1, P sources were classified for P-use efficiency in the order of PSSP = TSP > PTSP > PASSP > SSP > MAP > ASSP. Soil chemical properties [pH; P; potassium (K); calcium (Ca); magnesium (Mg); hydrogen (H) + aluminum (Al); cation exchange capacity (CEC); base saturation; Ca, Mg, and K saturation; acidity saturation; Ca/Mg, Ca/K, and Mg/K ratios] changed significantly with the addition of different P treatments.  相似文献   

2.
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.  相似文献   

3.
Rice is a staple food for about 50 percent of the world’s population. Potassium (K) is absorbed in large amounts by rice plants and adequate amounts of this element are fundamental to improve productivity and maintain sustainability of the cropping systems. A greenhouse experiment was conducted to determine the adequate rate of K for lowland rice grown on a Brazilian Inceptisol. The K rates used were 0, 50, 100, 200, 400, and 600 mg K kg?1 soil. Most of the growth, yield, and yield components were significantly and quadratically increased with increasing K levels. Based on a quadratic equation, maximum grain yield was obtained with the addition of 371 mg K kg?1 soil. Maximum plant height and shoot dry weight were obtained at 414 and 398 mg K kg?1 soil, respectively. Root growth (maximum length and dry weight) was also significantly increased in a quadratic fashion with the increasing K rate in the growth medium. Maximum root length was achieved at 58 mg K kg?1 whereas maximum root dry weight was obtained with the addition of 394 mg K kg?1 soil. Plant height, shoot dry weight, 1000-grain weight, root length, and root dry weight were significantly associated with grain yield. Hence, manipulation of these growth and yield components with the addition of K fertilizer can improve yield of lowland rice in varzea soils of central part of Brazil. Potassium uptake increased significantly in a quadratic fashion with increasing K rate. However, K-use efficiency (mg grain per mg K applied) decreased significantly with increasing K rate in a quadratic fashion. Maximum grain yield was obtained with 117 mg kg?1 Mehlich 1–extractable K, base saturation of 53 percent, Mg saturation of 9 percent, K saturation of 2 percent, and Ca/Mg ratio of 4.  相似文献   

4.
Rice (Oryza sativa L.) is a staple food for more than 50% of the world’s population, and phosphorus (P) is one of the most yield-limiting nutrients for rice production in tropical acidic soils worldwide. A greenhouse experiment was conducted to evaluate efficiency of six P sources for upland rice production. The P sources used were simple superphosphate (SSP), polymer-coated SSP (PSSP), triple superphosphate (TSP), polymer-coated TSP (PTSP), monoammonium phosphate (MAP), and polymer-coated MAP (PMAP). There were four P rates [50, 100 200, and 400 mg phosphorus (P) kg?1] applied with four sources plus one control treatment [0 mg phosphorus (P) kg?1]. Plant height, straw yield, grain yield, panicle density, root dry weight, maximum root length, and 1000-grain weight were significantly increased with increasing P rates in the range of 0 to 400 mg P kg?1. However, P-use efficiency (mg grain produced per mg P applied) was decreased with increasing P rate. Based on regression equation, overall maximum plant height was obtained with the application of 235 mg P kg?1, maximum straw yield with the application of 265 mg P kg?1, and maximum grain yield at 227 mg P kg?1. Based on maximum grain yield, the P source were classified as PMAP > SSP = MAP > PSSP > TSP > PTSP in the upland rice production efficiency. Overall, maximum panicle density was obtained with the addition of 231 mg P kg?1 and maximum 1000-weight was obtained with the addition of 226 mg P kg?1. Similarly, overall root dry weight and maximum root length were achieved with the application of 261 and 298 mg P kg?1 of soil. Most of the growth and yield components had a significant positive association with grain yield. Optimum soil acidity indices such as pH; exchangeable calcium (Ca), magnesium (Mg), and potassium (K); Ca, Mg, and K saturation; base saturation; and acidity saturation were established for maximum upland rice grain yield.  相似文献   

5.
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.  相似文献   

6.
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.  相似文献   

7.
Lowland or flooded rice is mainly responsible for about 76% of total rice production at global level, yet information on micronutrient requirements for this crop is limited. Six greenhouse experiments were conducted at the National Rice and Bean Research Center of EMBRAPA, Santo Antônio de Goiás, Brazil, to determine requirements of zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), manganese (Mn), and iron (Fe) for lowland rice grown on a Brazilian Inceptisol. The levels of micronutrients used were Zn (0, 10 20, 40, and 80 mg kg?1), Cu (0, 5, 10, 20, and 40 mg kg?1), B (0, 5, 10, 20, and 40 mg kg?1), Mo (0, 2, 4, 8, and 16 mg kg?1), Mn (0, 50, 100, 300, and 600 mg kg?1), and Fe (0, 250, 500, 1000, and 2000 mg kg?1). Grain yield was significantly increased in a quadratic fashion with the addition of Zn, Cu, B, Mo, Mn, and Fe. The adequate rates of micronutrients for maximum grain yield were Zn 33 mg kg?1, Cu 25 mg kg?1, B 26 mg kg?1, Mo 10 mg kg?1, Mn 250 mg kg?1, and Fe 1269 mg kg?1. In addition to grain yield, plant height, straw yield, panicle density, and root growth of lowland rice were also improved with the addition of most of these micronutrients. Improvement in root growth has special significance in improving nutrient-use efficiency under nutrient-stress conditions. Micronutrient-use efficiency (grain yield per unit nutrient applied) was in the order of Cu > Zn > Mn > Fe > Mo > B.  相似文献   

8.
Abstract

Use of adequate rates of phosphorus (P) in crop production on high‐P‐fixing acid soils is essential because of high crop response to P fertilization and the high cost of P fertilizers. Information on lowland rice response to thermophosphate fertilization grown on Inceptisols is limited, and data are also lacking for soil‐test‐based P fertilization recommendations for this crop. The objective of this study was to evaluate response of lowland rice to added thermophosphate and to calibrate P soil testing for making P fertilizer recommendations. A field experiment was conducted for two consecutive years in central Brazil on a Haplaquept Inceptisol. The broadcast P rates used were 0, 131, 262, 393, 524, and 655 kg P ha?1, applied as thermophosphate Yoorin. Rice yield and yield components were significantly increased with the application of P fertilizer. Average maximum grain yield was obtained with the application of 509 kg P ha?1. Uptake of macro‐ and micronutrients had significant quadratic responses with increasing P rates. Application of thermophosphate significantly decreased soil acidity and created favorable macro‐ and micronutrient environment for lowland rice growth. Across 2 years, soil‐test levels of Mehlich 1–extractable P were categorized, based on relative grain yield, as very low (0–17 mg P kg?1 soil), low (17–32 mg P kg?1 soil), medium (32–45 mg P kg?1 soil), or high (>45 mg P kg?1 soil). Similarly, soil‐test levels of Bray 1–extractable P across 2 years were very low (0–17 mg P kg?1 soil), low (17–28 mg P kg?1 soil), medium (28–35 mg P kg?1 soil), or high (>35 mg P kg?1 soil). Soil P availability indices for Mehlich 1 extractant were slightly higher at higher P rates. However, both the extracting solutions had highly significant association with grain yield.  相似文献   

9.
Nitrogen (N) deficiency is one of the most yield-limiting nutrients in upland rice growing regions word wide. A greenhouse experiment was conducted with the objective to evaluate nineteen upland rice (Oryza sativa. L.) genotypes for N use efficiency. The soil used in the experiment was an Oxisol and two N levels used were without N application (low level) and an application of 400 mg N kg?1 of soil (high level). Grain yield and yield components and N uptake parameters were significantly affected by N and genotype treatments. Regression analysis showed that plant height, shoot dry weight, number of panicles per pot, number of grains per panicle, grain harvest index, N uptake in shoot and grain were having significant positive relation with grain yield. Nitrogen concentration of 6.4 g kg?1 in the shoot is established as deficient level and 9.5 g kg?1 as sufficient level at harvest. Agronomic efficiency of N (grain yield/unit of N applied) and N utilization efficiency (physiological efficiency X apparent recovery efficiency) were significantly different among genotypes. These two N use efficiencies were having significant quadratic relationship with grain yield. Soil pH, exchangeable soil Ca and base saturation were having significantly positive association with grain yield. However, soil extractable phosphorus (P), potassium (K), hydrogen (H+), aluminum (Al) and cation exchange capacity were having significantly negative association with grain yield.  相似文献   

10.
《Journal of plant nutrition》2013,36(12):2793-2802
ABSTRACT

Phosphorus (P) deficiency is the most yield-limiting factor in lowland rice production in Inceptisols of Brazil. A greenhouse experiment was conducted to evaluate 12 genotypes of lowland rice (Oryza sativa L.) using an Inceptisol (Typic Haplaquepts). The P treatments were: low (0?mg?P?kg?1), medium (100?mg?P?kg?1), and high (400?mg?P?kg?1). Significant (P<0.01) genotypes differences in P-use efficiency were found. On the basis of P-use efficiency, genotypes were classified as efficient and responsive, efficient and non-responsive, non-efficient and responsive, and non-efficient and non-responsive. From a practical point of view, efficient and responsive and efficient and non-responsive genotypes are the most desirable ones. Among the 12 genotypes tested, none were found to be efficient and responsive and genotypes CNA7553, CNA7591, CNA7601, and Aliança were found to be efficient and non-responsive. Among the yield components, panicle length and harvest index were significantly affected by P levels and genotypes and P and genotypes interactions were significant for these two parameters. However, panicle number was significantly influenced only by P treatment. Among the yield components, panicle number, harvest index, and panicle length were significantly (P<0.01) related to grain yield.  相似文献   

11.
Rice is important crop for world population, including Brazil. Nitrogen (N) is one of the most yield limiting nutrients in rice production under all agro-ecological conditions. A greenhouse experiment was conducted to evaluate N responses to 12 lowland rice genotypes. Soil used in the experiment was a Gley humic according to Brazilian soil classification system and Inceptisol according to USA soil taxonomy classification. The N rates used were 0 mg kg?1 (low) and 300 mg kg?1 (high) of soil. Plant height, straw yield, grain yield, panicle density, 1000 grain weight, and root dry weight were significantly increased with the addition of N fertilization. These growth, yield, and yield components were also significantly influenced by genotype treatment. Grain yield had significant linear or quadratic association with shoot dry weight, panicle number and 1000 grain weight Based on grain efficiency index genotypes were classified as efficient, moderately efficient and inefficient in N use. The N efficient genotypes were ‘BRS Tropical’, ‘BRS Jaçanã’, ‘BRA 02654’, ‘BRA 051077’, ‘BRA 051083’, ‘BRA 051108’, ‘BRA 051130’ and ‘BRA 051250’. Remaining genotypes fall into moderately efficient group. None of the genotypes were grouped as inefficient in N use efficiency.  相似文献   

12.
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   

13.
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.  相似文献   

14.
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.  相似文献   

15.
Phosphorus (P) deficiency is one of the most yield limiting factors for dry bean (Phaseolus vulgaris) production in tropical acid soils. Dry beans are invariably grown as mono-crops or as inter-crops under the perennial tropical crops. Information is limited regarding the influence of phosphorus fertilization on dry bean yield and yield components and P use efficiency in tropical acid soils. A greenhouse experiment was conducted to evaluate the influence of phosphorus fertilization on dry bean growth, yield and yield components and P uptake parameters. Phosphorus rates used were 0, 50, 100, 150, 200, and 250 mg P kg?1 of soil. Soil used in the experiment was an acidic Inceptisol. Grain yield, shoot dry weight, number of pods, and 100 grain weight were significantly (P < 0.01) increased with phosphorus fertilization. Maximum grain yield, shoot dry matter, number of pods, and 100 grain weight were obtained with the application of 165, 216, 162, and 160 mg P kg?1 of soil, respectively, as calculated by regression equations. Grain yield was significantly and positively associated with shoot dry weight, number of pods, P concentration in grain and total uptake of P in shoot and grain. Phosphorus use efficiency defined in several ways, decreased with increasing P rates from 50 to 250 mg P kg?1 of soil. Maximum grain yield was obtained at 82 mg kg?1 of Mehlich 1 extractable soil P. Results suggest that dry bean yield in Brazilian Inceptisols could be significantly increased with the use of adequate rates of phosphorus fertilization.  相似文献   

16.
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).  相似文献   

17.
Dry bean is an important legume for human consumption in South America. A greenhouse experiment was conducted to evaluate uptake and use efficiency of macro- and micronutrients by six dry bean genotypes at two P levels (25 and 200 mg kg?1 soil). Shoot dry weight and grain yield varied significantly among genotypes and significantly increased with increasing phosphorus (P) levels. Grain harvest index (GHI) and 100-grain weight also differ significantly among genotypes and significantly increased with the increasing P levels. Based on grain yield efficiency index (GYEI), genotypes were classified as efficient and inefficient. The most efficient genotype was CNFP 10104, and inefficient genotypes were CNFP 10103 and CNFP 10120. Number of pods per plant and number of seeds per pod increased significantly with the addition of 200 mg P kg?1 of soil compared to the low level of P (25 mg P kg?1). Similarly, nitrogen (N), P, calcium (Ca), magnesium (Mg), sulfur (S), zinc (Zn), copper (Cu), and manganese (Mn) concentrations and uptake in the shoot and grain also significantly varied among genotypes. Uptake of macro- and micronutrients was greater under the greater P rate compared to the low P rate. This may be related to greater shoot or grain yield at 200 mg P kg?1 soil compared to 25 mg P kg?1 of soil.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
Dry bean is an important source of protein for the population of South America, and yield of this legume is very low in this continent. Knowledge of nutrient uptake and use efficiency of a crop is fundamental to improve yield. A greenhouse experiment was conducted to evaluate growth, nutrient uptake, and use efficiency of dry bean (Phaseolus vulgaris L., cv. BRS Valente) during the growth cycle. Plant samples were collected at 15, 30, 45, 60, 73, and 94 days after sowing. Root dry weight, maximum root length, shoot dry weight, and number of trifoliates were significantly increased in a quadratic fashion with the advancement of plant age. Root dry weight and number of trifoliates had significant positive association with shoot dry weight. Uptake of nutrients in the grain was in the order of nitrogen (N) > potassium (K) > calcium (Ca) > magnesium (Mg) > phosphorus (P) > iron (Fe) > manganese (Mn) > zinc (Zn) > copper (Cu). Hence, it can be concluded the N requirements for bean is greatest and Cu is minimal compared to other essential nutrients for grain yield. Uptake efficiency for root, shoot, and grain production was in the order of P > Mg > Ca > K > N > Cu > Zn > Mn > Fe. The greatest P-use efficiency among macro- and micronutrients can be considered a positive aspect of mineral nutrition of bean, because recovery efficiency of P in acidic Inceptsols is less than 20%.  相似文献   

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